ANTIARCHIThe peculiar armored placoderm, Bothriolepis, is a characteristic element of Late Devonian fresh-water faunas throughout much of the world.It is common in the western United States, but its remains are usually fragmentary or poorly preserved, so that identi- fication is difficult.Two specie

AbstractThe depth of active groundwater circulation is a fundamental control on stream flows and chemistry in mountain watersheds, yet it remains challenging to characterize and is rarely well constrained. We collected hydraulic conductivity, hydraulic head, temperature, chemical, noble gas, and 3H/

Results from this study suggest that selenium contamination in parts of the upper basin of the Colorado River should be a major concern to recovery efforts for endangered fish.

Close examination of zones of deformation bands in the Entrada Sandstone (Middle Jurassic) near Durango, Colorado suggests that the width of these vertical zones and the displacement across them is directly related to the porosity of the sandstone. Low porosity sandstone is less susceptible to fract

During the downward trend of Quaternary global temperatures, crown-group marmots evolved to occupy harsh, seasonal environments at high latitudes and elevations. Marmots evolved hibernation and large body size, which allowed them to cope with a long, cold season with low, stressful ambient temperatu

Aquilegia micrantha occurs in canyons of the Southwestern United States. The pinkish-yellow flowers are nodding or semi-nodding, mildly scented, protandrous, and secrete a concentrated nectar (46% total sugars). Seed set in flowers under pollinator exclosures was 25% compared with 63% for open-polli

When approached by a predator, prey make economic decisions between remaining where they are and obtaining benefits from their current activity or leaving and enhancing their safety. The "flush early and avoid the rush" hypothesis suggests that animals that flee to escape approaching threats flee so

Many plants that bear hidden or recessed floral nectar experience nectar robbing, the removal of nectar by a floral visitor through holes pierced in the corolla. Although robbing can reduce plant reproductive success, many studies fail to find such effects. We outline three mechanistic hypotheses th

Indirect effects of predators on primary producers vary over space and time. Key components of the environmental context underlying that variability include the bottom‐up supply of resources and the defense, mobility and foraging efficiency of primary consumers. We manipulated key resources that lim

AbstractThe mechanistic origin and shape of body‐size distributions within communities are of considerable interest in ecology. A recently proposed light‐limitation model provides a good fit to the distribution of tree sizes in a tropical forest plot. The maximum entropy theory of ecology (METE) als

Summary1. In lentic freshwater habitats, the composition of animal assemblages shifts along a gradient from temporary to permanent basins. When habitats with different degrees of permanence are at the scale of the home range of species, they constitute alternatives in terms of energy acquisition thr

A population of eight juvenile female yellow-bellied marmots was introduced into a marmot locality from which all other marmOTS were removed and the individual behavioral profile of each animal was determined by mirror image stimulation.

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

Larvae of 17 Lycaenidae butterfly species from Europe, North America, South East Asia and Australia were observed to retain at least some of their adaptations related to myrmecophily even after parasitic braconid larvae have emerged from them. The myrmecophilous glandular organs and vibratory muscle

Maria Paniw,1,2* Dylan Z. Natural populations are exposed to seasonal variation in environmental factors that simultane- Childs,3 Kenneth B. Armitage,4 ously affect several demographic rates (survival, development and reproduction). The resulting Daniel T. Blumstein,5,6 Julien covariation in these r

AbstractSulfur (S) is an essential macronutrient and important component of the earth’s crust, and its cycling has critical impacts on trace metal mobility, water quality, and human health. Pyrite weathering is the primary pathway by which sulfur enters surface waters. However, biogeochemical cyclin

It is suggested that basal metabolic rate is not an appropriate measure of the metabolic activity of free-ranging animals because basal metabolism is a stage on a food-deprivation curve.

A district in central Colorado is described in which coals of various ranks occur in a restricted area. Some of these coals have been altered by the intrusion of laccoliths whereas others have been affected only by minor folding. The individual effects of heat and pressure in the development of anth