BRONIKOWSKI, Anne M.*; BRUNET-ROSSINNI, Anja K.; ARNOLD, Stevan J.; Iowa State University; University of Wisconsin, LaCrosse; Oregon State University: Physiological evolution and aging in garter snakes

A primary theory on the evolution of senescence purports that different rates of aging may have evolved as part of a suite of co-evolved life-history traits involving trade-offs in energy allocation. Specifically, energy allocated to early growth and reproduction results in less energy for somatic maintenance and repair. Thus response to stresses, whether external or internally derived is less efficient in organisms that divert energy to other functions. Natural populations of garter snakes are the study subjects for this evolutionary ecological study of aging as it relates to oxidative stress. The garter snakes in this study are either fast growers or slow growers; this difference in growth phenotype is due to genetic differences between the two phenotypes. Slow growers have resultant long lifespan (median lifespan = 8 years); fast growers have shortened lifespan (median = 3 years). Mitochondrial oxygen consumption, P:O ratios, and H2O2 production are compared between the two phenotypes to test the hypothesis that differences in metabolism and free radical production result from different mitochondrial efficiency between the two genotypes.