Meeting Abstract
Life history trade-offs result from differential allocation of acquired energetic resources to phenotypic traits. In adults this often manifests as a trade-off between traits promoting survival versus current reproduction. However, the nature of trade-offs may be age-specific, and this age-specificity may be sex-specific. We determined how several life-history traits that are key to survival and future reproduction trade off in juvenile green anole (Anolis carolinensis) lizards. Specifically, we examined trade-offs among locomotor performance (endurance), growth, and immune function. Previous work on adult green anoles showed that forced allocation to performance, via endurance training, resulted in dramatic performance enhancement but at the cost of decreased immune function. Training enhanced growth. There were also sex differences, with females having a stronger response to training but lower immune responses. We extended this approach to juveniles where resource allocation priorities should be different. Most resources should be allocated to growth, especially for males, and little to reproduction, but survival-enhancing traits should also be important. Captive male and female green anole lizards were either endurance trained on a treadmill or exposed to handling stress over the course of nine weeks. We measured endurance capacity, growth, and immune function (bacterial killing capacity of plasma and swelling response to phytohemagglutinin) at the end of the experiment to determine the nature of trade-offs. We also examined whether trade-offs and allocation priorities were similar to those seen in adults, testing which trait(s) took priority over others and whether there were sex differences in trade-offs or priorities.
