Date of Award

Spring 5-1-2016

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Shawn McKinney

Second Committee Member

Cynthia Loftin

Third Committee Member

Jacquelyn L. Gill

Additional Committee Members

Malcolm L. Hunter, Jr

Abstract

Common species are fundamental to the structure and function of their communities, and they may enhance community stability through intraspecific functional diversity. We measured d15N and d13C stable isotope signatures of two common small mammal species to determine whether intraspecific functional diversity was evident in their diet and whether this intraspecific functional diversity enhanced population stability. Deer mouse (Peromyscus maniculatus) diet reflected the influence of external filters (e.g., climate), which decrease trait variation, and internal filters (e.g., competition), which increase trait variation. In contrast, Southern Red-backed Vole, (Myodes gapperi) diet reflected only internal filters. Peromyscus maniculatus relative abundance differed significantly between years, as did the overall small mammal community in deciduous forest where they were most abundant. Myodes gapperi relative abundance was stable, as was the small mammal community in coniferous forest where they were most abundant. Species responding to internal filters have greater intraspecific functional diversity, contributing to population stability relative to sympatric species responding to external filters. Common species with high intraspecific functional diversity may stabilize their communities. Factors affecting the abundance of common species will disproportionately affect community structure, so understanding the ecological trajectory of those species is important for conservation planning. We evaluated factors driving the abundance of three common small mammal species (Woodland Jumping Mouse, Napaeozapus insignis; M. gapperi; P. maniculatus) sampled at multiple sites along 1,000 m elevational gradients in the northern Appalachian Mountains, USA. We tested five hypotheses of small mammal abundance: climate, food, interspecific interactions, macro-, and micro-habitat structure. Generalized linear models indicated that food and, to a lesser extent, macro-habitat structure, drove the abundance of each species. We tested the average top model of each species’ abundance and tested its ability to predict independent data; accuracy varied uniquely by species and habitat, and decreased as observed abundance increased. Species respond individualistically to climate change; unique food and habitat structure needs may represent a common mechanism driving those changes. Community evenness, largely a function of core species abundance, may provide a sensitive measure of ecological change, and understanding the drivers of abundance may help predict species’ responses to climate change.

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