Heterogeneous distributions of resources and organisms are characteristic of most ecosystems, but empirical understanding of the causes and consequences of heterogeneity is limited. We investigated whether predatory fish influenced the heterogeneity (spatial variability) of resources (algae) by modi

It is hypothesized that the average rate of nectar production per flower for a population of plants is such than an individual plant which possesses this rate has maximum fitness (i.e., is optimal), and predictions concerning nectarProduction in scarlet gilia, a hummingbird pollinated plant are deve

AbstractWarm temperatures are required for insect flight. Consequently, warming could benefit many high‐latitude and high‐altitude insects by increasing opportunities for foraging or oviposition. However, warming can also alter species interactions, including interactions with natural enemies, makin

Evidence is presented in support of the suggestion that a hovering bird is able to move between flowers more quickly than one that is perching, however, this advantage to hovering may be offset by the higher energetic costs of hovering as compared with perching.

The dispersal was associated with changes in home ranges and with the avoidance of dominant animals by subordinate animals, and females moved from being concentrated in the centre of the colony to being more widely dispersed during the vernal period.

Global climate change is predicted to increase the intensity and frequency of future drought, which in turn may be expected to induce a range of biogeochemical climate feedbacks. A combination of model simulations and observational studies of a recent wide-scale drought, suggested that the drought i

Pseudoflowers induced by the rust fungus Puccinia monoica on Arabis spp. are flower—like in color, shape, size, nectar production, and scent. Pseudoflowers attract insects that aid the rust's reproduction in a way that is analogous to pollination in flowering plants. I explored the effects of pathog

Pianka's (1976) treatment of competition and niche theory is taken as an authoritative precis of the recent state of this school of thought, in turn aiming attention at the functional and evolutionary responses.

Several aspects of nectarivore foraging behavior have been interpreted as responses to spatial reward patchiness of the kind documented for Delphinium nelsonii floral nectar by Pleasants and Zimmerman (1979). Working with this same species over 3 yr, however, we were unable to detect substantial pat

Yellow-bellied marmots (Marmota flaviventris) eat a wide variety of grasses, forbs, and seeds, but do not feed on all items in proportion to their abundance in the environment. In this study, relationships between the marmot diet and estimated protein, water, caloric value, relative biomass, and tox

The statistical concept of home range as applied to the recapture radius of the deer-mouse (Peromyscus) and the calculation of homerange and density of small mammals is presented.

White adipose tissue (WAT) and plasma samples were obtained from yellow-bellied marmots (Marmota flaviventris) throughout the year. Mean plasma triacylglycerol (TG), free fatty acids (FFAs), and glycerol were determined. There was a clear increase in FFAs and decrease in mean TG and glycerol during

The newly described Gunnison sage-grouse (Centrocercus minimus) is a species of concern for management because of marked declines in distribution and abundance due to the loss and fragmentation of sagebrush habitat. This has caused remaining populations to be unusually small and isolated. We utilize

The overall sex ratio of weaned yellow-bellied marmots does not differ significantly from one. Litter size has no effect on the sex ratio of young. Stress, measured by eosinophil concentration and mirror-image stimulation, is not associated with biased sex ratios. Three-year-old females and females

Patterns of substrate size preference of predatory stoneflies were measured in a western Colorado, USA, stream and associations were examined between substrates and other physical and biological variables. Predatory Megarcys signata (Perlodidae) were found disproportionately on large stones that wer

AbstractQuestionsIs it possible to predict the composition of local plant assemblages? Trait‐based approaches have offered some promise, especially in cases where deterministic processes such as environmental filtering and niche differentiation shape communities. In this study, we asked how much int

The periodic cycles in populations of microtine rodents and hares are considered together to provide the suggestion that the natural period is endogenous and size-dependent, and may be a consequence of the physiological and reproductive pace of the life cycle that scales as the fourth root of body m

Journal Article The Annual Cycle and Fat Storage in Two Populations of Golden-Mantled Ground Squirrels Get access Barbara Hibbs Blake Barbara Hibbs Blake Department of Biology, Yale University, New Haven, Connecticut Search for other works by this author on: Oxford Academic Google Scholar Journal of

Many specialist herbivores eat foods that are apparently low quality. The compensatory benefits of a poor diet may include protection from natural enemies. Several bee lineages specialize on pollen of the plant family Asteraceae, which is known to be a poor-quality food. Here we tested the hypothesi