Model-based interpretation of solute exports and carbon partitioning during shale weathering in a mountainous hillslope - Lucien Stolze; Dipankar Dwivedi; Carl I. Steefel; Sergi Molins; Wenming Dong; Curtis A. Beutler; Alexander W. Newman; K. H. Williams (Water Resources Research, 2026)

Snow microphysical processes in orographic turbulence revealed by cloud radar and in situ snowfall camera observations - A. Kotsche; Maximilian Maahn; V. Ettrichrätz; Heike Kalesse-Los (Atmospheric Chemistry and Physics, 2026)

Depth of nutrient uptake by deep-rooted plants is regulated by water availability - Langlang Li; J. N. Christensen; Markus Bill; Wenming Dong; Yuxin Wu; Curtis A. Beutler; Matthias Sprenger; Brian Gulick; Sharon Bone; Boris Faybishenko; John Sanders; Chunwei Chou; et al. (PNAS, 2026)

Warming winters are disrupting the hidden world of fungi – the result can shift mountain grasslands to scrub - Stephanie N. Kivlin; Aimee T Classen; L.A. Souza (The Conversation, 2026)

An actinopterygian-dominated fish fauna from the Upper Cretaceous Williams Fork Formation, northwestern Colorado, and evidence for provinciality across Laramidia at the Campanian/Maastrichtian boundary - Joel Crothers; Jaelyn Eberle; Donald B. Brinkman; Alyssa Wurtz; Andrew Heckert; ReBecca K. Hunt-Foster; John R. Foster; Ida C. Dirkes; R. R. Dunn (Cretaceous Research, 2026)
The Williams Fork Formation (WFF) of northwestern Colorado preserves an understudied freshwater biota from the Campanian/Maastrichtian boundary. Here we describe a diverse actinopterygian-dominated fish assemblage from the ReBecca’s Hollow locality of Rio Blanco County. Chondrichthyans are rare from this site, but include a hybodontid, Lonchidion , and the hemiscyllid Chiloscyllium . A fragmentary element may represent a pycnodontiform. Chondrosteans are represented by a tentative acipenserid. Holosteans include the lepisosteids Atractosteus and an unnamed taxon, and the amiids Melvius , Cyclurus and Palaeolabrus . Teleosteomorphs at this site include Belonostomus , Paralbula casei , Coriops , Estesesox foxi , Acronichthys , hiodontids, and acanthomorphs. This locality yields at least 17 fish taxa, most of which have not been described previously from the WFF. Although the WFF is temporally correlative with the St. Mary River and Horseshoe Canyon Formations in Alberta and the Prince Creek Formation in Alaska, the ReBecca’s Hollow fish assemblage is markedly different from its northern contemporaries. Specifically, it contains several warm-climate taxa such as Lonchidion , Chiloscyllium , Melvius , Atractosteus , and Paralbula , and lacks higher latitude taxa such as Holostean A, documented from Alberta. The differences in these broadly contemporaneous fish assemblages supports the hypothesis that there was provincialism amongst freshwater fishes in Laramidia at the Campanian/Maastrichtian boundary. The fish fauna thus resembles that of Campanian localities in Utah, New Mexico, and Texas, and Maastrichtian (Lancian) localities in Montana, North Dakota, South Dakota, and Wyoming, suggesting that the boundary between these provincial zones remained north of the WFF locality throughout these periods of climate change. ● ReBecca’s Hollow (RH) (Williams Fork Formation) preserves at least 17 fish taxa ● RH’s fish fauna has key differences from coeval units in AK and AB ● RH’s fauna resembles that of assemblages from the Campanian of UT, NM, and TX ● RH’s fish assemblage also resembles that of the Maastrichtian of MT, ND, SD, and WY ● Laramidian fish were subject to provincialism at the Campanian–Maastrichtian boundary

Wind-driven seed dispersal differentially promotes seed trapping and retention across alpine plants - C. A. Ray; Savannah Troy; E. V. Xie; T. M. Jenkins; G. Belfry; A. Wells; P. de Valpine; B. Blonder (American Journal of Botany, 2026)

The Colorado River: Chasing Water - David J. Robertson (Natural Areas Journal, 2026)

Experimental warming decouples plant-fungal symbiont interactions and leads to a more conservative ecosystem - L.A. Souza; Aimee T Classen; Jennifer A. Rudgers; Charles Miller; J. A. M. Pyle; R. Simberloff; J. Fordyce; J. Harte; Stephanie N. Kivlin (PNAS, 2026)

Increasing aridity may threaten the maintenance of a plant defence polymorphism - L. Carley; T. Mitchell-Olds; William Morris (Ecology Letters, 2025)
It is unclear how environmental change influences standing genetic variation in wild populations. Here, we characterised envi- ronmental conditions that protect versus erode polymorphic chemical defences in Boechera stricta (Brassicaceae), a short-lived perennial wildflower. By manipulating drought and herbivory in a 4-year field experiment, we measured the effects of driver variation on vital rates of genotypes varying in defence chemistry and then assessed interacting driver effects on total fitness (estimated as each genotype's lineage growth rate, λ) using demographic models. Drought and herbivory interacted to shape vital rates, but contrasting defence genotypes had equivalent total fitness in many environments. Defence polymorphism thus may persist under a range of conditions; however, ambient field conditions fall close to the boundary of putatively polymorphic environment space, and increasing aridity may drive populations to monomorphism. Consequently, elevated intensity and/or frequency of drought under climate change may erode genetic variation for defence chemistry in B. stricta.

Is social plasticity good? Does lifetime social variation enhance LRS and longevity in yellow-bellied marmots? - T. Blakely (2025)
Social relationships have important fitness consequences in many taxa. Much of the prior literature on the adaptive value of social relationships has looked for associations between social network position, or social structure, and fitness correlates during a single period of time–often a year. However, individuals often vary in the strength and number of their relationships across their lifetimes. Thus, we asked whether deviations from an individual’s lifetime average social patterns, as measured using a set of social network statistics, were associated with lifetime reproductive success (LRS) and longevity in yellow-bellied marmots (Marmota flaviventer). We expected that increased social plasticity would be positively associated with both LRS and longevity, as deviations from lifetime average social network traits are associated with increased fitness at the annual scale. We used 20 years of data on social connectedness to fit a double hierarchical generalised linear model, which estimated an individual’s lifetime average of six social network traits and the corresponding variance of each. We then fitted generalised linear models to examine how variation in LRS and longevity may be explained by this variation in social traits. We found no significant association between levels of social plasticity and our fitness correlates except in one case. Overall, our data does not seem to indicate an inherent value to social plasticity.

Effects of elevation on salamander life strategies - T. Bulot (2025)
The Arizona Tiger Salamander (Ambystoma mavortium nebulosa) is a keystone species in the Rocky Mountains. Depending on how well they grow as larvae, these salamanders can either metamorphose to have terrestrial traits at maturity or retain their juvenile aquatic traits as adults. We expect that ponds at lower elevations, which are warmer and have longer growing seasons, will support faster growth, resulting in larger paedomorphs. To test this, salamanders will be surveyed at sites ranging from about 8,000 to over 11,000 feet in areas surrounding the RMBL townsite. Using dip nets, seine nets, and fyke nets, individuals were caught, recorded whether they were metamorphic or paedomorphic, measured for snout-vent-length (mm), weight (g), and noted their sex. Findings will be compared with climate data at each site and added to the ongoing 2020-2024 dataset.

Wild marmots’ social networks reveal controversial evolutionary theory in action - Conner S. Philson; Daniel T. Blumstein (The Conversation, 2025)

Rare species do not disproportionately contribute to phylogenetic diversity in a subalpine plant community - Leah N. Veldhuisen; Verónica Zepeda; Brian J. Enquist; Katrina M Dlugosch (American Journal of Botany, 2025)
We found that rare species, whether at low abundance or with a small range, do not disproportionately contribute to phylogenetic diversity in our subalpine plant community. These results were consistent across elevations. Instead, rare species might provide phylogenetic redundancy with common species. Deeper understanding of functional differentiation is needed to understand contributions of rare species to this system.

Harmonized aerosol size distribution, cloud condensation nuclei, chemistry and optical properties at 10 sites - E. D. Andrews; I. Zabala; G. Carrillo-Cardenas; G. Titos; J. A. Casquero-Vera; A. Gannet Hallar (Scientific Data, 2025)

Testing the marginal value theorem on Bombus appositus and Bombus nevadensis - Kevin Ryan (2025)
Previous studies on bumblebee foraging behavior found that bumblebees often exhibit optimal foraging behavior when collecting nectar and pollen. A popular theory is that bumblebee foraging can be represented by the marginal value theorem (MVT). This summer, I observed the foraging behavior of Bombus appositus and Bombus nevadensis workers in Gothic, Colorado, to analyze whether bumblebee foraging decisions on naturally occurring Delphinium barbeyi patches are consistent with the MVT. Specifically, I investigated 1) Do B. appositus and B. nevadensis workers spend more time foraging in denser patches of D. barbeyi, 2) do B. appositus and B. nevadensis workers visit proportionally fewer flowers in denser patches of D. barbeyi, and 3) are these trends less apparent at the end of the summer when all patches are D. barbeyi are more sparse. After following bumblebees throughout their foraging bouts and tracking their foraging decisions with a voice recorder, I found that patch flower density explains a significant amount of variation in the patch residence time and proportion of flowers visited by B. appositus workers. I found that patch flower density explains a significant amount of variation in the patch residence time, but not the proportion of flowers visited by B. nevadensis workers. Finally, I found that foraging behavior is not significantly different later in the summer when all D. barbeyi patches are more sparse.

Females know best: dispersal polymorphism maintained by sex-specific foraging - E. M. Johnston; H. H. Whiteman; H. S. Greig; B. J. Olsen; A. J. Klemmer (Behavioral Ecology and Sociobiology, 2025)

Biotic and abiotic drivers of pathogen prevalence in a rust fungus with multiple plant hosts - I. Ferrer (2025)
Pathogens can have strong negative effects on individual fitness that scale up to influence population dynamics. Because of this, understanding the ecological contexts that shape pathogen transmission and prevalence is critical for understanding community dynamics and ecosystem function. Puccinia monoica is a fungal pathogen with a complex life cycle that alternates between infecting grasses and forbs in the Brassicaceae. This study investigates how B. stricta and grass host densities, as well as abiotic factors such as drought, influence transmission of P. monoica. I conducted field surveys near Gothic, Colorado, to quantify environmental conditions across multiple sites with variation in host and pathogen abundance. Furthermore, to experimentally test the potential role of drought in facilitating pathogen spread, I performed controlled inoculations of grass hosts under drought and control conditions in a greenhouse. These integrated field and experimental approaches helped reveal how spatial variation in biotic and abiotic environments shape pathogen dynamics in multispecies communities. By quantifying relationships between host density, environmental stress, and pathogen transmission, this study supports our understanding of the population ecology of plant-pathogen systems which could inform models of disease spread under changing climate conditions.

Evaluating differences in water temperature and macroinvertebrate communities in BDA ponds, stream pools, and beaver dam ponds - R. Hinke (2025)
Beaver Dam Analogues (BDAs) are human-made structures mimicking beaver dams and are implemented in restoration projects to slow flow, aggrade sediment, and reconnect streams to floodplains or create wetland conditions. Despite the recent popularity of this technique, very little monitoring occurs at BDA sites. This study involved surveying and measuring beaver augmented BDA ponds, BDA ponds, and stream pools to assess differences in temperature and macroinvertebrate communities as an evaluation of how successful BDA installation has been. For each type of lentic habitat, we measured six different sites to get an accurate composition of the ecosystem for our data. Using temperature loggers and d-nets, we measured each restoration site over a period of 10 days. We found that the BDA ponds were comparable to beaver augmented BDA ponds in temperature, though the beaver-augmented ponds had a slightly lower mean daily maximum. In contrast, stream pools had a wide range of temperature fluctuation, with the lowest mean daily minimum and the highest mean daily maximum. The invertebrate community composition of each site was significantly different, with more lentic taxa in ponded sites than stream sites. The beaver-augmented BDA pond community was a more constrained subset of the BDA pond community, indicating that as those ponds change with beaver augmentation, the inhabiting invertebrates may be shifting towards more wetland-obligate taxa . These results suggest that BDA-based wetland restoration projects may require beaver to be successful or shorten the timeline to success.

Up high, hot and dry: Individual reproductive output in subalpine bees declines with increasing drought severity - Lydia H. Wong; B. D. Inouye; J. R. K. Forrest (Global Change Biology, 2025)
Wild bees play indispensable ecological roles in many ecosystems, yet declines in many species have been documented in recent years. These declines have been linked to numerous anthropogenic pressures, including climate change, which can influence bee populations directly (i.e., via physiological mechanisms) and indirectly (e.g., through changes to floral resource quantity and quality). Widespread changes in the distributions and abundances of many bee species have been linked to climate change at large spatial scales; yet, the local-scale processes that generate these broad-scale patterns are little known. Specifically, it is unclear how climate change influences the fitness of individual bees, despite the fact that broad-scale patterns of decline must be driven by individual-level processes. Our study examines the individual fitness responses (i.e., reproductive output) of five solitary bee species in the genus Osmia to variations in local climate variables in subalpine habitats. Over nine years, we tracked brood cell production in over 700 individual female bees, conducted repeated surveys of floral abundance (while taking into account the specific floral host taxa used by each bee species), and recorded local precipitation and temperature at seven sites. Our data revealed both direct and indirect (floral resource-mediated) negative effects of drought: the total number of brood cells produced by nesting females decreased significantly in summers characterized by greater drought severity and high temperatures-a relationship-driven partly by significant decreases in floral host-plant availability in hotter and drier years. Our study highlights how the negative consequences of climate change for bee populations can manifest at the level of individuals and the role of floral resources in mediating these relationships. Overall, our results suggest that the increasingly warm and dry conditions forecasted for our study area will have net negative effects on the demographic success of these solitary bees.

Temperature influences pollinators' choice of floral partners independently of community composition - Kaysee Arrowsmith; M. D. Strait; M. Chandar; A. Schiffer; B. J. Brosi (Journal of Animal Ecology, 2025)

Remote sensing strategies for surface mineral and contaminant detection - Kathleen Grant (2025)

Biofluorescence in Arizona Tiger Salamanders (Ambystoma mavortium nebulsoum) as an indicator of sexual readiness - K. Killian (2025)
Biofluorescence, the emission of visible light by organisms following the absorption of shorter wavelengths of light, has been identified recently in various amphibians but remains poorly understood in salamanders. This study investigates the potential relationship between biofluorescence and sexual readiness in Ambystoma mavortium nebulsoum, the Arizona tiger salamander. Specifically, we analyzed maximum gray values of the tail, cloaca, and full body through creating regions of interest from fluorescence images of the underbelly of animals in relation to morph (paedomorph and metamorph), sex, and degree of cloacal swelling, which serves as an external indicator of sexual readiness. Fluorescence was quanitified using ImageJ from standardized photographs of 146 individuals. ANOVA tests revealed significant differences in tail brightness between morphs (p > 0.05), confirmed by Tukey’s HSD post hoc tests (adjusted p < 0.05). Although sex differences in tail brightness were initially detected, post hoc comparisons did not reveal significant pairwise differences. Cloacal brightness appeared to vary with swelling level (p < 0.05), but this was not confirmed by adjusted post hoc tests. Full body brightness level showed no significant variation across morphs, sexes, or level of cloacal swelling. These findings suggest a morph-specific difference in tail biofluorescence, with other potential sexual or reproductive signals warranting farther study. Future analyses will incorporate a larger dataset, individual level comparisons over time, and additional body regions to better understand the biological role of fluorescence in salamander courtship and communication.

Does sodium in floral nectar enhance pollination & plant reproduction? - M. Hunt (2025)

Herbivory and water availability interact to shape the adaptive landscape in the perennial forb, Boechera stricta - M. I. Jameel; L. Duncan; K. A. Mooney; J. T. Anderson (Evolution, 2025)
Corydalis caseana ssp. brandegei (Fumariaceae) is a perennial plant that grows in moist, subalpine regions of south central Colorado, USA. Prior to this study, nothing was known of its reproductive biology. The most numerous visitors (59%), and the only known pollinators, were long-tongued bumblebees (Bombus appositus). Twenty-nine percent of visits were from short-tongued nectar-robbing bumblebees (Bombus occidentalis). Hum- mingbirds also visited the flowers but they did not pollinate them. Corydalis caseana flowers remained open and in good condition for approximately 4 days. During that time, in the absence of visitors, nectar containing 35% sugar accumulated at a rate of approxi- mately 1 mL per day. Corydalis caseana has a mixed-mating system. It is self-fertile, but the self-fertilized flowers produce fewer seeds per fruit than the outcrossed flowers (a mean of 2.9 compared with a mean of 4.7). Results suggest a possibility of inbreeding depression.

The effect of human pressure on the flight initiation of montane breeding birds throughout the summer breeding season - L. Higgins (2025)
The summer is a peak tourism season in the Colorado Rocky Mountains, but is also the breeding season for many montane bird species, resulting in an increase in bird-human interactions and coexistence. I measured the effect that human activity has on the flight initiation behavior of two montane bird species: the American Robin and the Mountain White-crowned Sparrow. I also looked at how these effects change over the course of the breeding season. I measured the flight initiation distance of individuals in high, moderate, and low human activity areas over the course of the breeding season to observe this. This research is important because human activity in wild spaces is increasing and understanding how birds respond and adapt to human activity is essential for their conservation. ​

The impact of soil moisture, nectar production, and spectral reflectance on hummingbird visitation patterns to the Scarlet Gilia (Ipomopsis aggregata) - A. M. Pantoja Alfaro (2025)
Climate change has brought intense disruptions to the natural patterns of growth and reproduction in sub-alpine ecosystems, generating changes to the food sources that Broad-tailed hummingbirds (Selasphorus platycerus), which breed in the Rocky Mountains, depend on. A hotter, dryer climate results in changing levels of soil moisture, which may impact floral traits such as color and sugar concentration in nectar. In order to find out how variations in these traits impact hummingbird visitation rates to certain flowers, we used data from HummerFlowerWatch, a long-term study gathering camera trap data (documenting every time a hummingbird visits a chosen flower) and transect data (measuring flower abundance), we collected specimens of the native Ipomopsis aggregata flower in Gothic, CO, and we noted the trail and measured soil moisture, glucose concentration in nectar, and spectral reflectance to determine correlations between these variables. We predicted higher soil moisture in Stupid Falls, causing higher sugar concentration in nectar, high general nectar output, and higher intensity of reflected red and UV wavelengths. We then expected current trends in visitation data to reflect higher visitation in Stupid Falls. In contrast, we predicted lower soil moisture in Judd Falls, causing lower sugar concentration in nectar, lower general nectar output, and lower intensity of reflected red and UV wavelengths. We also expected current trends in visitation data to reflect lower visitation in Judd Falls. After a 20-day research period for nectar studies, the data supports our hypothesis about Stupid Falls having higher soil moisture and nectar output, indicates a significant positive correlation between soil moisture and nectar output, and indicates a significant negative correlation between soil moisture and nectar concentration. No significant conclusions can be drawn about nectar concentration differences by trail. After a net data set of seven days of spectroscopy, our results show that reflectance does vary significantly by trail (Stupid Falls flowers reflected with greater intensity), but with a small effect size; there is still a lot of overlap between the spectral shape of flowers from both sites. Analysis also showed that Ipomopsis tubes reflect UV and red wavelengths at a higher intensity that the petals do. Overall, hummingbird visitation rates from 2022-2024 indicate a significant difference between trails, favoring Stupid Falls as the more highly visited sight possibly caused by greater nectar output and reflectance.

Understanding aquatic insect oviposition to increase aquatic insect recruitment rates - C. S. Baker (2025)
Aquatic insects play many critical ecological roles in their environments. Anthropogenic changes in these environments, particularly those already under stress, leave the insect community more prone to stochastic disturbances. Despite widespread efforts by conservationists, many projects fail to increase insect recruitment to pre-disturbance levels as much of the focus is centered on the larval stage. It is currently unknown how aquatic insects select sites for laying egg masses, a process known as selective oviposition. We aimed to understand the characteristics of emergent rocks favorable for insect-selective oviposition. We hypothesized that rock size would have the most significant impact on favorability and insect success rates. Data was collected in the East River in the Colorado Rockies, on the RMBL campus. These pairs of emergent rocks exhibit various qualities, including rock embedment, water flow rate, and rock size. We observe insect behavior using a time-lapse camera. Egg masses were counted before and after the trial. After reviewing the footage, we found that 1) insects are landing and submerging on embedded and unembedded rocks equally. 2) Insects are laying egg masses more on unembedded, but using a zero-inflated model, they are not laying egg masses equally across each treatment. I suggest that aquatic insects are unable to recognize embedded and unembedded rocks, and embedded rocks may act as an ecological trap.

Spatial and Temporal Variation in Phylogenetic Diversity in Rocky Mountain Plant Communities - Leah N. Veldhuisen (UA Campus Repository (The University of Arizona), 2025)
Phylogenetic diversity is an axis of biodiversity that captures the variation in evolutionary relationships present in a community, and is associated with important ecosystem functions. Interestingly, recent work has shown that phylogenetic diversity is often decoupled from other biodiversity metrics, such as richness and functional diversity. Phylogenetic diversity correlates more positively with biomass than does species richness or functional diversity, and promotes ecosystem stability, productivity and resistance to invasion. However, phylogenetic diversity is threatened by species loss and phylogenetically clustered extinction. Given the ecosystem benefits of phylogenetic diversity and its independence of other diversity metrics, it is critical to better understand its distribution and how it may respond to climate change. In this thesis, I investigate spatial and temporal variation in phylogenetic diversity in Rocky Mountain plant communities at the Rocky Mountain Biological Laboratory (RMBL; Gothic, CO, USA). Plant communities in this region are well-characterized, but phylogenetic patterns of species change are under-studied. Montane ecosystems are predicted to experience disproportionately intense impacts of climate change, therefore understanding the distribution of and variation in phylogenetic diversity in these communities is essential. First, I tested how evolutionary relationships between co-flowering species change over the growing season. I found that forb communities across an elevational gradient formed statistically significant groups of co-flowering species that flower in the early, middle and late growing season. Their phylogenetic diversity declined from early to late season at all elevations, indicating that late season conditions may constrain diversity. Next, I tested whether rare species, quantified by range size and local abundance, contribute disproportionately to phylogenetic diversity. I found that rare species by both metrics do not disproportionately contribute to phylogenetic diversity in this plant community. Instead, rare species might provide phylogenetic redundancy with common species, and a deeper understanding of functional differentiation is needed to understand contributions of rare species to this system. Third, I used experimentally warmed and cooled plant communities to ask how different aspects of community diversity change with the environment, and whether phylogenetic relationships predict individual species’ responses to change. I found that species’ responses were not phylogenetically conserved, and that changes in phylogenetic diversity were decoupled from changes in species richness and Shannon diversity. My results suggest that species losses in cooled plots were phylogenetically dispersed, increasing plots’ phylogenetic diversity, even as richness and Shannon diversity declined. In warmed plots, increasing richness and Shannon diversity suggested that new species from across the plant phylogeny can colonize after transplantation, stabilizing phylogenetic diversity under warming. Lastly, I investigated how phylogenetic diversity changed in four different elevational community types from 1950 to 2014 and whether individual species’ changes were phylogenetically conserved. I found that individual species’ responses to climate change were only phylogenetically conserved for two of three metrics in one community type each. Phylogenetic diversity changes varied by community type, with decreases in the sagebrush, increases in the spruce-fir and upland-herb, and no changes in the alpine, indicating unique evolutionary trajectories for each community type. Altogether, my dissertation studies highlight that aspects of the environment, whether seasonal variation, transplanting over space, or change over time, impact phylogenetic diversity, but sometimes in ways contrary to theoretical predictions. Understanding the distribution of phylogenetic diversity independently of other metrics is essential for tracking and forecasting changes and threats to diversity.

The role of snowmelt and subsurface heterogeneity in headwater hydrology of a mountainous catchment in Colorado: A model-data integration approach - L. Wang; Zexuan Xu; L. Wang; R. Thibaut; Craig Ulrich; Matthias Sprenger; Sebastian Uhlemann; Yuxin Wu; E. L. King; Haruko M. Wainwright; R. W. H. Carroll; Curtis A. Beutler; et al. (Water Resources Research, 2025)
Abstract Mountainous headwater streams are sustained by both snowmelt‐driven streamflow and groundwater discharge in the Upper Colorado River Basin. However, predicting headwater stream discharge magnitude and peak flow timing is challenging in mountainous terrains, where snowmelt rates vary with vegetation type and elevation, and heterogeneous subsurface physical properties influence groundwater storage and its release. We used a model‐data integration approach to investigate the roles of snowmelt and subsurface structure in stream discharge and groundwater level. We ran an ensemble of 100 integrated surface‐subsurface hydrologic models for a mountainous headwater catchment near Crested Butte, Colorado, USA. We also evaluated and calibrated these models against observed data sets, including snow depth measurements using distributed temperature probes, stream discharge, and groundwater levels. Calibration with multiple data sources using neural density estimators has further constrained uncertainty in subsurface properties and snowmelt rates. Results indicated that observed slower snowmelt rates in evergreen forests delayed the peak flow and baseflow onset. In upstream areas with lower subsurface permeability, water was stored within the subsurface but was not released as interflow or shallow groundwater flow, and thereby not contributing to downstream streamflow during recession limb periods. Double peaks in groundwater occurred in areas with spatial subsurface heterogeneity, in our case due to the contrast between granodiorite and Mancos shale. These process‐based insights into groundwater and snowmelt dynamics in mountainous headwaters will help improve predictions of headwater hydrology.

Host species and geographic location shape microbial diversity and functional potential in the conifer needle microbiome - R. M. Bowers; S. Bennett; R. Riley; J. C. Villada; I. R. Da Silva; T. Woyke; A. C. Frank (Microbiome, 2025)

Vegetation structure effect on bird foraging behavior across the summer season in montane wet-meadows - T. Blakelock (2025)
Mountain White-crowned Sparrows and Wilson’s Warblers rely on foraging microhabitats in montane wet meadows during the breeding season to find food for themselves and their offspring. The microhabitats are comprised of vegetation, which can be food itself, but it can also be a substrate for invertebrates that birds can consume. I investigated the differences in foraging microhabitat vegetation structure between these two species by conducting foraging observations accompanied by vegetative surveys. Observations took place in two survey periods to account for food availability and breeding season interferences: late June to early July and mid-July to late July. I found that vegetative structure had no significant effect on foraging efficiency. Additionally, neither bird was found to be significantly more efficient at foraging. I found that the two target birds forage significantly more efficiently later in the season.

Quantifying groundwater response and uncertainty in beaver-influenced mountainous floodplains using machine learning-based model calibration - L. Wang; T. Babey; Zach Perzan; Samuel Pierce; Martin Briggs; Kristin Boye; Katharine Maher (Water Resources Research, 2025)
AbstractBeavers (Castor canadensis) alter river corridor hydrology by creating ponds and inundating floodplains, and thereby improving surface water storage. However, the impact of inundation on groundwater, particularly in mountainous alluvial floodplains with permeable gravel/cobble layers overlain by a soil layer, remains uncertain. Numerical modeling across various floodplain structures considers topographic and sediment complexity and multidirectional flow, linking inundation to groundwater response. This study develops a model‐data integration workflow to address uncertainty in groundwater response to beaver‐induced inundations in a mountainous alluvial floodplain in the Upper Colorado River Basin. Uncertain factors include seasonal hydrologic dynamics, hydraulic conductivities, floodplain structures, and meteorological forcings. We employed an ensemble of groundwater models, based on geophysical and hydrologic data, with machine learning‐based calibration using a neural density estimator. This allowed us to quantify the vertical flux from the soil layer to the permeable gravel bed, the down‐valley underflow within the gravel bed, and their ratios. Results show a significant increase in the vertical flux relative to down‐valley underflow, from 2 during dry pond periods to 20 during wet periods, serving as an analogy for conditions without and with beaver ponds. The study highlights the influence of floodplain structure on groundwater storage, water balance, and water quality impacted by beaver ponds. A thick gravel bed layer, with a large down‐valley underflow, minimizes the effect of beaver‐induced inundation on water quality. We emphasize the need for field‐scale measurements of floodplain structure and improved characterization of evapotranspiration changes to reduce uncertainty in groundwater response.

Differences in gene expression and genetic variation underlying preference-performance mismatches: insights from a specialized native herbivore on an invasive toxic plant - Nitin Ravikanthachari; C. L. Boggs (Heredity, 2025)
The causes for preference-performance mismatches in a specialist native herbivore laying eggs on an invasive toxic plant are investigated, and genes related to successful detoxification and adaptive feeding were enriched in larvae feeding on native plants and toxic plants.

Courtship display behavior influences tail myology in Centrocercus minimus (Gunnison sage‐grouse) - Samantha J. Clark; Jessie Atterholt; Samantha J. Clark; Nathan Seward (Journal of Anatomy, 2025)
Abstract A variety of bird species engage in complicated, elaborate courtship displays to impress potential mates. Such displays include wing flaring, aerial acrobatics, choreographed dances, and tail fanning. Though these behaviors are often well studied, the underlying musculature facilitating them is poorly understood. Exemplars of unique avian courtship behaviors include species of the North American sage‐grouse ( Centrocercus ). Each spring, males gather in leks where they perform courtship displays which incorporate species‐specific sound production, nape feather movement, and importantly, the raising and spreading of their rectricial fan for prolonged periods of time. Here we describe the tail myology of the lekking sage‐grouse species Ce . minimus (Gunnison sage‐grouse). We compare the tail myology of this species to that of other, either closely related or similarly sized, bird species which do not engage in rectricial displays. Results indicate tail myology in Ce . minimus is adapted for unique courtship behaviors. Muscles of the rectricial apparatus in Ce . minimus have greater proportional mass relative to body mass compared to other species examined here, and nearly all other species previously examined. In particular, both overall mass and the mediolateral width of the origination surface of the m. levator caudae are hypertrophied compared to other species which do not incorporate a raised tail fan during courtship displays. Additionally, the muscles that primarily spread the tail fan have relatively more extensive origin surfaces in Ce . minimus . Our results provide evidence that the specialized courtship behaviors of Ce . minimus have a clear influence on the tail myology morphology of this species, and suggest that sexually selected displays alter the corresponding underlying musculature across birds.

Reproductive ecology and pollination biology of Geum triflorum (prairie smoke) - K. Hughes (2025)
Understanding plant reproductive strategies is important for interpreting population dynamics and species resilience. We investigated the mating system, pollen limitation, and pollinator interactions of Geum triflorum (prairie smoke), a subalpine wildflower. Experiments took place at the Rokcky Mountain Biological Laboratory in Gothic, CO. Using a randomized block design, we applied five pollination treatments: hand outcross, open outcross, hand self, autogamy, and control. We measured seed set, floral traits, and pollinator identity and activity in 26 naturally occurring G. triflorum rosettes. However, due to severe drought stress, widespread herbivory, and issues with pollinator exclusion bags, only three flowers produced seeds across all treatments. This precluded statistical analysis of reproductive success. Despite these limitations, results suggest G. triflorum does not reproduce via autonomous self-pollination and may be capable of some amount of self-fertilization via geitonogamy. Natural pollination was observed, though seed production was minimal. These findings, coupled with low visitation rates and reduced reproductive output in dry years support the hypothesis that G. triflorum may be pollinator-dependent. Future research should explore drought effects on reproduction more directly and use improved methods to reduce herbivory and bag failure.

Diurnal trends and meteorological factors influencing the variability of fluorescent bioaerosol in Mt. Crested Butte, Colorado during SAIL - A. Sayeed Md Shawon; Katherine Benedict; A. Gutierrez; Allison Aiken (Journal of Geophysical Research: Atmospheres, 2025)
Abstract Despite the crucial role of bioaerosol particles (BAP) in our climate system, local ecosystems, and human health, our grasp on their atmospheric interactions is hampered by a lack of high‐resolution and long‐term data, which is essential for understanding their abundance and variability in response to meteorological conditions. To discern these relationships in a high‐altitude mountainous terrain is even less well‐studied. Therefore, we deployed a Wideband Integrated Bioaerosol Sensor (WIBS‐Neo) for three months during the first biologically active season of the Surface Atmosphere Integrated Field Laboratory (SAIL) campaign in summer 2022 on Mt. Crested Butte in Colorado (elevation 3,140 m ASL). Here, we report real‐time fluorescent BAP (FBAP) data collected from 15 June to 13 September 2022, sampled from within the ARM Aerosol Observing System (AOS). To our knowledge, these are the first high altitude (>3,000 m ASL) continuous measurements of FBAP made in North America. During this deployment, we observed on average 21% and as many as 48% (hourly maximum) of particles within the detection size range ( to ) of the WIBS as FBAP. Our analysis presents the diurnal cycles for seven distinct types of FBAP, showing unique patterns and, in some cases, correlations with temperature and solar radiation cycles. Abundance and composition of FBAP varied with relative humidity and precipitation. Precipitation events appeared to both cause emission and removal of FBAP, whereas dust and smoke events had no significant effect, highlighting the critical role of meteorology on FBAP at high altitudes.

Range-wide study in a sexually polymorphic wild strawberry reveals climatic and soil associations of sex ratio, sexual dimorphism and sex chromosomes - N. Cullen; E. Richardson; T. Budinsky; R. Reeb; S. Mortimer; A. Liston; T. L. Ashman (Journal of Ecology, 2025)

Shorter seasonal snow cover poses a risk to solitary bee populations in a mountainous ecosystem - G. Quinlan; Melanie R Kazenel; M. Stemkovski; R. E. Irwin (Proceedings of the Royal Society B: Biological Sciences, 2025)

Comparing decomposition rates and detritivore preferences for caddisfly (Trichoptera) cases versus ambient detritus - E. Madden (2025)
Humans manage microbes in their built environments by lowering humidity, filtering outside air, and applying antimicrobials that together fosters the selective dominance of microorganisms that can tolerate these harsh conditions and selects for antimicrobial resistance. Other species, however, regulate decomposition of their built environments in warm, moist conditions with diverse microbial communities. For example, larval caddisflies that live in streams and ponds use their labial silk glands to weave detritus, pebbles, and other materials into portable cases. Premature decomposition of cases is detrimental to these invertebrates, as cases serve as protection for vulnerable larvae against predation, aid in respiratory efficiency, and ensure reproductive success of adults. Plant-based cases remain in wetland ponds in Colorado’s East River valley for up to nine months after caddisfly pupation and case abandonment, while the same detritus not associated with cases is absent from the pond bottom. Insect silk, which often contains antimicrobial peptides or proteins, may be a contributing factor in potential antimicrobial properties and decreased detritivore consumption of cases. In this study, I first quantified decomposition of caddisfly cases compared to that of the same non-case associated detritus, expecting caddisfly cases to possess slower rates of decomposition. Second, I explored the feeding preferences of a common invertebrate detritivore for the cases of different caddisfly species and the non-case associated detritus. Lastly, I quantified the fungal communities of cases and detritus as well as the feeding preference of detritivores. I hypothesized that cases contain less fungi, correlating to lower food value and a potential mechanism for detritivore avoidance of cases over non-case associated detritus. While A. bimaculata cases and C. aquatilis had similar slow rates of mass loss, L. externus and H. designatus cases rapidly decomposed over the course of four weeks. The latter cases with finer pieces of detritus also lost organic mass fastest, suggesting higher fungal activity and a strong detritivore feeding preference. L. externus and A. bimaculata larvae avoided A. bimaculata cases and preferred L. externus cases due to the potentially aggressive behavior of larger A. bimaculata larvae and physically easier to eat small pieces of detritus in L. externus cases. With the ideal conditions of agar plates, fungi on C. aquatilis cases possessed the highest colony morphotype diversity, but percent of fungal cover was similar across C. aquatilis, L. externus cases, and A. bimaculata cases. The behavior and case construction of caddisfly cases give insight into the diverse strategies these invertebrates employ to maintain their built environments in wetland ponds conducive to vigorous microorganism proliferation and decomposition of organic matter, informing future design of human-built environments.

Linking surface processes, solute generation, and CO2 budgets across lithological and land cover gradients in Rocky Mountain watersheds - J. R. Slosson; I. J. Larsen; M. J. Winnick; J. M. Marmolejo-Cossio; K. H. Williams (Water Resources Research, 2025)
Abstract Chemical weathering in mountain critical zones controls river chemistry and regulates long‐term climate. Mountain landscapes contain diverse landforms created by geomorphic processes, including landslides, glacial moraines, and rock glaciers. These landforms generate unique flowpaths and water‐rock interactions that modify water chemistry as precipitation is transformed to streamflow. Variations in lithology and vegetation also strongly control water chemistry. Prior work has shown that landslides generate increased dissolved solute concentrations in rapidly uplifting mountains. However, there is still uncertainty regarding the magnitude which different geomorphic processes and land cover variations influence solute chemistry across tectonic and climatic regimes. We measured ion concentrations in surface water from areas that drain a variety of landforms and across land cover gradients in the East River watershed, a tributary of the Colorado River. Our results show that landslides produce higher solute concentrations than background values measured in streams draining soil‐mantled hillslopes and that elevated concentrations persist centuries to millennia after landslide occurrence. Channels with active bedrock incision also generate high solute concentrations, whereas solute concentrations in waters draining moraines and rock glaciers are comparable to background values. Solute fluxes from landslides and areas of bedrock incision are 1.6–1.8 times greater than nearby soil‐mantled hillslopes. Carbonic acid weathering dominates surface water samples from watersheds with greater vegetation coverage. Geomorphically enhanced weathering generates hotspots for net CO 2 release or sequestration, depending on lithology, that are 1.5–3.5 times greater than background values, which has implications for understanding links among surface processes, chemical weathering, and carbon cycle dynamics in alpine watersheds.

Assessing anthropogenic effects on golden-mantled ground squirrel and least chipmunk flight initiation distances - S. Mikaru (2025)
Species who commonly occupy territories within human settlements are exposed to frequent human disturbance, which has been linked to significant shifts in wildlife behavior in past studies. As urbanization and rural development continue to increase, we can anticipate cohabitation between humans and wildlife to also increase, creating a growing need to understand the effects of repeated human disturbance on wildlife behavior across a variety of taxa. Flight initiation distance (FID) is a common metric used to quantify antipredator behavior and boldness in wildlife populations and is used to assess perceived risk of a pursuer from the perspective of a fleerer. We conducted FID trials on golden-mantled ground squirrels (Callospermophilus lateralis; GMGS) and least chipmunks (Tamias minimus; CPMK) across 11 sites of varying levels of human disturbance to determine the effect of human disturbance on FIDs through a generalized linear mixed effects model. We found a statistically significant positive relationship between proportion of impervious surfaces within a buffer range of the animal and FID for CPMK, as well as a reliably positive effect of distance to road on FID for CPMK. GMGS had reliably positive effects of distance to road and distance to trails on FID. Starting distance was significant for CPMK and GMGS.

The effects of snowmelt date, soil moisture, and precipitation on nectar and floral morphology of Ipomopsis - F. Morrison (2025)
Climate change is putting montane plant species at risk that rely on historical patterns of precipitation and snowmelt timing. Floral traits, such as nectar production and morphology can be impacted by water availability. Hybridization of plants has the potential to provide adaptation to climate change through an increase in genetic variation. This study looked at nectar production and concentration, corolla length, stamen length, and style length in response to snowmelt date, summer precipitation, and soil moisture content. The focus populations included Ipomopsis aggregata and hybrids of Ipomopsis aggregata and Ipomopsis tenuituba. I expected that nectar production, corolla length, stamen length, and style length would decrease as water availability in the soil decreased, while nectar concentration would increase. I also predicted that floral traits would respond less to water availability in hybrids than I. aggregata due to their more efficient water usage and occupation of drier, rockier soil. The response of I. aggregata was much more stable than the hybrid response to changes in water availability via precipitation. In 2025, average soil moisture was not found to affect average floral traits in specific plants, with all plants experiencing dry conditions. Both nectar related traits and floral morphological traits were not correlated with average soil moisture. Instead, the average nectar production decreased with Julian date as the average nectar concentration increased. Over 15 years, nectar production and concentration responded to summer precipitation, but only minimally to the date of snowmelt. Though 2025 was informative on the plants’ responses to changes in water availability, the severe drought conditions may have limited this study’s ability to determine the true effects of water availability on floral traits, given the narrow range of soil moisture.

Different aspects of dominance are not equivalent when testing for trade-offs in ant communities - A. S. Nelson; K. A. Mooney (Ecology and Evolution, 2025)

Using time-lapse imagery to determine snow heterogeneity - G. Elovitz (2025)

Alpine plant spatial clumping modifies leaf surface temperature - E. Ramsey (2025)
Alpine plant communities are particularly susceptible to the impacts of climate change, which makes predicting how these communities will respond important for their conservation. This can be better predicted by understanding how the communities assemble, which is highly influenced by species interactions like facilitation. In alpine environments, clustered plants may experience facilitative interactions that can improve vital rates like survival and fecundity. Alpine facilitation is known to occur via increased soil moisture and buffered air temperatures, but this is likely not the full extent of the facilitative interaction. Plant leaf temperature regulation is essential for photosynthesis, respiration, and water retention. Leaf temperature could also be influenced by facilitative interactions in spatially clumped plants. The goal of this study is to address the question: How does leaf surface temperature relate to neighbor density in alpine plant communities? I hypothesized that clumped plants will display smaller Average Tleaf measurements compared to spatially isolated plants and that plants will experience temperature buffering, causing leaves in clustered plants to be cooler relative to surrounding soils (larger Soil Plant Delta values). This research occurred in an alpine plant community in the Elk Mountains of Colorado during July and August 2025. Leaf temperature and surrounding soil temperature data were collected using an infrared thermometer for three focal species (Elymus lanceolatus, Eriogonum umbellatum, and Ivesia gordonii) when found alone and when clumped with each of the other focal species. Soil surface temperature, air temperature, plant area and height, and wind speed were also measured. Using linear mixed effects modelling, species were found to respond differently to the effects of clumping. Two species displayed lower Average Tleaf and higher Soil Plant Delta values in clumps, whereas the third showed no trend with either. Overall, clumping was determined to be a significant variable impacting both Average Tleaf and Soil Plant Delta. This difference in temperature means that plants found in clumps will have different responses to environmental temperature changes because their energy balance is impacted by clumping effects.

Quantifying ethanol in bumble bee honey and Colorado rocky mountain wildflowers - S. Bustamante (2025)
Ethanol is a natural byproduct of yeast fermentation of plant sugars. In flowering plants, yeasts often form mutualistic relationships by inhabiting nectar, where they benefit from access to sugar and confer antimicrobial protection through the production of ethanol. Ethanol in nectar not only shapes microbial communities but may also influence pollinator behavior. Prior studies have shown that pollinators such as honey bees and Oriental hornets are attracted to or tolerant of ethanol despite its toxicity. However, little is known about the actual concentrations of ethanol naturally present in the dietary sources of sugar for bees, namely their honey (in the case of eusocial bees) and foraged floral nectar. This study quantified ethanol levels in the honey of eight commercial bumble bee colonies and the floral nectar of five native plant species in the Colorado Rocky Mountains: Mertensia ciliata, Ipomopsis aggregata, Corydalis caseana, Delphinium barbeyi, and Aconitum columbianum. By providing quantitative data on natural ethanol levels, this study offers insight into the ecological significance of yeast-produced ethanol in pollination systems.

Quantifying physiological and behavioral differences in caddisfly larvae - C. Romo-Ornelas (2025)
The Mexican Cut Nature Preserve supports diverse populations of caddisflies (Limnephilus externus), whose larvae construct protective cases from environmental debris. Case morphology varies with ecological pressures, but gaps remain in understanding how intra- and interspecific interactions influence case size across larval development. This study quantified case size differences between permanent (high salamander density, HSD) and semi-permanent (low salamander density, LSD) ponds and assessed behavioral adaptations under controlled densities. Field surveys measured case sizes across larval instars via standardized net sweeps and photographic analysis. A semi-experimental design reared larvae from HSD and LSD sites at low (3 larvae/tank) and high (15 larvae/tank) densities to evaluate case construction and behavior. Contrary to predictions, larvae from LSD ponds constructed significantly larger cases across all instars (third: LSD 0.68±0.02 cm² vs HSD 0.52±0.03 cm², p<0.001; fifth: LSD 1.45±0.08 cm² vs HSD 1.82±0.07 cm², p<0.001). Experimentally, high density universally reduced case size (32% reduction, p=0.001), though LSD larvae maintained larger minimal cases. Behaviorally, HSD larvae showed threefold higher case-grazing probability (OR=2.85, p=0.003) and greater density- dependent increases in case-related behaviors. These results demonstrate that case size reflects integrated responses to predator identity (e.g., Dytiscus beetles in LSD ponds), intraspecific competition, and source-population adaptations, with behavioral plasticity compensating for structural defenses in HSD environments. Romo-Ornelas |2

Molecular diversity of dissolved organic matter reflects macroecological patterns in river networks - E. C. Freeman; M. K. Mudunuru; K. L. Feeser; E. A. McClure; R. Gonzalez-Pinzon; C. S. Ward; E. M. Bottos; S. Krause; J. Pena; Michelle Newcomer (Scientific Reports, 2025)

Modeling spatial distribution of snow water equivalent using transfer learning across mountainous basins - L. E. Halabi; Utkarsh Mital; Dipankar Dwivedi (Journal of Geophysical Research: Machine Learning and Computation, 2025)
Abstract Accurately estimating snow water equivalent (SWE) is crucial for understanding the impacts of climate change, urbanization, and population growth on water resources. High operational costs of lidar observations limit the frequency and coverage of SWE estimates at high spatial resolutions, leading to significant data gaps. We address this challenge with a transfer learning (TL) framework that leverages abundant SWE data from California to enhance predictions in Colorado, where data are scarce. From 2016 to 2019, the disparity in SWE data collection between these states was stark: 94 snowpack maps were recorded in California's Sierra Nevada versus only 12 in Colorado's Rocky Mountains. We hypothesized that geographic predictors (e.g., elevation and snowfall) would exhibit similar effects on SWE across these landscapes. By conducting an exploratory factor analysis, we validated this hypothesis and refined our TL model, which incorporated data based on 80 snowpack maps from California to predict SWE in Colorado. The analysis included six models: Local 1, Local 1W, TL1, TL2, TL1W, and TL2W. Local models were trained only on Colorado data, while TL models leveraged TL using a base model trained on California data. Weighted models (Local 1W, TL1W, TL2W) incorporated a weighting mechanism to emphasize critical predictors. Compared to using data from Colorado alone, TL improved the mean value from 0.45 to 0.54, representing a significant enhancement of 20% in predictive accuracy, while reducing bias from 0.24 to 0.17 (a 30% decrease). Our framework helps mitigate lidar data limitations, supporting water management.

Seven County Infrastructure Coalition v. Eagle County, Colorado - Cale Jaffe; Xiao Wang (SSRN Electronic Journal, 2025)

Celebrating Creation on the Colorado River - Kathleen Van Vlack; Richard W. Stoffle; Heather Lim; Simon Larsson (Heritage, 2025)
Ancient figures and symbols are carved into a high rock wall beside the Colorado River, just south of where a traditional Native American geotrail crosses the river near Moab, Utah, USA. Based on ethnographic interviews with tribal and pueblo representatives, the rock peckings identify an ancient ceremonial geosite, which, among other purposes, serves as a site for the Celebration of Creation. The interpretation of the site is situated within the geologically complex and ancient cultural heritage region composed of functionally interrelated nested geoscapes that surround the study area. The analysis is informed by ethnographic interviews from six U.S. federally funded studies that involved thirteen participating tribes and pueblos. The analysis is guided by an intellectual framework aligned with internationally recognized UNESCO heritage categories—namely, geosites, geotrails, and geoscapes. Grounded in these UNESCO heritage categories, the analysis advances new interpretive frameworks, theoretical insights, and culturally responsive strategies for heritage management.

Metagenome-assembled genomes for oligotrophic nitrifiers From a mountainous gravelbed floodplain - Anna N. Rasmussen; Bradley Tolar; John R. Bargar; Kristin Boye; Christopher Francis (Environmental Microbiology, 2025)
Riparian ﬂoodplains are important regions for biogeochemical cycling, including nitrogen. Here, we present MAGs from nitrifying microorganisms, including ammonia-oxidizing archaea (AOA) and comammox bacteria from Slate River (SR) ﬂoodplain sediments (Crested Bute, CO, US). Addionally, we explore MAGs from potenal nitrite-oxidizing bacteria (NOB) from the Nitrospirales. AOA diversity in SR is lower than observed in other western US ﬂoodplain sediments and Nitrosotalea-like lineages such as the genus TA-20 are the dominant AOA. No ammonia-oxidizing bacteria (AOB) MAGs were recovered. Microorganisms from the Palsa-1315 genus (clade B comammox) are the most abundant ammonia-oxidizers in SR ﬂoodplain sediments. Established NOB are conspicuously absent; however, we recovered MAGs from uncultured lineages of the NS-4 family (Nitrospirales) and Nitrospiraceae that we propose as putave NOB. Nitrite oxidaon may be carried out by organisms sister to established Nitrospira NOB lineages based on the genomic content of uncultured Nitrospirales clades. Nitriﬁer MAGs recovered from SR ﬂoodplain sediments harbor genes for using alternave sources of ammonia, such as urea, cyanate, biuret, triuret, and nitriles. The SR ﬂoodplain therefore appears to be a low ammonia ﬂux environment that selects for oligotrophic nitriﬁers. 3 14622920, 2025, 3, Downloaded from https://enviromicro-journals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.70060 by National Energy Technology Laboratory, Wiley Online Library on [11/08/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

Predicting the contribution of single trait evolution to rescuing a plant population from demographic impacts of climate change - Diane R. Campbell; J. M. Powers; Justin Kipness (Evolution Letters, 2025)
Evolutionary adaptation can allow a population to persist in the face of a new environmental challenge. With many populations now threatened by environmental change, it is important to understand whether this process of evolutionary rescue is feasible under natural conditions, yet work on this topic has been largely theoretical. We used unique long-term data to parameterize deterministic and stochastic models of the contribution of 1 trait to evolutionary rescue using field estimates for the subalpine plant Ipomopsis aggregata and hybrids with its close relative I. tenuituba. In the absence of evolution or plasticity, the 2 studied populations are projected to go locally extinct due to earlier snowmelt under climate change, which imposes drought conditions. Phenotypic selection on specific leaf area (SLA) was estimated in 12 years and multiple populations. Those data on selection and its environmental sensitivity to annual snowmelt timing in the spring were combined with previous data on heritability of the trait, phenotypic plasticity of the trait, and the impact of snowmelt timing on mean absolute fitness. Selection favored low values of SLA (thicker leaves). The evolutionary response to selection on that single trait was insufficient to allow evolutionary rescue by itself, but in combination with phenotypic plasticity it promoted evolutionary rescue in 1 of the 2 populations. The number of years until population size would stop declining and begin to rise again was heavily dependent upon stochastic environmental changes in snowmelt timing around the trend line. Our study illustrates how field estimates of quantitative genetic parameters can be used to predict the likelihood of evolutionary rescue. Although a complete set of parameter estimates are generally unavailable, it may also be possible to predict the general likelihood of evolutionary rescue based on published ranges for phenotypic selection and heritability and the extent to which early snowmelt impacts fitness.

Comparative life-cycle analyses reveal interacting climatic and biotic drivers of population responses to climate change - E. Ickin; Eva Conquet; B. Abrahms; S. D. Albon; Daniel T. Blumstein (PNAS Nexus, 2025)
Responses of natural populations to climate change are driven by how multiple climatic and biotic factors affect survival and reproduction, and ultimately shape population dynamics. Yet, despite substantial progress in synthesizing the sensitivity of populations to climatic variation, comparative studies still overlook such complex interactions among drivers that generate variation in population-level metrics. Here, we use a common framework to synthesize how the joint effects of climate and biotic drivers on different vital rates impact population change, using unique long-term data from 41 species, ranging from trees to primates. We show that simultaneous effects of multiple climatic drivers exacerbate population responses to climate change, especially for fast-lived species. However, accounting for density feedbacks under climate variation buffers the effects of climate change on population dynamics. In all species considered in our analyses, such interactions between climate and density had starkly different effects depending on the age, size, or life-cycle stage of individuals, regardless of the life history of species. Our work provides the first general framework to assess how covarying effects of climate and density across a wide range of population models can impact populations of plants and animals under climate change.

Multilevel selection on individual and group social behaviour in the wild - Conner S. Philson; J. G. A. Martin; Daniel T. Blumstein (Proceedings of the Royal Society B: Biological Sciences, 2025)
How phenotypes are shaped by multilevel selection-the theoretical framework proposing natural selection occurs at more than one level of biological organization-is a classic debate in biology. Though social behaviours are a common theoretical example for multilevel selection, it is unknown if and how multilevel selection acts on sociality in the wild. We studied the relative strength of multilevel selection on both individual behaviour and group social structure, quantified with social networks and 19 years of data from a wild, free-living mammal, the yellow-bellied marmot (Marmota flaviventer). Contextual analysis (exploring the impact of individual and group social phenotypes on individual fitness, relative to each other) revealed multilevel selection gradients in specific fitness and life history contexts, with selection for group social structure being just as strong, if not stronger, than individual social behaviour. We also found antagonistic multilevel selection gradients within and between levels, potentially explaining why increased sociality is not as beneficial or heritable in this system compared with other social taxa. Thus, the evolutionary dynamics of hierarchical or nested biological traits should be assessed at multiple levels simultaneously to tell a more accurate and comprehensive story. Overall, we provide empirical evidence suggesting that multilevel selection acts on social relationships and structures in the wild and provide direct evidence for a classic, unanswered question in biology.

Wild foundress queen bumble bees make numerous, short foraging trips and exhibit frequent nest failure: Insights from trap-nesting and RFID tracking - E. S. Gustilo; William Grover; S. Hollis Woodard (Ecology and Evolution, 2025)
The overwhelming majority of research on wild bumble bees has focused on the social colony stage. Nest-founding queens in the early season are difficult to study because incipient nests are challenging to find in the wild and the foundress queen flight period is very short relative to the entire nesting period. As a result, natural history information on foundress queens is exceedingly rare. New methodological approaches are needed to adequately study this elusive life stage. We trap-nested wild queen bumble bees in artificial nest boxes in Gothic, Colorado and used a custom-built radio frequency identification (RFID) system to contin- uously record queen foraging activity (inferred from entering and exiting the nest) for the majority of their spring flight periods. Foundress queens made frequent, short foraging trips, which tended to increase in duration over the course of the flight period. All queens who produced adult workers ceased foraging within approximately 1 week after workers emerged in the nest. We observed frequent nest failure among foundress queens: Fewer than one quarter of queens who laid eggs in nest boxes went on to produce reproductive gynes at the end of the season. We also report nest characteristics and curious phenomena we observed, in- cluding conspecific nest invasion and queens remaining outside the nest overnight. We present this trap-nesting and subsequent RFID tracking method as a valuable, albeit resource-intensive, path forward for uncovering new information about the elusive, incipient life stage of wild bumble bees.

Improving plant DNA metabarcoding accuracy with ecological filters and Angiosperms353: Field and pollen microscopy validation - R. C. Benkendorf; E. J. Woodworth; Paul J. CaraDonna; Jane E. Ogilvie; S. Taddeo; J. B. Fant (Applications in Plant Sciences, 2025)

The short life of upvalley wind in a high-altitude valley in the Colorado Rocky Mountains - Bianca Adler; V. Caicedo; Brian Butterworth; Laura Bianco; Christopher Cox; Gijs de Boer; Ethan Gutmann; Janet Intrieri; T. Meyers; Joseph Sedlar; D. D. Turner; James Wilczak (Journal of Geophysical Research: Atmospheres, 2025)
Abstract Thermally driven upvalley (UV) wind in the upper East River Valley in the Colorado Rocky Mountains often unexpectedly stops in midmorning and reverses back to downvalley (DV) wind. We use a comprehensive observational data set for a nearly two‐year long period to analyze the wind system and boundary layer evolution in this high‐altitude valley and determine the reason for this early wind reversal. Days with short UV wind predominantly occur during the warm season when the valley floor is free of snow and the convective boundary layer (CBL) grows well above the height of the surrounding ridges. UV wind persists throughout the day only on a few days during the warm season. We link differences in valley wind evolution to wind direction at upper levels at and above ridge height and propose forced channeling mechanisms to describe coupling between valley and upper‐level wind when the CBL grows above ridge height. The frequency distribution of upper‐level wind direction is such that channeling in the DV direction is favored, which explains the predominance of days with short UV wind. The deep CBL is supported by the presence of a deep weakly stably stratified residual layer with high aerosol content, which is regularly present over the mountain range during the warm season. On days when the CBL does not grow above ridge height, for example, when the valley floor is covered by snow, thermally driven UV wind is able to persist throughout the day independent of upper‐level wind direction.

Soil signals of key mechanisms driving greater protection of organic carbon under aspen compared to spruce forests in a North American montane ecosystem - L. Wang; S. A. Billings; Langlang Li; D. R. Hirmas; K. Johnson; D. Kerins; J. Pachon; Curtis A. Beutler; K. Jarecke; V. Varikuti; M. Unruh; H. Ajami; et al. (Biogeosciences, 2025)

Interpretable ensemble learning unveils main aerosol optical properties in predicting cloud condensation nuclei number concentration - Y. Wang; Y. Wang; C. Lu; B. Zhu; X. Yan; Y. Sun; J. Xu; J. Zhang; Z. Shen (NPJ Climate and Atmospheric Science, 2025)

A multi-year case study highlighting the influence of hydrological conditions on epidemic dynamics in a natural plant pathosystem - Keenan Duggal; Juliana Jiranek; Madison Machado; Peyton Smith; I. Miller; J. Metcalf (Oikos, 2025)
The scale of influence of hydrological and thermal conditions on disease remains uncertain for most wild plant pathosystems, thus restricting our ability to predict the impacts of climate change. Analysis of the spatiotemporal spread of a fungal rust pathogen throughout four naturally occurring flax populations over the course of five growing seasons reveals relationships between epidemic magnitude and snow cover, relative humidity and temperature, as well as an unexpectedly significant effect of severe drought on disease progression. These results indicate that climate change will likely disrupt wild plant epidemics, and points to a need for further epidemiological studies characterizing the effects of environmental conditions on population‐level disease dynamics in natural pathosystems.

Observing the effects of a nectar-inhabiting bacterium, Pantoea sp., and nectar robbing on male fitness in Ipomopsis aggregata - A. Litchfield (2025)
There is still much unknown about how microbes within flower nectars, specifically bacteria, impact pollinators. Hummingbirds use gustatory and visual cues to determine which flowers are most rewarding. The diversity in colonization of nectar-inhabiting microbes, such as bacteria, can alter the scent, taste, and chemical composition of a plant's nectar. Additionally, antagonistic nectar-robbing by insects can further alter the composition of nectar and affect a pollinator's perception of a floral reward. Despite this, there is very little research looking at the combined effect of nectar-inhabiting bacteria and nectar robbing on pollen movement and male flower fitness, within a natural system. We aim to observe this effect through inoculation of Pantoea sp. bacteria and application of a robbing treatment on Ipomopsis aggregata, a hummingbird- pollinated plant. We will track pollen donation using quantum dot fluorescent crystals. We expect to see lower male fitness and less pollen donation in plants that were robbed and inoculated with bacteria because Pantoea has been seen to ferment sugars within nectar, and robbing has previously been seen to deter pollinators.

The role of bedrock circulation depth and porosity in mountain streamflow response to prolonged drought - R. W. H. Carroll; Andrew H Manning; K. H. Williams (Geophysical Research Letters, 2025)
Abstract Quantitative understanding is lacking on how the depth of active groundwater circulation in bedrock affects mountain streamflow response to a multi‐year drought. We use an integrated hydrological model to explore the sensitivity of a variety of streamflow metrics to bedrock circulation depth and porosity under a plausible extreme drought scenario lasting up to 5 years. Endmember depth versus hydraulic conductivity relationships and porosity values for fractured crystalline rock are simulated. With drought, a deeper circulation system with higher drainable porosity more effectively buffers minimum flow and significantly limits perennial stream loss in comparison to a shallow circulation system. Streamflow buffering is accomplished through extensive groundwater storage loss. However, deeper circulation systems experience prolonged recovery from drought in comparison to storage‐limited shallow systems. Research highlights the importance of characterizing the deeper bedrock hydrogeology in mountainous watersheds to better understand and predict drought impacts on stream ecosystem health and water resource sustainability.

Examining the effects of environmental variation on sociality in yellow-bellied marmots utilizing a within-individual centering approach - I. J. Thomson (2025)
The relationship between environmental variation and fitness has been well established. However, fitness may also be indirectly impacted by environmental variation through the modulation of social behavior. We aim to quantify the effects of environmental variation on sociality, specifically social relationships, with the knowledge that the subsequent changes in social behavior can have fitness consequences. Previous studies on sociality have often relied on annual analyses and, by focusing on a single year of social behaviors, have been unable to account for an individual’s lifetime patterns. A within-individual centering approach offers the ability to examine how sociality changes over an individual's lifetime and account for an individual's lifetime patterns. By utilizing the within-individual centering approach, we are able to utilize an individual’s lifetime average social position as a baseline to quantify the deviation in that individual's levels of social relationships each year. We quantified the social relationships of a well-studied population of yellow-bellied marmots using six social network traits and fitted a series of Generalized Linear Mixed Models (GLMM) to quantify the relationship between environmental variation and sociality. We found statistically significant relationships between body condition and rainfall on select social network traits for females and males, respectively. Additionally, group size was shown to impact a suite of social network traits for both males and females. Social and demographic variables seem to have larger impacts on an individual’s social plasticity than environmentally driven variables in this system. Following work should investigate how social context drives these important deviations in individual behavior.

Increased temperature and CO2 induce plasticity and impose novel selection on plant traits - D. A. Denney; J. T. Anderson (Integrative and Comparative Biology, 2025)
Climate change is simultaneously increasing atmospheric carbon dioxide concentrations ([CO2]) and temperatures. We conducted a multi-factorial growth chamber experiment to examine how these climate change factors interact to influence the expression of ecologically relevant morphological and phenological traits, clines in these traits, and natural selection on these traits using diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado, USA. Plastic shifts in a key allocation trait (root mass fraction) in response to temperature accorded with the direction of selection via the probability of flowering, indicating that plasticity in this trait could be adaptive. However, plasticity in a foliar functional trait (leaf dry matter content) in response to temperature and [CO2] did not align with the direction of selection, indicating that plasticity could reduce fitness . For another ecologically important phenotype, selection favored resource acquisitive trait values (higher specific leaf area) under elevated [CO2] and resource conservative trait values (lower specific leaf area) at lower [CO2], despite the lack of plasticity in this trait. This pattern of selection counters published reports that elevated [CO2] induces low specific leaf area but could enable plants to reproduce across a greater period of the growing season under increasingly warm climates. Indeed, warmer temperatures prolonged the duration of flowering. This plasticity is likely adaptive, as selection favored increased flowering duration in the higher temperature treatment level. Thus, climate change could impose novel and unanticipated patterns of natural selection on plant traits, and plasticity in these traits can be a maladaptive response to stress.

Canopy structure modulates the sensitivity of subalpine forest stands to interannual snowpack and precipitation variability - Max Berkelhammer; G. Page; F. Zurek; C. Still; Mariah Carbone; W. Talavera; L. Hildebrand; J. Byron; K. Inthabandith; A. Kucinski; M. Carlson; K. Foss; et al. (Hydrology and Earth System Science, 2025)
Abstract. A declining spring snowpack is expected to have widespread effects on montane and subalpine forests in western North America and across the globe. The way that tree water demands respond to this change will have important impacts on forest health and downstream water subsidies. Here, we present data from a network of sap velocity sensors and xylem water isotope measurements from three common tree species (Picea engelmannii, Abies lasiocarpa and Populus tremuloides) across a hillslope transect in a subalpine watershed in the Upper Colorado River basin. We use these data to compare tree- and stand-level responses to the historically high spring snowpack but low summer rainfall of 2019 against the low spring snowpack but high summer rainfall amounts of 2021 and 2022. From the sap velocity data, we found that only 40 % of the trees showed an increase in cumulative transpiration in response to the large snowpack year (2019), illustrating the absence of a common response to interannual spring snowpack variability. The trees that increased water use during the year with the large spring snowpack were all found in dense canopy stands – irrespective of species – while trees in open-canopy stands were more reliant on summer rains and, thus, more active during the years with modest snow and higher summer rain amounts. Using the sap velocity data along with supporting measurements of soil moisture and snow depth, we propose three mechanisms that lead to stand density modulating the tree-level response to changing seasonality of precipitation: Topographically mediated convergence zones have consistent access to recharge from snowmelt which supports denser stands with high water demands that are more reliant and sensitive to changing snow. Interception of summer rain in dense stands reduces the throughfall of summer rain to surface soils, limiting the sensitivity of the dense stands to changes in summer rain. Shading in dense stands allows the snowpack to persist deeper into the growing season, providing high local reliance on snow during the fore-summer (early-summer) drought period. Combining data generated from natural gradients in stand density, like this experiment, with results from controlled forest-thinning experiments can be used to develop a better understanding of the responses of forested ecosystems to futures with reduced spring snowpack.

The sound of fear is heritable - Daniel T. Blumstein; N. Vu; M. N. Edic; L. Vo; J. G. A. Martin (Current Zoology, 2025)
The nonlinearity and fear hypothesis predicts that highly aroused vocal mammals and birds produce vocalizations (notably alarm calls and screams) which contain a variety of nonlinear phenomena (NLP). Such vocalizations often sound “noisy” because vocal production systems are over-blown when animals are highly aroused. While much is known about the conditions under which animals produce vocalizations containing NLP and how species respond to them, there is little research about the heritability of such behavioral traits. Using the quantitative genetic ani- mal model, we estimated the genetic basis of “noise” in alarm calls produced by females and found significant heritability in call entropy—our measure of the noisiness. About 9% of the variance in noisiness can be accounted for by genetic differences. Taken together, these findings suggest that the degree to which marmots produce noisy calls is modestly heritable and can be thus subject to further evolution via natural selection. Key words: acoustic communication, animal model, fear communication, heritability of vocalizations, yellow-bellied marmot.

The effects of drought on wildflower size and seed set - G. Shirley (2025)
Climate change is leading to shifts in precipitation, including longer and more severe droughts. Perennial wildflowers in subalpine dry meadows are affected by current and potentially future droughts in the Rocky Mountains, and several species have shown phenotypic plasticity in response to environmental factors such as temperature, snowmelt date, and soil moisture. I compared the floral size and number of seeds between control and rainout-covered transects for the three plant species Delphinium nuttallianum, Eremogone (Arenaria) congesta, and Erigeron flagellaris. I found no significant difference between treatments in the flower size, nectar tube depth, or inflorescence height of any focal species. Seed set also did not vary significantly between rainout and control transects, and I did not find a correlation between floral size and seed set. These results do not indicate that the plants’ reproduction is negatively impacted by increased drought stress beyond that already present in the year of study.

Moss and vascular plant cover across elevational gradients in a changing alpine climate - E. Ristau (2025)
Mosses are foundational members of alpine plant communities but are often excluded from vegetation monitoring. In this study, I surveyed moss and vascular plant cover across five alpine ridges near Gothic, Colorado to understand how environmental variables shape moss abundance. I analyzed vegetation composition using data and related moss prevalence to elevation, slope, wetness, and climate trends. Moss presence was low across all sites, with most quadrats containing less than 5% moss cover. Wetness emerged as the strongest predictor of moss prevalence, with slope and elevation also influencing patterns in combination. Moss response to climate change was site-specific: rates of change in growing degree days and snowpack persistence over the past 2-3 decades showed inconsistent effects, with only one site (Crystal) showing a positive relationship between warming and moss prevalence. These findings suggest mosses occupy a narrow and shifting niche in alpine habitats, shaped by fine-scale topography and moisture availability. The patchy, low-cover distributions documented here highlight the need for continued monitoring of mosses in alpine climate change research.

Nutrient niche dynamics among wild pollinators - J. A. Bain; Jane E. Ogilvie; William K. Petry; Paul J. CaraDonna (Proceedings of the Royal Society B: Biological Sciences, 2025)
Food underpins fitness and ecological interactions, yet how nutrient availability shapes species interactions in natural communities remains poorly understood. Most nutritional ecology research focuses on laboratory or single-species systems, limiting insight into how nutrient use and nutrient niche dynamics occur in complex, multispecies assemblages in the wild. We combined long-term plant-pollinator interaction data with pollen macronutrient analyses to examine how wild bumble bees exploit macronutrients and whether they occupy distinct nutrient niches. Pollen macronutrient composition varied across plant species and over the season, with protein-rich pollen peaking in spring and lipid- and carbohydrate-rich pollen increasing by late summer. Across this nutrient landscape, bumble bee species occupied two distinct macronutrient niches: one high in protein and low in lipid and carbohydrate, and the other lower in protein but moderate in lipid and carbohydrate. Nutrient niche partitioning was associated with differences in feeding morphology and colony life stage (but not phenology). We found little evidence that nutrient niche breadth differed among species or was explained by feeding morphology or colony life stage. Our results extend nutritional ecology to a multispecies context, provide evidence for nutrient niche partitioning among wild pollinators and highlight the need to consider species-specific nutritional requirements in pollinator conservation.

Is the propensity to alarm-call heritable and related across multiple contexts? - Daniel T. Blumstein; C. J. Velasquez; K. A. Adler; J. G. A. Martin (Animal Behaviour, 2025)
Alarm calling is an important antipredator behaviour by which individuals alert conspecifics and heterospecifics of possible danger and/or ward off potential predators. The propensity to utter calls may reflect the amount of risk an individual experiences and a variety of other internal and environmental factors that may be context and species specific. However, whether the propensity to utter alarm calls is heritable has not been studied. Using a quantitative genetic animal model, we estimated the heritability of alarm calling in yellow-bellied marmots, Marmota flaviventer . We found significant heritability in the propensity to utter naturally elicited alarm calls (0.06) and trap-elicited alarm calls when marmots were trapped (0.21). There was a small but significant genetic correlation between these traits (0.338). Together, these results show that the propensity to utter alarm calls is individually variable and context dependent and can evolve in response to natural selection. • We estimated heritability of natural vs trap-elicited alarm-calling propensity. • Alarm calling propensity was heritable in both contexts. • Natural calling rates had lower heritability than trap-elicited calling rates. • There was a small, but significant, genetic correlation between calling in both contexts. • The propensity to utter alarm calls can evolve in response to natural selection.

Running on Empty: Climate Change and the Future of the Colorado River Basin - Mehdi Nemati; Daniel Crespo; Ariel Dinar; Paloma Avila (Scientia, 2025)
Amid growing pressures from climate change and population growth, water availability in the Colorado River Basin is declining while demand continues to rise. At the Water Dialogue Lab at the University of California, Riverside (UCR), Prof Mehdi Nemati and his colleagues, Dr Daniel Crespo, Prof Ariel Dinar, and Ms Paloma Avila from UCR’s School of Public Policy, along with Mr Zachary Frankel and Mr Nicholas Halberg from the Utah Rivers Council, have developed integrated models to assess changes in water availability, use, and associated economic values across the Basin. Their research evaluates the effects of climate change and policy interventions on both physical water supply and economic outcomes. Their findings highlight the need for adaptive planning, improved economic resilience, and policy reforms to ensure long-term sustainability in the region.

Phenology: An Integrative Environmental Science - David W. Inouye; F. E. Wielgolaski; F. E. Wielgolaski; David W. Inouye (2025)

A nectar-inhabiting bacterium may not influence female fitness in Ipomopsis aggregata - I. Garcia (2025)
Hummingbirds are known to select which floral resource to utilize based on visual and olfactory cues. The role that microbes play in mediating the mutualism between hummingbirds and flowers is mostly unexplored in the field of microbial and pollination ecology. Bee pollinators are known to be deterred by high concentration of bacterial nectar, and the same has been shown for hummingbirds but only in one highly controlled setting with artificial flowers. There is limited evidence on how bacterial nectar influences hummingbird pollination, especially in wild systems. We tested if the presence of Pantoea sp., a plant generalist bacterium, in floral nectar influences the female fitness of Ipomopsis aggregata, a hummingbird-pollinated wildflower. Plants were inoculated with sterile or bacterial nectar, at the end of the growing season, seed set, fruit set, and fly larval predation were calculated to test the effects of bacterial nectar on plant fitness. Floral and vegetative plants were also accounted for in our fitness models. We found no significant differences in seed set, fruit set, or predation between our Pantoea-treated plants and sterile nectar treatments. We found that larger floral and vegetative traits of I. aggregata were associated positively with seed set and predation, but not fruit set. Pollen limitation was found to be minimal or absent, hand pollination did not prove to significantly improve seed or fruit production. Hummingbird pollination or female fitness of Ipomopsis aggregata was not affected by Pantoea sp. in floral nectar in field realistic conditions. Plant morphology was found to play a more important role in reproductive success than microbial nectar dynamics. These results suggest that microbial mediation of plant-pollinator mutualisms may be context-dependent and not universally disruptive.

Nonlinear phenomena in marmot alarm calls: a mechanism encoding fear? - Daniel T. Blumstein (Philosophical Transactions of the Royal Society B, 2025)
I review a case study of marmots that contributed to the empirical basis of the nonlinearity and fear hypothesis, which explains why certain nonlinear acoustic phenomena (NLP) are produced in extremely high-risk situations and communicate high urgency. In response to detecting predatory threats, yellow-bellied marmots (Marmota flaviventer) emit alarm calls and, in some situations, emit fear screams. Prior work on marmots has shown that call production is associated with the degree of risk the caller experiences and that they are individually distinctive. Receivers respond to calls and are sensitive to variation in caller reliability. Calls also contain nonlinear acoustic phenomena. Work has shown that socially isolated animals and those infected with Eimeria, an intestinal parasite, produced 'noisier' calls. However, animals that were likely under greater stress (as measured with faecal glucocorticoid metabolites) produced more structured and less noisy calls. The addition of NLP increases responsiveness in receivers. NLP in alarm calls have modest heritability. Taken together, the study of NLP in marmots has enhanced our understanding of the potential information encoded in alarm calls and is consistent with the hypothesis that variation in NLP production communicates fear, which stimulates work with other species, including humans.This article is part of the theme issue 'Nonlinear phenomena in vertebrate vocalizations: mechanisms and communicative functions'.

Conditional syndromes: Effect of human disturbance and age on the correlation between flight initiation distance and vigilance in marmots - K. Uchida; I. DeVito; J. G. A. Martin; Daniel T. Blumstein (Behavioral Ecology and Sociobiology, 2025)
Behavioral syndromes—suites of correlated behaviors across different situations and contexts—are widespread and can have important ecological consequences because correlations between distinct behaviors shape how animals respond to changing environmental conditions and can limit behavioral plasticity. Behaviors such as vigilance, foraging, and explora- tion are correlated in many species and thus constitute a syndrome. Studying the structure of such syndromes is important to understand potential constraints on an animal’s behavioral response to the environment. Importantly, we know rela- tively little about antipredator behavioral syndromes and how their structure is associated with environmental conditions. Here, we estimated the correlation between two antipredator behaviors in yellow-bellied marmots (Marmota flaviventer): flight initiation distance (FID), which quantifies the flightiness of an animal in response to a potential predator and time allocation to vigilance while foraging, which represents an individual’s baseline level of wariness. We also examined the correlation between these traits under two different human disturbance levels by fitting a bivariate model on data collected over 18 years from 739 individuals. We found a modest positive among-individual correlation between FID and vigilance in adults, but no correlation between those variables in the much larger yearling cohort, nor when datasets for yearlings and adults were combined. We found no support for the hypothesis that human disturbance changed the structure of the syndrome (when present). Our study suggests that antipredator syndromes may be age-specific, and thus constraints on the independent expression of the behaviors underlying those are age-specific as well. Significance statement Understanding the structure of antipredator behavioral syndromes is important to better predict how animals behave in response to environmental changes, including anthropogenic disturbance. This study examined the correlation between flight initiation distance (FID), which quantifies flightiness of individuals to an approaching predator, and time allocation to vigilance while foraging, which represents an individual’s baseline level of wariness in yellow-bellied marmots. We also compared the syndrome structure in two different anthropogenically disturbed environments (highly- vs. less- disturbed). We found a positive correlation between FID and vigilance in adult marmots, but no correlation in yearlings. Anthropo- genic disturbance did not modify the correlation structure between FID and vigilance. Overall, antipredator syndromes appear to be age-specific, and human disturbance, as quantified in the present study, does not influence the structure of antipredator syndromes. Our results suggest that flexible behavior plays a key role in allowing marmots to cope with human disturbance.

Brief for 30 Members of the U.S. House and Senate as Amici Curiae in Support of Respondents, Seven County Infrastructure Coalition v. Eagle County Colorado - Cale Jaffe (SSRN Electronic Journal, 2025)

Picky eater? How different environmental factors affect broad-tailed hummingbirds’ (Selasphorus platycercus) foraging patterns in the Rocky Mountains - T. Ngo (2025)
Plant and pollinator interactions are a form of mutualism requiring a careful balance between floral traits and pollinator behavior to maximize both pollination success and nectar consumption. This delicate relationship can result in detrimental effects on one party when the other shifts. Namely, global warming is causing phenological mismatches in many different ecosystems, where migratory species’ resources are impacted due to advanced flowering phenology. For example, many studies conducted at the Rocky Mountains Biological Laboratory (RMBL) in Gothic, Colorado have shown that the breeding season of Broad-tailed hummingbirds (Selasphorus platycercus) is shortened due to advanced blooming of early season species and no extension in late species’ blooming period. Moreover, climate change can affect environmental patterns like temperature, snowmelt timing or precipitation, which can alter resource availability for the hummingbirds within their breeding season. In this study, I analyzed the correlations between snowmelt date, daily temperature fluctuations, rainfall, floral abundance, nectar quality, and studied how these factors relate to hummingbird foraging patterns by analyzing available long-term data sets. In my results, I found little statistical evidence for a direct correlation between hummingbird visitation rate and these biotic and abiotic factors. However, I found many underlying patterns when looking at different combinations of variables. For example, temperature can increase or decrease nectar quality depending on the flower species, and the relationship between visitation rate for each species and daily temperature varies. This study reinforces the complex, interdependent way in which different abiotic and biotic factors interact to influence Broad-tailed hummingbirds’ foraging patterns, highlighting how the cascading ecological effects of climate change on the plant-pollinator mutualism. 6

Reimagining river governance: Insights from the Colorado river crisis - Geraldo Wilson Fernandes; Geraldo Wilson Fernandes; Cássio Cardoso Pereira; Jessica Raty; Kevin Wheeler (BioScience, 2025)

Controls from above and below: Snow, soil, and steepness drive diverging trends of subsurface water and streamflow dynamics - D. Kerins; A. Knapp; F. S. Liu; V. D. Smykalov; M. P. Berzonsky; A. Vierbicher; K. Sadayappan; Brandy Stewart; E. D. Andrews; P. Sullivan; H. R. Barnard; J. Seibert; et al. (Hydrological Processes, 2025)

Society formation and maintenance in yellow-bellied marmots - Daniel T. Blumstein (Animal Behaviour, 2025)
Yellow-bellied marmots, Marmota flaviventer , are facultatively social and may form multigenerational societies, which are characterized by individuals sharing and defending space, possessing the ability to distinguish group members from outsiders and potentially persisting for many generations. I review some 63 years of continuous study that has revealed a number of insights about the adaptive value of sociality and societies. Because of their facultative sociality and because we have studied social behaviour and societies a variety of different of ways over the years, this social variation makes it difficult to make simple summary statements about society structure and formation. None the less, this variation may make them a good system in which to study incipient society formation. • Yellow-bellied marmots are facultatively social and at times live in societies. • Societies form when adult females recruit their daughters. • Males may interact with one or more societies. • I discuss the structure of these societies and some outstanding questions about them.

Genetic basis of an adaptive polymorphism controlling butterfly silver iridescence - L. Livraghi; J. J. Hanly; L. S. Loh; A. Henry; M. T. C. Keck; V. M. Shirey; C. C. Tsai; N. Yu; S. M. Van Bellegham; W. M. Roberts; C. L. Boggs; A. Martin (Current Biology, 2025)

Fitness costs and benefits of a non-native floral resource for subalpine solitary bees - Charlotte M. Cahill; Paul J. CaraDonna; J. R. K. Forrest (Oikos, 2025)
Organisms inhabiting seasonal environments must fit their life cycle into a limited time window while also synchronizing periods of resource consumption with timing of resource availability. Introduced non‐native species, which often differ in phenology from natives, can alter and expand the seasonal window of resource availability for native consumers, providing potential fitness benefits. However, if these non‐native resources are nutritionally unsuitable for native consumers, their presence could elicit foraging behaviour that proves maladaptive – i.e. they could act as an ecological trap. Here, we used multi‐year field observations and a laboratory experiment to investigate the impacts of a common non‐native plant species on two components of fitness in three solitary bee species (all specialist consumers of pollen from the plant family Asteraceae) native to the Colorado Rocky Mountains. First, we tested whether individual bees that collect pollen from the non‐native common dandelion Taraxacum officinale produce more offspring than those that do not, thanks to the unusually early flowering phenology of the non‐native. Second, we compared survival of bee larvae experimentally reared on Taraxacum pollen to that of larvae reared on native Asteraceae pollen. Bees that used at least some non‐native Taraxacum pollen produced more potentially viable offspring, but larval survival was significantly reduced for bee larvae experimentally fed provisions dominated by Taraxacum pollen. Therefore, survival costs may negate the potential fitness benefits of early nesting, indicating that non‐native floral resource use may act as an ecological trap for native bees. Using a series of simple simulations informed by our results, we explore the fitness effects of non‐native floral resource use, demonstrating that the net cost or benefit depends on how bees respond to resource shortages. Our results highlight the importance of considering organisms' full life cycles when evaluating the fitness consequences of resource availability and species introductions.

Adaptation and gene flow are insufficient to rescue a montane plant under climate change - J. T. Anderson; M. L. Demarche; D. A. Denney; Ian K Breckheimer; J. Santangelo; Susana M. Wadgymar (Science, 2025)
Climate change increasingly drives local population dynamics, shifts geographic distributions, and threatens persistence. Gene flow and rapid adaptation could rescue declining populations yet are seldom integrated into forecasts. We modeled eco-evolutionary dynamics under preindustrial, contemporary, and projected climates using up to 9 years of fitness data from 102,272 transplants (115 source populations) of Boechera stricta in five common gardens. Climate change endangers locally adapted populations and reduces genotypic variation in long-term population growth rate, suggesting limited adaptive potential. Upslope migration could stabilize high-elevation populations and preserve low-elevation ecotypes, but unassisted gene flow modeled with genomic data is too spatially restricted. Species distribution models failed to capture current dynamics and likely overestimate persistence under intermediate emissions scenarios, highlighting the importance of modeling evolutionary processes.

Functional morphology of pollen capture in Syrphid flies (Diptera syrphidae): The effects of pile density and body region - J. Devora (2025)
This paper will focus on Syrphidae, an understudied but potentially impactful pollinator. Specifically, I will investigate how the density of the pile (hair) affects the amount of pollen grains carried. This research has the potential to significantly contribute to the field of entomology, as it addresses the controversy about the efficiency of Syriphidae as pollinators, especially in the context of the global decline of primary pollinators such as bees. To conduct this, I will gather Syrphids using the established protocol from the Berry Brosi Lab. The Syrphids will be microscopically examined to determine their pile density and the number of pollen grains present. I expect that as the pili are more dense, more pollen grains will be gathered by a Syrphid fly. Additionally, I will be examining six body parts and comparing the differences in the amount of pollen grains they can carry. I expect essential body parts for pollination, such as the face and ventral thorax, will contain more pollen grains than passive body parts. This research is significant due to the lack of comprehensive studies on Syriphidae, particularly regarding their roles as pollinators.

The effect of changing floral density on pollinator networks in a subalpine meadow environment - R. Jewett (2025)
Plant-pollinator networks shape the populations of flowering plants across the world. Ecosystems face increasing challenges that decrease floral density and threaten to restructure plant-pollinator networks. The responses of these networks will play a critical role in the fates of plant species, because pollinator foraging decisions are made in the context of a multispecies floral community. Pollinators make foraging decisions to optimize the foraging cost/benefit ratio based on factors including energy expended and gained. The loss of a single generalist plant species has been observed to disproportionately impact the pollinator network, decreasing visitation rates to surrounding plants. However, it is unknown how the concurrent decline of multiple flower species might affect the pollinator community and network. Understanding the impact of floral density on the pollinator network is critical for predicting the effects of ecosystem change. We applied clipping treatments to thirty-six eight-by-eight meter plots to create gradients of floral density for four wildflower species. Pollinator observation data was used to quantify pollinator community variation across plots and calculate network metrics to understand the impact of floral density on the pollinator network. Our findings suggest that changing floral density affects pollinator composition, total pollinator visits, and visitation rate, and has no effect on nestedness or specialization. This has implications for the resilience of plant-pollinator networks and their ability to withstand future threats because these relationships have the potential to increase or decrease plant resilience, an outcome that will help determine the fate of plant populations as they respond to environmental change.

Visitors to Red-Naped Sapsucker sap wells and the effectiveness of artificial wells - S. M. Graham (2025)

Beyond static color: Exploring spatial and temporal dimensions of animal visual signals - A. Miller (2025)

The impacts of environmental change on plant and microbial communities: A turf transplant experiment in the Colorado Rocky Mountains - L. Seltzer (2025)
Climate change is altering both above-ground plant communities and below-ground microbial assemblages, yet their simultaneous responses to altered climate remain poorly understood. To address this, we conducted a whole-community transplant experiment across a 400-meter elevation gradient in the Colorado Rocky Mountains, examining how plant and soil fungal and bacterial/archaeal communities respond to experimental warming and cooling. Transplantation to warmer sites led to rapid, directional shifts of all groups, with compositions changing to resemble those at lower, warmer sites, and diverging from higher origin sites. Soil bacteria and archaea responded most strongly, followed by fungi and then plants, indicating W differing sensitivities. Variation in responses may lead to novel communities, potentially disrupting relationships that affect ecosystem resilience. In contrast, transplantation to cooler IE sites led to weaker, slower, and more variable responses, with limited evidence of community turnover. This indicates that low elevation species may successfully establish upslope if dispersal EV barriers are overcome, potentially increasing the vulnerability of high elevation communities to novel competitors. PR

Hydrologic connectivity shapes watershed response to climate variability from local to global scales - K. Johnson (2025)
Gynodioecy is a mode of sex expression where male sterlie (hereafter female) plants and hermaphroditic plants coexist within a population. In order for the females to be maintained by natural selection, they must have experienced an increased fitness. Fitness is defined as the ability of genotype or phenotype to contribute genes to the pool of seeds for the next generation. Since females only transmit their genes through seed production, their inability to produce pollen has to be compensated for. Experimental evidence from a variety of gynodioecious species have not found the theoretically required fitness advantage for females. This is in part may be due to interactions of the plant with its local frequency and density and not the global population characteristics. Females in particular may become pollen limited as the density and frequency of hermaphrodites declines. I present the results of a study that examined the effect of hermaphrodite density and frequency at three spatial scales on pollen receipt of Geranium richardsonii in four populations in Gothic, CO. In the lower density, patchy populations the smaller spatial scales seem to be more important to female pollination success . As the density of the populations increased the total hermaphrodite density and female frequency become able to explain more of the variation in female pollen receipt. The small spatial scales did not seem to determine the hermaphrodites pollination success as a large portion of the variation could be explained by the total hermaphrodite density.

Dimensions of difference: Multi-scale consequences of trait variation in bumble bees - J. L. Fitzgerald (2025)
Body size is arguably one of the most important traits influencing the physiology and ecology of animals. Shifts in animal body size have been observed in response to climate change, including in bumble bees (Bombus spp.). Bumble bee size shifts have occurred concurrently with the precipitous population declines of several species, which appear to be related, in part, to their size. Body size variation is central to the ecology of bumble bees, from their social organization to the pollination services they provide to plants. If bumble bee size is shifted or constrained, there may be consequences for the pollination services they provide and for our ability to predict their responses to global change. Yet, there are still many aspects of the breadth and role of bumble bee body size variation that require more study. To this end, we review the current evidence of the ecological drivers of size variation in bumble bees and the consequences of that variation on bumble bee fitness, foraging, and species interactions. In total we review: (1) the proximate determinants and physiological consequences of size variation in bumble bees; (2) the environmental drivers and ecological consequences of size variation; and (3) synthesize our understanding of size variation in predicting how bumble bees will respond to future changes in climate and land use. As global change intensifies, a better understanding of the factors influencing the size distributions of bumble bees, and the consequences of those distributions, will allow us to better predict future responses of these pollinators.

Investigating KDP signatures inside and below the dendritic growth layer with W-band Doppler radar and in situ snowfall camera - A. Kotsche; A. Myagkov; L. von Terzi; Maximilian Maahn; V. Ettrichrätz; T. Vogl; A. Ryzhkov; P. Bukovic; D. Ori; Heike Kalesse-Los (Atmospheric Chemistry and Physics, 2025)

Evaluation of cloud height, optical thickness, and phase retrievals from the CHROMA algorithm applied to Sentinel-3 OLCI data - A. M. Sayer; B. Cairns; K. D. Knobelspiesse; L. Lelli; C. Rajapakshe; S. E. Giangrande; Gavin H. Thomas; D. Zhang (Atmospheric Measurement Techniques, 2025)

Best restoration practices: Do BDAs mimic inundation patterns of natural beaver dams? - A. Daniel (2025)
​ Watershed degradation in the Western United States is a continuing issue under climate change. The headwaters to the Colorado River in the Rocky Mountains are experiencing dryness, altered chemistry, and flashiness due to climate change. Management practices involving artificial beaver dams (BDAs) have been used to counteract these issues. Though well intentioned, lack of monitoring has led to a lack of understanding of how these BDAs are impacting streams. There are uncertainties of how inundation patterns behind BDAs will change in shape, width, depth, and sediment deposition after a beaver further engineers the dams. We sampled six BDA ponds and beaver-augmented BDA ponds to compare a variety of morphological characteristics related to hydrology The beaver-augmented BDA ponds were significantly deeper than the BDA ponds since continuous engineering on the dams allows for more water impoundment and therefore a deeper pond. The BDA ponds had lower surface areas than the beaver-augmented BDA ponds since they had significantly shorter dams, and the beaver-augmented ponds were also rounder. There were not significant differences in the sediment grain size between treatment types since the beaver-augmented BDA ponds are so new. By comparing BDA habitats to beaver dams, this study improved understanding of the impacts of restoration using BDAs, and can be used in future conservation efforts.

A Bayesian record linkage approach to applications in tree demography using overlapping LiDAR scans - Lane Drew; Andee Kaplan; Ian K Breckheimer (Annals of Applied Statistics, 2025)
In the information age, it has become increasingly common for data containing records about overlapping individuals to be distributed across multiple sources, making it necessary to identify which records refer to the same individual. The goal of record linkage is to estimate this unknown structure in the absence of a unique identifiable attribute. We introduce a Bayesian hierarchical record linkage model for spatial location data motivated by the estimation of individual specific growth-size curves for conifer species using data derived from overlapping LiDAR scans. Annual tree growth may be estimated dependent upon correctly identifying unique individuals across scans in the presence of noise. We formalize a two-stage modeling framework, connecting the record linkage model and a flexible downstream individual tree growth model, that provides robust uncertainty quantification and propagation through both stages of the modeling pipeline via an extension of the linkage-averaging approach of Sadinle (2018). In this paper, we discuss the two-stage model formulation, outline the computational strategies required to achieve scalability, assess the model performance on simulated data, and fit the model to a bi-temporal dataset derived from LiDAR scans of the Upper Gunnison Watershed provided by the Rocky Mountain Biological Laboratory to assess the impact of key topographic covariates on the growth behavior of conifer species in the Southern Rocky Mountains (USA).

Warming disrupts plant–fungal endophyte symbiosis more severely in leaves than roots - Justin D. Edwards; Melanie R Kazenel; Y. Luo; J. S. Lynn; R. L. Mcculley; L.A. Souza; C. Young; Jennifer A. Rudgers; Stephanie N. Kivlin (Global Change Biology, 2025)
Disruptions to functionally important symbionts with global change will negatively impact plant fitness, with broader consequences for species' abundances, distribution, and community composition. Fungal endophytes that live inside plant leaves and roots could potentially mitigate plant heat stress from global warming. Conversely, disruptions of these symbioses could exacerbate the negative impacts of warming. To better understand the consistency and strength of warming-induced changes to fungal endophytes, we examined fungal leaf and root endophytes in three grassland warming experiments in the US ranging from 2 to 25 years and spanning 2000 km, 12°C of mean annual temperature, and 600 mm of precipitation. We found that experimental warming disrupted symbiosis between plants and fungal endophytes. Colonization of plant tissues by septate fungi decreased in response to warming by 90% in plant leaves and 35% in roots. Warming also reduced fungal diversity and changed community composition in plant leaves, but not roots. The strength, but not direction, of warming effects on fungal endophytes varied by up to 75% among warming experiments. Finally, warming decoupled fungal endophytes from host metabolism by decreasing the correlation between endophyte community and host metabolome dissimilarity. These effects were strongest in the shorter-term experiment, suggesting endophyte-host metabolome function may acclimate to warming over decades. Overall, warming-driven disruption of fungal endophyte community structure and function suggests that this symbiosis may not be a reliable mechanism to promote plant resilience and ameliorate stress responses under global change.

Riming-dependent snowfall rate and ice water content retrievals for W-band cloud radar - N. Maherndl; A. Battaglia; A. Kotsche; Maximilian Maahn (Atmospheric Measurement Techniques, 2025)

Observations of surface energy fluxes and meteorology in the seasonally snow-covered high-elevation East River watershed during SPLASH, 2021–2023 - Christopher Cox; Janet Intrieri; Brian Butterworth; Gijs de Boer; M. Kate Gallagher; J. Hamilton; Erik Hulm; T. Meyers; S. Morris; Jackson Osborn; P. O. G. Persson; Benjamin Schmatz; et al. (Earth System Science Data, 2025)

Colorado River Basin: conflict management under hydrologic stress and institutional gridlock - Neil S. Grigg (International Journal of River Basin Management, 2025)
In the Colorado River, hydrologic and legal conditions create difficulty in sharing water effectively and equitably during a deep 22-year drought. Demand outstrips supply, water entitlements are over-appropriated, and institutional arrangements are nearly gridlocked. The crisis poses challenges not experienced before, and these may worsen with climate change and warming. It threatens the water supplies of major cities like Los Angeles and Las Vegas, as well as critical agricultural regions in the U.S. The background began to unfold more than 100 years ago, prior to signing of the Colorado River Compact in 1922. The decade prior to 1922 was relatively wet, and the Compact made water allocations that are not sustainable. Institutional challenges are caused by the rigidity of the rules governing river operations and the complex array of stakeholder organizations and management authorities. Although a wet 2022-3 winter provided temporary and only incremental relief, without a hydrologic reversal and/or effective regulatory controls, water levels in Lakes Powell and Mead will decline further and no storage water will be available to satisfy downstream interests. To avoid that scenario, it is likely that drastic curtailments will occur but forecasting them involves uncertainties and speculation. Achieving effective river basin management during the drought will likely require involuntary cuts, voluntary cuts, and possibly litigation, which will be expensive and long-lasting. Federal funding may help on a temporary basis. Involuntary cuts will require a forceful mechanism to push ahead with solutions despite lack of consensus. Lessons include the challenges in creating equity and sustainable conditions in the dry regions with water right systems based on prior appropriation and how to manage transboundary water conflicts within a federal system of government.

Foraging preferences of generalist Megachilidae - G. Churchland (2025)
Subalpine ecosystems are home to hundreds of species of wildflowers, many of which are endemic and very vulnerable to climate change. Megachilidae are a family of primarily solitary bees that are very efficient pollinators, making them crucial components of subalpine ecosystems. Some Megachilidae species are generalists, meaning they visit a wide variety of flower species, but their exact foraging preferences remain poorly understood. Since some flowers are more affected by climate change than others, understanding generalists’ flower preferences is necessary in predicting their responses to climate change, and in protecting subalpine ecosystems. In this research project I (1) collected pollen samples from generalist Megachilidae nests and analyzed the pollen composition under a microscope, (2) compared the floral abundance in nests with the floral abundance in intentionally placed transects, (3) analyzed any foraging difference across genera, specifically between Osmia and Hoplitis fulgida, and finally (4) analyzed the relationship between transects and quadrats to see if transects were sufficient in estimating overall floral abundance at a site. I found that abundance in the field has differing effects on nest abundance depending on the flower species, with some species found in nests at disproportionately higher or lower rates than their transect abundance. This indicates that Megachilidae have foraging preferences, selectively choosing which flowers to collect from, and these preferences seem to be the most pronounced at low species abundance. In particular, flowers such as Ipomopsis aggregata, Eriogonum umbellatum, and Lathyrus leucanthus were found in lower abundances in the nest as compared with other flower species. Additionally, Linum lewisii had a significantly larger slope than the average species, indicating a preference for L. lewisii as it grew in abundance. I found no significant differences between the foraging preferences of Osmia and Hoplitis, and the floral abundance described by quadrats vs transects was very consistent, indicating that transects are a good method of estimating general floral abundance at a site. 2

Hidden features: How subsurface and landscape heterogeneity govern hydrologic connectivity and stream chemistry in a montane watershed - K. Johnson; K. H. Williams; J. N. Christensen; R. W. H. Carroll; Langlang Li; Curtis A. Beutler; K. Swift Bird; Wenming Dong; P. Sullivan (Hydrological Processes, 2025)
ABSTRACT Hydrologic connectivity is defined as the connection among stores of water within a watershed and controls the flux of water and solutes from the subsurface to the stream. Hydrologic connectivity is difficult to quantify because it is goverened by heterogeniety in subsurface storage and permeability and responds to seasonal changes in precipitation inputs and subsurface moisture conditions. How interannual climate variability impacts hydrologic connectivity, and thus stream flow generation and chemistry, remains unclear. Using a rare, four‐year synoptic stream chemistry dataset, we evaluated shifts in stream chemistry and stream flow source of Coal Creek, a montane, headwater tributary of the Upper Colorado River. We leveraged compositional principal component analysis and end‐member mixing to evaluate how seasonal and interannual variation in subsurface moisture conditions impacts stream chemistry. Overall, three main findings emerged from this work. First, three geochemically distinct end members were identified that constrained stream flow chemistry: reach inflows, and quick and slow flow groundwater contributions. Reach inflows were impacted by historic base and precious metal mine inputs. Bedrock fractures facilitated much of the transport of quick flow groundwater and higher‐storage subsurface features (e.g., alluvial fans) facilitated the transport of slow flow groundwater. Second, the contributions of different end members to the stream changed over the summer. In early summer, stream flow was composed of all three end members, while in late summer, it was composed predominantly of reach inflows and slow flow groundwater. Finally, we observed minimal differences in proportional composition in stream chemistry across all four years, indicating seasonal variability in subsurface moisture and spatial heterogeneity in landscape and geologic features had a greater influence than interannual climate fluctuation on hydrologic connectivity and stream water chemistry. These findings indicate that mechanisms controlling solute transport (e.g., hydrologic connectivity and flow path activation) may be resilient (i.e., able to rebound after perturbations) to predicted increases in climate variability. By establishing a framework for assessing compositional stream chemistry across variable hydrologic and subsurface moisture conditions, our study offers a method to evaluate watershed biogeochemical resilience to variations in hydrometeorological conditions.

Measurement report: An investigation of the spatiotemporal variability in aerosols in the mountainous terrain of the upper Colorado River basin using SAIL-Net - L. D. Gibson; E. J. T. Levin; E. Emerson; N. Good; A. Hodshire; G. McMeeking; K. K. Patterson; B. Rainwater; T. Ramin; B. Swanson (Atmospheric Chemistry and Physics, 2025)
Abstract. In the western US and similar topographic regions across the world, precipitation in the mountains is crucial to local and downstream freshwater supplies. Atmospheric aerosols can impact clouds and precipitation by acting as cloud condensation nuclei (CCN) and ice-nucleating particles (INPs). Previous studies suggest that there is increased aerosol variability in these regions due to their complex terrain, but none of these studies have quantified the extent of this variability. In the fall of 2021, Handix Scientific contributed to the Surface Atmosphere Integrated Field Laboratory (SAIL), funded by the US Department of Energy (DOE) and situated in the East River watershed (ERW; Colorado, USA), by deploying SAIL-Net, a novel network of six aerosol measurement nodes spanning the horizontal and vertical domains of SAIL. The ERW is a topographically diverse region, meaning individual measurement sites can miss important observations of aerosol–cloud interactions. Each measurement node included a small particle counter (the Portable Optical Particle Spectrometer – POPS), a miniature CCN counter (CloudPuck), and a filter sampler (the Time-Resolved Aerosol Particle Sampler – TRAPS) for INP analysis. SAIL-Net studied the spatiotemporal variability in aerosols and the usefulness of dense measurement networks in complex terrain. After the project's completion in the summer of 2023, we analyzed the data to explore these topics. We found increased variability compared to a similar study over flat land. This variability was correlated with the elevation of the sites, and the extent of the variability changed seasonally. These data and analyses serve as a valuable resource for continued research into the role of aerosols in the hydrologic cycle and as the foundation for designing measurement networks in complex terrain.

The role of soil in regulating plant performance in Valeriana edulis - C. Boxwell (2025)
Climate change is currently shifting the ranges of plant species, and while climate-based variables trigger migration, sessile plants may reach an expansion limit due to variations in the characteristics of local soils. To better understand the effects of soil on plant performance, we paired 13 years of demographic data on Valeriana edulis with gridded and field-collected soil data, then built vital rate models with these soil covariates to determine their impact on plants across the life cycle. We found that average grain size was highly influential on the survival, flowering, and seed production rates of Valeriana edulis. Water holding capacity and pH had moderate effects on flowering, and nitrogen had no meaningful impact. By analyzing how individual soil characteristics the performance of Valeriana edulis across its life cycle, we can make informed predictions about the eventual fate of the species under new environmental regimes.

Salamanders impact on L. externus population densities - T. Kelley (2025)
The caddisfly L. externus has been observed to have a decline in population density over the summer months as the larvae develop. However this pattern has not been formally tested, so collecting population density data is important for future research and understanding changes in densities over time. At the Mexican Cut, L. externus is common prey to tiger salamanders which may impact the magnitude of the density decline. This leads us to the question: How does the population number of L. externus decline over time in ponds with and without salamander predation? My hypothesis is the L. externus population density will decline at a steeper rate in ponds with salamanders than those without salamanders. Eight ponds were sampled with four being salamander and the other half being non salamander. The results found were that in the salamander ponds there was a steeper slope but a higher abundance at the beginning and in the non salamander ponds there was still a slope but significantly, statistically different (P<0.05).

Abiotic influences on continuous conifer forest structure across a subalpine watershed - H. Marshall Worsham; Haruko M. Wainwright; T. Powell; Nicola Falco; L. M. Kueppers (Remote Sensing of Environment, 2025)
Understanding the abiotic drivers of high-elevation forest physiognomy is essential for forecasting how mountain ecosystems will respond to emerging environmental pressures. Most prior studies of these relationships have relied on small samples of the full landscape, resulting in limited power to detect dominant covariates and their interactions. Here we report the first evaluation of abiotic influences on a complement of accurate, wall-to-wall estimates of conifer forest structure and composition at the watershed scale. In a subalpine conifer domain in the Colorado Rocky Mountains (USA), we developed a novel method for deriving stand structure metrics from waveform LiDAR data, which showed high fidelity with field inventory. We quantified the relationships between structural and compositional metrics and climate, topographic, edaphic, and geologic factors. Our results showed that peak snow water equivalent (SWE), snow disappearance rate, and elevation explained most of the variation in forest structure. The highest stand density, basal area, maximum canopy height, and quadratic mean diameter occurred in sites with SWE around one standard deviation below mean, but with long snow residence times. Stand density decreased linearly with elevation, while other metrics peaked between 3000 m.a.s.l. and 3200 m.a.s.l. Substrate properties had weaker influence. Continuous mapping of through-canopy forest structure enabled our novel findings of the dominant role of snowpack in explaining structural and compositional variation, and of elevation thresholds. Our reproducible approach facilitates assessment of forest-topoclimate relationships in other conifer-dominated landscapes and improves understanding of the baseline patterns controlling forest structure, which is needed for predicting long-term ecological change. • Novel waveform LiDAR workflow yields accurate subalpine conifer forest metrics. • Snow and elevation explain the most variation in forest structure and composition. • Maximum stand density and stature map water-energy limitation thresholds. • Species composition mediates snow effects on stand density.

Dispersal of the golden-mantled ground squirrel (Callospermophilus lateralis) - N. Nguyen; Caitlin P. Wells; D. H. Van Vuren (Journal of Mammalogy, 2025)
Dispersal is common in mammals and can have an important role in shaping demography, genetics, distribution, and social structure. Dispersal entails potential costs but also potential benefits, and the dispersal decision is thought to be conditional; the potential disperser assesses prospects for success at its current location and disperses to improve its fitness. However, the costs and benefits of dispersal, as well as factors influencing the dispersal decision, are not well known. We used trapping and observation to study dispersal in the Golden- mantled Ground Squirrel (Callospermophilus lateralis), a species for which dispersal is largely unknown. We characterized the dispersal process by evaluating dispersal timing and distance, assessed factors that might influence the dispersal decision, and analyzed the fitness cost of dispersal after settlement. We found that most dispersal occurred during the summer of birth, as is expected for a small-bodied sciurid. However, some squirrels delayed dispersal until early in their yearling summer. Dispersal was male-biased in dispersal tendency, and it was also male-biased in dispersal distance, but only over shorter dispersal distances. The dispersal decision for juvenile females appeared to originate as soon as 10 days after they emerged from the natal burrow, and the decision was not associated with body mass or several measures of competition. Instead, dispersal of juvenile females was associated with the number of littermate sisters, with each sister present increasing the likelihood of dispersal by 26%. Littermate sisters might be a cue foretelling the effects of kin competition the following year. We did not find a significant difference in lifetime reproductive success between philopatric and dispersing females after settlement, suggesting that for golden-mantled ground squirrels, any cost of dispersal is experienced primarily during the transience phase.

Climatic variation and risk assessment in a highly seasonal mammal - M. Sanchez; J. G. A. Martin; Daniel T. Blumstein (Current Zoology, 2025)
Climate change and its resulting effects on seasonality are known to alter a variety of animal behaviors including those related to foraging, phe- nology, and migration. Although many studies focus on the impacts of phenological changes on physiology or fitness enhancing behaviors, fewer have investigated the relationship between variation in weather and phenology on risk assessment. Fleeing from predators is an economic deci- sion that incurs costs and benefits. As environmental conditions change, animals may face additional stressors that affect their decision to flee and influence their ability to effectively assess risk. Flight initiation distance (FID)—the distance at which animals move away from threats—is often used to study risk assessment. FID varies due to both internal and external biotic and physical factors as well as anthropogenic activities. We asked whether variation in weather and phenology is associated with risk-taking in a population of yellow-bellied marmots (Marmota flaviven- ter). As the air temperature increased marmots tolerated closer approaches, suggesting that they either perceived less risk or that their response to a threat was thermally compromised. The effect of temperature was relatively small and was largely dependent upon having a larger range in the full data set that permitted us to detect it. We found no effects of either the date that snow disappeared or July precipitation on marmot FID. As global temperatures continue to rise, rainfall varies more and drought becomes more common, understanding climate-related changes in how animals assess risk should be used to inform population viability models. Key words: climate change, flight initiation distance, phenology, temperature, yellow-bellied marmots.

The Ohio Mine, Ouray County, Colorado: A Famous Quartz Locality Revisited - Jasper Bertisen; Robert Stoufer (Rocks & Minerals, 2025)

Matrix diffusion controls mountain hillslope groundwater ages and inferred storage dynamics - Nicholas Thiros; E. R. Woodburn; William Payton Gardner; P. James Dennedy-Frank; K. H. Williams (Groundwater, 2025)
Groundwater age distributions provide fundamental insights on coupled water and biogeochemical processes in mountain watersheds. Field-based studies have found mixtures of young and old-aged groundwater in mountain catchments underlain by bedrock; yet, the processes that dictate these groundwater age distributions are poorly understood. In this work, we use the coupled ParFlow-CLM integrated hydrologic and EcoSLIM particle tracking models to simulate groundwater age distributions on a lower montane hillslope in the East River Watershed, Colorado (USA). We develop a convolution-based approach to propagate fracture-matrix diffusion processes to the EcoSLIM advection-dominated age distributions. We compare observed 3 H and 4 He concentrations from two groundwater wells against model predictions that have varying advective transport times and matrix diffusion magnitudes. Based on a Monte Carlo analysis that considers uncertain matrix and fracture parameters, we find that matrix diffusion is needed to jointly predict 3 H and 4 He observations at both wells. The advection-dominated age distributions lack adequate mixing of young and old-aged water to capture the observed co-occurrence of 3 H and 4 He. The model scenario that best matches the 3 H, 4 He, and water level observations when considering both advective flowpath and matrix diffusion mixing processes has a dynamic bedrock groundwater reservoir that is susceptible to considerable storage losses during low-snow periods. This dynamic groundwater system amplifies the need to assimilate deeper bedrock groundwater into watershed hydro-biogeochemical predictions. This work further highlights the importance of considering matrix diffusion when interpreting environmental tracers in bedrock groundwater systems.

Opportunistic short-term water uptake dynamics by subalpine trees observed via in situ water isotope measurements - Matthias Sprenger; Stefan Seeger; Max Berkelhammer; N. A. Bogie; Raymond J. Hess; W. Brown; S. Kuppel; J. Knighton (Water Resources Research, 2025)
Abstract Variations in tree water sources are important to understand in semi‐arid ecosystems because climatic shifts towards lower snowpack and increased drought affect water availability in subalpine forests of the western US. Here, we use daily in situ measurements of stable isotopes ( 2 H & 18 O) in soil and tree stem water, soil matric potential and sap flow to study tree water uptake dynamics. We instrumented three soil profiles down to 90 cm, as well as three aspen and engelmann spruce trees near Gothic, Colorado, in the East River watershed. We observed the fate of natural isotopic variations in rainfall, soil, and plants from June to October 2022, and in August 2023 we conducted a 2 H labeled irrigation experiment. Our observations showed that all studied aspen trees compensated for water scarcity in the shallow soil by shifting the dominant water source at 60(±20) cm to ⅔ of uptake from 90 cm within a few days of a dry period. Both species relied on snowmelt stored in the subsoil to sustain transpiration. Intense rainfall caused the plant water uptake to shift partially to top soil layers within 2 days. Spruce transpiration was lower and relied more on snowmelt, because rainfall infiltration was low in the spruce stand due to high canopy interception. Our findings highlight the important role of snowmelt stored in the deep soil layers for subalpine forest drought response and the dominant fate of monsoonal rainfall to become transpiration rather than recharging groundwater and streams in the Upper Colorado River.

How strong is Snow? Spatial correlations of snowpack load bearing capacity and micromechanics from NASA SnowEx SnowMicroPen Data at Grand Mesa, Colorado - Molly E. Tedesche; Aaron C. Meyer; Sergey N. Vecherin; Tate G. Meehan (Cold Regions Science and Technology, 2025)

Does rainfall or temperature influence antipredator vigilance in a hibernating mammal? - K. Bobb; K. A. Adler; J. G. A. Martin; Daniel T. Blumstein (Behavioral Ecology, 2025)

Sick and alone? Evaluating how immune response is associated with social network position in yellow-bellied marmots - B. Stup (2025)

Effects of experimental warming on floral scent, display and rewards in two subalpine herbs - C. A. Wu; J. M. Powers; D. Hopp; Diane R. Campbell (Annals of Botany, 2025)
Our results suggest that floral traits can show different levels of plasticity to temperature changes in subalpine environments, with potential effects on animal behaviours that help or hinder plant reproduction. They also illustrate the need for more long-term field warming studies, as shown by responses of floral volatiles in different ways to weeks of warming vs. temperature at the time of sampling.

Seasonality and albedo dependence of cloud radiative forcing in the Upper Colorado River Basin - William Rudisill; Daniel Feldman; Christopher Cox; L. D. Riihimaki; Joseph Sedlar (Journal of Geophysical Research: Atmospheres, 2025)
Abstract Mountains create and enhance their own clouds, which both scatter and absorb shortwave radiation from the sun and absorb and re‐emit land surface and atmospheric longwave radiation. However, the impacts of clouds on the surface radiation balance in high elevation snowy mountain terrain are poorly explored. In this study, we use data collected by the SAIL field campaign and partner organizations in the upper elevations (2,880 m.a.s.l) of the Upper Colorado River Basin (UCRB) over a 21‐month period from September 2021 to June 2023 to estimate Cloud Radiative Forcing (CRF) in the shortwave, longwave, and the net effect. Longwave warming effects dominate during the winter when snow albedos are high (0.8–0.9) and the background atmospheric precipitable water vapor is low (0.5 cm), yielding a maximum monthly average net CRF of +34.7 W·m −2 , meaning that clouds increase the net radiation relative to clear skies during this time period. The sign of net CRF switches in the warm season as snow recedes, sun‐angles increase, and the North American monsoon arrives, yielding a minimum monthly average net CRF of −47.6 W·m −2 with hourly minima of −600 W·m −2 . The sign of net CRF is typically positive, even at solar noon, when the surface is snow covered, except for a brief period over melting, low‐albedo snow (0.5–0.6) impacted by dust impurities. Sensitivity tests elucidate the role of the surface albedo on the net CRF. The results suggest that net CRF will increase in magnitude and lead to a more persistent cooling effect on the surface net radiation budget as the snow cover declines.

Out of sight, out of mind: The role of carcass burial and maintenance in reducing competition in Nicrophorus investigator - K. Chamberlin (2025)
Competition for ephemeral resources like carrion is intense among necrophagous insects, particularly burying beetles (Nicrophorus spp.), where reproductive success is limited by access to carcasses. Burial and post-burial maintenance behaviors are hypothesized to reduce carcass detection by competitors through the suppression of volatile organic compounds (VOCs). I investigated the relative importance of burial and maintenance in reducing discovery of small vertebrate carcasses by other carrion beetles. In a field study in a montane meadow in Colorado, I established can-based enclosures containing Peromyscus maniculatus carcasses under three treatments: surface (unburied), N. investigator pairs allowed to bury carcasses, but then removed to prevent further maintenance, and -N. investigator pairs allowed to bury carcasses and continue maintenance behaviors. Carcasses were protected from direct intrusion but exposed to visiting insects via screened funnel traps. Over two trials of daily monitoring (3 days each) and one trial of delayed monitoring (7 days), I recorded visitor identity, sex, and size, and measured burial depth and soil temperature. Surface and unburied carcasses had significantly higher discovery rates than buried carcasses (χ² = 7.83, p = 0.005). Across all treatments, discovery proportions differed significantly (Fisher’s exact test, p = 0.011), with maintained carcasses having the lowest detection. Mean visitor counts trended higher for surface carcasses, though differences were not significant (p = 0.096). Burial depth did not significantly influence discovery (p = 0.586), indicating that even shallow burial reduced detection. These findings support the hypothesis that burial and maintenance function as effective exploitative competition strategies in N. investigator, likely mediated through VOC suppression. Such behaviors may contribute to priority effects that facilitate competitive coexistence. Future work should examine habitat- specific VOC dynamics and the individual contributions of maintenance behaviors.

An uphill grind for wild plant populations - Sally N. Aitken (Science, 2025)

Social security: individuals in socially reciprocal groups may perceive security from predators - Conner S. Philson; C. Klassen; K. Uchida; Daniel T. Blumstein (Behavioral Ecology, 2025)

The heritability of fear: decomposing sources of variation in marmot flight initiation distance - M. A. Scurka; J. G. A. Martin; Daniel T. Blumstein (Animal Behaviour, 2025)

Temperature and relative humidity effects on nectar quantity, nectar quality, and plant-pollinator interactions - E. Wheeler (2025)
Nectar plays a critical role in attracting pollinators, thereby facilitating pollination and the spread of pollen. Nectar traits like volume and sugar concentration are strongly influenced by environmental factors such as temperature and relative humidity. Yet, there is little understanding of how these environmental and biological variables combine to influence the ability for a plant to attract insect pollinators. This study examined how temperature and relative humidity influence nectar volume and sugar concentration, and how these factors, in turn, affect pollinator visitation rates. We conducted this research at three subalpine wildflower meadows in Gunnison County, Colorado, from July 2 to August 1, 2025. We surveyed plant-pollinator interactions, collected ambient temperature and relative humidity data, and examined nectar volume and sugar concentration. Using mixed effects models, we found that an increasing temperature significantly increased nectar volume but decreased sugar concentration. Similarly, higher relative humidity led to a significant increase in nectar volume and a significant decrease in concentration. Notably, higher relative humidity and nectar volume were associated with a statistically significant increase in pollinator visitation rates. In contrast, temperature and nectar concentration did not have a statistically significant effect on visitation. These findings highlight the importance of environmental conditions in shaping plant–pollinator interactions. Understanding how temperature and humidity influence nectar traits and pollinator behavior is essential for predicting the impacts of climate change on ecological relationships. Key words plant-pollinator interactions, nectar concentration, nectar volume, temperature, relative humidity

Flying by night: Comparing nocturnal pollinator networks over time in the Colorado Rocky Mountains - Daria Syskine; C. L. Boggs (Ecological Entomology, 2025)
Abstract Where climate is seasonal, such as in high‐altitude ecosystems, the occurrence and activity patterns of insect pollinators may vary with the varying occurrence of floral resources. This high turnover of species occurrence and interactions may lead to changes in the structure and properties of plant–pollinator networks. Here, we systematically compared the properties of moth pollen‐transport networks in Colorado, USA, over the course of a season, and tested for a link between moth species specialisation and morphology. We predicted that network properties would change through the season as the abundance and diversity of available floral resources increased. We also predicted that there would be a link between moth specialisation and morphology, as moth proboscis length can restrict their ability to utilise different floral resources. We sampled moths for pollen over 9 weeks in June through August 2021. We then constructed pollen‐transport networks, and used mixed models to test for differences in network indices between different parts of the 2021 season; we also tested for a relationship between moth proboscis length, the duration of moth species' presence across the season and the number of flower species pollinated. As expected, we found high rates of species turnover and high rates of plant–pollinator interactions over the summer. However, linkage density and robustness were the only overall network metrics that changed. We also found that longer proboscis lengths and more persistent species occurrence over the season were predictive of higher generalisation among moth species. We suggest that even with high rates of species turnover, nocturnal moth pollen‐transport networks may maintain their overall structure over a season, with variations in the availability of floral resources driving limited variation in some network metrics. Our study highlights the necessity of continuing to research moth pollen‐transport networks over different temporal scales, to better understand how ecological factors can lead to changes in network structure over time.

Relaxation of the leaf economics spectrum within and across quaking aspen Populus tremuloides genotypes - J. Rieksta; Bente J. Graae; K. Helsen; R. E. Kapas; R. Strimbeck; B. Blonder (Oikos, 2025)

Does pollination interact with the abiotic environment to affect plant reproduction? - I. B. Rodelius; Amy M. Iler (Annals of Botany, 2025)
Although we found some evidence for the effect of a biotic interaction depending on abiotic conditions, it was only for one aspect of reproduction in one species, and it was in an unexpected direction. Our work highlights interactions between the abiotic and biotic components of the environment as an area of further research for improving our understanding of how plant reproduction responds to global change.

Contrasting depth dependencies of plant root presence and mass across biomes underscore prolific root-regolith interactions - S. A. Billings; P. Sullivan; Langlang Li; D. R. Hirmas; J. B. Nippert; H. Ajami; Alejandro Flores; K. Singha (AGU Advances, 2025)

Responses to climate change – insights and limitations from herbaceous plant model species - N. J. Kooyers; J. T. Anderson; A. L. Angert; M. L. Avolio; Diane R. Campbell; M. Exposito-Alonso; T. E. Juenger; D. A. Moeller; J. R. Napier; S. N. Sheth (New Phytologist, 2025)

Prevalence and severity of Melampspora lini on Linum lewisii under early snowmelt conditions - W. Goetting (2025)
Plant-pathogen interactions act as a selective pressure on both parties involved. Changes in their environment can cause these relationships to shift in favor of either party. Subalpine ecosystems are experiencing increased drought, early snowmelt, and advancing phenology as a result of climate change. Snowmelt typically signals key life cycle events for subalpine plants. Linum lewisii is a perennial subalpine plant that is experiencing changes in phenology as snowmelt dates shift. Melampspora lini is a fungal parasite that relies on Linum lewisii for its entire life cycle. As the phenology of L. lewisii changes with early snowmelt, is it unclear how prevalence and severity of M. lini will change. There is the potential for negative impacts on both parties, so comparing infection to demographic metrics like size and reproductive success can help us understand how climate change will affect subalpine plants; both directly through life cycle changes, and indirectly through changing plant-pathogen dynamics. Following 430 individuals, we analysed the variation in prevalence, severity, and reinfection across treatment, and the variation in demography with infection status. Size was found to be the largest determinant of infection status, so we controlled for it as a covariate in all analyses. Broadly we found a higher prevalence of rust in control treatments, and we found that infected plants were more likely to flower. Both of these factors can shift community demographics in unexpected ways, which will likely occur more frequently as climate change progresses.

Legacy effects and arbuscular mycorrhizal fungi of Linaria vulgaris invasion in Colorado and Illinois, USA - L. Novak; G. M. Mueller; L. M. Egerton-Warburton (Invasive Plant Science and Management, 2025)
Abstract Invasive plants’ ability to extend their range depends upon their local environments and both positive and negative interactions with native species. Interactions between invasive and native plants may be indirectly linked to the soil fungal community, which may enhance or suppress invasion through mutualism or parasitism. Many invasive plants preferentially select fungal communities or change soil chemistry to gain a competitive advantage, and such changes can remain even after the invader is removed, known as legacy effects. Yellow toadflax ( Linaria vulgaris Mill.) is an invasive forb that is aggressive in the western United States but is nonaggressive in the midwestern United States. We evaluated the relationship between soil abiotic properties, nitrogen (N) enrichment, arbuscular mycorrhizal fungal (AMF) community composition, and L. vulgaris invasion in aggressive (CO) and nonaggressive (IL) populations. We collected soil from uninvaded and invaded sites in Gothic, CO, and near Chicago, IL, and sequenced AMF community composition in each site. Using the same soil, we grew L. vulgaris and native species in pots for 120 d, with half of the pots receiving N fertilization, and harvested biomass. We also injected a 15 N-labeled tracer in pots and analyzed plant tissue for 15 N enrichment and net uptake rates (NUR). In CO soil, L. vulgaris rhizomes sprouted more in invaded soil, whereas in IL soil, L. vulgaris only sprouted in uninvaded soil. N fertilization had no impact on biomass, and NUR did not differ significantly between any treatments. AMF communities differed between the two sites but were not significantly influenced by invasion history. Our results suggest that L. vulgaris leaves legacy effects but that these effects are different between aggressive and nonaggressive populations. Legacy effects may facilitate reinvasion in CO, but we did not find conclusive evidence of legacy effects in IL, and differences between the sites could be shaped by endemic AMF communities.

Natural selection on floral volatiles and other traits can change with snowmelt timing and summer precipitation - J. M. Powers; H. M. Briggs; Diane R. Campbell (New Phytologist, 2025)
Climate change is disrupting floral traits that mediate mutualistic and antagonistic species interactions. Plastic responses of these traits to multiple shifting conditions may be adaptive, depending on natural selection in new environments. We manipulated snowmelt date over three seasons (3-11 d earlier) in factorial combination with growing-season precipitation (normal, halved, or doubled) to measure plastic responses of volatile emissions and other floral traits in Ipomopsis aggregata. We quantified how precipitation and early snowmelt affected selection on traits by seed predators and pollinators. Within years, floral emissions did not respond to precipitation treatments but shifted with snowmelt treatment depending on the year. Across 3 yr, emissions correlated with both precipitation and snowmelt date. These effects were driven by changes in soil moisture. Selection on several traits changed with earlier snowmelt or reduced precipitation, in some cases driven by predispersal seed predation. Floral trait plasticity was not generally adaptive. Floral volatile emissions shifted in the face of two effects of climate change, and the new environments modulated selection imposed by interacting species. The complexity of the responses underscores the need for more studies of how climate change will affect floral volatiles and other floral traits.

Quantifying the effect of petrogenic carbon on SOC turnover for two Rocky Mountain soils: when are petrogenic carbon corrections required? - E. H. Williams; C. R. Lawrence (Journal of Geophysical Research: Biogeosciences, 2025)

The Effect of Globalization on the Places of Summit County, Colorado - Lucas Gauthier (University of Colorado Honors Journal, 2025)
The movement of people, capital, and culture associated with increasing globalization has had a profound impact on shaping the places we inhabit, the cultures we interact with, and the ways we live. The development of Summit County, Colorado, represents one of the most profound landscape evolutions of the past 160 years. In less than two centuries, the forces of globalization developed an isolated area with limited agricultural potential, unruly topography, and an inhospitable climate into one of the most expensive and well-known tourist destinations in the United States (Blevins, 2023). The progression of this process underscores how the imposing force of globalism can reframe our understanding of place and, by extent, reinforce or challenge existing cultural, social, and ideological norms. By examining how the changing focus and intensity of globalization have been reflected in present and historic development paradigms in Summit County, Colorado, we can see the profound power of globalization in shaping the ways we interact with and consume nature and the places that surround it.

The effects of natural sun exposure on the intensity and distribution of salamander biofluorescence - J. Chairez (2025)
Salamanders have been used in a variety of different experiments to determine the health of various ecosystems. Biofluorescence was recently studied in amphibians in a study done in 2020. Not much is known about all its functions, more studies are needed to fully understand how it works and how it can be affected by environmental factors. Learning more about the functions of salamander biofluorescence could lead to a greater understanding of how pollutants and human impacts can affect salamanders and the health of their ecosystems. This project aimed to focus on tiger salamander biofluorescence and how its distribution and intensity is affected by the exposure of natural sunlight. Unmarked, 2nd year larval salamanders were taken from a single diverse pond to control for any differences among the ponds. The larvae were exposed to three different light treatments being dark, dimmed, and light. Within these light treatments there were also two time treatments that were six and twelve days. Their biofluorescence was photographed before and after the time treatments with a blue excitation light and a 500 nm long- pass filter. All images were quantified using ImageJ. The results from this experiment support the idea that salamander biofluorescence may be partly environmentally dependent and this could provide useful information for future studies to further understand the functions of amphibian biofluorescence. Furthermore, more extensive research into this topic could provide a new indicator of ecosystem health for use in conservation. 2

Sensory cues and memory in Lepidopteran mud puddling behavior - F. von Wallmenich (2025)
​ Puddling is a form of supplemental feeding for nectivorous Lepidoptera to acquire necessary mineral nutrients, primarily sodium, that are otherwise absent from their nectar diets. For many species sodium is important for growth, nervous system function, and egg production. However, the mechanisms through which Lepidoptera locate puddling sites is unknown. I investigated three potential factors influencing puddling site selection: visual cues from landscape contrast, olfactory cues from bacterial volatiles, and memory. Knowing the factors that influence lepidopteran puddling site selection can help us better understand how they find the resources necessary to survive and reproduce, as well as provide insight to the learning and memory capacities of Lepidoptera. Landscape contrast had a significant effect on lepidopteran puddling site selection, with butterflies on average choosing spots lighter than the surrounding area. Temperature and shade also affected butterfly puddling, with butterflies across families showing a preference for warmer sites in direct sunlight. Between families, there were significant differences for puddling preferences for sites with certain temperatures and water contents. It is unclear if Lepidoptera use scent to find puddling sites. Overall, returns to specific puddling sites were rare and Lepidoptera do not seem to be using short term memory to relocate spots, but more data would need to be conducted to say anything conclusive.

Does pollination interact with the abiotic environment to affect plant reproduction? - I. B. Rodelius; Amy M. Iler; I. B. Rodelius; Amy M. Iler (Annals of Botany, 2025)
Although we found some evidence for the effect of a biotic interaction depending on abiotic conditions, it was only for one aspect of reproduction in one species, and it was in an unexpected direction. Our work highlights interactions between the abiotic and biotic components of the environment as an area of further research for improving our understanding of how plant reproduction responds to global change.

Phylogeny does not predict the outcome of heterospecific pollen–pistil interactions in a species-rich alpine plant community - R. Cohen; Asstan Cisse; James V. Jones; J. H. Williams; D. A. R. Eaton (American Journal of Botany, 2025)
Our results show that even in communities where HPT is common, pre-zygotic post-pollination mechanisms do not provide strong barriers to interspecific fertilization. HPT can result in the loss of ovules even between highly diverged plant species.

Impacts of earlier snowmelt on fruiting phenology and seed success of Rocky Mountain wildflowers - S. Andrewlavage (2025)
Phenology, or the timing of biological events, has been found to shift in response to changing climates and key environmental cues such as spring temperatures and snowmelt date. These phenological shifts have been observed to be particularly extreme in mid-to-high latitude alpine environments, like Rocky Mountain ecosystems, where a variety of spring wildflowers have already been observed to be changing their flowering phenology. While flowering has been extensively studied, fruiting phenology remains largely unexplored, despite this stage being arguably more telling of reproductive output as the culmination of successful flowering and pollination events. Understanding how mean fruiting time and duration are impacted by shifting environmental cues will be critical in understanding the effects of future climate change on wildflower reproduction and population. To more thoroughly understand exactly how these potential shifts in fruiting phenology may be impacting wildflower reproductive output and future populations, seed success - assessed through seed mass, total fruit count, and viable seed counts - will be examined. The results of this study found there to be an advance in mean fruiting time for three of the five study species in response to the early snowmelt treatment, but this shift in fruiting mean did not translate to an observed change in fruiting duration with the exception of one species. Seed characteristics and success were found to be trait-responsive to the early snowmelt treatment. For example, Delphinium nuttallianum, was found to have a lower seed mass for individuals in the early snowmelt treatment plots, but total fruit count or viable seed counts were unaffected. These trait-specific responses highlight the importance of more holistic assessments of seed quality and success as using only one determinant could tell a different story than including multiple.

Long-term measurements of ice nucleating particles at Atmospheric Radiation Measurement (ARM) sites worldwide - J. M. Creamean; C. C. Hume; M. Vazquez; Adam Theisen (Earth System Science Data, 2025)

Alpine plants of Mt. Baldy: modeling phenology and documenting biodiversity - Hillary Xu (2025)
Alpine ecosystems are disassembling and reassembling due to climate change. The phenology of alpine plants has shifted, but empirical evidence for how spatial clustering patterns could impact this shift is lacking. This study investigated the phenology of spatially clustered versus isolated alpine plants in the Colorado Rocky Mountains, using linear models that considered co-variables such as plant size, snowmelt timing, and topography. A total of three focal species (Senecio crassulus, Lupinus argenteus, and Ivesia gordonii) with ca. 20 individuals per species were surveyed twice-weekly throughout July and August of 2025. We found that different aspects of phenology were affected by different variables. In 1 general, phenology shifts earlier due to snowmelt timing and shifts later due to the clustering effect. Natural history observations of ant behavior and a survey of the surrounding plant community supplement the understanding of the long-term Mt. Baldy research site.

Is early life adversity associated with adult stress in a wild rodent? - A. Y. Kong; X. Ortiz Ross; Daniel T. Blumstein (Ecology and Evolution, 2025)
The period before sexual maturity is a sensitive life stage where most development and change occur. Studies in humans and other animals show that early adverse experiences contribute to poor health and survival. However, the mechanisms are still unclear. Some have found that early life adversity (ELA) can lead to elevated glucocorticoids later in life, dysregulate the stress re- sponse, and increase the impact of later stressors. However, most animal studies have focused on individual stressors. Protecting wild populations that are exposed to multiple stressors requires a better understanding of the physiological consequences of several co-occurring stressors. We used a cumulative adversity index (CAI) to ask whether early adverse experiences were as- sociated with increased levels of adult fecal glucocorticoid metabolites (FGM) in wild female yellow-bellied marmots (Marmota flaviventer). We found a significant interaction between adversity and elevation that explained variation in FGMs. Thus, we infer that ELA can modulate FGMs, but contrary to similar research in other mammals, the trend was toward downregulation under more environmentally relaxed conditions (lower elevation). Our results highlight the value of studying the relative importance of early and later stressors in the physiology of different wild taxa when investigating the mechanisms of early life adversity.

37Slabs of White: Panoramic Whales and Photographic Guano in the Mid-Nineteenth Century - Conor Lauesen (2025)
This article explores both the content and meaning of

This House Is Not A Home: Navigating Latinx Women’s Survival in Mexico - Ana Larissa Soares Cruz (2024)
For generations, Latinx women have often been expected to uphold the expectations of

Diverse and unconventional methanogens, methanotrophs, and methylotrophs in metagenome-assembled genomes from subsurface sediments of the Slate River floodplain, Crested Butte, CO, USA - Anna N. Rasmussen; Bradley Tolar; John R. Bargar; Kristin Boye; Christopher Francis (mSystems, 2024)
We use metagenome-assembled genomes (MAGs) to understand single-carbon (C1) compound-cycling-particularly methane-cycling-microorganisms in montane riparian floodplain sediments. We generated 1,233 MAGs (>50% completeness and <10% contamination) from 50- to 150-cm depth below the sediment surface capturing the transition between oxic, unsaturated sediments and anoxic, saturated sediments in the Slate River (SR) floodplain (Crested Butte, CO, USA). We recovered genomes of putative methanogens, methanotrophs, and methylotrophs (n = 57). Methanogens, found only in deep, anoxic depths at SR, originate from three different clades (Methanoregulaceae, Methanotrichaceae, and Methanomassiliicoccales), each with a different methanogenesis pathway; putative methanotrophic MAGs originate from within the Archaea (Candidatus Methanoperedens) in anoxic depths and uncultured bacteria (Ca. Binatia) in oxic depths. Genomes for canonical aerobic methanotrophs were not recovered. Ca. Methanoperedens were exceptionally abundant (~1,400× coverage, >50% abundance in the MAG library) in one sample that also contained aceticlastic methanogens, indicating a potential C1/methane-cycling hotspot. Ca. Methylomirabilis MAGs from SR encode pathways for methylotrophy but do not harbor methane monooxygenase or nitrogen reduction genes. Comparative genomic analysis supports that one clade within the Ca. Methylomirabilis genus is not methanotrophic. The genetic potential for methylotrophy was widespread, with over 10% and 19% of SR MAGs encoding a methanol dehydrogenase or substrate-specific methyltransferase, respectively. MAGs from uncultured Thermoplasmata archaea in the Ca. Gimiplasmatales (UBA10834) contain pathways that may allow for anaerobic methylotrophic acetogenesis. Overall, MAGs from SR floodplain sediments reveal a potential for methane production and consumption in the system and a robust potential for methylotrophy.IMPORTANCEThe cycling of carbon by microorganisms in subsurface environments is of particular relevance in the face of global climate change. Riparian floodplain sediments contain high organic carbon that can be degraded into C1 compounds such as methane, methanol, and methylamines, the fate of which depends on the microbial metabolisms present as well as the hydrological conditions and availability of oxygen. In the present study, we generated over 1,000 MAGs from subsurface sediments from a montane river floodplain and recovered genomes for microorganisms that are capable of producing and consuming methane and other C1 compounds, highlighting a robust potential for C1 cycling in subsurface sediments both with and without oxygen. Archaea from the Ca. Methanoperedens genus were exceptionally abundant in one sample, indicating a potential C1/methane-cycling hotspot in the Slate River floodplain system.

Hydrology outweighs temperature in driving production and export of dissolved carbon in a snowy mountain catchment - D. Kerins; K. Sadayappan; Wei Zhi; P. Sullivan; K. H. Williams; R. W. H. Carroll; H. R. Barnard; Matthias Sprenger; Wenming Dong; J. Perdrial; Langlang Li (Water Resources Research, 2024)
Abstract Terrestrial production and export of dissolved organic and inorganic carbon (DOC and DIC) to streams depends on water flow and biogeochemical processes in and beneath soils. Yet, understanding of these processes in a rapidly changing climate is limited. Using the watershed‐scale reactive‐transport model BioRT‐HBV and stream data from a snow‐dominated catchment in the Rockies, we show deeper groundwater flow averaged about 20% of annual discharge, rising to ∼35% in drier years. DOC and DIC production and export peaked during snowmelt and wet years, driven more by hydrology than temperature. DOC was primarily produced in shallow soils (1.94 ± 1.45 gC/m 2 /year), stored via sorption, and flushed out during snowmelt. Some DOC was recharged to and further consumed in the deeper subsurface via respiration (−0.27 ± 0.02 gC/m 2 /year), therefore reducing concentrations in deeper groundwater and stream DOC concentrations at low discharge. Consequently, DOC was primarily exported from the shallow zone (1.62 ± 0.96 gC/m 2 /year, compared to 0.12 ± 0.02 gC/m 2 /year from the deeper zone). DIC was produced in both zones but at higher rates in shallow soils (1.34 ± 1.00 gC/m 2 /year) than in the deep subsurface (0.36 ± 0.02 gC/m 2 /year). Deep respiration elevated DIC concentrations in the deep zone and stream DIC concentrations at low discharge. In other words, deep respiration is responsible for the commonly‐observed increasing DOC concentrations (flushing) and decreasing DIC concentrations (dilution) with increasing discharge. DIC export from the shallow zone was ~66% of annual export but can drop to ∼53% in drier years. Numerical experiments suggest lower carbon production and export in a warmer, drier future, and a higher proportion from deeper flow and respiration processes. These results underscore the often‐overlooked but growing importance of deeper processes in a warming climate.

Optimizing Field-linked simulations of dry season uptake and monsoon infiltration within an aspen-mixed conifer forest - Raymond J. Hess (2024)
Climate models forecast that headwater catchments in the western U.S. will undergo a reduction in snowpack, early season snowmelt, and increases in evapotranspiration. The resulting extended dry season will stress vegetation in mountainous watersheds throughout the Upper Colorado River Basin. We investigate infiltration patterns and root water uptake in response to dry season disturbances within the East River watershed in Colorado. To do this, we collected soil cores, measured matric potential and sap flow, and monitored tree xylem and soil for stable isotopes of water (2H, 18O) in two soil profiles to 90 cm depth (with three Engelmann spruce and three aspen trees instrumented, respectively). Sub-daily stable water isotope dynamics were analyzed between mid-June and late October of WY-22 using a cavity ring-down spectrometer. HYDRUS-1D was calibrated with both field measurements of matric potential and δ2H to simulate the ecosystem response to late summer dry spells and monsoonal rainfall for the 128-day time domain. Simulations show both aspen and spruce trees relying heavily on headwater snowmelt. Water-use analysis reveals a reduction in transpiration during the late summer and early autumn months, particularly in September, the driest month of WY-22. Spruce trees appear more tolerant of dry soil conditions than aspen trees. As a result, it is likely that spruce will outcompete aspen in the future, given forecasted shifts in climate and changes in the timing of snowmelt. This study highlights the benefits of coupling high frequency stable water isotope data and more commonly used matric potential field measurements for parameter optimization in numerical modeling.

The Power of Playing with Genre: The Western Gothic Melodrama in Jane Campion’s The Power of the Dog (Netflix, 2021) - Hervé Mayer (SPIRE - Sciences Po Institutional REpository, 2024)
International audience

Effects of trophic phenological synchrony or dyssynchrony on maternal investment of a small herbivorous mammal (Callospermophilus lateralis) - E. Grimland (2024)

Investigating the role of climate on juvenile Golden-mantled ground squirrel (Callospermophilus lateralis) growth and behavior - K. Simmons (2024)
Changes to climate can have a variety of consequences on organisms across all taxa. Though we are seeing climate changes across the globe, these effects can often be greater in high-elevation regions. For mammals in these environments, climate change can alter phenology, survival, and reproduction. Increasing temperatures have also been found to affect body mass, though this has been inadequately explored. This study investigated the effects of climate on the body mass and behavior of a high-elevation, hibernating small mammal, the golden-mantled ground squirrel (Callospermophilus lateralis). We compared the temperature and precipitation faced during a critical two-week growth period in juvenile ground squirrels to daily growth rates to determine any effects of climatic conditions on development. Additionally, we monitored juvenile squirrel behavior to compare time spent above ground and foraging to the temperature during that time. We found that temperature does significantly negatively affect time spent above ground and foraging, and that number of days with rain during the growth period was a significant negative predictor of growth rate. Furthermore, the number of days over 25 °C was a significant positive predictor of growth rate. Additionally, we found that year and maternal ID accounted for up 15% and 30% of the variation in growth rate, respectively. Together, these results aid in our understanding of how climate and other variables can affect body mass and behavior in small mammals.

Variation of wasp behavior patterns and pollination behavior on Ligusticum porteri - S. Joseph Wright (2024)

What are parasitoid wasps visiting Helianthella quinquenervis targeting, and could they influence plant fitness and reproduction? - D. Esquivel (2024)

Estimating Local Abundance of Bombus Queens in Meadows of Rocky Mountains, Colorado, USA - M. Shaffer (2024)

Interpopulation variation and optimal mating in the perennial herb, Polemonium brandegeei - J. Poortvliet (2024)
Generalist pollinated plants receive pollination services from a wide range of animals, but pollinator effectiveness varies. More effective pollinators in generalist systems optimize pollen transfer by promoting outcrossing between more distant plants. This leads to increased pollinator mediated selection by these pollinators on floral traits and variation in pollinator abundance may therefore cause population genetic and phenotypic differentiation across the range of a species. However, variation may also be caused by plastic responses to variable environmental conditions. Here, I analyze the prevalence and potential causes of interpopulation variation as well as optimal mating distance in generalist pollinated Polemonium brandegeei. I compared morphology and floral scent (1) among four field populations and (2) between field and greenhouse grown plants sourced from the same populations. Populations varied in morphology and floral scent profile and the southernmost population was most distinct with floral traits consistent with increased selection by hawkmoths or hybridization events. All major among population differences were preserved in the greenhouse which suggests a genetic component to phenotypic variation but there was an overall increase in flower size and total scent emission in the greenhouse. Field hand crosses indicated that mating in P. brandegeei was optimized provided crosses were made between plants at least 1 – 3.5m apart, and that environmental variability influenced mating success. These findings may reflect differences in pollinator abundance and/or pollinator mediated selection among populations or hybridization events and offer support for past selection by more effective pollinators (hawkmoths and hummingbirds) which transport pollen over larger distances. ii

Coexistence in Burying Beetles: The Niche of Reproductive Temperatures - K. Muse (2024)
Coexistence among species can occur in a variety of ways through niche partitioning. Two major niche components for many organisms are temperature and soil moisture and variation in these may occur with habitat heterogeneity. Near Gothic, Colorado at the Rocky Mountain Biological Laboratory, there are two habitats that pose differences in temperature and soil moisture: aspen forests and montane meadows. Two burying beetles species co-occur in these habitats (Nicrophorus defodiens and Nicrophorus investigator) and overlap significantly in their activity periods, diet, and reproductive behaviors. Temperature and soil moisture impact beetle development, adult flight, burial behaviors, and survival. Larvae are subject to temperature changes, where high temperatures lead to fatality and low temperatures slow development. Adults are subject to high temperatures and desiccation both aboveground and belowground. Aspen forests and montane meadows provide habitat heterogeneity (differing temperatures and soil moistures). I tested the hypothesis that each species has better reproductive success (higher fitness) in different habitats, thus providing a mechanism for their coexistence. I found that N. defodiens had a greater fitness (brood success, larvae number and larvae mass) in the aspen compared to N. investigator, and N. investigator had a higher fitness in the meadow compared to N. defodiens. N. investigator did have similar brood success to N. defodiens in the aspen, but there may be consequences later in their development.

How do Bombus appositus and Bombus bifarius worker tongue lengths vary within a season? - O. Schenker (2024)
Schenker 1 Intraspecific trait variation – the variation among individuals within the same species – is seen within all natural populations and strongly affects the dynamics of and interactions between populations, communities, and ecosystems. Individual trait variation fluctuates across space and time, and understanding these patterns can provide a fuller understanding of species ecology and their interactions. Here, we quantified the degree of variation in worker tongue (proboscis) length, across a season within two wild bumble bee species (Bombus appositus and Bombus bifarius) throughout the Colorado Rocky Mountains. Specifically, we examined how the mean and variation of worker tongue length changes within a season. First, we measured the proboscis length and intertegular distance (ITD) – a strong proxy of body size – of workers. Second, we created an allometric scaling slope between proboscis length and body size to produce a robust estimate of this relationship. Third, we applied this scaling relationship to past Bombus appositus and Bombus bifarius worker size data from the Rocky Mountain Biological Laboratory to estimate worker tongue length. Fourth, we used the estimated tongue length calculations and measured tongue length values to quantify how Bombus worker proboscis length varies across a season. Fifth, we used the estimated tongue length calculations and measured proboscis length values to visualize how Bombus worker tongue length varies across season and year. When years were pooled together, we found that Bombus appositus worker tongue length increases over a season, but Bombus bifarius worker tongue length did not. In addition, we found evidence that supports the hypothesis that Bombus appositus worker tongue length inconsistently varies each year across a season, with a similar trend seen for Bombus bifarius. Our findings suggest that tongue length may be a consequence of the developmental environment rather than a life history strategy, since no consistent pattern of variation across seasons was observed. These results may have major implications for the future since tongue length mediates the ecological niches species occupy, plant-pollinator interactions, and community dynamics, and if tongue length is changing, these structures and networks may vary as well. Further work is required to confirm the mechanisms that are driving this intraspecific trait variation across a season.

Social Security: Do Individuals in Tight-Knit Social Groups Perceive Greater Security? - C. Klassen (2024)
Antipredator behavior is influenced by many factors including group size. Group size effects are seen when animals in larger social groups allocate less time to antipredator vigilance while foraging, but group size alone does not capture the diversity and complexity of sociality and behavior. An individual’s ‘sense of security’, or their perception of predation risk, is also influenced by an individual’s social behavior, but it is unknown is whether a group’s social structure – the pattern of all social interactions in a group – could explain variation in an individual’s perceptions of security. Using time allocated to vigilance during foraging and flight initiation distance (FID) as two measures of an individual’s sense of security, we explored whether individual yellow-bellied marmot (Marmota flaviventer) in tightly connected social groups looked less while foraging and had shorter FIDs compared to individual marmots in less- connected social groups. Using linear mixed effect models, we found modest support for the Social Security Hypothesis as individuals in more socially reciprocal groups spent less time looking for predators while foraging. We found no measures of group social structure explained variation in FID. We also found that measures of the immediate environment (number of individuals within 10 meters for vigilance and distance from burrow and alert distance for FID) had effect sizes an order of magnitude greater than the social network measures, suggesting an individual’s immediate environment has more of an impact on their antipredator behavior than the structure of their social group.

Solitary bee genera differ in foraging activity timing and temperature; Evidence of a seasonal dietary shift in Hoplitis fulgida - J. Ives (2024)
Global warming, and exacerbated warming temperatures with humane activity, could impose novel conditions on the lives of many organisms. Of those, the behaviors and diets of solitary bees face adaptive stress as their optimal foraging conditions and preferred floral resources fluctuate. Trap nests make the perfect study system to investigate climatic consequences, because of their easily observable and accessible nature. Using this study system, we sought to answer two main questions: (1) How do foraging time of day and temperature differ among trap-nesting bee taxa? and (2) how does the pollen diet of Hoplitis fulgida vary seasonally? Trap nests and their hosts, particularly pertaining to the questions being asked here, have been largely understudied, despite the possibility for broad inference on the temporal, thermal, and spatial differences in inter- and intraspecific solitary bee behaviors. Previous work has been done on the foraging activity of Osmia, though these studies haven’t directly investigated niche partitioning in the presence of other taxa; similarly, there has been dietary study for solitary bees, but the literature lacks in study of Hoplitis. Our linear-mixed effect models revealed significant partitioning of both temporal and thermal periods between Osmia and Hoplitis. A combined principal component analysis and permanova distinguishes a notable degree of difference in the pollen diet of Hoplitis fulgida spatially. Visualization of fulgida’s seasonal diet across all sites reveals a significant degree of change over the course of the season. From our results, we surmise that Osmia and Hoplitis may face compressing or dividing pressures on their temporal/thermal segmentation, and that adverse nutritional and energetic consequences for Hoplitis could impact brood sizes, composition and survival.

Dissecting phenotypic variation in the montane forb, Boechera stricta - M. I. Jameel (2024)

Context dependence of warming induced shifts in montane soil microbial functions - Sydne Spinella; Aimee T Classen; Nathan J. Sanders; Jennie R McLaren (Functional Ecology, 2024)
Abstract High elevation and latitude ecosystems are experiencing high levels of anthropogenic atmospheric warming. Climate warming may directly change soil microbial activity and alter ecosystem carbon dynamics and productivity, but increasing evidence suggests these responses may depend on other biotic factors such as plant community composition and abiotic factors such as moisture. We examined how abiotic (warming) and biotic (presence of dominant plant species) factors interact to affect soil microbial processes. Our experiment deployed the independent and combined treatments of experimental warming and dominant plant species removal in a high and low elevation montane meadows. We analysed multiple soil microbial responses to warming and the presence of a dominant plant at three times throughout the growing season, including soil respiration, microbial metabolic functional diversity, microbial biomass carbon and nitrogen, and extracellular enzyme potential activity. Overall, there were few independent microbial responses to either the warming or the removal treatments. There was a significant interaction between warming and the removal of a dominant plant species, where microbial biomass and the activity of some microbial enzymes were lower in warmed plots where the dominant species was removed relative to control plots. The effect of warming on extracellular enzyme activity was typically observed only at the high‐elevation site. In contrast, we found that effects of warming were consistent across the growing season, despite strong temporal variation in microbial properties. Our results emphasize the need to further consider soil microbial responses to warming under multiple environments, including shifts in both biotic and abiotic factors, to aid in predictions of carbon dynamics under future global change. Read the free Plain Language Summary for this article on the Journal blog.

Stream water sourcing from high-elevation snowpack inferred from stable isotopes of water: a novel application of d-excess values - Matthias Sprenger; R. W. H. Carroll; David W. Marchetti; C. Bern; H. Beria; W. Brown; Alexander W. Newman; Curtis A. Beutler; K. H. Williams (Hydrology and Earth System Sciences, 2024)
Abstract. About 80 % of the precipitation at the Colorado River's headwaters is snow, and the resulting snowmelt-driven hydrograph is a crucial water source for about 40 million people. Snowmelt from alpine and subalpine snowpack contributes substantially to groundwater recharge and river flow. However, the dynamics of snowmelt progression are not well understood because observations of the high-elevation snowpack are difficult due to challenging access in complex mountainous terrain as well as the cost and labor intensity of currently available methods. We present a novel approach to infer the processes and dynamics of high-elevation snowmelt contributions predicated upon stable hydrogen and oxygen isotope ratios observed in streamflow. We show that deuterium-excess (d-excess) values of stream water could serve as a comparatively cost-effective proxy for a catchment-integrated signal of high-elevation snowmelt contributions to catchment runoff. We sampled stable hydrogen and oxygen isotope ratios of the precipitation, snowpack, and stream water in the East River, a headwater catchment of the Colorado River, and the stream water of larger catchments at sites on the Gunnison River and Colorado River. The d-excess of snowpack increased with elevation; the upper subalpine and alpine snowpack (> 3200 m) had substantially higher d-excess compared to lower elevations (< 3200 m) in the study area. The d-excess values of stream water reflected this because d-excess values increased as the higher-elevation snowpack contributed more to stream water generation later in the snowmelt/runoff season. End-member mixing analyses based on the d-excess data showed that the share of high-elevation snowmelt contributions within the snowmelt hydrograph was on average 44 % and generally increased during melt period progression, up to 70 %. The observed pattern was consistent during 6 years for the East River, and a similar relation was found for the larger catchments on the Gunnison and Colorado rivers. High-elevation snowpack contributions were found to be higher for years with lower snowpack and warmer spring temperatures. Thus, we conclude that the d-excess of stream water is a viable proxy to observe changes in high-elevation snowmelt contributions in catchments at various scales. Inter-catchment comparisons and temporal trends of the d-excess of stream water could therefore serve as a catchment-integrated measure to monitor if mountain systems rely on high-elevation water inputs more during snow drought compared to years of average snowpack depths.

Effects of Dissolved Oxygen & Iron II Concentration Fluxes in Beaver-Impacted Floodplains - W. Hoins (2024)

Elucidating the influence of a nectar yeast and nectar robbing on bumblebee foraging tactic constancy - H. Thomas (2024)
Animal pollination services are vital for plant reproduction, with approximately 90% of plant species benefitting from this mutualistic relationship. Nectar is one of the most common floral rewards offered by plants in exchange for pollination services. Similarly, nectar is vital for bumbles as they consume it for flight fuel and nourishment for larvae and their colonies. However, not all floral visitors are pollinators. A forager may choose to forage legitimately (pollinate) or may choose to forage illegitimately (nectar rob). Nectar robbers bypass anthers at the floral opening and collect nectar by chewing a hole on the nectar spur or finding a pre-existing hole. Nevertheless, it has been shown that foraging patterns can be influenced by microbial presence and community structure implying that the presence of nectar inhabiting microbes (NIMs) can influence floral visitors’ behavior. We investigate how Metschnikowia reukaufii plays a role within this relationship, looking to further understand how NIMs may affect quality and signal of floral rewards. By manipulating the presence of M. reukaufii in the nectar of flowers of Corydalis caseana, we can observe the foraging patterns of bumblebees which can facultatively act as both legitimate pollinators and secondary robbers and are therefore capable of tactic switching. This research will elucidate the influence, if any, of NIMs on bumblebee’s foraging strategies which may disrupt pollination services by promoting floral larceny.

Intraspecific body size variation across distributional moments reveals trait filtering processes - J. L. Fitzgerald; Jane E. Ogilvie; Paul J. CaraDonna (Journal of Animal Ecology, 2024)
Natural populations are composed of individuals that vary in their morphological traits, timing and interactions. The distribution of a trait can be described by several dimensions, or mathematical moments-mean, variance, skew and kurtosis. Shifts in the distribution of a trait across these moments in response to environmental variation can help to reveal which trait values are gained or lost, and consequently how trait filtering processes are altering populations. To examine the role and drivers of intraspecific variation within a trait filtering framework, we investigate variation in body size among five wild bumblebee species in the Colorado Rocky Mountains. First, we examine the relationships between environmental factors (climate and floral food resources) and body size distributions across bumblebee social castes to identify demographic responses to environmental variation. Next, we examine changes in the moments of trait distributions to reveal potential mechanisms behind intraspecific shifts in body size. Finally, we examine how intraspecific body size variation is related to diet breadth and phenology. We found that climate conditions have a strong effect on observed body size variation across all distributional moments, but the filtering mechanism varies by social caste. For example, with earlier spring snowmelt queens declined in mean size and became negatively skewed and more kurtotic. This suggests a skewed filter admitting a greater frequency of small individuals. With greater availability of floral food resources, queens increased in mean size, but workers and males decreased in size. Observed shifts in body size variation also correspond with variation in diet breadth and phenology. Populations with larger average body size were associated with more generalized foraging in workers of short-tongued species and increased specialization in longer-tongued workers. Altered phenological timing was associated with species- and caste-specific shifts in skew. Across an assemblage of wild bumblebees, we find complex patterns of trait variation that may not have been captured if we had simply considered mean and variance. The four-moment approach we employ here provides holistic insight into intraspecific trait variation, which may otherwise be overlooked and reveals potential underlying filtering processes driving such variation within populations.

Firmicutes and Bacteroidetes contribute to mass gain variation in female obligate hibernators - S. Degregori; G. C. Johnson; P. H. Barber; Daniel T. Blumstein (Journal of Mammalogy, 2024)
Abstract Obtaining body condition is an important life history challenge that directly impacts individual fitness and is particularly important for hibernating animals, whose maintenance of adequate body fat and mass is essential for survival. It is well-documented that host-associated microorganisms play a vital role in animal physiology and behavior. Recent work demonstrates that gut microbes are associated with fat accumulation and obesity, particularly the phyla Firmicutes and Bacteroidetes. The focus of most microbiome studies has been on human health or involved lab-reared animals used as a model system. However, these microbes likely are important for individual fitness in wild populations and provide potential mechanistic insights into the adaptability and survival of wildlife. Here we tested whether symbiotic microorganisms within the phyla of Firmicutes and Bacteroidetes were associated with summer mass gain in an exceptionally well-studied wild population of yellow-bellied marmots (Marmota flaviventer) by analyzing 207 fecal samples collected over 5 summer active seasons. Results showed that marmots with higher mass gain rates had a greater relative abundance of Firmicutes. In contrast, a higher relative abundance of Bacteroidetes was associated with lower mass gain rates, but only for marmots living in harsher environments. Similar patterns were found at the family level where Ruminococcaceae, a member of Firmicutes, was associated with higher mass gain rates, and Muribaculaceae, a member of Bacteroidetes, was associated with lower mass gain rates in harsher environments. Although correlative, these results highlight the potential importance of symbiotic gut microbiota to mass gain in the wild—a trait associated with survival and fitness in many taxonomic groups.

Timing of seasonal events is correlated with social network position in a wild mammal - Conner S. Philson; C. Bruebach; T. Bastian; Billy Barr; Daniel T. Blumstein (Behavioral Ecology and Sociobiology, 2024)
Across animal systems, abiotic environmental features, including timing of seasonal events and weather patterns, affect fitness. An individual’s degree of social integration also has fitness consequences, but we lack an understanding of how abiotic features relate to patterns of individual sociality. A deeper understanding of this relationship could be developed from studying systems where these two links with fitness have already been identified. We explored the relationship between individual social behavior and seasonal timing, seasonal length, and weather patterns. We used social network analysis on a sixteen-year dataset of a wild population of hibernating yellow-bellied marmots (Marmota flaviventer). We fit a series of generalized linear mixed models and found that longer growing seasons before winter hibernation and longer winters were associated with increased individual sociality in the following spring. However, later snowmelt was associated with decreased sociality that spring. We found no relationship between individual sociality and various measures of precipitation and tem- perature. This suggests that seasonal timing and length may be a more important driver of sociality than weather patterns in this system, both as a lag and contemporary effect. Seasonal timing and length may mediate the opportunity or intensity of social interactions. The entwined relationships between the seasonal schedule and weather, and the seemingly contradictory role of winter length and snowmelt, suggests the timing of seasons and its relationship with sociality is complex and further exploration of environment-sociality relationships is required across taxa. Significance statement While the adaptive benefits of social behavior are well studied, less is known about how features of the abiotic environment drive variation in individual social behavior. Given increasing stochasticity in the timing of seasonal events and weather pat- terns, mapping the environment-sociality relationship will provide important insights to the drivers of sociality in the wild. This is particularly salient for species most vulnerable to climate and environmental change, such as seasonal hibernators, like yellow-bellied marmots (Marmota flaviventer). We found that features of seasonal duration were positively associated with increased sociality, whereas the timing of seasonal onset was negatively associated. This work provides empirical evidence towards an important gap in the behavioral ecology literature.

Declining groundwater storage expected to amplify mountain streamflow reductions in a warmer world - R. W. H. Carroll; Richard Niswonger; Craig Ulrich; Charuleka Varadharajan; Erica R. Siirila-Woodburn; K. H. Williams (Nature Water, 2024)
Abstract Groundwater interactions with mountain streams are often simplified in model projections, potentially leading to inaccurate estimates of streamflow response to climate change. Here, using a high-resolution, integrated hydrological model extending 400 m into the subsurface, we find groundwater an important and stable source of historical streamflow in a mountainous watershed of the Colorado River. In a warmer climate, increased forest water use is predicted to reduce groundwater recharge resulting in groundwater storage loss. Losses are expected to be most severe during dry years and cannot recover to historical levels even during simulated wet periods. Groundwater depletion substantially reduces annual streamflow with intermittent conditions predicted when precipitation is low. Expanding results across the region suggests groundwater declines will be highest in the Colorado Headwater and Gunnison basins. Our research highlights the tight coupling of vegetation and groundwater dynamics and that excluding explicit groundwater response to warming may underestimate future reductions in mountain streamflow.

Costly calling: Marmots who alarm call at higher rates are less likely to survive the summer and live shorter lives - Daniel T. Blumstein; K. A. Adler; J. Uy (Current Zoology, 2024)
Emitting alarm calls may be costly, but few studies have asked whether calling increases a caller's risk of predation and survival. Since observing animals calling and being killed is relatively rare, we capitalized on over 24,000 h of observations of marmot colonies and asked whether variation in the rate that yellow-bellied marmots (Marmota flaviventer) alarm called was associated with the probability of summer mortality, a proxy for predation. Using a generalized mixed model that controlled for factors that influenced the likelihood of survival, we found that marmots who called at higher rates were substantially more likely to die over the summer. Because virtually all summer mortality is due to predation, these results suggest that calling is indeed costly for marmots. Additionally, the results from a Cox survival analysis showed that marmots that called more lived significantly shorter lives. Prior studies have shown that marmots reduce the risk by emitting calls only when close to their burrows, but this newly quantified survival cost suggests a constraint on eliminating risks. Quantifying the cost of alarm calling using a similar approach in other systems will help us better understand its true costs, which is an essential value for theoretical models of calling and social behavior.

Recent Upper Colorado River Streamflow Declines Driven by Loss of Spring Precipitation - D. Hogan; Jessica D. Lundquist (Geophysical Research Letters, 2024)
Abstract Colorado River streamflow has decreased 19% since 2000. Spring (March‐April‐May) weather strongly influences Upper Colorado River streamflow because it controls not only water input but also when snow melts and how much energy is available for evaporation when soils are wettest. Since 2000, spring precipitation decreased by 14% on average across 26 unregulated headwater basins, but this decrease did not fully account for the reduced streamflow. In drier springs, increases in energy from reduced cloud cover, and lowered surface albedo from earlier snow disappearance, coincided with potential evapotranspiration (PET) increases of up to 10%. Combining spring precipitation decreases with PET increases accounted for 67% of the variance in post‐2000 streamflow deficits. Streamflow deficits were most substantial in lower elevation basins (<2,950 m), where snowmelt occurred earliest, and precipitation declines were largest. Refining seasonal spring precipitation forecasts is imperative for future water availability predictions in this snow‐dominated water resource region.

The hole truth: why do bumble bees rob flowers more than once? - J. L. Bronstein; G. Davidowitz; E. Litchenberg; R. E. Irwin (Plants, 2024)
Primary nectar-robbers feed through holes they make in flowers, often bypassing the plant's reproductive organs in the process. In many robbed plants, multiple holes are made in a single flower. Why a flower should be robbed repeatedly is difficult to understand: a hole signals that a nectar forager has already fed, which would seem likely to predict low rewards. We tested three explanations for this pattern in Corydalis caseana (Fumariaceae), a bumble bee pollinated and robbed plant: (1) multiple holes appear only after all flowers have been robbed once; (2) individual foragers make multiple holes during single visits; and (3) it is more profitable for bees to rob older flowers, even if they have already been robbed. We tested these hypotheses from 2014 to 2016 in a Colorado, USA population using data on robbing rates over time, floral longevity, nectar accumulation in visited and unvisited flowers, and the accumulation of robbing holes across the life of flowers. Multiple holes were already appearing when two-thirds of flowers still lacked a single hole, allowing us to reject the first hypothesis. The second hypothesis cannot offer a full explanation for multiple robbing holes because 35% of additional holes appeared in flowers one or more days after the first hole was made. Repeated sampling of bagged and exposed inflorescences revealed that flowers filled at a constant rate and refilled completely after being drained. Consequently, young flowers are of consistently low value to foragers compared to older flowers even if they had previously been robbed, consistent with the third hypothesis. While further studies are needed, these results offer a simple explanation for the paradoxical clustering of nectar-robbing damage in this and possibly other plant species.

Biofluorescence as a Mechanism of Sexual Selection in Ambystoma mavortium nebulosum - S. von der Ohe (2024)
Biofluorescence, the re-emission of absorbed light at lower energy wavelengths, has been widely documented in marine organisms and recently observed in amphibians. This phenomenon, particularly in amphibians such as frogs, salamanders, and newts, suggests potential roles in ecological interactions, including communication, mate selection, and predator avoidance. Despite advancements, the functional role of biofluorescence, especially regarding sexual selection, remains unclear. This study investigated the role of biofluorescence in sexual selection among Arizona Tiger Salamanders (Ambystoma tigrinum nebulosum), focusing on its behavioral functions and implications for conservation at the Mexican Cut in Colorado over the summer of 2024. Using a series of controlled experiments, we examined salamander preferences for different colored light and biofluorescent versus non-biofluorescent potential mates under blue light exposure. Results from glow stick and blue light control experiments indicate no significant sex-based differences in trap choices, but a general attraction to green and blue light was observed. In biofluorescence choice experiments, females showed a significant preference against biofluorescent males, whereas males exhibited no preference for biofluorescent females. These findings suggest that while blue light is a crucial visual cue, biofluorescence may not play a significant role in sexual selection in this species. Understanding the role of biofluorescence in amphibians could enhance non-invasive monitoring techniques and conservation strategies, particularly given the global decline in amphibian populations. This research provides new insights into amphibian behavior and ecology, contributing to improved conservation methods and a deeper understanding of biofluorescence's ecological and evolutionary significance.

Local Adaptations and Fitness of Transplants in the Lewis Flax – Flax Rust Coevolutionary System - K. Moussaoui (2024)
Disease progresses differently in varying environments. In coevolutionary interactions, species that interact frequently may adapt to their environment and to each other in a process called local adaptation. However, there may be trade-offs between adapting to the environment and to a coevolving partner. We used the host–pathogen system of Lewis flax and its coevolved fungal pathogen, flax rust, to study how the environment mediates adaptation to locally common pathogens. To separate these environmental and genetic effects, we placed sibling seedlings in their home environments, in different environments of similar elevation, and in environments of different elevations, and compared disease resistance to the local flax rust spores at the test site. We predicted that: 1) regardless of genetic resistance, lower elevation populations would present with less disease on average than higher elevation populations because of inhibitory effects of temperature; and 2) that seedling transplants would be more adapted to the locally common pathogens in their sites of origin than foreign transplants would be. This research will help us to disentangle the effects of the environment from geography on the Lewis Flax- Flax Rust system in the high mountain elevations at the Rocky Mountain Biological Laboratory in Colorado. It will also contribute to the broader study of how hosts balance adapting to both pathogens and the abiotic environment. Building on previous studies of local adaptations across large scales, our experiment attempted to study local adaptation on a smaller scale in an effort to isolate the effects of genetic lineage from environmental changes to phenotypes.

Seasonal controls on microbial depolymerization and oxidation of organic matter in floodplain soils - C. Anderson; Malak M. Tfaily; Rosalie K. Chu; Nikola Tolic; P. M. Fox; P. Nico; Scott Fendorf; Marco Keiluweit (Environmental Science & Technology, 2024)
Floodplain soils are vast reservoirs of organic carbon often attributed to anaerobic conditions that impose metabolic constraints on organic matter degradation. What remains elusive is how such metabolic constraints respond to dynamic flooding and drainage cycles characteristic of floodplain soils. Here we show that microbial depolymerization and respiration of organic compounds, two rate-limiting steps in decomposition, vary spatially and temporally with seasonal flooding of mountainous floodplain soils (Gothic, Colorado, USA). Combining metabolomics and -proteomics, we found a lower abundance of oxidative enzymes during flooding coincided with the accumulation of aromatic, high-molecular weight compounds, particularly in surface soils. In subsurface soils, we found that a lower oxidation state of carbon coincided with a greater abundance of chemically reduced, energetically less favorable low-molecular weight metabolites, irrespective of flooding condition. Our results suggest that seasonal flooding temporarily constrains oxidative depolymerization of larger, potentially plant-derived compounds in surface soils; in contrast, energetic constraints on microbial respiration persist in more reducing subsurface soils regardless of flooding. Our work underscores that the potential vulnerability of these distinct anaerobic carbon storage mechanisms to changing flooding dynamics should be considered, particularly as climate change shifts both the frequency and extent of flooding in floodplains globally.

The Fate of Burying Beetles and their Carcasses: Hardships, Competition and Environmental Factors - J. Cantu (2024)
Burying Beetles face both intraspecific and interspecific competition throughout the whole process of rearing a brood. Nicrophorus (burying beetles) are a well-studied genus that provides bi-parental care on the carcass resource that they bury for rearing their brood. Because carcasses are often rare, there is a threat of intruders that may take over the resource. Lab studies have shown a significant cost of intruders, and the roles that the adults play in defense. However, few studies have been done on intraspecific intrusion in the wild, or how these might be affected by developmental stage, carcass size, and habitat type. This research at RMBL can help provide further information on the factors that influence the reproductive success of N. investigator and N. defodiens. Overall, no successful intrusion happened in any of the experiments with 72 mice placed out across 2 experiments. Aspen habitat had the most successful reproduction with 7 total successful broods of larvae, five N.defodiens, and two N.investigator. Meadow overall had more beetles finding the carcasses but had almost every single carcass abandoned due to factors such as competition, soil moisture, and high temperatures. The meadow had a single successful brood of larvae with N. investigator. Intrusion might not happen as frequently as previously thought in the wild.

Fit or Unlit: using quantum dots to investigate the effects of a floricolous yeast and nectar robbing on male fitness in Ipomopsis aggregata - G. Thoresen (2024)
The interaction network between pollinators, plants, and the microbes that inhabit them is not yet widely understood. Most studies of floral microbes have focused on the role of nectar yeasts (e.g., Metschnikowia reukaufii) in the behavior of bumblebee pollinators and how they affect the fitness of plant subjects. However, little is known about the effects of these microbes on the hummingbird-pollinated wildflower Ipomopsis aggregata. We used a full factorial experimental design with two treatment levels: supplementation with sterile vs. M. reukaufii-inoculated nectar analogue and artificial nectar robbing vs. no nectar robbing. We used fluorescent quantum dots to quantify how these factors affected the dispersal of pollen grains from donor plants by comparing pollen donation across the four plant treatments. Our results suggest potential male fitness advantage on robbed plants, evidenced by significantly higher pollen donation from robbed donor plants to neighboring individuals, irrespective of the presence of yeast. This indicates that nectar robbing in I. aggregata may promote outcrossing, impacting hummingbird visitation and pollen dispersal.

Plant-Pollinator Interactions between Erigeron speciosus and Heterotheca villosa in Virginia Basin - J. Vanston (2024)
Vanston 2 Plant-pollinator communities are complex networks that are essential to the promotion of biodiversity and ecosystem health. Plant pollinator networks are sensitive to environmental change, and climate change poses a severe threat to the dynamics of these networks. It is important to examine the individual dynamics within these communities to understand how they will be affected by climate change and increasing global temperatures. The focus of this study is to compare the individual mutualistic plant-pollinator relationships of Erigeron speciosus and Heterotheca villosa, two species of Asteraceae, the Daisy flower family, in Virginia Basin, Gothic, CO. Although H. villosa was more abundant than E. speciosus, E. speciosus was more attractive to pollinators. Bombus seemed to prefer H. villosa, but more sampling should be done. E. speciosus is likely more attractive due to its larger surface area of disc flowers. Further research should continue network sampling at Virginia Basin and investigate flower tube length and pollinator tongue length relationships and the role of flower scent and floral volatiles.

The Effects of Temperature and N:P Ratios on Didymo Algae Growth - I. MacDougall (2024)
Didymosphenia geminata (didymo) is a species of algae that is native to North America, but has been producing unprecedented blooms during the last several decades. Climate change and nitrogen deposition are two hypothesized drivers of this phenomenon. The purpose of this research project is to better understand the conditions that drive didymo algae blooms in the Colorado Rocky Mountains. We hypothesize that didymo blooms will be greatest at high temperatures and under high N:P ratio treatments. In order to test this hypothesis, we used an experimental stream side channel experiment along the East River at the Rocky Mountain Biological Laboratory. There were five different N:P ratio treatments (2, 8, 16, 32, 100) and three temperature treatments combined in a factorial design (5 x 3). This experimental design will help us determine the correlation between temperature and N:P ratio treatments on didymo algae blooms. There were two statistical tests that we used for our data analysis, which were an ANCOVA and ANOVA test. We compared Added N:P Ratios with Didymo Cell Density, and we correlated Temperature Treatment with its Temperature Value. Based on these statistical tests that we ran, we determined that there was no statistical significance among N:P ratio treatments. On the other hand, there was a statistical difference between temperature treatments, but the temperature values were not different.

Relational River: Arizona v. Navajo Nation & the Colorado - Jason Anthony Robison (SSRN Electronic Journal, 2024)

Getting to the Root of It: Effects of Castilleja Root Hemiparasitism on Plant Community Structure and Function - A. Hastings (2024)

Reproductive ecology of Erigeron speciosus, a montane perennial herb: Evidence of self-incompatibility - D. D. Ingold; Paul J. CaraDonna; J. L. Dooley; Amy M. Iler (The Southwestern Naturalist, 2024)
Realizamos un experimento para determinar la biología reproductiva de Erigeron speciosus (Asteraceae), una hierba montano perenne que se extiende por el Oeste de Norteamérica. Polinización de E. speciosus fue manipulado para entender: (1) >cuál es el sistema de apareamiento para E. speciosus (cruzamiento vs. autofecundación)? (2) >Es E. speciosus autoincompatible? (3) >La distancia del donador de polen afecta el éxito de la reproducción? (4) >El éxito de la reproducción será limitada por la recepción de polen (i.e., limitación polínica)? Comparamos la producción de semillas y la viabilidad de semillas por cinco tratamientos de polinización: polinización ambiente (control), exclusión de polinización (flores embolsadas), autopolinización solamente, y dos tratamientos de cruzamiento (donadores de polen cercanos y lejanos). Encontramos que E. speciosus es por gran parte autoincompatible y depende en cruzamiento para su reproducción. Aun así, la reproducción no fue limitada por polen en el sitio de nuestra investigación. También encontramos evidencia que la reproducción de E. speciosus es susceptible a depresión por exogamia.

Forest composition and structural controls on canopy snow interception in a Colorado watershed - Curtis A. Beutler (2024)
Globally and across the Western United States shifting climate regimes have the ability to propagate change throughout ecosystems and affect their associated hydrologic functions. In mountain regions, which serve as “water towers” for much of humanity, the complex interactions between vegetation and water are especially vulnerable to climate change as they are subject to both ecological and hydrological disturbances. Forests exhibit major controls on the hydrology of mountain systems, of which a primary mechanism is the interception of falling snow in forest canopies which can result in up to 50% of intercepted snow being lost back to the atmosphere through sublimation. Despite being an important driver of forest-snow interactions, scientific inquiry on canopy snow interception has been limited to small spatial scales and limited observations due to the difficult nature of measuring snow in forest canopies. We used Terrestrial Laser Scanning (TLS) to quantify interception rates and interrogate how tree species, forest structure, and weather conditions influence canopy snow interception potential in a high elevation Colorado watershed. Our results represent a step forward in expanding the spatial scale of canopy snow observations and elucidating the differences in interception rates across different tree species, forest compositions, and structures. We compared deciduous tree stands comprised of Quaking Aspen against 3 prevalent coniferous tree species at this altitude (Lodgepole Pine, Engelmann Spruce, and Subalpine Fir) and found that on average conifer forests intercepted an order of magnitude greater snow volume. Analysis of a supplementary dataset on snowpack depth revealed that aspen stands had a 22% greater snow depth on average, despite wide ranges

A tale of two catchments: causality analysis and isotope systematics reveal mountainous watershed traits that regulate the retention and release of nitrogen - Nicholas J. Bouskill; Michelle Newcomer; R. W. H. Carroll; Curtis A. Beutler; Markus Bill; W. Brown; M. Conrad; Wenming Dong; Nicola Falco; Taylor Maavara; Alexander W. Newman; Patrick O. Sorensen; et al. (JGR Biogeosciences, 2024)
Abstract Mountainous watersheds are characterized by variability in functional traits, including vegetation, topography, geology, and geomorphology, which determine nitrogen (N) retention, and release. Coal Creek and East River are two contrasting catchments within the Upper Colorado River Basin that differ markedly in total nitrate (NO 3 − ) export. The East River has a diverse vegetation cover, and sinuous floodplains, and is underlain by N‐rich marine shale. At 0.21 ± 0.14 kg ha −1 yr −1 , the East River exports ∼3.5 times more NO 3 − relative to the conifer‐dominated Coal Creek (0.06 ± 0.02 kg ha −1 yr −1 ). While this can partly be explained by the larger size of the East River, the distinct watershed traits of these two catchments imply different mechanisms controlling the aggregate N‐export signal. A causality analysis shows physical and biogenic processes were critical in determining NO 3 − export from the East River catchment. Stable isotope ratios of NO 3 − (δ 15 N NO3 and δ 18 O NO3 ) show the East River catchment is a strong hotspot for biogeochemical processing of NO 3 − at the hillslope soil‐saprolite. By contrast, the conifer‐dominated Coal Creek retained nearly all atmospherically deposited NO 3 − , and its export was controlled by catchment hydrological traits (i.e., snowmelt periods and water table depth). The conservative N‐cycle within Coal Creek is likely due to the abundance of conifer trees, and smaller riparian regions, retaining more NO 3 − overall and reduced processing prior to export. This study highlights the value of integrating isotope systematics to link watershed functional traits to mechanisms of watershed element retention and release.

Social security: Does social position influence flight initiation distance? - T. Szulanski; Conner S. Philson; T. Szulanski; K. Uchida; Daniel T. Blumstein (Behavioral Ecology, 2024)
A variety of factors can influence an individual’s antipredator behavior including their group size because simply being around conspecifics may reduce predation risk. Recent work has shown that it is not just being around others, but rather the specific social relationships that individuals have with others may also modulate perceptions of risk and explain variation in a variety of antipredator behaviors. We asked whether and how yellow-bellied marmots’ (Marmota flaviventer) position in their social network explains variation in flight initiation distance (FID). We examined the relationship of both direct and indirect measures of sociality and separated models by age and sex classes to isolate the relationships for individuals with different life histories. Following the “social security” hypothesis, we predicted that more socially connected individuals would have a lower FID. We found that the magnitude and direction to which sociality was associated with FID varied based on age and sex. When examining all age- sex cohorts there was a weak effect of strength on FID: individuals in stronger relationships tolerated closer approaches. When examining each cohort independently, we found adult male’s FID was not associated with any social network measure, while female adults fled at greater distances as degree increased. Yearlings of both sexes, however, seemingly benefited from Commented [TS1]: but the directions of the effects are different for both cohorts. AD * closeness increases stronger social relationships, but only when perceived risk was high. These results are consistent FID in FY, but lowers it in MY. is this not important to include in the abstract? with the social security hypothesis; the degree of social connectedness may explain variation in FID in at least some age and sex cohorts.

Pollen chemical and mechanical defences restrict host-plant use by bees - S. Rivest; M. Muralidhar; Jessica R. K. Forrest (Proceedings of the Royal Society B, 2024)
Plants produce an array of chemical and mechanical defences that provide protection against many herbivores and pathogens. Putatively defensive compounds and structures can even occur in floral rewards: for example, the pollen of some plant taxa contains toxic compounds or possesses conspicuous spines. Yet little is known about whether pollen defences restrict host-plant use by bees. In other words, do bees, like other insect herbivores, tolerate the defences of their specific host plants while being harmed by non-host defences? To answer this question, we compared the effects of a chemical defence from Lupinus (Fabaceae) pollen and a putative mechanical defence (pollen spines) from Asteraceae pollen on larval survival of nine bee species in the tribe Osmiini (Megachilidae) varying in their pollen-host use. We found that both types of pollen defences reduce larval survival rate in some bee species. These detrimental effects were, however, mediated by host-plant associations, with bees being more tolerant of the pollen defences of their hosts, relative to the defences of plant taxa exploited by other species. This pattern strongly suggests that bees are adapted to the pollen defences of their hosts, and that host-plant use by bees is constrained by their ability to tolerate such defences.

Climate mediates the trade-offs associated with phenotypic plasticity in an amphibian polyphenism - M. A. Kirk; A. C. R. Lackey; K. E. Reider; Sean C. Thomas; H. H. Whiteman (Journal of Animal Ecology, 2024)
Polyphenisms occur when phenotypic plasticity produces morphologically distinct phenotypes from the same genotype. Plasticity is maintained through fitness trade-offs which are conferred to different phenotypes under specific environmental contexts. Predicting the impacts of contemporary climate change on phenotypic plasticity is critical for climate-sensitive animals like amphibians, but elucidating the selective pressures maintaining polyphenisms requires a framework to control for all mechanistic drivers of plasticity. Using a 32-year dataset documenting the larval and adult histories of 717 Arizona tiger salamanders (Ambystoma mavortium nebulosum), we determined how annual variation in climate and density dependence explained the maintenance of two distinct morphs (terrestrial metamorph vs. aquatic paedomorph) in a high-elevation polyphenism. The effects of climate and conspecific density on morph development were evaluated with piecewise structural equation models (SEM) to tease apart the direct and indirect pathways by which these two mechanisms affect phenotypic plasticity. Climate had a direct effect on morph outcome whereby longer growing seasons favoured metamorphic outcomes. Also, climate had indirect effects on morph outcome as mediated through density-dependent effects, such as long overwintering coldspells corresponding to high cannibal densities and light snowpacks corresponding to high larval densities, both of which promoted paedomorphic outcomes. Both climate and density dependence serve as important proxies for growth and resource limitation, which are important underlying drivers of the phenotypic plasticity in animal polyphenisms. Our findings motivate new studies to determine how contemporary climate change will alter the selective pressures maintaining phenotypic plasticity and polyphenisms.

Ecosystem-size relationships of river populations and communities - A. R. McIntosh; H. S. Greig; H. J. Warburton; J. D. Tonkin; C. M. Febria (Trends in Ecology & Evolution, 2024)
Knowledge of ecosystem-size influences on river populations and communities is integral to the balancing of human and environmental needs for water. The multiple dimensions of dendritic river networks complicate understanding of ecosystem-size influences, but could be resolved by the development of scaling relationships. We highlight the importance of physical constraints limiting predator body sizes, movements, and population sizes in small rivers, and where river contraction limits space or creates stressful conditions affecting community stability and food webs. Investigations of the scaling and contingency of these processes will be insightful because of the underlying generality and scale independence of such relationships. Doing so will also pinpoint damaging water-management practices and identify which aspects of river size can be most usefully manipulated in river restoration.

Patterns of genetic variation and local adaptation of a native herbivore to a lethal invasive plant - Nitin Ravikanthachari; Rachel A Steward; C. L. Boggs (Molecular Ecology, 2024)
Understanding the evolutionary processes that influence fitness is critical to pre- dicting species' responses to selection. Interactions among evolutionary processes including gene flow, drift and the strength of selection can lead to either local adap- tation or maladaptation, especially in heterogenous landscapes. Populations experi- encing novel environments or resources are ideal for understanding the mechanisms underlying adaptation or maladaptation, specifically in locally co-evolved interac- tions. We used the interaction between a native herbivore that oviposits on a patchily distributed introduced plant that in turn causes significant mortality to the larvae to test for signatures of local adaptation in areas where the two co-occurred. We used whole-genome sequencing to explore population structure, patterns of gene flow and signatures of local adaptation. We found signatures of local adaptation in response to the introduced plant in the absence of strong population structure with no genetic differentiation and low genetic variation. Additionally, we found localized allele fre- quency differences within a single population between habitats with and without the lethal plant, highlighting the effects of strong selection. Finally, we identified that se- lection was acting on larval ability to feed on the plant rather than on females’ ability to avoid oviposition, thus uncovering the specific ontogenetic target of selection. Our work highlights the potential for adaptation to occur in a fine-grained landscape in the presence of gene flow and low genetic variation.

Impacts of assisted migration: An introduced herbivore has short-term and long-term effects on its native host plant population - Nitin Ravikanthachari; L. L. Burch; Rachel Powell; Danielle Scott; Charlotte Wayne; K. Niitepold; R. H. Rosenberg; C. L. Boggs (Entomologia Experimentalis et Applicata, 2024)
Abstract Assisted migration consists of the introduction of a species to previously inhabited areas or to new suitable regions. Such introductions have been touted as a viable tool for conserving the earth's biodiversity. However, both the likely success of assisted migrations and the impacts on local communities are hotly debated. Empirical data on the local impacts of assisted migration are particularly lacking. We examined the short and long time‐scale effects of herbivory on Lonicera involucrata (Richards) Banks ex. Spreng (Caprifoliaceae) after an introduction of Euphydryas gillettii Barnes (Lepidoptera: Nymphalidae, Melitaeini) to Gunnison County, Colorado, USA, via an assisted migration in 1977. The plant is the primary larval host plant for the butterfly. We quantified plant seed production, plant survival, and population stage structure in two sets of observational experiments. We found that herbivory by E. gillettii increased L . involucrata reproduction on an annual time scale, independent of plant size and local microhabitat characteristics. Over the time since the butterfly's introduction, herbivory by E . gillettii resulted in a plant population structure biased toward smaller plants in the butterfly introduction and satellite sites compared with sites without the butterfly. Our results highlight the importance of studying the effects of assisted migrations on native populations at different temporal scales. As assisted migration becomes an indispensable tool for species conservation, our work adds to the understanding of the multi‐trophic impacts of assisted introductions on local populations and communities.

Decomposing an elevational gradient in predation by insectivorous birds - L. S. Dean; C. Vazquez-Gonzalez; S. Hellwitz; Luis Abdala-Roberts; K. A. Mooney (Ecosphere, 2024)
Abstract Insectivorous birds have ecologically important effects on prey abundance, behavior, and evolution, and through top‐down control, birds indirectly reduce herbivory and promote plant growth. While several studies sought to characterize biogeographic patterns in top‐down control by birds, variation in bird predation along elevational gradients is not well characterized in terms of both its commonness and the mechanisms underlying such variation. Here, we characterized variation in bird predation along a 700‐m montane elevation gradient using artificial clay caterpillars, assessing the roles of variation in aridity, other elevational effects not associated with aridity (e.g., most notably growing season length), and bird abundance and diversity. Multivariate models revealed increasing attack rates with aridity (when controlling for the effects of elevation) and elevation (when controlling for aridity). Because aridity declines with elevation, elevational patterns were not detectable in a univariate analysis. Bird abundance (but not diversity) decreased with elevation (but not aridity) and did not provide an explanation for our results, suggesting that the underlying mechanisms were behaviorally based. We speculate that the declining abundance of insect prey with elevation and aridity leads to increased bird foraging efforts and thus the likelihood of attacking clay caterpillars. If widespread, these dynamics have important consequences for both the interpretation of predation bioassays generally and our understanding of the multivariate drivers of variation in top‐down control by predators and predation risks experienced by prey.

Consequences of pollen defense compounds for pollinators and antagonists in a pollen rewarding plant - S. Rivest; Stephen T. Lee; Daniel Cook; Jessica R. K. Forrest (Ecology, 2024)
Plants produce an array of defensive compounds with toxic or deterrent effects on insect herbivores. Pollen can contain relatively high concentrations of such defense compounds, but the causes and consequences of this enigmatic phenomenon remain mostly unknown. These compounds could potentially protect pollen against antagonists but could also reduce flower attractiveness to pollinators. We combined field observations of the pollen-rewarding Lupinus argenteus with chemical analysis and laboratory assays to test three hypotheses for the presence of pollen defense compounds: (1) these compounds are the result of spillover from adjacent tissues, (2) they protect against pollen thieves, and (3) they act as antimicrobial compounds. We also tested whether pollen defense compounds affect pollinator behavior. We found a positive relationship between alkaloid concentrations in pollen and petals, supporting the idea that pollen defense compounds partly originate from spillover. However, pollen and petals exhibited quantitatively (but not qualitatively) distinct alkaloid profiles, suggesting that plants can adjust pollen alkaloid composition independently from that of adjacent tissues. We found no relationship between pollen alkaloid concentration and the abundance of pollen thieves in Lupinus flowers. However, pollen alkaloids were negatively associated with bacterial abundance. Finally, plants with more alkaloids in their pollen received more pollinator visits, but these visits were shorter, resulting in no change in the overall number of flowers visited. We propose that pollen defense compounds are partly the result of spillover from other tissues, while they also play an antimicrobial role. The absence of negative effects of these compounds on pollinator visitation likely allows their maintenance in pollen at relatively high concentrations. Taken together, our results suggest that pollen alkaloids affect and are mediated by the interplay of multiple interactions.

Latest Pleistocene glacial chronology and paleoclimate reconstruction for the East River watershed, Colorado, USA - Brendon Quirk; I. J. Larsen; A. J. Hidy (Quaternary Research, 2024)
Reconstructing Pleistocene glaciation timing and extent is vital for understanding paleoclimate. Whereas late Pleistocene glaciation has been studied extensively in western North American mountain ranges, the glacial history of the western Elk Range in Colorado remains understudied, particularly in the East River watershed, a site of intense scientific focus. Here we use cosmogenic nuclide exposure and depth–profile dating methods to determine the timing of glaciation in the East River watershed. We use glacier modeling to reconstruct paleoglacier extents and quantify past climate conditions. Our findings indicate that the East River glacier retreated from its maximum position approximately 17–18 ka, moving to recessional positions between 13 and 15 ka, before experiencing more substantial retreat to high-elevation cirques around 13 ka. Glacier modeling suggests that the maximum ice extents at 17–18 ka could have been sustained by temperature depressions of approximately −6.5°C compared to modern conditions, assuming consistent precipitation. Additionally, the ice position at 13–15 ka could have been supported by temperature depressions of around −4.0°C. These results offer insights into the deglaciation timeline in the East River watershed and broader western Elk Range as well as paleoclimate conditions during the late Pleistocene, which may aid future research on critical zone evolution in the East River watershed.

Cold-season precipitation sensitivity to microphysical parameterizations: hydrologic evaluations leveraging snow lidar datasets - William Rudisill; Alejandro Flores; H. P. Marshall; Erica R. Siirila-Woodburn; Daniel Feldman; Alan Rhoades; Zexuan Xu; A. Morales (Journal of Hydrometeorology, 2024)
Abstract Cloud microphysical processes are an important facet of atmospheric modeling, as they can control the initiation and rates of snowfall. Thus, parameterizations of these processes have important implications for modeling seasonal snow accumulation. We conduct experiments with the Weather Research and Forecasting (WRF V4.3.3) Model using three different microphysics parameterizations, including a sophisticated new scheme (ISHMAEL). Simulations are conducted for two cold seasons (2018 and 2019) centered on the Colorado Rockies’ ∼750-km 2 East River watershed. Precipitation efficiencies are quantified using a drying-ratio mass budget approach and point evaluations are performed against three NRCS SNOTEL stations. Precipitation and meteorological outputs from each are used to force a land surface model (Noah-MP) so that peak snow accumulation can be compared against airborne snow lidar products. We find that microphysical parameterization choice alone has a modest impact on total precipitation on the order of ±3% watershed-wide, and as high as 15% for certain regions, similar to other studies comparing the same parameterizations. Precipitation biases evaluated against SNOTEL are 15% ± 13%. WRF Noah-MP configurations produced snow water equivalents with good correlations with airborne lidar products at a 1-km spatial resolution: Pearson’s r values of 0.9, RMSEs between 8 and 17 cm, and percent biases of 3%–15%. Noah-MP with precipitation from the PRISM geostatistical precipitation product leads to a peak SWE underestimation of 32% in both years examined, and a weaker spatial correlation than the WRF configurations. We fall short of identifying a clearly superior microphysical parameterization but conclude that snow lidar is a valuable nontraditional indicator of model performance.

Extending the social cohesion hypothesis: is group social structure associated with dispersal in yellow-bellied marmots (Marmota flaviventer)? - S. Schneidman; Conner S. Philson; Daniel T. Blumstein (Current Zoology, 2024)
Dispersal is an important individual decision which may influence individual fitness as well as population viability. The social cohesion hypothesis posits more social individuals remain at home, which is supported by prior work across taxa. However, how the sociality and connectivity of the group an individual resides in-their group social structure-relates to dispersal decisions has not been explored. We extend the social cohesion hypothesis to predict individuals residing in more social groups would remain at home, and we quantified the affiliative and agonistic social network structure of female yellow-bellied marmots (Marmota flaviventer), a facultatively social ground-dwelling squirrel, where about half of all females disperse. Using mixed-effects models, we found no support for the hypothesis that affiliative group structure explained any variation in a marmot's decision to disperse. We did find marmots in groups with less agonistic centralization (around one or few individuals) were less likely to disperse. The former finding may result from limited ability to perceive group structure whereas the latter may reflect individuals in less agonistically centralized groups are less likely to be reproductively suppressed. These results suggest individual dispersal decisions are more impacted by individual sociality and not that of their social group. Thus, the social cohesion hypothesis may not scale to the level of the group. Further work is required to determine whether dispersal decisions in obligately social species are influenced by group social structure.

Does current weather or seasonality influence antipredator vigilance in a hibernating mammal? - K. Bobb (2024)

Bee phenological distributions predicted by inferring vital rates - M. Stemkovski; A. Fife; R. Stuart; Pearse W.D. (The American Naturalist, 2024)
AbstractHow bees shift the timing of their seasonal activity (phenology) to track favorable conditions influences the degree to which bee foraging and flowering plant reproduction overlap. While bee phenology is known to shift due to interannual climatic variation and experimental temperature manipulation, the underlying causes of these shifts are poorly understood. Most studies of bee phenology have been phenomenological and have only examined shifts of point estimates, such as first appearance or peak timing. Such cross-sectional measures are convenient for analysis, but foraging activity is distributed across time, and pollination interactions are better described by overlap in phenological abundance curves. Here, we make simultaneous inferences about interannual shifts in bee phenology, emergence and senescence rates, population size, and the effect of floral abundance on observed bee abundance. We do this with a model of transition rates between life stages implemented in a hierarchical Bayesian framework and parameterized with fine-scale abundance time series of the sweat bee Halictus rubicundus at the Rocky Mountain Biological Laboratory in Colorado. We find that H. rubicundus's emergence cueing was highly sensitive to the timing of snowmelt but that emergence rate, senescence rate, and population size did not differ greatly across years. The present approach can be used to glean information about vital rates from other datasets on bee and flower phenology, improving our understanding of pollination interactions.

Marmots could have the solution to a long-running debate in evolution - M. Le Page (New Scientist, 2024)

Old-Aged groundwater contributes to mountain hillslope hydrologic dynamics - Nicholas Thiros; Erica R. Siirila-Woodburn; Matthias Sprenger; K. H. Williams; P. James Dennedy-Frank; R. W. H. Carroll; William Payton Gardner (Journal of Hydrology, 2024)
Understanding connectivity between the soil and deeper bedrock groundwater is needed to accurately predict a watershed’s response to perturbation, such as drought. Yet, the bedrock groundwater dynamics in mountainous environments are typically under-constrained and excluded from watershed hydrologic models. Here, we investigate the role of groundwater characterized with decadal and longer water ages on the hydrologic and mass-transport processes within a steep snow-dominated mountain hillslope in the Central Rocky Mountains (USA). We quantify subsurface and surface water mass-balance, groundwater flowpaths, and age distributions using the ParFlow-CLM integrated hydrologic and EcoSLIM particle tracking models, which are compared to hydrometric and environmental tracer observations. An ensemble of models with varied soil and hydrogeologic parameters reproduces observed groundwater levels and century-scale mean ages inferred from environmental tracers. The numerical models suggest soil water near the toe of the hillslope contains considerable (>60 % of the mass-flux) contributions from bedrock flowpaths characterized with water ages >10 years. Flowpath connectivity between the deeper bedrock and soil systems is present throughout the year, highlighting the potentially critical role of groundwater with old ages on processes such as evapotranspiration and streamflow generation. The coupled numerical model and groundwater age observations show the bedrock groundwater system influences the hillslope hydrodynamics and should be considered in mountain watershed conceptual and numerical models.

Shifting groundwater fluxes in bedrock fractures: Evidence from stream water radon and water isotopes - K. Johnson; J. N. Christensen; William Payton Gardner; Matthias Sprenger; Langlang Li; K. H. Williams; R. W. H. Carroll; Nicholas Thiros; Curtis A. Beutler; Alexander W. Newman; P. Sullivan (Journal of Hydrology, 2024)

Sodium enriched nectar shapes plant–pollinator interactions in a subalpine meadow - Ethan VanValkenburg; T. Goncalves Souza; Nathan J. Sanders; Paul J. CaraDonna (Ecology and Evolution, 2024)
Many plants have evolved nutrient rewards to attract pollinators to flowers, but most research has focused on the sugar content of floral nectar resources. Concentrations of sodium in floral nectar (a micronutrient in low concentrations in nectar) can vary substantially both among and within co-occurring species. It is hypothesized that sodium concentrations in floral nectar might play an important and underappreciated role in plant-pollinator interactions, especially because many animals, including pollinators, are sodium limited in nature. Yet, the consequences of variation in sodium concentrations in floral nectar remain largely unexplored. Here, we investigate whether enriching floral nectar with sodium influences the composition, diversity, and frequency of plant-pollinator interactions. We experimentally enriched sodium concentrations in four plant species in a subalpine meadow in Colorado, USA. We found that flowers with sodium-enriched nectar received more visits from a greater diversity of pollinators throughout the season. Different pollinator species foraged more frequently on flowers enriched with sodium and showed evidence of other changes to foraging behavior, including greater dietary evenness. These findings are consistent with the "salty nectar hypothesis," providing evidence for the importance of sodium limitation in pollinators and suggesting that even small nectar constituents can shape plant-pollinator interactions.

Model and remote-sensing-guided experimental design and hypothesis generation for monitoring snow-soil–plant interactions - Haruko M. Wainwright; Baptiste Dafflon; Erica R. Siirila-Woodburn; Nicola Falco; Yuxin Wu; Ian K Breckheimer; R. W. H. Carroll (Frontiers in Water, 2024)
In this study, we develop a machine-learning (ML)-enabled strategy for selecting hillslope-scale ecohydrological monitoring sites within snow-dominated mountainous watersheds, with a particular focus on snow-soil–plant interactions. Data layers rely on spatial data layers from both remote sensing and hydrological model simulations. Specifically, a Landsat-based foresummer drought sensitivity index is used to define the dependency of the annual peak plant productivity on the Palmer drought severity index in the early growing season. Hydrological simulations provide the spatiotemporal dynamics of near-surface soil moisture and snow depth. In this framework, a regression analysis identifies the key hydrological variables relevant to the spatial heterogeneity of drought sensitivity. We then apply unsupervised clustering to these key variables, using the Gaussian mixture model, to group hillslopes into several zones that have divergent relationships regarding soil moisture, snow dynamics, and drought sensitivity. Using the datasets collected in the East River Watershed (Crested Butte, Colorado, United States), results show that drought sensitivity is significantly correlated with model-derived soil moisture and snow-free timing over space and time. The relationship is, however, non-linear, such that the correlation decreases above a threshold elevation and in a heavy snow year due to large snowpacks, lateral flow, and soil storage limitations. Clustering is then able to define the zones that have high or low sensitivity to drought, as well as the mid-elevation regions where sensitivity is associated with the topographic aspect and net potential radiation. In addition, the algorithm identifies the most representative hillslopes with road/trail access within each zone for installing monitoring sites. Our method also aims to significantly increase the use of ML and model-simulation results to guide critical zone and watershed monitoring activities.

Hydrological control of rock carbon fluxes from shale weathering - Jiamin Wan; Tetsu Tokunaga; Curtis A. Beutler; Alexander W. Newman; Wenming Dong; Markus Bill; W. Brown; A. N. Henderson; Anh Phuong Tran; K. H. Williams (Nature Water, 2024)
Shale bedrocks hold Earth’s largest carbon inventory. Although water is recognized for cycling elements through terrestrial environments, understanding how hydrology controls ancient rock carbon (Crock) release is limited. Here we measured depth- and season-dependent subsurface water fluxes and pore-water and pore-gas geochemistry (including radiocarbon) over five vastly different water years along a hillslope. The data reveal that the maximum depth of annual water table oscillations determines the weathering depth. Seasonally varying subsurface water fluxes determine the export forms and rates of weathered Crock. Eighty percent of released Crock is emitted as CO2 to the atmosphere primarily during warmer and lower water table seasons and 20% of released Crock as bicarbonate exports mostly during months of snowmelt to the hydrosphere. Thus, the rates and forms of Crock weathering and export are clearly controlled by climate via hydrologic regulation of oxygen availability and subsurface flow. The approaches developed here can be applied to other environments. This study shows that climate-driven hydrology primarily controls subsurface rock carbon weathering, with the groundwater table regulating the weathering depth and subsurface water fluxes determining the transported forms and rates of carbon released from rocks, based on measurements in the East River watershed, Rocky Mountains, United States.

Does Floral Nectar Depth Correlate With Pollinator Proboscis Length? - S. Bograd (2024)
Pollination is essential for maintaining global biodiversity and our world’s food supply. Climate change is causing inefficiencies in plant-pollinator networks, so understanding the factors that determine which pollinators visit which plants will be exceedingly important for a sustainable future. Our study examined the effects of floral nectar depth on visitor proboscis length in a dry subalpine meadow at the Rocky Mountain Biological Laboratory. We conducted 46.5 hours of pollinator observations in addition to using historic observations in the same plant-pollinator community and historic measurements on the floral nectar depths and pollinator proboscis length, to test if pollinator visitation was affected by size thresholds or size matching. We found that flowers with greater nectar depths were visited by pollinators with longer proboscis, and that the meadow’s pollinators tend to visit flowers which have similar nectar depths to their proboscis length. Our results suggest that size-matching influences plant-pollinator networks. As a result, short-tongued pollinators may be particularly vulnerable to the loss of flowers with shallow nectar depths and long-tubed flowers to pollinators with long proboscis.

The effects of advanced plant phenology on herbivory and plant demography - K. Dawdy (2024)

Effects of water availability on expression of vegetative traits in Ipomopsis across space and time - L. Emanuel (2024)
In subalpine ecosystems, climate change has contributed to an earlier snowmelt as a result of warmer temperatures in the winter and spring. This shift may act to limit water availability for plant communities by prolonging the period between initial snowmelt and late-season monsoon rains, placing these systems at risk of more frequent and severe drought. The genus Ipomopsis—a perennial subalpine plant—has been the subject of a long-term study at RMBL examining the effects of climate change on phenotype. Previous research has identified several vegetative traits in the genus whose expression can vary based on environmental factors including snowmelt date and soil moisture. This project aims to examine how water availability, specifically soil moisture, affects the expression of vegetative traits in Ipomopsis using both spatial (2024 data) and long-term temporal comparisons. Four traits—trichome density, specific leaf area (SLA), leaf volumetric water content (VWC), and photosynthetic water use efficiency (WUE)—were measured, along with soil moisture, from plants in three populations. Additionally, historical data were analyzed to compare vegetative traits and snowmelt date over 15 years. Relationships between trait expression and water availability were found to be stronger in historical comparisons than in spatial comparisons, likely as a result of abnormally wet conditions during June of 2024. Higher soil moisture, however, predicted higher leaf VWC in this year’s data, and years with later snowmelt date had higher SLA. Trichome density did not change significantly with snowmelt date. Finally, WUE was influenced by an interaction between site and snowmelt date. 1