The Role of Testosterone and Training on Locomotor Performance in a Non-Territorial Lizard
The effects of testosterone (T) on territorial lizards have been studied extensively; however, the effects of T on non-territorial lizards have not. In territorial lizards, T has been suggested as a possible mediator of seasonal increases in whole-animal performance capacities (i.e. sprint speed and bite force), which are important factors in maintaining territories and winning male-male competitions. Previous work in our lab has shown that in Aspidoscelis sexlineata, a common non-territorial lizard, bite force, locomotor performance (measured as the max. time until exhaustion), and T are each greatest during the breeding season; thereby suggesting that T also mediates seasonal increases in performance for this species. Furthermore, T implants have been shown to successfully elevate circulating T levels in A. sexlineata. However, the T implants failed to increase whole-animal performance capacities, and hence suggest a training effect. The current study will test the effects of training on locomotor performance capacities and morphology (i.e. locomotor muscle size & composition). Thirty adult male A. sexlineata were assigned to one of three treatment groups: T implant + training, empty implant + training, and empty implant without training. Training consisted of 3 performance measures: treadmill endurance, burst speed, and maximal exertion. At the end of the study, changes in muscle size, muscle fiber size, or fiber-type composition were assessed for multiple hindlimb muscles using histochemical analyses to determine the influence of treatment group (T, training regime). This research will further isolate the role of T and training on the morphological factors affecting seasonal locomotor performance in non-territorial species.
Society for Integrative and Comparative Biology Annual Meeting (SICB)
O'Conner, Jennifer L., Lance D. McBrayer, Timothy E. Higham, David C. Rostal.
"The Role of Testosterone and Training on Locomotor Performance in a Non-Territorial Lizard."
Biology Faculty Presentations.