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Date of Award


Document Type

Dissertation-ISU Access Only

Degree Name

Doctor of Philosophy (PhD)


School of Biological Sciences

First Advisor

Rachel M. Bowden

Second Advisor

Laura A. Vogel


All jawed vertebrates have innate and adaptive immune responses, and the same major components of these responses, including toll-like receptors, macrophages, complement, T cells, and B cells. However, despite this broad similarity, there is much natural variation in immune responses both within and among taxa. This variation may be explained by the fact that an organism can allocate resources toward different components of its immune system in response to varying pressures. Examples of pressures include environmental changes, reproductive state, or exposure to pathogens. I define an organism's immune strategy as how an organism utilizes its various components of its immune system as a result of such pressures. The goal of my dissertation was to explore the immune strategy of a long-lived ectotherm, the red-eared slider turtle, Trachemys scripta. Specifically, I examined the effects of age, temperature, and steroids on a variety of immune measures in a natural population of sliders. I found evidence for a humoral immune response that relies on innate, natural antibodies rather than adaptive, specific antibodies. I also found little evidence for a decline in humoral immune responses with age when assays were run at a constant temperature. However, B cells from older individuals did respond less to antigen stimulation than B cells from younger turtles when assays were run at higher temperatures. I also found no evidence for an effect of estrogens on the development of the red-eared slider turtle. Overall, my research suggest the red-eared slider uses an immune strategy that relies heavily on innate responses rather than adaptive.


Imported from ProQuest Zimmerman_ilstu_0092E_10088.pdf


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