Date of Award:
Doctor of Philosophy (PhD)
Investing resources into reproduction can limit energy available to other competing demands, such as fighting off an infection; yet, both processes are necessary for organisms to survive and pass on their genes to the next generation. These strategies often follow patterns associated with lifespan, such that shorter-lived animals are more likely to invest more resources into reproduction over survival, and vice versa in long-lived animals. However, environmental change caused by urbanization can disrupt these relationships, and the within- and transgenerational costs of urbanization on females and offspring are unknown. I address these uncertainties in three research chapters to better understand the effects of urbanization on reproductive investment in female Side-blotched Lizards (Uta stansburiana), a small and abundant species of reptile found throughout the western United States. In my second chapter, I examine general variation in female immunity and stress and how it relates to egg number, egg mass, and egg yolk immunity and stress. I found oxidative stress and immunity vary in females depending on how many eggs they produced, and that larger eggs had lower yolk stress levels. I built upon this by examining how metabolism differs across the reproductive cycle and tested whether simulating an infection in females affected immunity, stress, and metabolism. Metabolism was higher at the onset of reproduction and decreased until ovulation, and females differentially responded to infection depending on their stage in the reproductive cycle, which may suggest limited resources underly these findings. In my final chapter, I investigated the impacts of urbanization on female and egg yolk physiology and tested whether simulating infection altered female investment into egg yolk. I found immunity and stress in females and eggs were only apparent in rural females with ectoparasites, but not in urban females and eggs. Fertilization rates were lower in urban populations, which also influenced egg yolk physiology. Differential physiological investment can drastically alter offspring traits; therefore, it is imperative to develop a better understanding of the transgenerational costs of inhabiting an urban environment.
Virgin, Emily E., "Immunological Tradeoffs and the Impacts of Urbanization on the Reproductive Ecology and Physiology of the Side-Blotched Lizard (Uta stansburiana)" (2022). All Graduate Theses and Dissertations. 8666.
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