FRENCH, S.S.*; MOORE, M.C.; Arizona State University; Arizona State University: Immune Function Varies with Reproductive Stage in Female Tree Lizards, Urosaurus ornatus

A major challenge in integrative biology is understanding the mechanisms by which organisms regulate trade-offs among various functions competing for limiting resources. Key among these competing processes are reproduction and immune function, and optimizing both appears to be difficult. To test the hypothesis that the resource demands of reproduction compromise immune function, we measured rates of wound healing, an integrated measure of innate immunity, across different reproductive stages in female tree lizards in both the field and the laboratory. This hypothesis predicts that immune function will be lowest when resource demands of reproduction are highest, i.e., during vitellogenesis. In the field, vitellogenic females indeed had significantly less healed wounds than other females when relocated. However, in the laboratory, vitellogenic females had a healing rate similar to that of other females. The field results support the hypothesis of a trade-off between reproduction and immune function, and suggest that reproduction is given priority. However, the laboratory results indicate that a decrease in immune function is not hard-wired into the reproductive process and that instead it depends in some way on the current resource balance of the individual.