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One of Darwin’s (1859) greatest insights was recognizing that species were not homogeneous units of ecologically equivalent individuals but conspecifics that differ in traits such as sex, age, morphology, physiology and behavior and that these among-individual differences provide the substrate on which natural selection can act. In this time of unprecedented global change, understanding variation in behavior and resource use among individuals within populations of conservation and management concern is fundamental for safeguarding the critical resources diverse individuals need for responding to environmental change. In collaboration with multiple state and federal agencies, The WECOS Lab is using stable isotope analyses in combination with behavioral, physiological, hormonal, reproductive, and survival data to examine how intraspecific differences in resource use impact the health and fitness of wildlife across dynamic ecosystems.


The American marten (Martes americana) is a species of cultural significance to Indigenous people across much of North America and as a species sensitive to forest perturbations, serves as an indicator species of forest ecosystem health. Historically, American marten were one of the most valuable furbearer species across much of North America, although overexploitation and habitat loss due to forest exploitation resulted in American marten being listed as threatened across much of their North American range. Across Alaska, however, American marten populations have historically and continue to occur at densities that permit a substantial annual harvest. As such, The WECOS Lab is collaborating with Alaska Department of Fish and Game to take advantage of the annual American marten harvest to collect tissue samples, sex and reproductive data from legally harvested animals. With more than 10 years of American marten samples, we are using stable isotope analyses and niche modeling to examine spatial and temporal variation in American marten diet, body condition, and reproduction and whether among-individual variation in trophic niche relates to changes in environmental conditions over time (e.g., climate, forest management practices). Our finding will be used by wildlife managers to make science-informed decisions regarding future harvest management. 

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Wildlife populations that occur across spatially and temporally dynamic environments are thought to exhibit substantial among-individual ecological plasticity and phenotypic variation. A relatively ubiquitous manifestation of among-individual ecological plasticity is variation in behavior, particularly foraging behavior. The niche variation hypothesis (Van Valen 1965) posits that populations with greater niche breadths should display higher levels of among-individual phenotypic and behavioral variation and that behaviorally flexible individuals should have an adaptive advantage over individuals that are less plastic. As such, ecologically flexible individuals should be able to meet their energetic needs by exploiting underutilized resources, thereby reducing competition among conspecifics without sacrificing their fitness. Over the past 20 years, ecologists have provided overwhelming evidence that many wildlife populations are comprised of individuals that exist across a foraging gradient that ranges from generalist to specialist consumers. While foraging plasticity within diverse species is now well-documented, the integration of this knowledge into wildlife management and policy has been limited. However, by ignoring among-individual variation in food resource use, we run the risk of ignoring “unique” segments of the population and the underlying eco-evolutionary processes that maintain that variation, which is critical to ensure populations are comprised of diverse individuals that can effectively respond to environmental change. Using brown bears (Ursus arctos) and black bears (U. amerianus) as ecological models and stable isotope analysis as an investigative tool, The WECOS Lab collaborates with state and federal partners to quantify among-individual trophic niche variation to help shape wildlife and habitat management to ensure these culturally, ecologically, and economically important species have the full range of resources they need for responding to human-mediated environmental change. 

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