Flowers frequently receive both self (S) and outcross (OC) pollen, but S pollen often sires proportionally fewer seeds. Failure of S pollen can reflect evolved mechanisms that promote outcrossing and/or inbreeding depression expressed during seed development. The relative importance of these two pro

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 a

Ecological factors explain variation in sociality both within and between species of marmots—large alpine ground squirrels. Fifty years of study, by me and my colleagues, of the yellow-bellied marmots (Marmota flaviventris) at the Rocky Mountain Biological Laboratory, near Crested Butte, CO, USA, ha

Radioactive age determinations have been made on 16 minerals from the Brown Derby pegmatite and the Quartz Creek granite. A high degree of consistency has been found among the Rb-Sr ages measured on micas and feldspars. A similar degree of consistency exists in the K-A ages of micas. These consisten

Animals employ a variety of behaviors to reduce or manage predation risk. Often, these are studied in isolation, but selection may act on packages of behavior that are referred to as behavioral syndromes. We focused on yellow- bellied marmots (Marmota flaviventris) and examined three commonly studied

Research Article| January 01, 1995 Sackungen at the Aspen Highlands Ski Area, Pitkin County, Colorado JAMES P. McCALPIN; JAMES P. McCALPIN GEO-HAZ Consulting, Inc., P. O. Box 1377, Estes Park, CO 80517 Search for other works by this author on: GSW Google Scholar JAMES R. IRVINE JAMES R. IRVINE Consu

Ecological communities consist of species that are joined in complex networks of interspecific interaction. These interactions often form and dissolve rapidly, but this temporal variation is not well integrated into our understanding of the causes and consequences of network structure. If interspeci

Environmental parameters, population dynamics, resource utilization patterns, and social dynamics were evaluated in terms of their relationships to population density, intraspecific competition, parent—offspring relations, and male territoriality.

Theory and empirical studies suggest that cannibalism in age‐structured populations can regulate recruitment depending on the intensity of intraspecific competition between cannibals and victims and the nature of the cannibalism window, i.e., which size classes interact as cannibals and victims. Her

AbstractWe studied two components of predator risk assessment in birds. While many species are limited to seeking safety under cover or under ground, some birds can fly away from their predators and escape to trees. If birds in fact ‘feel’ safer (e.g. perceive less risk) in trees, we would expect th

Paedogenesis in varying degrees is exhibited by many species of North American salamanders, particularly of the genus Ambystoma. On the basis of a consideration of the ecology of these species, it is proposed that paedogenesis is evolutionarily adaptive and the following hypothesis is presented. In

AbstractNatural genetic variants at the phosphoglucose isomerase, PGI, gene differ in spatial patterning of their polymorphism among species complexes ofColiasbutterflies in North America. In both lowland and alpine complexes, molecular–functional properties of the polymorphic genotypes can be used

Lepidoptera feed at mud puddles, dung, and carrion in a behavior known as puddling. Sodium and sometimes protein are feeding cues, are actively collected, and play a potentially important role in lepidopteran nutritional and mating ecology. We showed that montane butterfly species have feeding prefe

The Urad and Henderson stockwork molybdenite orebodies at Red Mountain, Clear Creek County, Colorado, are related to a rhyolitic subvolcanic center of Oligocene age referred to as the Red Mountain Complex. The two orebodies are well separated in space and are specifically related to different intrus

The results of the laboratory experiment suggest that this species can metamorphose with a detritus-only diet, but development is extremely protracted, which is consistent with recent growth-development models that predict coupled rather than tradeoff responses to pre-threshold manipulation of larva

The outcome of species interactions is often difficult to predict, depending on the organisms involved and the ecological context. Nectar robbers remove nectar from flowers, often without providing pollination service, and their effects on plant reproduction vary in strength and direction. In two ca

The satyrine butterfly Erebia epipsodea shows a population structure unlike that of any other butterfly studied in detail. Rather than being divided into numerous small populations which only rarely exchange individuals, E. epipsodea occurs in vast, effectively panmictic populations which may cover

EvolutionVolume 43, Issue 1 p. 220-223 Note and CommentFree Access GERMINATION SCHEDULES OF POLLEN GRAINS: IMPLICATIONS FOR POLLEN SELECTION James D. Thomson, James D. Thomson Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, NY, 11794 Rocky Mountain Biol

Despite the large variation in pollinator abundance over time and space, one species of bumble-bee or hawkmoth tended to predominate in each population each year. Future studies of Aquilegia coerulea should examine the specific influences of pollinators and the environment on flower colour and of ha