Pollinator-mediated reproductive isolation is often a principal factor in determining the rate of hybridization between plant species. Pollinator preference and constancy can reduce interspecific pollen transfer between otherwise interfertile, coflowering species. The importance of this ethological

Despite extensive study of pollination and plant reproduction on the one hand, and of plant demography on the other, we know remarkably little about links between seed production in successive generations, and hence about long-term population consequences of variation in pollination success. We brid

It is suggested that nectar with low alkaloid concentrations may be beneficial to plant fitness by limiting adverse effects on pollinator activity and optimal defense theory.

Many animals have the potential to discriminate nonspectral colors. For humans, purple is the clearest example of a nonspectral color. It is perceived when two color cone types in the retina (blue and red) with nonadjacent spectral sensitivity curves are predominantly stimulated. Purple is considere

It is argued that as an alternative to analyzing the species composition of whole insect communities, focusing on variation in the composition of behavioral trait groups is likely to provide increased understanding of how stream insect communities are assembled, thereby linking behavioral, populatio

Gut contents of 1,463 stonefly nymphs, comprising 10 species, from the Gunnison River, Colorado, were analyzed from Dec., 1974–Oct., 1975, in relation to food availability. Pteronarcella badia fed primarily on detritus and moss. Perlidae and Perlodidae mature nymphs were all carnivorous, but showed

The success of the butterfly simulator in mimicking Colias thermal characteristics confirms the preliminary understanding of the physical bases for and heat transfer mechanisms underlying thermoregulatory adaptations in these butterflies.

Individuals within natural populations can experience very different abiotic and biotic conditions across small spatial scales owing to microtopography and other micro-environmental gradients. Ecological and evolutionary studies often ignore the effects of micro-environment on plant population and c

Apparent random spatial heterogeneity is expected if gene flow is extensive enough to prevent a rapid decline in genetic correlation with distance; it also might be promoted by a leapfrog pattern of gene flow.

The preference–performance hypothesis predicts that when female herbivorous insects determine where to position offspring of low mobility, they will select sites that maximize development and survival of those offspring. How this critical relationship responds to variation in climatic and habitat co

Weasels were determined to be more effective predators of pikas than martens, and these asymmetries in behavior and alarm vocalizations may indicate that responses reduce an individual's risk of predaton by weasels.

Play has been defined as apparently functionless behaviour, yet since play is costly, models of adaptive evolution predict that it should have some beneficial function (or functions) that outweigh its costs. We provide strong evidence for a long-standing, but poorly supported hypothesis: that early

The data support either the view that the D. pulex species group is one widespread and variable species, or that it is comprised of a much larger number of species than presently recognized.

Pre-Potosi volcanic rocks

Anaerobic methane oxidation exerts a key control on greenhouse gas emissions 1 , yet factors that modulate the activity of microorganisms performing this function remain poorly understood. Here we discovered extraordinarily large, diverse DNA sequences that primarily encode hypothetical proteins thr

Abstract and SummaryAdult spatial relationships and social organization in a marked population of alpine mammals, the pika (Ochotona princeps), were studied over a 3‐year period in the Rocky Mountains of Colorado. Home range size, distances between centers of activity of dyads, and weighted overlaps

1. In streams, mayflies (Order Ephemeroptera) are at risk from fish feeding visually in the water column. The effect of fish odour on the behaviour of Baetis bicaudatus from a fishless stream and a trout stream was investigated in four large oval tanks supplied with water from the fishless stream.2.

Dispersal affects a wide array of ecological and evolutionary processes, but has been difficult to estimate empirically. A 15 Nitrogen stable isotope enrichment technique was used to passively mark all developing Callibaetis ferrugineus hageni (Eaton) mayfly larvae in a beaver pond that had previous

Drift collections from a Rocky Mountain stream were used to examine the hypothesis that, because risk of predation by fish is greatest for large individuals during the day, aquatic insects should become increasingly nocturnal in their drift periodicity as they grow in size. Seven taxa common in the