Dissertation Research: Natural and acquired immunity within Yellowstone's wolves: consequences for disease severity, survival, and reproduction

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The immune system plays a critical role in maintaining overall health and keeping parasites at bay. While investment in immune function may improve survival, it may also come at a cost to reproduction, either because of limited resources or an over-reactive immune system attacking the body. Here, the authors aim to explore the evidence for relationships between immune investment, disease severity, survival, and reproduction in a wild population of gray wolves. Gray wolves were reintroduced into Yellowstone National Park in 1995, and within this population, researchers have studied the natural process of parasite infections. This work has shown that individual wolves vary in their response to infection with canine distemper virus and sarcoptic mange, despite the high survival-costs associated with an inability to control infection. None of this variation is explained by host characteristics such as age, sex, and social status. This project will test the hypothesis that a tradeoff between immune function and reproduction explains the maintenance of immune variation among individuals. Several indices of immune investment (natural antibodies, specific antibodies, and total antibodies) will be measured as predictors of disease severity and survival through known disease outbreaks. This information will be matched to reproductive fitness in order to test whether increased immune responsiveness comes at a cost to reproduction. This work will further test the specific prediction that costs to reproduction occur in the form of decreased litter sizes, and that these costs may be offset during disease outbreaks in the form of increased litter survival. Results from this research will improve our understanding of the mechanisms by which variation in immune function is maintained in wildlife populations, which has important applications in conservation biology and wildlife management. The project will build on a rich, long-term public dataset on a wild carnivore being reintroduced to national parks, and will further our understanding of the drivers of an iconic conservation species. Results from this study will be published on a citizen science website, and disseminated via public lectures through the National Park Service and to school groups. This study will also expand the research training and skill sets of a doctoral student.