FRENCH, S. S.*; MOORE, M. C.; Arizona State University; Arizona State University: Immune and Reproductive Systems Compete for Resources in Female Tree Lizards (Urosaurus ornatus)

When resources are scarce, organisms are faced with critical challenges trying to optimize competing vital functions. Key among these competing processes are reproduction and immune function. However, few studies have directly demonstrated competition for resources between these two processes. We performed a series of experiments in female tree lizards (Urosaurus ornatus), which demonstrated that resource availability drives the trade-off between the reproductive and immune systems. We found that animals on ad libitum food were able to sustain both reproduction and immune function whereas animals maintained on a restricted, maintenance diet were not. Specifically, food restricted animals forced to invest in reproduction via FSH injections showed a decreased immune response and food restricted animals forced to mount an immune response showed decreased reproductive investment. These experiments clearly demonstrate resource competition between reproduction and immune function. They further emphasize how resource availability can affect life-history trade-offs.