Meeting Abstract

141.1  Monday, Jan. 7  Plasticity and evolution of stress response networks in divergent life-history phenotypes SCHWARTZ, TS*; BRONIKOWSKI, AM; Iowa State University; Iowa State University schwartz@iastate.edu

The complex molecular network that underlies physiological stress response is comprised of nodes (proteins, metabolites, mRNAs) whose connections span cells, tissues, and organs. Variable nodes are points in the network upon which natural selection may act. Our aim is to identify variable nodes that will reveal how the molecular stress network may evolve among populations, and how it might impact life-history evolution. We utilize natural populations of garter snakes (Thamnophis elegans) that have diverged along the pace-of-life continuum; the slow-living phenotype has slower growth, smaller reproductive bouts, and extended median lifespan relative to the fast-living phenotype. We take a multifaceted approach to test whether these phenotypes vary concomitantly at candidate nodes of the stress response network under unstressed and induced-stress conditions. In response to heat stress, some measures increased in both life-history phenotypes: plasma corticosterone; State III mitochondrial respiration; expression of heat shock proteins; and transcription of mitochondrial rRNAs. As well, the phenotypes diverged at multiple nodes: overall mitochondrial transcription; State IV mitochondrial respiration; circulating levels of ROS; and DNA damage. Additionally, mitochondrial haplotypes were unique to each phenotype. Our results indicate these evolutionarily divergent life-history phenotypes have diverged in their molecular stress response networks; and we identified specific nodes involved in oxidative stress and mitochondrial function at which selection appears to be acting. Further, these results support the prediction of tightly integrated molecular interactions between stress networks and life-history traits.