The previously described allelic frequencies and linkage disequilibrium among the active and null alleles of four tightly linked loci coding for the alpha-esterases were found to be maintained by one population for 5 years, and were found to be present in two other populations which were shown to be

The combined results of these experiments suggest that caddisfly distributions along permanence gradients depend on a suite of primary and secondary predator defenses that include larval and pupal case structure, predator-specific escape behaviors, and the phenology of larval development.

Status of the Colorado River population of the endangered Colorado squawfish Ptychocheilus lucius (recently renamed the Colorado pikeminnow) was investigated by (1) estimating adult numbers, (2) evaluating frequency of reproduction and recruitment, (3) identifying trends via changes in size structur

Abstract Interactions between ants and aphids range from mutualistic to antagonistic. Understanding the ecological basis for such interactions requires understanding the costs and benefits to the aphids of ant-tending. Such an analysis is not simple, because ants can simultaneously have positive and

Three species of aphids in the genus Aphis and one in the genus Macrosiphum feed on fireweed in the Rocky Mountains of Colorado, U.S.A. These species differ in their time of colonization of fireweed, time of maximum number of colonies, feeding position on fireweed, relationships to tending ants, lif

Contrary to expectations, clones at their site of origin had less disease, less herbivory, and higher fitness than foreign clones, suggesting that the number of sites and clones needed to thoroughly test the hypothesis of negative frequency-dependent selection in this system is very large.

Snow derived water is a critical component of a large part of the US water supply. Measurements of the Snow Water Equivalent (SWE) and associated predictions of peak SWE and snowmelt onset are essential inputs for water management efforts. This paper aims to develop a data-driven approach for estima

The basic tenet of sex allocation theory is that an organism's reproductive success, through either male or female function, can be represented as a sex-specific, monotonic, increasing function of the organism's investment of resources in that function. The shapes of these curves determine what patt

Land cover change due to drought and insect-­‐induced tree mortality or altered vegetation succession is one of the many consequences of anthropogenic climate change. While the hydrologic response to land cover change and increases in temperature have been explored independently, few studies have co

The effect of introduced detritus on the colonization of cages by benthic invertebrates within the substrate of two stony streams was examined. Pairs of substrate-filled screen cages were buried to a depth of 10–20 cm within the substrate of Otter Creek, Sauk County, Wisconsin, and the East River, G

Numbers of Broad-tailed Hummingbirds (Selasphorous platycercus) captured each summer from 1979-1989 at the Rocky Mountain Biological Laboratory were quite variable, ranging from 115 (1981) to 348 (1989), with new birds usually outnumbering returning (previously banded) birds. Capture numbers were ne

Abstract Recent reports of insect declines have caused concern among scientists and the public. Declines in insect abundance and biomass are ubiquitous across many climatic zones and have been largely attributed to anthropogenic land use intensification and climate change. However, there are few exa

In the last few years there has been an explosion of information concerning electrophoretic variation at enzyme loci. These data are being increasingly employed in attempts to elucidate biosystematic and phylogednetic relationships. As the evolutionary role of these allozyme polymorphisms is not wel

Concentration-discharge (C-Q) relationships have been widely used as “hydrochemical tracers” to determine the variability in riverine solute exports across event, seasonal, annual, and decadal time scales. However, these C-Q relationships are limited to investigating solute transport dynamics at ind

Behavior of Baetis bicaudatus (Ephemeroptera; Baetidae) was video taped in a western Colorado, USA stream to identify the specific stimuli eliciting noncontact responses to predatory stoneflies (Kogotus modestus; Plecoptera; Perlodidae). In situ behavioral and feeding trial experiments were also con

The mode of inheritance of the 15 electrophoretically different α-naphthyl acetate-specific esterases found in five population samples of Drosophila montana collected near Gothic, Colorado, was delineated by mating a strain which exhibited no esterase activity to 237 wild-caught flies, and analyzing

Emitting alarm calls may directly benefit individuals if callers have an increased chance of surviving, if calling increases the caller’s status, or if calling functions through reciprocity. Although previous studies have examined the costs and benefits of alarm calling, few have examined how an ind

These are the first results to directly link the range of worker sizes to a component of colony fitness in a natural setting.

Abstract Ecological communities often show changes in populations and their interactions over time. To date, however, it has been challenging to effectively untangle the mechanisms shaping such dynamics. One approach that has yet to be fully explored is to treat the varying structure of empirical co

Evapotranspiration (ET) is a key component of the water balance, which influences hydrometeorology, water resources, carbon and other biogeochemical cycles, and ecosystem diversity. This study aims to investigate the spatio-temporal variations of ET at the East River watershed in Colorado and analyz