In this study, we use 12 months of data from 11 ant assemblages to test whether seasonal variation in ant diversity is governed by either the structuring influences of interspecific competition or environmental conditions. Because the importance of competition might vary along environmental gradients, we also test whether the signature of competition depends on elevation. We find little evidence that competition structures the seasonal patterns of activity in the ant assemblages considered, but find support for the effects of temperature on seasonal patterns of diversity, especially at low-elevation sites. Although, in general, both competition and the environment interact to structure ant assemblages, our results suggest that environmental conditions are the primary force structuring the seasonal activity of the ant assemblages studied here.

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Production was estimated (size frequency method) for five species of Hydropsychidae and two species of Philopotamidae at two sites on the impounded North Anna River and two sites on the free-flowing South Anna River. Total production was highest (3250.0 g dry weight (DW)∙ha−1∙year−1 at the site immediately below the dam. At the other sites total production ranged from 94.0 to 515.1 g DW∙ha−1∙year−1. An attempt was made to determine the influence of various factors on production. From an analysis of the trophic dynamics of production, seston energetics, and rates of consumption we conclude that the zooplankton released from the reservoir greatly enriches the seston in a narrow size range (105–864 μm) that corresponds to the size of the zooplankton released from the reservoir and the capture net mesh size of the hydropsychids. The extremely high density of filter feeders below the dam reduces the food quality of the seston and limits production downstream. Ecological interactions also were found to influence production, requiring detailed knowledge of the biology of individual species to understand the dynamics of a system.

Using mitochondrial DNA (mtDNA) restriction analysis and starch‐gel electrophoresis of the CK‐A2 locus product, we examined genetic variation in 311 brook trout (Salvelinus fontinalis) from 11 native, 5 hatchery‐derived, and 8 hybrid populations in the southern Appalachian Mountains. Native southern Appalachian fish were genetically distinct from hatchery‐derived fish. Southern and hatchery‐derived fish were reliably distinguished based on three mtDNA restriction sites. Native southern haplotypes differed from hatchery‐derived haplotypes by an average of 0.84%. Northern hatchery‐derived haplotypes varied little in mtDNA compared to native southern haplotypes. Introgression of mtDNA haplotypes and the CK‐A2 locus varied among populations, and introgression of allozyme and mtDNA markers was positively correlated. Continued introductions of nonnative strains of brook trout in the southern Appalachians could simplify the genetic structure of native brook trout populations and eliminate unique genotypes.

Starch gel electrophoresis was used to examine the protein products of 34 presumptive loci in nine populations of brook trout Salvelinusfontinalis from Great Smoky Mountains National Park and in two brook trout hatchery strains that were derived from northeastern U.S. populations and used extensively for stocking in the southern Appalachian Mountains. Five of the streams sampled had not been stocked and presumably contained only native brook trout. Three other streams contained native populations but also had been stocked, and the remaining stream originally was devoid of natives and presumably contained only introduced brook trout. Mean genetic similarity was high among the native populations (7 = 0.985 ± 0.017 SE) and among the hatcheryderived populations (7 = 0.986 ± 0.003). Mean genetic similarity between the native populations and hatchery stocks was 0.906 ± 0.024. These results are consistent with previous studies suggesting that native brook trout in the southeastern United States are taxonomically distinct from northeastern brook trout. Genotypes at diagnostic loci demonstrate that introgressive hybridization has occurred between hatchery and native trout in all three stocked populations. Average individual heterozygosity was lowest in the native populations (/)Q -0.025), highest in the hatchery stocks (//o = 0.112), and intermediate in the stocked populations (H Q = 0.053).