Variation in timing and abundance of flowering by Delphinium barbeyi Huth (Ranunculaceae): the roles of snowpack, frost, and La Niña, in the context of climate change - David W. Inouye; M. A. Morales; G. J. Dodge (Oecologia, 2002)

Holarctic marmots as a factor of biodiversity - O. A. Schwartz; Kenneth B. Armitage (2002)

Feeding strategies of an adult stonefly (Plecoptera): implications for egg production and dispersal - K. H. Macneale; Gene E Likens; B. L. Peckarsky (Verhandlungun Internationale Verein Limnologie, 2002)
Feeding in the Perlodidae and Chloroperlidae may, therefore, be important for survival and possibly for the final stages of egg development in the population dynarnics of aquatic insects.

Reach-scale Manipulations show invertebrate grazers depress algal resources in streams - B. W. Taylor; A. R. McIntosh; B. L. Peckarsky (Limnology and Oceanography, 2002)
Experimental tools that enable manipulations of organisms at larger scales allow for comparisons of processes across multiple spatial scales and expand our ability to make predictions about ecological processes. We performed reach scale (i.e., 50 m2) manipulations of invertebrate communities in streams using a modified electroshocking technique to nondestructively remove invertebrates. In addition, we conducted a microcosm experiment (i.e., 157 cm2) with different grazer densities that enabled comparison of the strength of grazer‐algal interactions at large and small spatial scales. In high elevation headwater streams, electroshocking reduced total invertebrate abundance by 84% in a 50‐m2 reach of stream. Although mobile invertebrates recolonized the manipulated area rapidly, daily electroshocking maintained the density reduction. Electroshocking reduced the density of herbivorous invertebrates 86%, which resulted in a 57% increase in algal biomass, whereas in a stream that was not electroshocked, invertebrate density and algal biomass changed much less, only 16 and 8%, respectively. Comparison of grazer effect on periphyton between microcosm and reach‐scale experiments revealed that the per capita interaction strength of grazers on primary producers was three times greater in the reach‐scale manipulation than that observed in the microcosm experiments. Reach‐scale manipulation of invertebrate grazers in streams provides a powerful method to experimentally test patterns observed in the field at a large spatial scale, with more realism than streamside microcosms or small cages in streams.

Predator chemicals induce changes in mayfly life history traits: a whole-stream manipulation - B. L. Peckarsky; A. R. McIntosh; B. W. Taylor; J. Dahl (Ecology, 2002)
In high-elevation streams of western Colorado, mayflies (Baetis bicaudatus) develop faster, but mature at a smaller size where trout are present compared to streams where fish are absent. These life history traits reduce the time of larval exposure to trout predation, but cost reduced fecundity. We designed a field experiment involving manipulation of whole streams to determine whether these changes were caused by the presence of brook trout, and specifically, whether they could be triggered by trout chemical cues. In 1999 and 2000, we introduced water from containers with brook trout (Salvelinus fontinalis) into five naturally fishless streams, and fishless stream water into five adjacent control streams, to determine whether these cues alone could induce the mayfly life history traits we have observed in natural trout streams. As in previous small-scale experiments, the size at which mayflies matured declined significantly in streams with added trout chemicals but did not change in streams with fishless water only. Thus, life history traits similar to those observed in the field were induced within the natural variability inherent in streams. These results demonstrate the strength of this predator–prey interaction and indicate that brook trout are an important agent of natural selection on mayfly life history traits.

Evaporite tectonism in the lower Roaring Fork River valley, west-central Colorado - Robert M. Kirkham; Randall K. Streufert; Michael J. Kunk; James R. Budahn; Mark R. Hudson; William Perry (Geological Society of America eBooks, 2002)

Volatile production by the buds and corollas of two sympatric, confamial plants, Ipomopsis aggregata and Polemonium foliosissimum - R. E. Irwin; B. Dorsett (Journal of Chemical Ecology, 2002)

Induced morphological defenses in the wild: predator effects on a mayfly, Drunella coloradensis - J. Dahl; B. L. Peckarsky (Ecology, 2002)

Resistance to pre-dispersal seed predators in a natural hybrid zone - Diane R. Campbell; M. Crawford; Alison K. Brody; T. A. Forbis (Oecologia, 2002)

Tinajas of southern Utah: reproductive strategies and the habitat template - C. Anderson (2002)

The effects of plant succession and ant nest on soil organic matter and soil moisture - R. M. Rizo (2002)
An earthflow that occurred in Gunnison County, Colorado created a natural laboratory to study plant succession. Plant succession and ants can effect the soil composition of grounds left bare and depleted of organic matter by the landslide. This study was conducted to examine if the described successional pathway and ant nests changed soil composition in the landslide. The study revealed that the described successional pathway increased soil organic content if it begins from bare ground and ends with possible climax community. Pioneer species did not initially contribute to a significant change on soil organic content. Ant nests, on the other hand, do increase soil organic content. Moisture results reveal that all sites differ in soil moisture and soil moisture retention. Observe interactions between ants and pioneer species has also raised question on the importance of insect and plant interaction during succession.

Predicting patterns of mating and potential hybridization from pollinator behavior - Diane R. Campbell; Nickolas M. Waser; G. T. Pederson (American Naturalist, 2002)
Hybridization in flowering plants is determined in part by the rate at which animal pollinators move between species and by the effectiveness of such movements in transferring pollen. Pollinator behavior can also influence hybrid fitness by determining receipt and export of pollen. We incorporated information on pollinator effectiveness and visitation behavior into a simulation model that predicts pollen transfer between Ipomopsis aggregata, Ipomopsis tenuituba, and hybrids. These predictions were compared with estimates of pollen transfer derived from movement of fluorescent dyes in experimental plant arrays. Interspecific pollen transfer was relatively uncommon in these arrays, whereas transfer between hybrids and the parental species was at least as common as conspecific transfer. Backcrossing was asymmetrical; I. aggregata flowers frequently received mixed loads of hybrid and conspecific pollen. The simulation suggests that these patterns of pollen transfer are largely explained by the visitation sequences of hummingbird and insect pollinators, with little contribution from mechanical isolation. Pollen receipt by hybrids exceeded that of both parental species in a year when pollinators preferred to visit F1 and F2 hybrids and was intermediate in another year when they preferred to visit I. aggregata. This suggests that natural variation in pollination may produce spatiotemporal variation in hybridization and hybrid fitness.

Dynamic nectar replenishment in flowers of Penstemon (Scrophulariaceae) - M. C. Castellanos; P. Wilson; J. D. Thomson (American Journal of Botany, 2002)
Plants that experience variation in pollinator visitation rates or fluctuations in weather conditions may be expected to have evolved homeostatic mechanisms that regulate their nectar offerings, thereby providing a more constant reward to the pollinators. A limited degree of such nectar homeostasis is reported here for Penstemon. First, nectar removal stimulates replenishment: when nectar was removed hourly for 6 h from P. speciosus, twice as much nectar was secreted cumulatively as when nectar was removed only at the beginning and end of the same 6‐h period. Second, replacing artificial nectar in the nectaries of P. speciosus prevents replenishment. Third, the hummingbird‐adapted P. barbatus made more nectar before leveling off than the bee‐adapted P. strictus. Our work and previous studies with other plants imply mechanisms for dynamic regulation of nectar offerings, at least within broad limits. We speculate about the proximate physiology underlying this behavior and its evolutionary significance.

Does butterfly diversity predict moth diversity? Testing a popular taxon at local scales - T. H. Ricketts; G. C. Daily; P. R. Ehrlich (Biological Conservation, 2002)
Results suggest that butterflies are unlikely to be useful indicators of moth diversity at a local scale, phylogenetic relatedness is not a reliable criterion for selecting appropriate indicator taxa, and a habitat-based approach would more effectively conserve moth diversity in this landscape.

Relative survival rate of Pieris napi larvae in the field on different host (Cruciferae) plants - T. Paape (2002)

Swarming and mating behavior of a mayfly Baetis bicaudatus suggest stabilizing selection for male body size - B. L. Peckarsky; A. R. McIntosh; C. C. Caudill; J. Dahl (Behavioral Ecology and Sociobiology, 2002)

Climate-ecosystem interactions in montane meadows - J. Harte (2002)

Using mixed models in SAS for ecological analyses - F. Saavedra; L. Douglass (Bulletin of the Ecological Society of America, 2002)

Protogyny, pollination, and sex expression of andromonoecious Pseudocymopterus montanus (Apiaceae, Apioideae) - M. A. Schlessman; L. M. Graceffa (International Journal of Plant Sciences, 2002)

Biotic and abiotic effects on ant community structure - J. A. S. Nilsen (2002)
Previous studies have shown that plant species diversity, habitat type, elevation, and temperature affect ant community structure. In this study, I examined the roles of these factors at 10 sites in and around Gothic, CO in aspen stands and meadows. Data gathered through baiting experiments and pitfall trapping found that there was no significant difference in the species richness between habitats. There was a difference, however, in ant abundance, with significantly more ants in the meadow than the aspen stand. There were also no significant effects of elevation, temperature, or plant species diversity. However, trends suggest that these factors may influence ant activity in meadows.

Self-Similarity in the Distribution of Plant Species Across a Successional Gradient - L. Cushing (2002)
Valerian edulis is a perennial dicot growing in montane and subalpline regions. It is a polygamo dioecious species and popular host plant for aphids. Because of such characteristics, it was chosen to study the effects of resource allocation dependency. This study examined the specific effects of aphid-ant mutualisms, aphid herbivory and the use of fertilizer on the resource allocation of Valerian edulis. Results gave no significant evidence that indicated the presence of aphids, ants or the addition of fertilizer effect resource allocation in this plant species. However, results did support previous studies that indicate growth dependence on aphids and ants.

Variation in nectar robbing over time, space, and species - R. E. Irwin; J. E. L. Maloof (Oecologia, 2002)
Variation in the interactions between a nectar-robbing bumblebee and its host plants may have important consequences with respect to the population dynamics of host plants as well as selection on floral and flowering traits.

Effects of climatological factos on annual growth of shrubby species of the rocky mountains - E. McCullough (2002)

Nests of Preble's Meadow Jumping Mouse (Zapus hudsonius preblei) in Douglas County, Colorado - Matthew R. Bain; Tanya M. Shenk (The Southwestern Naturalist, 2002)

Holarctic marmots as a factor of biodiversity - Kenneth B. Armitage; K. E. Wynne-Edwards (2002)
Unlike the majority of small mammals and similar to other Marmotini, female reproduction in Marmota flaviventris was characterized by increased progesterone levels during lactation as well as gestation. Elevated levels of progesterone during lactation could be an important component of a feedback mechanism that prevents subsequent ovarian activity and ovulation in this obligate annual breeder. High levels of P4 in non-breeding yearling females suggest that there may be critical priming events in reproduction that occur the year before behavioral estrus. Nipple index is associated with the progesterone cycle and is a good index of breeding or attempted breeding by female marmots. Key-words: progestrone, nipple index, gestation, lactation. Pesztome Y oxeamobpioxux cypkoe, 6 omiuiue om bonbuuncmea npedcmaésumeneii Marmotini, 60 6pema bepemeHHocmu u jakmayuu nadaem codepocanue npozecmepoua 6 Kposu. Tlogbimenue KOHYeHMpaYyuU 3m0zZO ZOPMOHA, No ecel BudUMOCMU, AGNARMCA MeXAHU3MOM, OnpedeNAIOWUM NOdaBReHUe akmuéHocmu AliyeKnemoK u oeyaayuu. Bercoxu ypoeenb P4 y HEPA3MHOHCAIOWUXCA Z2O006ANLIX CAMOK nNodmeepxCOaem, 4MO OHU He CnOcObHet K PasMHOHceHUIO 6 9MOM Bo3pacme, HecMompa Ha Hanuyue y Hux 9cmpyca. Tloxazamenb PAI6UMUA ZPYOHLIX WNC CBAZAH C YUKNOM BbIpabomKU Npozecmepoua u ABAREMCA XOPOULUM UHOUKAMOPOM CNOCOGHOCMU CAMOK K PAIMHOHCEHUN. Kuouveepste ci06ea: npozecmepOH, UHOEKC PAIGUMUR 2PVOHbIX WCeNE3, 6epemennocmp, akmayuan. Résumé Contrairement 4 la majorité des petits mammiféres, mais comme les autres Marmotinl, /a reproduction des femelles chez Marmota flaviventris est caractérisée par une augmentation des taux de progestérone pendant /a lactation ainsi que pendant /a gestation, Des taux élevés de progestérone au cours de /a lactation pourraient constituer une composante importante d’un mécanisme de rétroaction qui prévient une activité ovarienne et une ovulation ultérieures chez cet animal 4 reproduction strictement annuelle. Des niveaux élevés de P4 chez des femelies d’un an non reproductrices suggérent qu’il peut y avoir des événements initlateurs de la repoduction qui se produisent l'année précédant l’oestrus comportemental. L’évolution des mamelons suit le cycle de la progestérone et constitue un bon indice de reproduction ou d'une tentative de reproduction chez Jes marmottes femelles. Mots clés : progestérone, indice de reproduction, gestation, lactation. CYPKU TONAPKTUKUY KAK ®AKTOP BUOPA3SHOOBPA3UA K.6. Apmumetiox, K.E. BuHH-Sdeapdc KOOHLIEHTPALYA TIPOTECTEPOHKA ...

Thermoregulatory strategies of Northern House Wrens (Troglodytes aedon) during nestling phase in a western Colorad high altitude population - C. Clapp (2002)

The effect of protozoan parasitism on the variation of song characteristics of male mountain white-crowned sparrows (Zonotrichia leucophrys oriantha) - O. Crino (2002)

Outcrop to subsurface stratigraphy of the Pennsylvanian Hermosa Group southern Paradox Basin U.S.A. - Alan Brown (2002)
Pennsylvanian (Desmoinesian) sedimentary rocks within the Paradox Basin Four Corners area of the western United States afford a unique opportunity to study the development of sedimentary successions in a complex marine to nonmarine depositional setting. The close association of thick intervals of nonmarine fan-delta facies adjacent to and in time equivalent position to marine carbonate-evaporite facies suggests complex relationships between the factors affecting deposition. Development of an effective scheme to differentiate the depositional signatures from within these sedimentary successions is the primary goal of this study. To achieve this goal, two objectives were pursued. The first was to calibrate the diverse range of rock-types in the Hermosa Group to in-situ wellbore measurements. To facilitate this process, a neural network evaluation procedure coupled with standard petrophysical evaluation techniques were employed to aid in facies succession prediction and lateral facies correlation. This process proved to be as accurate as standard wireline analysis procedures and was able to account for variations not as detectable in conventional scheme. The second objective was to correlate the stratigraphy of the Hermosa Group from outcrops of the Animas Valley to the subsurface along the southern Paradox Basin. The key to understanding the depositional sequences within the Middle Pennsylvanian section is to determine spatial and temporal relationships between the evaporites and black-shale deposits associated with carbonate algal mound buildups and juxtaposed terrigenous clastic fan-delta depositional facies. Once the relationships of these facies successions are delineated, then a three dimensional architectural framework can be manipulated to examine all possible lateral facies successions. By utilizing these analyses, several members of the Paradox Formation were shown to be laterally equivalent and physically continuous with parts of the previously designated undifferentiated Honaker Trail Formation of the San Juan Dome region. The study required a rigorous integration process utilizing a digital workstation environment combining large and more diverse datasets than previously utilized for improved correlation control. Techniques for evaluation of facies successions involved core (42), subsurface wells (4000+), and measured sections (12+) were employed.

Holarctic Marmots as a Factor of Biodiversity - B. C. Woods; Kenneth B. Armitage; Daniel T. Blumstein (2002)
Circadian rhythms of body temperature were evident during deep torpor in 11 of 12 individuals. The mean period was 23.94 hours. Circadian cycles of oxygen consumption were apparent in Jive of 14 marmots. Arousal tended to occur during the increase phase of the cycle. This report may be the Jirst to demonstrate cycles of oxygen consumption during deep torpor. Ke ey-words: Circadian rhythm, body temperature, oxygen consumption, torpor. Pe3iome L[upxadueie pummbi memnepamyper mena Gen oveeuduel 6 mexenue nepuoda eny6oxoi cnauxu y 11 uz 12 ocobeii. Cpedxuti nepuod Gem 23.94 yaca. Tupxadnere yuxnoi nompebnenua xucnopoda Geviu oveeuduer y 5 uz 14 cypKoe. Ipo6yocdenue umeno mexdenyurw npoucxodume 6 mexenue cmaduu yeenuyenua yuxna. Imo coobyenue moxcem 6voimp nepébiM, Oe¢MOHCMpupyouyUM YyuKIdt nompebRenua KuCROpoda 6 MeveHUe amy6oKon cnauKu, Karoueeote CNOG6Q: yupKadnpie PUMMbI, MeMnepamypa mela, nompebnenue Kucnopoda, cnauKa. Résumé Des rythmes circadiens de la température corporelle étaient évidents pendant fa torpeur profonde chez | | individus sur 12, La période moyenne était de 23,94 heures. Des rythmes circadiens de consommation de Voxygéne étaient évidents chez 5 marmottes sur 14. L’éveil tend 4 se Produire au cours de la phase croissante du cycle. Ce rapport pourrait étre la premiére démonstration de lexistence de cycle de consommation d’oxygéne pendant la torpeur profonde. Mots-clés : Rythme circadien, température corporelle, consommation doxygéne, torpeur. 389 CYPKY FONAPKTUKU KAK ®AKTOP BUOPASHOOBPA3UA B.K. Bydc u dp. COXPAHEHWE LIAPKAQHbIX PHTMOB ...

Holarctic Marmots as a Factor of Biodiversity - Kenneth B. Armitage (2002)

Post-copulatory benefits to male burying beetles, Nicrophorus investigator, and the analysis of sequential reproductive behaviors: why do male beetles perform parental care? - M. Takahashi (2002)

Host effects on herbivory and pollination in a hemiparasitic plant - L. S. Adler (Ecology, 2002)
The indirect effects of hosts on interactions between parasites and other species are not well understood, and it may be difficult to predict the outcome of host species effects on parasite performance due to the complexity of potential direct and indirect effects. For example, parasitic plants obtain defensive compounds as well as nutrients from their hosts, and thus many attributes of parasitic plants are dependent on the quality of their host species. Here I measure the effect of a lupine host species (Lupinus argenteus) compared to other host species on herbivory, pollination, and female plant fitness in the hemiparasite Indian paintbrush (Castilleja miniata) using a series of field experiments. Association with lupine was determined in the field by assaying Indian paintbrush leaves for lupine alkaloids. I found that Indian paintbrush plants parasitizing lupines experienced reduced herbivory from plume moth larvae, agromyzid fly larvae, and deer, relative to Indian paintbrush plants parasitizing other host species. However, there was no correlation between alkaloid content of inflorescences and plume moth performance. Host species did not affect pollinator preference for Indian paintbrush in the field. Indian paintbrush parasitizing lupines produced twice as many seeds overall as Indian paintbrush parasitizing other host species. Correlations suggest that this benefit arises both from reduced herbivory and increased nitrogenous resources. The reduction of herbivory in Indian paintbrush plants parasitizing lupines indicates that host species can affect performance of hemiparasites via indirect pathways, and that the larger community of herbivores could alter the impact of a host on its plant parasites.

The effects of ungulate herbivory and nutrient variation on pollen reciept in Ipomopsis aggregata - A. L. Rogers (2002)
The purpose of this study was to investigate the effects of ungulate herbivory (clipped, unclipped) and nutrient variation (ambient, water added, fertilizer and water added) on conspecific and heterospecific pollen receipt to Ipomopsis aggregata. I found that both clipping and adding nutrients influenced pollen receipt. Pollen receipt was highest in unclipped plants given fertilizer treatments. There was also a temporal effect on pollen receipt of conspecific pollen in unclipped plants. Pollen receipt decreased as the season progressed. As this paper is a study of the indirect effects of herbivory and nutrient variation on plant reproduction, it raises questions about the influence of herbivory and varied nutrients on plant reproduction, aside from seed production and other direct effects.

The role of competition in the foraging ecology of two herbivorous stream mayflies - P. Ode (2002)

Drilling of the Kiowa Core, Elbert County, Colorado - R. G. Raynolds (Rocky Mountain Geology, 2002)

Effects of nectar availability, floral display, and herbivore damage on pollinator visitation rates in Castilleja miniata and Castilleja linariifolia - E. J. Case (2002)

History, Geology, and Mineralogy of the Brooklyn Mine, San Juan County, Colorado - Tom Rosemeyer (Rocks & Minerals, 2002)

The relationship between the distribution of worker sizes and new worker production in the ant Formica neorufibarbis - Ian Billick (Oecologia, 2002)
These are the first results to directly link the range of worker sizes to a component of colony fitness in a natural setting.

The distribution of Cirsium arvense when in the presence of legumes - B. Weathersby (2002)

Asymmetry as an Indicator of Habitat Quality and Foraging Ability in the Arizona Tiger Salamander, Ambystoma tigrinum nebulosum - A. Benson (2002)

Mapping Bedrock Depths with Electromagnetic Induction in Costilla County, Colorado - Jim Doolittle; Alan Stuebe; Alan Price; Eugene Kelly (Soil Survey Horizons, 2002)

Rock glaciers in southwestern Colorado as indicators of late-Holocene climate change: A lichenometric study using Rhizocarpon subgenus Rizocarpon - K. A. Refsnider (2002)

Toward a synthesis of the Newtonian and Darwinian worldviews - J. Harte (Physics Today, 2002)
Physicists seek simplicity in universal laws. Ecologists revel in complex interdependencies. A sustainable future for our planet will probably require a look at life from both sides.

Determining the relationship between an invasive plant, cirsium arvense, and insect species richness - M. Giometti (2002)

Avian Incubation: Behavior, Environment, and Evolution - W. A. Calder (2002)

Hematological parameters of high-elevation bushy-tailed woodrats - B. A. Frase (The Southwestern Naturalist, 2002)

Holarctic marmots as a factor of biodiversity - Kenneth B. Armitage; K. E. Wynne-Edwards; Daniel T. Blumstein; O. A. Schwartz; B. C. Woods; B. C. Woods; Kenneth B. Armitage; Kenneth B. Armitage; Kenneth B. Armitage; Kenneth B. Armitage; Daniel T. Blumstein; Daniel T. Blumstein (2002)
Emergence mass is highly correlated with immergence mass, but explains about 55% of the variation. There is a 2- fold difference in body mass among marmot species. Total mass loss during hibernation is correlated with immergence mass. All measures of mass loss are correlated with each other. Big species may be big because they require the use of considerable mass during hibernation; however, mass loss is not significantly correlated with the length of hibernation. Body mass is related to the age of first reproduction and length of the active season. Environmental harshness may provide a unifying theme that integrates life-history traits and patterns of mass loss. Evidence for environmental harshness is derived from patterns of female reproduction, mass loss following emergence, variation in home-range size, time of mating, and reproductive skipping. The major sources of mass loss are maintenance during hibernation, reproduction, social thermoregulation, and post-emergence environmental stress. The importance of these four sources of mass loss vary among species and should determine the differences in body mass among species of marmots. Patterns of mass loss are related to social systems.

Variation in the benefits of nutrient addition in Ipomopsis aggegata: A work in progress - J. G. Stuber (2002)

Effect of larval body size on overwinter survival and emerging adult size in the burying beetle, Nicrophorus investigator - R. J. Smith (Canadian Journal of Zoology, 2002)
Body size may influence both adult fecundity and the probability of survival through each life stage. Previous studies of burying beetles (Nicrophorus, Coleoptera: Silphidae) have revealed reproductive advantages for larger adults and the role of parental care in determining larval size and number. In this study I measure the effect of size on survival over the winter period and the correlation between larval size and the size of emerging adults. I collected data from 24 groups of 2025 larvae sorted by size and overwintered outside under natural conditions in Colorado, U.S.A. There was a significant positive correlation between larval size and adult size at emergence and a significant effect of size on overwinter survival. Data from 2 years yielded the following mean survival rates: small, 47.3 ± 1.0%; medium, 73.2 ± 0.7%; large, 85.7 ± 0.4%. These values were then used to accurately predict adult emergence from broods of larvae whose range of size was measured prior to the overwinter period. The results indicate that selection for large body size may result from an overwinter survival advantage and not just from reproductive success. This has implications for fitness models of parental care and models of population dynamics.

Acid mine drainage effects on algal species composition in a Rocky Mountain Stream - M. S. Winters; B. W. Taylor (2002)

The evolution of wing color in Colias butterflies: heritability, sex linkage, and population divergence - J. Ellers; C. L. Boggs (Evolution, 2002)
We investigated the genetic background of intraspecific variation in wing color across an elevational gradient in the butterfly Colias philodice eriphyle. The degree of wing melanization was an accelerating function of elevation, and differences in wing melanization persisted in a common environment. Full-sibling analysis and parent-offspring regression yielded consistent, moderate to high heritabilities for the degree of wing melanization. The breeding experiments also demonstrated that wing melanization is strongly sex linked. Because traits that differentiate sister species also tend to be sex linked, our results suggest that the genetic mechanisms underlying intraspecific differences in wing melanization are not fundamentally different from those that have been shown to differentiate sister species.

High Plains to Rio Grande Rift: Late Cenozoic Evolution of Central Colorado - Eric M. Leonard; Mary S. Hubbard; Shari A. Kelley; Emmett Evanoff; C. S. Siddoway; Charles G. Oviatt; Michael T. Heizler; Mike Timmons (Geological Society of America eBooks, 2002)
The central Colorado landscape bears a strong imprint of post-Laramide (late Eocene to Quaternary) tectonics, volcanism, climate change, and drainage rearrangement. This field trip will examine the post-Laramide evolution of central Colorado, traversing the Front Range, from the Colorado Piedmont on the east to the upper Arkansas valley segment of the Rio Grande Rift on the west (Fig. 1). The first day of the trip will involve a transect from the Denver-Colorado Springs section of the Piedmont across the southern Front Range, South Park, and Mosquito Range to the upper Arkansas valley. On this day we will focus...

Influence of plant abundance on pollination and selection on floral traits of Ipomopsis aggregata - C. M. Caruso (Ecology, 2002)

The Combined Effects of Aphid-Ant Mutualism and Fertilizer on the Resource Allocation of Valerian edulis - D. Dupuy (2002)
Valerian edulis is a perennial dicot growing in montane and subalpline regions. It is a polygamo dioecious species and popular host plant for aphids. Because of such characteristics, it was chosen to study the effects of resource allocation dependency. This study examined the specific effects of aphid-ant mutualisms, aphid herbivory and the use of fertilizer on the resource allocation of Valerian edulis. Results gave no significant evidence that indicated the presence of aphids, ants or the addition of fertilizer effect resource allocation in this plant species. However, results did support previous studies that indicate growth dependence on aphids and ants.

Renewable and non-renewable resources: the role of amino acid turnover in allocation to reproduction in Lepidoptera - D. M. O'Brien; M. L. Fogel; C. L. Boggs (Proceedings of the National Academy of Sciences, 2002)

The impact of floral larceny on individuals, populations, and communities - R. E. Irwin; Alison K. Brody; Nickolas M. Waser (Oecologia, 2001)
A meta-analysis on existing studies shows that larceny has an overall detrimental effect on female reproductive success of plants, and that effect size depends on the types of robbers, thieves, and pollinators that interact as well as on the reproductive biology of the plant.

Avian risk assessment in three dimensions - O. LeDee (2001)

The effect of Yellow bellied marmot (Marmota flaviventris) on the sub-alpine vegetation of the Colorado rocky mountains - C. D. Johnson (2001)

Model ecosystems in behavioral ecology - N. E. Pierce (2001)

Plant resource allocation and herbivory for Helianthella quinquenervis (Asteraceae) over an elevational gradient - R. Davis S (2001)
Resources obtained from the environment are allocated to many plant parts and functions. Resource allocation into defense, growth, and reproduction was examined for Helianthella quinquenervis, the Aspen sunflower, for three field sites over an elevational gtadient. H. quinquenervis has evolved a mutualism with ants for defense against seed predators. Timing of flower opening and pollination success for plants were also studied. The results indicated that ratios of defense to reproduction and reproduction to growth are statistically equivalent for Helianthella at all the field sites. Defense to growth ratios were different for the high and middle, and the high and low elevations, Timing of flower opening was statistically different for the middle elevation site, however pollination success was similar over sites. KEY WORDS _ant-plant mutualism insect herbivory biotic defense pollination success extrafloral nectar resource allocation Helianthella quinquenervis seed predation

Publilia modesta (Membracidae) and the effect of moisture availability on host plant selection - S. Martinez (2001)

Density dependence and colony growth in the ant species Formica neorufibarbis - Ian Billick (Journal of Animal Ecology, 2001)

Trophic structure of montane meadows and a testing of the constant food web connectance in space - E. Mudrak (2001)

Evolutionary Ecology: Concepts and Case Studies - Nickolas M. Waser; C. F. Williams (2001)

Long-distance pollinator flights and pollen dispersal between populations of Delphinium nuttalianum - B. Schulke; Nickolas M. Waser (Oecologia, 2001)

The relationship between abiotic factors and species-level self-similarity of sagebrush, Artemisia tridentata - W. Hoyer (2001)
Two of the predominant interests in ecology are patterns in the distributions and abundances of organisms and the interrelationships of organisms with their environment. Many naturally occurring phenomena take on self-similar distributions, appearing the same over different spatial scales. I tested to see if sagebrush, Artemisia tridentata, was self-similarly distributed and whether three abiotic factors - slope, aspect and soil moisture, are themselves self-similarly distributed and correlated with the presence or absence of the sagebrush at three sites in the East River Valley, Gunnison County, Colorado. At one of the site there was a significant difference in soil moistures between sites with sagebrush present and those without, and at another site aspect appeared to have a significant impact on the presence of sagebrush. The power law exponent, y’, related to the fractal box counting dimension, of the abiotic factors were the same as the y’ values for the distribution of sagebrush at each site. Semivariogram analysis also indicated a self similar distribution of many of the abiotic factors. It is unclear why the y’ values of the abiotic factors would be related so closely to those of the sagebrush.

Hunter-Gatherer Archaeology of the Colorado High Country - Mark Stiger (Digital Collections of Colorado (Colorado State University), 2001)
An overview of both past research and significant new findings and interpretations of archaeological work conducted in Colorado's Upper Gunnison Basin, including a massive body of data from the author's eight years of work at the Tenderfoot lithic-scatter site. This important new contribution to archaeology in the southern Rocky Mountains uses an organizational approach to describe and interpret prehistoric cultural change across wide areas of Western Colorado.

Control of litter decomposition in a subalpine meadow-sagebrush steppe ecotone under climate change - M. Shaw; J. Harte (Ecological Applications, 2001)

Tectonic controls on a large landslide complex: Williams Fork Mountains near Dillon, Colorado - Karl S Kellogg (Geomorphology, 2001)

The effects of a bumble bee nectar robber on plant reproductive success and pollinator behavior - J. E. L. Maloof (American Journal of Botany, 2001)
Interactions between a plant species (Corydalis caseana), a bumble bee nectar robber (Bombus occidentalis), and a bumble bee pollinator (B. appositus) were studied. There were no significant differences between naturally robbed and unrobbed flowers in fruit set or mean seed set per fruit. Plots of C. caseana plants were subjected to treatments of robbing and no robbing using commercially available colonies of B. occidentalis. Robbers did not pollinate the flowers. Pollinator behavior was observed to determine (1) the number of bees attracted to each plot, (2) the number of inflorescences visited in a plot, (3) the number of flowers visited on each inflorescence, and (4) the distance flown between inflorescences. There were no significant differences in the number of inflorescences visited per bee or the number of flowers visited per inflorescence per bee when robbed and unrobbed treatments were compared. Of the parameters measured, only distance flown between inflorescences differed in the robbed and the unrobbed treatments. Bees flew significantly further between inflorescences in the robbed plots than in the unrobbed plots. The results indicate that the nectar robbers have no negative effect on fruit set or seed set in C. caseana and that they may cause increased pollen flow distances by changing the behavior of the pollinator.

Connecting pollination deficits and pollinator declines: can theory guide us? - J. D. Thomson (Conservation Ecology, 2001)

Wildlife Responses to Climate Change: North American Case Studies - F. Saavedra (2001)

Tests of pre- and postpollination barriers to hybridization between sympatric species of Ipomopsis (Polemoniaceae) - P. G. Wolf; Diane R. Campbell; Nickolas M. Waser; S. D. Sipes; T. R. Toler; J. K. Archibald (American Journal of Botany, 2001)
The Ipomopsis aggregata species complex (Polemoniaceae) includes species pairs that hybridize readily in nature as well as pairs that meet along contact zones with no apparent hybridization. Artificial hybrids can be made between I. aggregata and I. arizonica, yet morphological intermediates between these two species have not been observed in natural populations. This apparent lack of hybridization is perplexing given that plants of the two species often grow within a few metres of each other and both species have red flowers visited by the same species of hummingbirds. We used trained hummingbirds to examine pollen transfer within and between species. We also hand‐pollinated flowers to examine paternal success of heterospecific and conspecific pollen, testing paternity with electrophoretic examination of seeds. Hummingbirds were not simply better at transferring pollen within than between species. Instead, I. arizonica was a better pollen donor so that considerable pollen transfer was observed from I. arizonica to I. aggregata, but very little in the opposite direction. Conversely, once pollen arrived at stigmas, I. arizonica pollen performed very poorly on I. aggregata pistils. However, pollen from I. aggregata could, in some cases, sire seeds on I. arizonica. We hypothesize that hybrids are scarce in nature, in part, because of asymmetric barriers to reproduction: little pollen transfer in one direction and poor pollen performance in the other.

Sampling stream invertebrates using electroshocking techniques: implications for basic and applied research - B. W. Taylor; A. R. McIntosh; B. L. Peckarsky (Canadian Journal of Fisheries and Aquatic Science, 2001)

Bioassessment and Management of North American Freshwater Wetlands - J. L. Bogo; R. B. Rader; S. G. Ingmire; D. P. Batzer; S. A. Wissinger; S. A. Wissinger (2001)

Variation of pollinator species at different times of day - D. H. Ikeda (2001)

Resurrecting the Dammed: A Look at Colorado River Restoration - JEFFREY P. COHN (BioScience, 2001)

The effect of nest box temperature on nestlings growth rate and parental feeding rates in a montane population of house wrens, Troglodytes aedon - Z. T. Vasquez (2001)

Metapopulation biology of the callibaetis ferrugineus hageni in high elevation beaver ponds - C. C. Caudill (2001)

Sheeting and dyking emplacement of the Gunnison annular complex, SW Colorado - B. Lafrance; B.E. John (Journal of Structural Geology, 2001)

Patterns of association between crucifers and their flower mimic pathogens: host jumps are more common than coevolution or cospeciation - B. A. Roy (Evolution, 2001)

6PGD2 allozyme differentiation in Ipomopsis aggregata: a biochemical adapatation to soil moisture - B. Blackman (2001)

Linking pollinator behavior and pollen receipt in Ipomopsis aggregata - C. E. Engel (2001)

Bioassessment and Management of North American Freshwater Wetlands - S. A. Wissinger; S. G. Ingmire; J. L. Bogo (2001)

Pollinator corridors - David W. Inouye (Conservation Biology in Practice, 2001)

Inter- and intra-specific competition between and among Nicrophorus investigator and Nicrophorus defodiens - M. Buehner (2001)

Cognitive ecology of pollination - Nickolas M. Waser (2001)

Differential selection on floral traits of Ipomopsis aggregata growing in contrasting environments - C. M. Caruso (Oikos, 2001)

Experimental manipulation of plant density and its effect on pollination and reproduction of two confamilial montane herbs - M. Bosch; Nickolas M. Waser (Oecologia, 2001)
In three replicate experiments with D. nuttallianum, pollinator visitation rate and seed set were indistinguishable in sparse and dense arrays, consistent with the interpretation that environmental quality contributed to the earlier result in natural populations of this species.

Exploring the "Most effective pollinator principal" with complex flowers: Bumblebees and Ipomopsis aggregata - M. M. Mayfield; Nickolas M. Waser; Mary V. Price (Annals of Botany, 2001)

Variation in mayfly size at metamorphosis as a developmental response to risk of predation - B. L. Peckarsky; B. W. Taylor; A. R. McIntosh; M. A. McPeek; D. A. Lytle (Ecology, 2001)
Animals with complex life cycles often show large variation in the size and timing of metamorphosis in response to environmental variability. If fecundity increases with body size and large individuals are more vulnerable to predation, then organisms may not be able to optimize simultaneously size and timing of metamorphosis. The goals of this study were to measure and explain large-scale spatial and temporal patterns of phenotypic variation in size at metamorphosis of the mayfly, Baetis bicaudatus (Baetidae), from habitats with variable levels of predation risk. Within a single high-elevation watershed in western Colorado, USA, from 1994 to 1996 we measured dry masses of mature larvae of the overwintering and summer generations of Baetis at 28 site-years in streams with and without predatory fish (trout). We also estimated larval growth rates and development times at 16 site-years. Patterns of spatial variation in mayfly size could not be explained by resource (algae) standing stock, competitor densities, or physical–chemical variables. However, size at metamorphosis of males and females of summer generation Baetis was smaller in fish streams than in fishless streams and decreased as densities of predatory stoneflies increased. Furthermore, overwintering individuals matured at larger sizes than summer generation Baetis, and the size of emerging Baetis declined over the summer, but predominantly in trout streams. Theoretical consideration of the effect of predation risk on size and timing of metamorphosis accurately predicted the observed temporal variation in size and timing of mayflies at emergence in fish and fishless streams. Baetis populations had similar growth rates but followed different developmental trajectories in high and low risk environments. In risky environments larval development was accelerated, resulting in metamorphosis of younger and smaller individuals, minimizing exposure of larvae to risk of mortality from trout predation, but at the cost of future reproduction. In safe environments, larvae extended their development, resulting in larger, more fecund adults. Thus, we propose that large-scale patterns of variation in size and timing of metamorphosis represent adaptive phenotypic plasticity, whereby mayflies respond to variation in risk of predation, thereby maximizing their fitness in variable environments.

Drosera rotundifolia monitoring protocol - Ian Billick (2001)

The new encyclopedia of mammals - Kenneth B. Armitage (2001)

Resource availability and population dynamics of Nicrophorus investigator, an obligate carrion breeder - R. J. Smith; M. J. Merrick (Ecological Entomology, 2001)
Summary 1. Food resources for rearing young may influence insect populations. This is particularly true for insects that breed obligately on rare, ephemeral resources such as dung, fungi, or carrion. 2. Beetles in the genus Nicrophorus bury small vertebrate carcasses for rearing their young. Studies reviewed by have found a positive relationship between carcass mass and total brood size. It is likely that access to carcasses suitable for breeding, and not food or mates, limits reproduction in both male and female Nicrophorus . Thus, small mammal densities could determine Nicrophorus population sizes. 3. The work reported here examined the relationship between Nicrophorus investigator (Coleoptera: Silphidae) population size and small mammal abundance at two sites over a 4‐year period. 4. Nicrophorus investigator buried and reared young on all the native small rodent species trapped at two sites in south‐western Colorado, U.S.A. ( Peromyscus maniculatus , Microtus montanus , Zapus princeps , Tamias minimus , Thomomys talpoides ). They preferred to bury and reproduce on rodent carcasses weighing between 16 and 48 g; rodents of this size represented 82% of captures. 5. Population sizes of N. investigator and small rodents were estimated simultaneously using mark‐recapture censuses over a 4‐year period. Considering only rodents within the size range used by N. investigator , the estimated small mammal biomass per hectare in one year and the beetle population size in the following year were correlated significantly.

Mineral Occurrences in the Leadville Limestone, Ouray County, Colorado - Tom Rosemeyer (Rocks & Minerals, 2001)
(2001). Mineral Occurrences in the Leadville Limestone, Ouray County, Colorado. Rocks & Minerals: Vol. 76, No. 5, pp. 332-346.

Assessment of Grid-Based Whole-Rock D Surveys in Exploration: Boulder County Epithermal Tungsten Deposit, Colorado - C. M. Rice (Economic Geology, 2001)

Plant responses to experimental warming in a montane meadow - P. DeValpine; J. Harte (Ecology, 2001)

Multiple-paternity in burying beetles Nicrophorus investigator - M. B. Moheno (2001)

Songbird and Medium‐Sized Mammal Communities Associated with Exurban Development in Pitkin County, Colorado - E. Odell; Richard L. Knight (Conservation Biology, 2001)
Abstract: Residential development is occurring at unprecedented rates in the Rocky Mountain region of the United States, with unknown ecological consequences. We conducted our research in exurban development in Pitkin County, Colorado, between May and June in 1998 and 1999. Unlike suburban development, exurban development occurs beyond incorporated city limits, and the surrounding matrix remains the original ecosystem type. We surveyed songbirds and medium‐sized mammals at 30, 180, and 330 m away from 40 homes into undeveloped land to examine the effect of houses along a distance gradient, and in developments of two different housing densities as well as undeveloped sites to examine the effect of housing density. We placed bird species into one of two groups for the house‐distance effect: (1) human‐adapted species, birds that occurred in higher densities close to developments and lower densities farther away and (2) human‐sensitive species, birds that occurred in highest densities farthest from homes and in lowest densities close to development. For both groups, densities of individual species were statistically different between the 30‐ and 180‐m sites. Six species were classified as human‐adapted, and six were classified as human‐sensitive for the house‐distance effect. Dogs ( Canis familiaris ) and house cats ( Felis domesticus ) were detected more frequently closer to homes than farther away, and red foxes ( Vulpes vulpes ) and coyotes ( Canis latrans ) were detected more frequently farther away from houses. With respect to the effect of housing density, most avian densities did not differ significantly between high‐ and low‐density development but were statistically different from undeveloped sites. Six species were present in higher densities in developed areas, and eight species were present in higher densities in undeveloped parcels. Similar results were found for mammalian species, with dogs and cats detected more frequently in high‐density developments and red foxes and coyotes detected more frequently in undeveloped parcels of land. From an ecological standpoint, it is preferable to cluster houses and leave the undeveloped areas in open space, as opposed to dispersing houses across the entire landscape.

The effect of hermaphrodite density and frequency at three spatial scales on the polen receipt and seed set of gynodioecious Geranium richardsonii (Geraniaceae) - M. Piantek (2001)
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.

Cognitive ecology of pollination - J. D. Thomson; L. Chittka (2001)

Influence of Changes in Sagebrush on Gunnison Sage Grouse in Southwestern Colorado - Sara J. Oyler-McCance; Kenneth P. Burnham; Clait E. Braun (The Southwestern Naturalist, 2001)
The decline in abundance of the newly recognized Gunnison sage grouse (Centro- cercus minimus) in southwestern Colorado is thought to be linked to loss and fragmentation of its habitat, sagebrush (Artemisia) vegetation. We documented changes in sagebrush-dominated areas between the 1950s and 1990s by comparing low level aerial photographs taken in these time periods. We documented a loss of 20% or 155,673 ha of sagebrush-dominated areas in south- western Colorado between 1958 and 1993. The amount of sagebrush-dominated area was much higher and loss rates were much lower in the Gunnison Basin. We also found that 37% of plots sampled underwent substantial fragmentation of sagebrush vegetation. If current trends of habitat loss and fragmentation continue, Gunnison sage grouse (and perhaps other sagebrush-steppe obligates) may become extinct. Protecting the remaining habitat from further loss and fragmen- tation is paramount to the survival of this species.

Cognitive ecology of pollination - L. Chittka; L. Chittka; J. D. Thomson; J. D. Thomson (2001)

Assessing the quality of different ant species as partners of a myrmecophilous butterfly - A. M. Fraser; A. H. Axen; N. E. Pierce (Oecologia, 2001)
Assessment of the quality of different ant species as partners of the facultatively myrmecophilous lycaenid butterfly Glaucopsyche lygdamus found that F. obscuripes may act as a parasite of the general association between G. lyg damus and ants under certain conditions.

The natural history of bumblebees - C. A. Kearns; J. D. Thomson (2001)

On the Lake Fork of the Gunnison - Catharine Savage Brosman (Critical Quarterly, 2001)

Predation on yellow-bellied marmots (Marmota flaviventris) - D. H. Van Vuren (American Midland Naturalist, 2001)

North American dipteran pollinators: assessing their value and conservation status - C. A. Kearns (Conservation Ecology, 2001)
"Recent attention to pollinator declines has focused largely on bees and vertebrates. However, few pollination systems are obligate, and pollinators that complement the role of bees may respond differently to environmental disturbance. The conservation status of North American fly pollinators remains undocumented. In this paper, methods for monitoring shifts in dipteran pollinator abundance are discussed. The need for further basic research into pollination by flies is addressed, and the significance of dipteran conservation is considered."

The matrix matters: effective isolation in fragmented landscapes - T. H. Ricketts (American Naturalist, 2001)
Traditional approaches to the study of fragmented landscapes invoke an island‐ocean model and assume that the nonhabitat matrix surrounding remnant patches is uniform. Patch isolation, a crucial parameter to the predictions of island biogeography and metapopulation theories, is measured by distance alone. To test whether the type of interpatch matrix can contribute significantly to patch isolation, I conducted a mark‐recapture study on a butterfly community inhabiting meadows in a naturally patchy landscape. I used maximum likelihood to estimate the relative resistances of the two major matrix types (willow thicket and conifer forest) to butterfly movement between meadow patches. For four of the six butterfly taxa (subfamilies or tribes) studied, conifer was 3–12 times more resistant than willow. For the two remaining taxa (the most vagile and least vagile in the community), resistance estimates for willow and conifer were not significantly different, indicating that responses to matrix differ even among closely related species. These results suggest that the surrounding matrix can significantly influence the "effective isolation" of habitat patches, rendering them more or less isolated than simple distance or classic models would indicate. Modification of the matrix may provide opportunities for reducing patch isolation and thus the extinction risk of populations in fragmented landscapes.

Pollinator-mediated selection on a flower color polymorphism in experimental populations of Antirrhinum (Scrophulariaceae) - K. N. Jones; J. Reithel (American Journal of Botany, 2001)
We quantified pollinator visit behavior, pollen receipt and export, and changes in allele and genotype frequencies from initial Hardy‐ Weinberg conditions in experimental arrays of two color morphs of snapdragons (Antirrhinum majus) visited by freely foraging bumble bees (Bombus appositus and B. flavifrons). The number of pollen grains received by a flower depended most on the number of pollinator visits to the flower, whereas the number of grains exported was best predicted by the total time pollinators spent inside the flower. The pattern of mating generally was assortative with respect to color, as bees tended to overvisit one color or the other within a foraging bout. In arrays where nectar was augmented in one color, the augmented color received both more visits and longer visits. Allele and genotype frequencies in offspring samples were in accord with qualitative expectations based on the pollinator observations, demonstrating that pollinators can directly influence the evolution of single‐locus floral traits, at least under simplified experimental conditions.

Food limitation of planktonic rotifers: field experiments in two mountain ponds - S. E. Cordova; J. Giffin; K. L. Kirk (Freshwater Biology, 2001)
1. Resource competition is thought to be important in controlling zooplankton population dynamics and structuring zooplankton communities. Resource competition requires that resources are limiting. Ten field experiments were conducted to determine the presence and intensity of resource limitation of herbivorous planktonic rotifers in two mountain ponds. The intensity of food limitation was measured as Δr, the difference between population growth rates in food supplemented versus control enclosures.2. Rotifers were significantly food limited (Δr > 0) in most experiments. The intensity of food limitation varied between species. In Grady Lake, mean Δr was 0.26 day−1 for Polyarthra vulgaris and 0.43 day−1 for an unidentified Synchaeta sp. In L1 Pond, mean Δr was 0.07 day−1 for Keratella cochlearis and 0.28 day−1 for S. oblonga. The frequent and intense food limitation suggests that edible phytoplankton in both ponds were often present at low densities, were of low nutritional quality, or both. The intensity of food limitation often changed rapidly over time, indicating rapid temporal variation in resource availability.3. For P. vulgaris, Δr was not correlated with its population growth rate in Grady Lake. Thus, although food limitation was common, population dynamics may have been more strongly affected by other factors. For K. cochlearis, Δr increased as population density increased, suggesting the existence of intraspecific resource competition that may regulate population dynamics.

Genotype-by-environment interaction and the fitness of plant hybrids in the wild - Diane R. Campbell; Nickolas M. Waser (Evolution, 2001)
Natural hybrid zones between related species illustrate processes that contribute to genetic differentiation and species formation. A common viewpoint is that hybrids are essentially unfit, but they exist in a stable tension zone where selection against them is balanced by gene flow between the parent species. An alternative idea is that selection depends on the environment, for example, by favoring opposite traits in the two parental habitats or favoring hybrids within a bounded region. To determine whether selection of hybrids is environment dependent, we crossed plants of naturally hybridizing Ipomopsis aggregata and I. tenuituba in the Colorado Rocky Mountains and reciprocally planted the seed offspring into a suite of natural environments across the hybrid zone. All types of crosses produced similar numbers and weights of seeds. However, survival of the offspring after 5 years differed markedly among cross types. On average, the F1 hybrids had survival and growth rates as high as the average for their parents. But hybrid survival depended strongly on the direction of a cross, that is, on which species served as the maternal parent. This fitness difference between reciprocal hybrids appeared only in the parental environments, suggesting cytonuclear gene interactions that are environment specific. These results indicate that complex genotype-by-environment interactions can contribute to the evolutionary outcome of hybridization.

Response of nitrogen cycling to simulated climate change: differential responses along a subalpine ecotone - R. G. Shaw; J. Harte (Global Change Biology, 2001)
SummaryIn situnitrogen (N) transformations and N availability were examined over a four‐year period in two soil microclimates (xeric and mesic) under a climate‐warming treatment in a subalpine meadow/sagebrush scrub ecotone. Experimental plots that spanned the two soil microclimates were exposed to anin situinfrared (IR) climate change manipulation at the Rocky Mountain Biological Laboratory, near Crested Butte, Colorado. Although the two microclimates did not differ significantly in their rates of N transformations in the absence of heating, they differed significantly in their response to increased IR. Under a simulated warming in the sagebrush‐dominated xeric microclimate, gross N mineralization rates doubled and immobilization rates increased by up to 60% over the first 2 years of the study but declined to predisturbance rates by the fourth year. This temporal pattern of gross mineralization rates correlated with a decline in SOM. Concurrently, rates of net mineralization rates in the heated plots were 60% higher than the controls after the first year. There were no differences in gross or net nitrification rates with heating in the xeric soils. In contrast to the xeric microclimate, there were no significant effects of heating on any N transformation rates in the mesic microclimate. The differing responses in N cycling rates of the two microclimate to the increased IR is most certainly the result of differences in initial soil moisture conditions and vegetation type and cover.

The relationship between ant-tending and maternal care in the treehopper Publilia modesta - Ian Billick; M. Weidmann; J. Reithel (Behavioral Ecology and Sociobiology, 2001)
It is concluded that ant-tending provides an ecological context that favors maternal care in this treehopper species and the primary benefit of maternal care is to attract ants while nymphs are small and few in number.

Global warming and terrestrial ecosystems: response from Harte - J. Harte (BioScience, 2001)

The volcanology, petrology and geochronology of the Fish canyon magmatic system, San Juan volcanic field, U.S.A - Olivier Bachmann (Archive ouverte UNIGE (University of Geneva), 2001)
Il y a 28 millions d'années, l'une des plus grandes éruptions explosives connues a pris place dans le sud de l'actuel Colorado, aux États-Unis. Cette unité volcanique, dénommée le Tuf de Fish Canyon, ainsi que deux plus petites éruptions qui lui sont associées, ont permis d'étudier plusieurs aspects de ces phénomènes rares mais d'une puissance capable d'affecter la terre dans son ensemble. Cette thèse aborde trois sujets principaux. Tout d'abord, une étude volcanologique sur les dépôts précédant l'unité climatique a permis de documenter un style éruptif nettement moins explosif pour cette unité précurseur probablement à l'origine du déclenchement de l'éruption principale. Deuxièmement, une étude texturale et géochimique a démontré que le magma de Fish Canyon a été réactivé par une injection de basalte, menant à la remobilisation de tout le corps magmatique. Finalement, une étude géochronologique a permis de contraindre la vitesse de ces phénomènes magmatiques.

Pollination, breeding system, and genetic structure in two sympatric Delphinium (Ranunculaceae) species - C. F. Williams; J. Ruvinsky; P. E. Scott; P. K. Hews (American Journal of Botany, 2001)
Two sympatric Delphinium species, D. barbeyi and D. nuttallianum, are ecologically and morphologically similar. However, D. barbeyi has multiple, large inflorescences while D. nuttallianum has a single, small inflorescence. These differences in floral display should result in greater intraplant pollen transfer in D. barbeyi, leading to higher rates of self‐pollination through geitonogamy. Reduced gene flow by pollen should in turn produce greater population differentiation among populations of D. barbeyi relative to D. nuttallianum. We tested these predictions by comparing pollinator behavior, breeding systems, outcrossing rates, and population genetic structure of sympatric populations of the two species in Colorado. Bumble bee and hummingbird pollinators visit more flowers and inflorescences per foraging bout in D. barbeyi than in D. nuttallianum. The species differed in breeding system; D. barbeyi produced more seeds by autogamy (9 vs. 2%) than D. nuttallianum and suffered no reduction in seed set in hand‐self vs. outcross pollinations, in contrast to a 41% decline in D. nuttallianum. The outcrossing rate in one D. barbeyi population was 55%, but ranged from 87 to 97% in four D. nuttallianum populations. Genetic differentiation among population subdivisions estimated by hierarchical F statistics was >10 times greater in D. barbeyi ( = 0.055–0.126) than D. nuttallianum ( = 0.004–0.009) at spatial scales ranging from metres to 3.5 km. Spatial autocorrelation analysis also indicated more pronounced local genetic structure in D. barbeyi than D. nuttallianum populations. Fixation indices (FIS) of D. barbeyi adults were much lower than expected based on mating system equilibrium and suggest that differences in the degree of self‐compatibility and/or the timing of postpollination selection/inbreeding depression between the two species further contribute to the genetic differences between them.

Living Homes: Sustainable Architecture and Design - Terrence Moore; Nora Burba Trulsson; Terrence Moore (Medical Entomology and Zoology, 2001)
A lavishly illustrated tour of twenty-two houses built using alternative methods, Living Homes proves that sustainability and high style are not diametrically opposed. Broken down into sections exploring four styles of homes--straw bale, rammed earth, adobe, and recycled materials, each method is explained and illustrated. Beautifully photographed, Living Homes includes urban homes as well homes in such idyllic locations as Crested Butte, Colorado, Tassajara Canyon, California, and the Jemez Mountains, New Mexico. Illustrates an organic sensibility in tune with the weather, the light, and the homes' natural surroundings.

Flies and flowers: taxonomic diversity of anthophiles and pollinators - B. M. H. Larson; P. G. Kevan; David W. Inouye (Canadian Entomologist, 2001)
AbstractThe Diptera are the second most important order among flower-visiting (anthophilous) and flower-pollinating insects worldwide. Their taxonomic diversity ranges from Nematocera to Brachycera, including most families within the suborders. Especially important are Syrphidae, Bombyliidae, and Muscoidea. Other families, especially of small flies, are less appreciated and often overlooked for their associations with flowers. We have compiled records of their flower visitations to show that they may be more prevalent than usually thought. Our knowledge of anthophilous Diptera needs to be enhanced by future research concerning (i) the significance of nocturnal Nematocera and acalypterate muscoids as pollinators, (ii) the extent to which the relatively ineffective pollen-carrying ability of some taxa can be compensated by the abundance of individuals, and (iii) the role of Diptera as pollinators of the first flowering plants (Angiospermae) by using phylogenetic and palaeontological evidence. Specializations in floral relationships involve the morphology of Diptera, especially of their mouthparts, nutritional requirements, and behaviour, as well as concomitant floral attributes. The South African flora has the most highly specialized relations with dipterous pollinators, but in arctic and alpine generalist fly–flower relations are important in pollination and fly nutrition.

Hummingbird avoidance of nectar-robbed plants: spatial location or visual cues - R. E. Irwin (Oikos, 2000)
Broad‐tailed and rufous hummingbirds avoid plants and flowers that have recently been visited by nectar‐robbing bees. However, the cues the hummingbirds use to make such choices are not known. To determine the proximate cues hummingbirds use to avoid visiting nectar‐robbed plants, I conducted multiple field experiments and one aviary study using the nectar‐robbed, hummingbird‐pollinated plant Ipomopsis aggregata . In the first field experiment, free‐flying hummingbirds were presented with plants in which I manipulated nectar volume and the presence of nectar‐robber holes. Hummingbirds visited significantly more plants with nectar and probed more available flowers on those plants, regardless of the presence of nectar‐robber holes. Thus, I hypothesized that hummingbirds may avoid robbed plants based on their spatial memory of unrewarding plants and/or visual cues that nectar absence provides. In an aviary study, I removed spatial cues by re‐randomizing the position of plants after each hummingbird‐foraging bout, but hummingbirds still selected plants with nectar. Nectar may provide a visual cue in I. aggregata flowers because corollas are translucent, and nectar is visible through the side of the corolla. To determine if hummingbirds use this visual cue to avoid plants with no nectar, I masked corolla translucence in a field study by painting flowers with acrylic paint. Hummingbirds still visited significantly more plants with nectar and probed more flowers on those plants, whether or not the corollas were painted. These results suggest that hummingbirds use nectar as a proximate cue to locate and avoid non‐rewarding, nectar‐robbed plants, even in the absence of spatial cues and simple visual cues.

Are leafhoppers to blame? A study of the damage in aspen clones in Gunnison County, CO - K. Emerson (2000)

Interspecific pollen transfer as a mechanism of competition: effect of Castilleja linariaefolia pollen on seed set of Ipomopsis aggregata - C. M. Caruso; M. Alfaro (Canadian Journal of Botany, 2000)

Methods in Ecosystem Science - K. P. Shen; J. Harte (2000)

Climate change impacts on community and ecosystem properties: Integrating manipulations and gradient studies in montane meadows - J. A. Dunne (2000)

Photosynthetic responses to a climate-warming manipulation for contrasting meadow species in the Rocky Mountains, Colorado, USA - M. E. Loik; S. P. Redar; J. Harte (Functional Ecology, 2000)
Abstract1. Microclimate was measured and photosynthetic responses to a climate warming manipulation were compared for the evergreen shrub Artemisia tridentata and the herbaceous forb Erigeron speciosus in the Rocky Mountains, Colorado, USA.2. Soil was warmer and drier under infra‐red heaters compared with control plots.3. Midday xylem pressure potential did not differ for A. tridentata on heated vs control plots but was lower for E. speciosus on heated plots compared with controls. Leaf temperatures did not vary for the two species on heated or control plots.4. There were no significant treatment or species differences in the diurnal patterns of CO2 assimilation or stomatal conductance to water vapour. Also, there were no differences in responses to leaf temperature.5. The quantum yield for CO2 assimilation over a range of PPFD was lower for plants on heated plots. There was a marked difference between species in the pattern of stomatal conductance to water vapour over a range of PPFD, but no differences as a result of the heating treatment.6. The quantum efficiency of PSII electron transport was significantly affected by heating. Non‐radiative energy dissipation was greater for A. tridentata compared with E. speciosus. There was recovery of FV/FM for A. tridentata but not for E. speciosus.7. Heating appears to affect plants via changes in soil water content rather than by increasing leaf temperature. The deciduous species E. speciosus appears to undergo some permanent closure of PSII on heated plots, in contrast to the evergreen shrub A. tridentata. Such differences may help explain the increase in above‐ground biomass accumulation in response to heating for shrubs, compared with the decrease observed for deciduous herbaceous species.

Reproductive biology of a North American subalpine plant: Corydalis caseana A. Gray ssp. brandegei (S. Watson) G. B. Ownbey - J. E. L. Maloof (Plant Species Biology, 2000)
Abstract 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 ). Hummingbirds 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 approximately 1 μ L 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.

Pollen presentation and pollination syndromes, with special reference to Penstemon - J. D. Thomson; P. Wilson; M. Valenzuela; M. Malzone (Plant Species Biology, 2000)
Abstract Pollen presentation theory (PPT) allows for a re‐examination of some classic themes in pollination biology. Here, we outline its implications in the context of bee‐ and bird‐adapted species of Penstemon and Keckiella (Scrophulariaceae). PPT models the optimal schedule of pollen presentation, based on the frequency of visits by pollinators, and the capacities of those pollinators to remove and deposit pollen. High visitation rates, high removal and low deposition all favor plants that present pollen in many small doses. Dosing is achieved through gradual opening of anthers and through anthers opening only narrowly. We hypothesize that bees have higher rates of removal and lower rates of deposition than birds; therefore, bee‐pollinated species should have anthers that open more gradually and less completely than bird‐pollinated species. Before presenting preliminary results that affirm this prediction, we critically discuss the characterization of species by pollination syndrome. PPT sheds new light on why plants may specialize on particular pollinators. Stebbins’ most effective pollinator can be recast as the pollinator that deposits more of the pollen that it removes, thereby making other visitors into conditional parasites. Pollinator shifts might occur when a pollinator with low removal and high deposition becomes abundant; the plants would then be selected to discourage their previous pollinators who are now parasites. Bird‐pollination may favor anthers that open quickly and widely, thereby making bees wasteful parasites. Bee‐pollination may favor anthers that open slowly and narrowly, thereby making birds ineffective pollinators. In paired comparisons of closely related species, the hummingbird‐visited species were redder, had narrower or longer floral tubes, more exserted anthers and stigmas, less pronounced landing platforms, more inclined orientation, produced more nectar of a lower concentration, and had anthers that dehisce faster and more extensively.

Responses of subalpine meadow vegetation to four years of experimental warming - Mary V. Price; Nickolas M. Waser (Ecological Applications, 2000)
Ecosystems at high elevations may be especially sensitive to global warming, because productivity is limited to a snow-free growing season, and warming is expected to cause earlier snowmelt. Here we report on vegetation responses to experimental warming in a subalpine meadow in the Colorado Rocky Mountains. We found no evidence that the plant community changed during four years of warming. Species composition in warmed plots did not change more through time than in control plots, nor did warmed plots diverge from adjacent control plots through time. Contrary to an earlier report, we found no evidence that warming facilitated adults or seedlings of sagebrush, a shrub characteristic of lower elevation ecosystems; nor did it facilitate short-lived plant species as a group. Total vegetation cover, as well as cover of graminoids, forbs, and shrubs, did not differ between control and warmed plots, nor did species richness or species' distributions along a small elevational gradient within each plot. Shrub cover tended to increase more, and forb cover to decrease more, in warmed than in control plots during one summer season, but not significantly so. This lack of detectable plant community response contrasts with pronounced responses to warming in some arctic and alpine ecosystems over similar time spans. Warming in these ecosystems is thought to act indirectly via increased mobilization of soil nutrients. One possible reason for the lack of response in our system is that drying of soil limits microbial activity, photosynthesis, and plant growth sooner in the season in warmed plots, canceling out effects of earlier snowmelt. If this is correct, and if summer precipitation patterns are unchanged under global warming, then vegetation in arid high-elevation ecosystems may change only slowly.

Social enhancement of fitness in yellow-bellied marmots - Kenneth B. Armitage; O. A. Schwartz (Proceedings of the National Academy of Sciences, 2000)
The yellow-bellied marmot ( Marmota flaviventris ) is a social, ground-dwelling squirrel that lives either individually or in kin groups of from two to five adult females. Philopatry and daughter recruitment lead to the formation and persistence of matrilines at habitat sites. By using 37 years of demographic data for 12 habitat sites, we could determine long-term trends in the effects of group size on two measures of fitness, survivorship and net reproductive rate, which otherwise are obscured by annual fluctuations in these measures. Both size and number of matrilines varied among sites and survivorship and net reproductive rate varied among sites and among matriline sizes. The role of social organization was explored further by examining the effect of matriline size, averaged over all years and sites, on fitness. For both survivorship and net reproductive rate the relationship with matriline size was curvilinear. Fitness increased with the increase in matriline size and then decreased in the largest groups. Decreased fitness in matrilines of four or five was associated with agonistic behavior, a large number of 2-year-old females in the social group, and reproductive suppression. There is no evidence that females acted to increase their fitness by increasing indirect fitness; i.e., by assisting relatives, but attempted to increase direct fitness. Direct fitness increased when mortality and fission of large matrilines reduced group size and the surviving females increased reproduction.

Topoclimatic habitat models - P. M. Rich; P. Fu (2000)

Altitudinal variation in body size and population density of Nicrophorus investigator (Coleoptera: Silphidae) - R. J. Smith; A. Hines; S. Richmond; M. J. Merrick; A. Drew; R. Fargo (Environmental Entomology, 2000)

The scale of resource specialization and the distribution and abundance of lycaenid butterflies - J. B. Hughes (Oecologia, 2000)
How hostplant specialization and abundance affect the relative abundance and distribution of lycaenid butterflies is considered and it is suggested that abundance-distribution relationships might emerge at regional and continental scales if local abundance were averaged across many habitat types.

The evolution, ecology, and systematics of marmots - Kenneth B. Armitage (Oecologia Montana, 2000)

Are nectar robbers cheaters or mutualists? - J. E. L. Maloof; David W. Inouye (Ecology, 2000)
Nectar robbers are birds, insects, or other flower visitors that remove nectar from flowers through a hole pierced or bitten in the corolla. This paper is a review of the effects of nectar robbers on pollinators, pollination, and fitness of the plants they rob. Charles Darwin assumed that nectar robbers had a negative impact on the plants that they visit, but research done in the last 50 years indicates that they often have a beneficial or neutral effect. Several studies document that robbers frequently pollinate the plants that they visit. Robbers may also have an indirect effect on the behavior of the legitimate pollinators, and in some circumstances, the change in pollinator behavior could result in improved fitness through increased pollen flow and outcrossing. The effects of nectar robbers are complex and depend, in part, on the identity of the robber, the identity of the legitimate pollinator, how much nectar the robbers remove, and the variety of floral resources available in the environment.

Potential impact of climate change on the phenology and reproduction of Delphinium nuttallianum (Ranunculaceae) - F. Saavedra (2000)

A geometric solar radiation model and its applications in agriculture and forestry - P. Fu; P. M. Rich (2000)

Climate change is affecting altitudinal migrants and hibernating species - David W. Inouye; Billy Barr; Kenneth B. Armitage; David W. Inouye (Proceedings of the National Academy of Science, 2000)
Calendar date of the beginning of the growing season at high altitude in the Colorado Rocky Mountains is variable but has not changed significantly over the past 25 years. This result differs from growing evidence from low altitudes that climate change is resulting in a longer growing season, earlier migrations, and earlier reproduction in a variety of taxa. At our study site, the beginning of the growing season is controlled by melting of the previous winter's snowpack. Despite a trend for warmer spring temperatures the average date of snowmelt has not changed, perhaps because of the trend for increased winter precipitation. This disjunction between phenology at low and high altitudes may create problems for species, such as many birds, that migrate over altitudinal gradients. We present data indicating that this already may be true for American robins, which are arriving 14 days earlier than they did in 1981; the interval between arrival date and the first date of bare ground has grown by 18 days. We also report evidence for an effect of climate change on hibernation behavior; yellow-bellied marmots are emerging 38 days earlier than 23 years ago, apparently in response to warmer spring air temperatures. Migrants and hibernators may experience problems as a consequence of these changes in phenology, which may be exacerbated if climate models are correct in their predictions of increased winter snowfall in our study area. The trends we report for earlier formation of permanent snowpack and for a longer period of snow cover also have implications for hibernating species.

Variation in behavior of lycaenid larvae when attended by different ant species - A. H. Axen (Evolutionary Ecology, 2000)

Conservation of insect diversity: a habitat approach - J. B. Hughes; G. C. Daily; P. R. Ehrlich (Conservation Biology, 2000)

Colorado River Clams Provide Benchmark - Mark Muro (Science, 2000)
Conservationists have long contended, largely in impressionistic terms, that 70 years of American dam building and water diversion have destroyed the biological richness of the Colorado River delta, a key nursery of marine life at the end of the Southwest's great watercourse. Now researchers have confirmed those suspicions, using an important ecological player--clams--as a quantitative marker.

Oviposition and Diapause Behavior in Colorado Potato Beetle (Coleoptera: Chrysomelidae) Populations from East Central Minnesota and the Valley of the Red River of the North - Dhammika G. Senanayake; Edward B. Radcliffe; Neil J. Holliday (Environmental Entomology, 2000)
Abstract Oviposition and diapause behavior were compared among populations of Colorado potato beetle, Leptinotarsa decemlineata (Say), from six locations in 1994 and 1995. Locations ranged from Winnipeg, Manitoba (49° 49′ N), to Rosemount in east central Minnesota (44° 44′ N). Newly emerged first summer generation adults were held in field cages at each location for 7–14 d, then observed for 7 d in the laboratory for frequency of oviposition and frequency of burrowing behavior associated with diapause. Females from the Red River Valley seldom oviposited and although frequency of burrowing varied among locations it was independent of field and laboratory conditions. Under long-day laboratory conditions, 9–15% of females from east central Minnesota oviposited with frequency dependent on photoperiod experienced in the field, the critical photoperiod was 15.8 h. Under long-day laboratory conditions, 18–52% of beetles from east central Minnesota burrowed with frequency dependent on cumulative temperatures experienced in the field. Cool conditions were associated with higher frequencies of burrowing. Beetles from Rosemount exhibited identical responses under short-day and long-day laboratory conditions. In contrast, under short-day conditions, beetles from Big Lake did not oviposit and frequency of burrowing was not dependent on field conditions. We concluded that there is local geographic variation in Colorado potato beetle populations not only between the Red River Valley and east central Minnesota, but also among the different locations within these two areas.

A positive association betwween oviposition and fruit set: female choice or manipulation? - Alison K. Brody; S. Morita (Oikos, 2000)

Competition for pollination influences selection on floral traits of Ipomopsis aggregata - C. M. Caruso (Evolution, 2000)

"A Promise Long Deferred": Federal Reclamation on the Colorado River Indian Reservation - Ann Caylor (Pacific Historical Review, 2000)
Research Article| May 01 2000 "A Promise Long Deferred": Federal Reclamation on the Colorado River Indian Reservation Ann Caylor Ann Caylor Search for other works by this author on: This Site PubMed Google Scholar Pacific Historical Review (2000) 69 (2): 193–215. https://doi.org/10.2307/3641438 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Ann Caylor; "A Promise Long Deferred": Federal Reclamation on the Colorado River Indian Reservation. Pacific Historical Review 1 May 2000; 69 (2): 193–215. doi: https://doi.org/10.2307/3641438 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentPacific Historical Review Search This content is only available via PDF. Copyright 2000 The Pacific Coast Branch, American Historical Association Article PDF first page preview Close Modal You do not currently have access to this content.

Gas exhange and water relations of two Rocky Mountain shrub species exposed to a climate change manipulation - M. Shaw; M. E. Loik; J. Harte (Plant Ecology, 2000)

Comparison of reproductive success of in-situ burial verrsus the use of abandoned burrows for carcass interment by Nicrophorus investigator (Coleoptera:Silphidae) - R. J. Smith; M. Bonilla; C. Calahan; J. Mann (Journal of the Kansas Entomological Society, 2000)

New material ofDinochelys whiteiGaffney, 1979, from the Dry Mesa Quarry (Morrison Formation, Jurassic) of Colorado - Donald B. Brinkman; KENNETH L. STADTMAN; DAVID K. Smith (Journal of Vertebrate Paleontology, 2000)
ABSTRACT A specimen of a juvenile individual of Dinochelys from the Dry Mesa Quarry, Morrison Formation, provides the first record of the skull and neck in this genus. Dinochelys is interpreted as related to Glyptops on the basis of a similar development of sculpture on the vertebral scutes of juvenile individuals, and a similar development of a beak on the premaxilla and dentary. Desmemys, a turtle from the Early Cretaceous of Europe is interpreted as closely related to Dinochelys on the basis of similarities in the proportions of the scutes of the carapace and similar development of fenestration on the carapace and plastron. The relationship between Desmemys and Dinochelys further emphasizes the connections between the turtle assemblages of North America and Europe during the Jurassic and Early Cretaceous.

Impact of the Western Thatching Ant (Formica obscuripes) on insect abundance and diversity - K. Jenks (2000)

Environmental effects on woody growth of sagebrush Artemisia tridentata - T. Perfors (2000)

A geometric solar radiation model with applications in landscape ecology - P. Fu (2000)

The herbivory effect of ant tended membracids on Wyethia - C. Trebesch (2000)

Water Quality in Alluvial Aquifers of the Southern Rocky Mountains Physiographic Province, Upper Colorado River Basin, Colorado, 1997 - L. E. Apodaca; J. B. Bails (2000)

Leaf breakdown in a regulated desert river: Colorado River, Arizona, U.S.A. - Kimberly E. Pomeroy; Joseph P. Shannon; Dean W. Blinn (Hydrobiologia, 2000)
Dual stable isotope analysis showed that leaf material was not the primary food for invertebrates associated with leaf packs, and processing rates for all leaf types were slow in the regulated Colorado River compared to rates reported in many other systems.

Responses to herbivory in Ipomopsis aggregata; implications for fitness and biotic interactions - R. S. Freeman; K. Sharaf (2000)

Webs in space III: Link-area relationships among three montane meadows - D. Ignace (2000)

Absence of conspecific pollen advantage in the dynamics of an Ipomopsis (Polemoniaceae) hybrid zone - R. Alarcon; Diane R. Campbell (American Journal of Botany, 2000)

Consequences of nectar robbing for realized male function in a hummingbird-pollinated plant - R. E. Irwin; Alison K. Brody (Ecology, 2000)
The effects of nectar robbers on plants and their mutualistic pollinators are poorly understood due, in part, to the paucity of studies examining male reproductive success in nectar-robbed plants. Here we measured the effects of a nectar-robbing bumblebee, Bombus occidentalis, on realized male reproductive success (seeds sired) in a hummingbird-pollinated plant, Ipomopsis aggregata. To determine the effects of nectar robbing on paternity, we used a series of experimental populations of plants containing a known allozyme marker. In each population, we experimentally controlled the levels of nectar robbing on each I. aggregata plant by cutting a hole in the corolla with dissecting scissors and removing nectar with a micro-capillary tube. We measured hummingbird-pollinator foraging behavior and fruit and seed production (maternal function) for each plant. We then genotyped seeds for the allozyme marker to determine the number of seeds sired by plants with known levels of robbing. Heavy nectar robbing (> 80% of flowers robbed) significantly reduced the number of seeds sired, as well as the number of seeds produced due to pollinator avoidance of heavily robbed plants. Total plant reproduction, both male and female contributions, were reduced by 50% due to high levels of robbing. To date, no other studies have measured the effects of nectar robbing on realized male function (number of seeds sired). Ours is the first study to demonstrate that robbing can simultaneously decrease realized male reproductive success as well as female reproductive success, and that the effects are incurred indirectly through pollinator avoidance of robbed plants.

Outbreeding depression varies among cohorts of Ipomopsis aggregata planted in nature - Nickolas M. Waser; Mary V. Price; R. G. Shaw (Evolution, 2000)

Floral dimorphism, pollination, and self-fertilization in gynodioecious Geranium richardsonii (Geraniaceae) - C. F. Williams; M. A. Kuchenreuther; A. Drew (American Journal of Botany, 2000)
The selective maintenance of gynodioecy depends on the relative fitness of the male‐sterile (female) and hermaphroditic morphs. Females may compensate for their loss of male fitness by reallocating resources from male function (pollen production and pollinator attraction) to female function (seeds and fruits), thus increasing seed production. Females may also benefit from their inability to self‐fertilize if selfing and inbreeding depression reduce seed quality in hermaphrodites. We investigated how differences in floral resource allocation (flower size) between female and hermaphroditic plants affect two measures of female reproductive success, pollinator visitation and pollen receipt, in gynodioecious populations of Geranium richardsonii in Colorado. Using emasculation treatments in natural populations, we further examined whether selfing by autogamy and geitonogamy comprises a significant proportion of pollen receipt by hermaphrodites. Flowers of female plants are significantly smaller than those of hermaphrodites. The reduction in allocation to pollinator‐attracting structures (petals) is correlated with a significant reduction in pollinator visitation to female flowers in artificial arrays. The reduction in attractiveness is further manifested in significantly less pollen being deposited on the stigmas of female flowers in natural populations. Autogamy is rare in these protandrous flowers, and geitonogamy accounts for most of the difference in pollen receipt between hermaphrodites and females. Female success at receiving pollen was negatively frequency dependent on the relative frequency of females in populations. Thus, two of the prerequisites for the maintenance of females in gynodioecious populations, differences in resource allocation between floral morphs and high selfing rates in hermaphrodites, occur in G. richardsonii.

Effects of nectar-robbing bumblebees on hummingbird-pollinator behavior and plant reproductive success in Ipomopsis aggregata (Polemoniaceae) - R. E. Irwin (2000)

The ecological and evolutionary significance of frost in the context of climate change - David W. Inouye (Ecology Letters, 2000)
The effects that below‐freezing temperature (frost) can have at times of year when it is unusual are an interesting ecological phenomenon that has received little attention. The physiological consequence of formation of ice crystals in plant tissue is often death of the plants, or at least of sensitive parts that can include flower buds, ovaries, and leaves. The loss of potential for sexual reproduction can have long‐lasting effects on the demography of annuals and long‐lived perennials, because the short‐term negative effects of frosts can result in longer‐term benefits through lowered populations of seed predators. The loss of host plants can have dramatic consequences for herbivores, even causing local extinctions, and the loss of just flowers can also affect populations of seed predators and their parasitoids. Frosts can cause local extinctions and influence the geographical distribution of some species. The potential for global climate change to influence the frequency and distribution of frost events is uncertain, but it seems likely that they may become more frequent in some areas and less frequent in others.

Roots, shoots and ladders: Variation in growth, mortality, and biomass allocation in a potentially invasive species(Matricaria perforata in response to elevation, microhabitat, and herbivory - K. Gravuer (2000)

Avoiding paradigm-based limits to knowledge of evolution - W. B. Watt (Evolutionary Biology, 2000)
The “Modern Synthesis” brought paleontology and systematics together with population genetics to endorse Darwin’s insights and to lay the foundation of steady progress in understanding.

Topoclimatic determinants of distribution of a montane shrub, Pentaphylloides floribunda (Pursh) Love - P. McDonald (2000)

Hydrologic and behavioral constraints on oviposition of stream insects: implications for adult dispersal - B. L. Peckarsky; B. W. Taylor; C. C. Caudill (Oecologia, 2000)
Oviposition and emergence of a bivoltine population of B. bicaudatus in multiple stream reaches in one high-altitude watershed in western Colorado over 3 years was surveyed to determine whether hydrologic variation necessitated dispersal of females to find suitable oviposition sites and whether the local supply of females could provide the supply of local recruits, and whether local recruitment determined the local production of adults.

Ecological and economic analysis of natural capital: assessing and modeling the substitutability of mitigation wetlands for natural sites - J. J. Gutrich (2000)

Global warming and terrestrial ecosystems: a conceptual framework for analysis - G. R. Shaver; J. Canadell; F. S. Chapin; J. Gurevitch; J. Harte; G. H. R. Henry; P. Ineson; S. Jonasson; J. Melillo; L. Pitelka; L. Rustad (BioScience, 2000)
raise global mean temperature over the next century by 1.0–3.5 °C (Houghton et al. 1995, 1996). Ecologists from around the world have begun experiments to investigate the effects of global warming on terrestrial ecosystems, the aspect of global climate change that attracts the most public attention (Woodwell and McKenzie 1995, Walker and Steffen 1999). The effort to understand response to warming builds on a history of investigations of the effects of elevated CO 2 on plants and ecosystems (Koch and Mooney 1996, Schulze et al. 1999). There are important differences, however, between increases in atmospheric CO 2 and temperature change, both in the temporal and spatial patterns of change and in how they affect ecosystems. The scientists involved in temperature change research have had to face new technical and conceptual challenges in designing and interpreting their experiments (Schulze et al. 1999). In this paper we describe these challenges and present a conceptual framework for interpreting experimental results and predicting effects of warming on ecosystems.

Pollinator selection and interspecific pollen transferrates in an Ipomopsis hybrid zone - G. T. Pederson (2000)

Experimental tests of sex-allocation theory in plants - Diane R. Campbell (Trends in Ecology and Evolution, 2000)
Experimental studies provide tests of sex-allocation theory by measuring male and female fitness gains, and examining the trade-off assumption, to show how fitness responds to shifts in allocation.

The use of rodent burrows by burying beetles, Nicrophorus investigator: A case of behavioral plasticity - C. Calahan (2000)

Herbivory and pollination in hemiparasitic plants: effects of host plant and host-obtained alkaloids - L. S. Adler (2000)

The microtine rodents from the Pit locality in Porcupine Cave, Park County, Colorado - Christopher J. Bell; Anthony D. Barnosky (Annals of the Carnegie Museum, 2000)
This report presents the results of an analysis of the microtine rodents from the Pit locality, one of four localities within Porcupine Cave that have a relatively long stratigraphic sequence. At 2900 m elevation. Porcupine Cave is the highest elevation site in North America to have produced a diverse microtine rodent assemblage. At least 11 species are distributed through 14 stratigraphic levels: Phenacomys gryci, Phenacomys sp., Mimomys (Cromeromys) cf. M. virginianus, Ondatra sp., Allophaiomys pUocaenicus, Terricola meadensis, Mictomys cf. M. meltoni, Microtus paroperarius, Microtus sp. (not M. paroperarius), Lemmiscus curtatus, and Lemmiscus sp. All but one of these {Phenacomys sp. not P. gryci) occur within a single stratigraphic level (level 4), making the assemblage of microtines unique in species composition and among the most diverse known from any fossil deposit. The diversity of the assemblage probably results from the location of the site within a topographically diverse ecotonal region that allowed sampling of a wide range of nearby microhabitats by the carnivores and raptors that initially collected the bones. The unique species assemblage is likely related to the high elevation of the site, which differentiates it physiographically from any other fossil deposit that has produced microtine rodents in abundant numbers, and perhaps because the Rocky Mountain backbone served as both a dispersal corridor and refugium as taxa adjusted biogeographic ranges in response to glacial-interglacial transitions and other climatic changes.

Molecular-functional studies of adaptive genetic variation in prokaryotes and eukaryotes - W. B. Watt; A. M. Dean (Annual Review of Genetics, 2000)
▪ Abstract  Knowledge of both prokaryotic and eukaryotic organisms is essential to the study of molecular evolution. Their common ancestry mandates that their molecular functions share many aspects of adaptation and constraint, yet their differences in size, ploidy, and structural complexity also give rise to divergent evolutionary options. We explore the interplay of adaptation, constraint, and neutrality in their evolution by the use of genetic variants to probe molecular function in context of molecular structure, metabolic organization, and phenotype-environment interactions. Case studies ranging from bacteria to butterflies, flies, and vertebrates emphasize, among other points:a. the importance of moving from initial recording of evolutionary pattern variation to studying the processes underlying the patterns, by experiment, reconstructive inference, or both; b. the complementarity, not conflict, of finding different performance and fitness impacts of natural variants in prokaryotes or eukaryotes, depending on the nature and magnitude of the variants, their locations and roles in pathways, the nature of molecular function affected, and the resulting organismal phenotype-environment interactions leading to selection or its absence; c. the importance of adaptive functional interaction of different kinds of variants, as in gene expression variants versus variants altering polypeptide properties, or interaction of changes in enzymes' active sites with complementary changes elsewhere that adjust catalytic function in different ways, or coadaptation of different steps' properties in pathways; d. the power afforded by combining structural and functional analyses of variants with study of the variants' phenotype-environment interactions to understand how molecular changes affect (or fail to affect) adaptive mechanisms “in the wild.”Comparative study of prokaryotes and eukaryotes in this multifaceted way promises to deliver both new insights into evolution and a host of new and productive questions about it.

Enlightenment for mapping systems: solar radiation models look to the sun for answers - P. M. Rich; P. Fu (Resource Magazine, 2000)

The effects of plant size and local population structure on pollinator attraction in gynodioecious Geranium richardsonni (Geraniaceae) - A. Gibson (2000)

From populations to ecosystems: studies on the distribution, importance, and loss of biodiversity - J. B. Hughes (1999)

Courtship behavior in a polymorphic population of the Tiger Salamander, Ambystoma tigrinum nebulosum - H. H. Whiteman; J. J. Gutrich; R. S. Moorman (Journal of Herpetology, 1999)

A comparison effort between hermaphrodites and females of Geramium richarsonii; Implications for maintenance of gynodioecy - M. Tovar (1999)

The effects of variable nutrient environments on protein concentrations in male accessory glands in Speyeria mormonia - L. Anderson (1999)

Effects of disturbance on the growth and invasive potential of Matricaria perforata in a sub-alpine meadow - K. Regan (1999)

Do species interactions underlie changes in vegetation observed in a meadow-warming experiment? - G. Peterson (1999)

Foraging trade-offs along a predator-permanence gradient in subalpine wetlands - S. A. Wissinger; H. H. Whiteman; G. B. Sparks; G. L. Rouse; W. Brown (Ecology, 1999)
Scott A. Wissinger, Howard H. Whiteman, Grace B. Sparks, Gretchen L. Rouse, Wendy S. Brown, Foraging Trade-Offs along a Predator-Permanence Gradient in Subalpine Wetlands, Ecology, Vol. 80, No. 6 (Sep., 1999), pp. 2102-2116

Factors affecting scent marking behavior in the North American Beaver (Castor canadensis) - J. Pierce (1999)

A Census of Molothrus ater in the East RIver and Ohio Creek Valleys - P. Pressman (1999)

Colonial Costs and their Effects on the Behavior of Nestling Feeding and Nest Occupation in the Cliff Swallow - C. Hess (1999)

Gatherings of Angels: Migrating Birds and Their Ecology - W. A. Calder (1999)

The Effects of Competition on the Establishment of Festuca thurberi onto the Gothic Earthflow - R. Leary; M. Palomino; G. Tedeschi (1999)

Vertebrate and Invertebrate Pollinators of Distegia involucrata/Lonicera involucrata (Capriofoliaceae) of RMBL Gothic, CO - R. Hackney (1999)

Rapid size-specific changes in the drift of Baetis bicaudatus (Ephemeroptera) caused by alterations in fish odour concentration - A. R. McIntosh; B. L. Peckarsky; B. W. Taylor (Oecologia, 1999)

Invertebrates in Freshwater Wetlands of North America: Ecology and Management - S. A. Wissinger; A. Bohonak; H. H. Whiteman; W. Brown (1999)

From Reclamation to Sustainability: Water, Agriculture, and the Environment in the American West - Lawrence MacDonnell (eYLS (Yale Law School), 1999)
This digital resource contains only an abstract, cover image and table of contents information from the published book. Print copy of book is available in the University of Colorado’s Wise Law Library: http://lawpac.colorado.edu/record=b236740~S0 Contents: Introduction : Living in a land of limited water -- PART 1. THE LOWER ARKANSAS VALLEY : AFTER THE WATER IS GONE: Colorado's Arkansas River -- Watering and cultivating the prairie -- Stretching a limited water supply -- Irrigation water for sale? -- A hostile takeover? -- Looking ahead -- PART 2. THE GRAND VALLEY, COLORADO : WHERE FRUIT, FISH, AND GROWTH COLLIDE: Growing peaches in an arid mountain valley -- The problem of salt -- Competition from across the Divide and closer to home -- Water for native fish -- The promise-and problems-of water conservation -- PART 3. THE TRUCKEE AND CARSON BASINS : SHARING WATER IN A DESERT: Life in a land in between -- Redeeming the "irredeemable" -- An environmental reckoning -- The ongoing search for redemption -- What happens to irrigation? -- What next? -- PART 4. THE YAKIMA BASIN, WASHINGTON : MAKING THE "OLD WEST" WORK: The place -- The first people -- Reclamation in the Yakima -- A tale of two irrigation districts -- Adjudicating water rights -- The salmon -- Taking stock -- PART 5. FROM RECLAMATION TO SUSTAINABILITY: From reclamation to sustainability -- Reducing the gap between diversion and consumption -- Allowing our rivers to function like rivers -- Water that changes use to meet demand -- Getting there -- Epilogue : A Faustian bargain?

Estimating species-area relationships from plot to landscape scale using species spatial-turnover data - J. Harte; S. McCarthy; K. J. Taylor; A. Kinzig; M. L. Fischer (Oikos, 1999)
John Harte, Sarah McCarthy, Kevin Taylor, Ann Kinzig, Marc L. Fischer, Estimating Species-Area Relationships from Plot to Landscape Scale Using Species Spatial-Turnover Data, Oikos, Vol. 86, No. 1 (Jul., 1999), pp. 45-54

Invertebrates in Freshwater Wetlands of North America: Ecology and Management - S. A. Wissinger; L. J. Gallagher (1999)

The Commonality of Herbivorous Trophic Links with Regard to Spatial Scale - L. B. Buckley (1999)

Assessment of a revegetation project on Mt. Crested Butte - K. Mahady (1999)

Floristic Inventory of the Northern Gunnison Basin - K. J. Taylor (1999)

Scent-marking in the yellow-bellied marmot Marmota flaviventris - K. M. Brady; Kenneth B. Armitage (Ethology, Ecology and Evolution, 1999)
Cheek-marking in yellow-bellied marmots (Marmota flaviventris) was studied by observations of cheek-marking in two colonies from 10 June to 6 August, 1996 and by experimental studies of responses to olfactory secretions from the perioral gland. The rate of cheek-marking declined significantly as the season progressed. Most cheek-marking occurred within 3 m of the main burrow system and was primarily associated with sitting or lying and short locomotory bouts around the main burrow area. Cheek-marking rates of individuals differed significantly and adults appeared to mark more than yearlings. In the experiment, marmots cheek-marked stakes with perioral secretions significantly more than stakes without secretions. However, they marked unfamiliar and familiar smells equally. Marmots investigated strange secretions longer than familiar secretions and familiar secretions longer than the blank treatment. Functionally, cheekmarking is a multipurpose activity. It provides cues for young of the year to learn the safe areas in the home range, imparts familiarity with the burrow area, communicates burrow occupancy, and functions in territorial defense.

Pollination of Ipomopsis aggregata (Polemoniacea): Effects of Intra-vs. Interspecific competition - C. M. Caruso (American Journal of Botany, 1999)

The evolution of functionally referential alarm communication: multiple adaptations; multiple constraints - Daniel T. Blumstein (Evolution of Communication, 1999)

Preferential Placement vs. Selective Mortality of Aspen Ramets in Canopy and Canopy Gap - A. Capacchione; P. Pressman (1999)