Interactive effects of one species on another may simultaneously influence mortality, growth, and fecundity. To quantify the strength of an interaction between two species, we must therefore use techniques that integrate these various responses into estimates of overall effect. Demographic models of

Pollination by animals is critical to sexual reproduction of most angiosperms. However, little is known about variation in pollination service to single plant species. We report results of a long-term study of Ipomopsis aggregata, a semelparous montane herb whose flowers are visited by hummingbird a

Foraging determines an organism's intake of resources (water, nutrients or energy), while life-history patterns (survival, reproduction, growth) result from resource expenditure on fitness-related activities. Allocation of a limited resource pool among competing life-history traits links foraging an

Yellow-bellied marmots, Marmota flaviventris were reported to produce qualitatively different alarm calls in response to different predators, but there was significant individual variation in call structure, but acoustic parameters that were individually variable were not used to communicate variati

ABSTRACT Electrophoretic variants of phosphoglucose isomerase (PGI) in Colias butterflies have been studied from field and laboratory viewpoints. The transmission pattern is that of a dimeric enzyme controlled by one structural gene locus. Populations usually harbor four to six allelic mobility clas

Core Ideas Development of a 300‐km 2 mountainous headwater testbed began in 2016 in the East River. The testbed can be used to explore how watershed changes impact downgradient water availability and quality. System‐of‐system, scale‐adaptive approaches can potentially improve watershed dynamics simu

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.

Nocturnal drift of stream invertebrates is examined as a predator avoidance adaptation via the hypothesis that those taxa or growth stages which are large, and thus subject to intense predation relative to smaller forms, should be most strongly constrained to nocturnal drift activity. Smaller taxa o

Distributional patterns and species diversity of benthic insects in an alpine stream in Gunnison County, Colorado, USA were investigated on several levels of spatial scale, from faunal replacement over 1,000 vertical m to microdistribution within the stony substratum. Ecotones including zonation in

An experimental reduction in trout density was carried out for 4 yr to determine whether the numbers or species composition of aquatic invertebrates would be affected. In a Colorado stream, the standing crop of trout (mainly Salvelinus fontinalis) prior to this study was 4.86 g/m2, typical of infert

John Harte,1* Adam B. Smith1 and Classic theory predicts species richness scales as the quarter-power of area, yet species– David Storch2,3 area relationships (SAR) vary widely depending on habitat, taxa, and scale range. Because 1 Energy and Resources Group, power-law SAR are used to predict specie

Clines across hybrid zones can be produced by several forms of natural selection. We illustrate an approach to studying pollinator-mediated selection in plant hybrid zones, using two species of Ipomopsis (Polemoniaceae) as a model system. We measured visitation to flowers in natural and experimental

(1) Per-flower insect visitation rates on two plant species within Rocky Mountain subalpine meadows were measured using fluorescent powders and found to be positively correlated with local flower density, suggesting that insects concentrate their foraging in dense patches of flowers. (2) Visitation

This study identifies the physical determinants of thermoregulation in Colias, develops and tests models that predict the patterns of body temperature and flight activity along an elevational gradient, and explores the relationship of the thermoreGulatory characteristics to these patterns among Coli

As a case study of adaptive strategies in temporally varying environments, thermoregulation in three populations of Colias butterflies along an elevation gradient in Colorado is studied in relation to the fluctuating meteorological environment. Emphasis is placed on short time scale (15-300 s) varia

Animals must use cues from smells, sounds, and sights to reduce uncertainty about the environment. Despite the ecological relevance of multisensory perception in helping animals cope with uncertainty, empirical support from natural systems is rarely placed within an adaptive framework. The field of

We conducted manipulative field experiments in artificial ponds to quantify the predatory impact of larvae of a migratory dragonfly (Tramea lacerata) on a common resident dragonfly species (Erythemis simplicicollis), and on damselflies as shared prey of the two dragonflies. We found that the combine

Plants are under siege from a diversity of enemies that consume both leaf and floral parts. Plants resist damage to leaves in a variety of ways, and we now have a rich literature documenting how plants defend themselves against herbivore attack. In contrast, the mechanisms by which plants resist ene

In some salamander species the retention of larval characteristics in sexually mature adults (paedomorphosis) is an alternative to metamorphosis. In many species paedomorphosis is facultative, thus offering a unique opportunity to test predictions on the evolution of life history variation. Here I e