<p> Individual variation and fitness are the cornerstones of evolution by natural selection. The trophic niche represents an important source of phenotypic variation on which natural selection can act. Although individual variation is fundamental to species-level ecological and evolutionary change, individual variation is often ignored in population-level approaches to wildlife ecology, conservation and management. Failing to link individual resource use to fitness or to biological outcomes related to fitness limits us to managing for the average resource needs of a population, which may be insufficient for protecting the diversity of resource use within populations and the underlying eco-evolutionary processes that generate that diversity. My goals were to provide insights into the mechanisms that generate and constrain intrapopulation trophic niche variation, evaluate whether linkages exist between individual biological outcomes and variation in food habits across the range of resources consumed within generalist consumer populations and examine how that variation manifests in population-level responses. </p><p> I investigated the causes and physiological consequences of intrapopulation trophic niche variation in two generalist consumers, the American black bear (<i>Ursus americanus</i>) and brown bear (<i>U. arctos</i>) across three sites in British Columbia, CAN and at one site in Alaska, USA. My primary tools included stable isotope analysis to estimate diet, enzyme-linked immunoassay of hair to quantify the hormone cortisol for indexing physiological stress, and genetic analyses to identify individuals, species, and sex and to estimate ancestry. I found that individual differences in resource use can result in similar biological outcomes and that similar resource use can result in different biological outcomes. Intra- and interspecific competition, sex-based differences in nutritional and social constraints and annual variation in food availability all influenced trophic niche variation and the resultant biological outcomes. I also found evidence of a link between intrapopulation trophic niche variation and population genetic structure. My results highlight the diverse ecological drivers and diverse consequences of trophic niche variation, which further illuminates why the trophic niche is a nexus for eco-evolutionary dynamics.</p>

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Thesis (Ph. D. - Renewable Natural Resources)--University of Arizona, 1980. / Includes bibliographical references.

Thesis (Ph.D.)--Tufts University, 2003. / Director: J. Michael Reed. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 97-114). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1991. / Includes bibliographical references (leaves 75-86).

Thesis (Ph.D.)--Murdoch University, 2007. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 237-261.

Thesis (Ph.D.) - James Cook University, 2007. / Typescript (photocopy) Bibliography: leaves 340-376.

Thesis (M.S.)--Oregon State University, 1999. / Typescript (photocopy). Includes bibliographical references (leaves 61-69). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Michigan, 1942. / Cover title. "Literature cited": p. 118-121.