This research will examine how populations of the garter snake Thamnophis elegans, descended from the same ancestral population, have evolved genetically divergent life history characteristics. Snakes from meadow habitats exhibit slower growth rates, lower annual reproduction, and longer lifespans relative to lakeshore populations. Insulin-like growth factor-1 (IGF-1) is a hormone pivotally involved in promoting growth and reproduction, as well as reducing lifespan. Therefore, a differentiation in the IGF-1 system could account for increased growth and reproduction and reduced survival in lakeshore versus meadow populations. This hypothesis will be tested by examining multiple levels of the IGF-1 system in snakes both in the wild and in the lab, so that environmental and genetic effects can be distinguished.
IGF-1 belongs to a family of insulin-like signaling molecules that have been highly conserved over evolutionary time, and play pivotal roles in both vertebrate and invertebrate physiology. Thus this research will have important ramifications across animal taxa. Furthermore, it will significantly contribute to our knowledge of reptile ecology, life history, and population dynamics, crucial for successful management of natural populations, and will increase our understanding of the physiological and genetic determinants of longevity relevant to concerns of human aging and health
