Date of Award:
Doctor of Philosophy (PhD)
Susannah S. French
Survival is a prerequisite for successful reproduction, and is thus intertwined with fitness. Some physiological systems can improve survival, like the immune system, but compete with other processes for resources. Because animals evolved with resource limitation, it is important to understand how these resource-allocation decisions are made. To meet this end, I performed four investigations addressing how life-history characteristics shift in side-blotched lizards (Uta stansburiana) using laboratory studies and multi-year field sampling. First, I measured metabolic rates in response to different immune challenges and different energy states in male lizards. I found that, surprisingly, cutaneous biopsies were associated with a downregulation of metabolic rate, lipopolysaccharide injection did not affect metabolic rate, and the fastest-healing individuals had the largest decrease in metabolic rate, regardless of feeding treatment. In my second experiment, female lizards were challenged with a cutaneous biopsy and follicle-stimulating hormone to force a trade-off between the reproductive and immune systems. I learned that follicle-stimulating hormone increased metabolic rates and cutaneous biopsies decreased them, and that a combination of both treatments reduced metabolic rate the most. In my third experiment, I sampled wild lizards from northern populations in eastern Oregon and southern populations in southern Utah. In the first year, longer-lived northern lizards had higher circulating corticosterone concentration, decreased reproductive investment, and increased microbiocidal ability, but the subsequent year did not hold to these trends. A subsequent common-garden experiment revealed that southern lizards were faster at healing cutaneous wounds, but lost much more body mass than the northern individuals, which healed more slowly but maintained body mass. Finally, I have conducted a 5-year field investigation addressing the life-history trade-offs associated with urbanization, which reveals interesting effects of precipitation on survival and reproductive effort at urban and rural sites.
Smith, Geoffrey David Stuart, "Natural and Anthropogenic Effects on Life History Characteristics in the Side-blotched Lizard (Uta stansburiana)" (2017). All Graduate Theses and Dissertations. 6624.
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