Doctoral Dissertation: Endocrine-Mediated Evolution of Life History Traits: A Study of Insulin-Like Growth-Factor and Population Divergence in the Garter Snake Thamnophis elegans

这项研究将研究如何从同一祖先种群中进化出遗传上不同的生活史特征的束带蛇Thamnophis elegans种群。 相对于湖岸种群，来自草甸栖息地的蛇表现出较慢的生长速度、较低的年繁殖率和较长的寿命。胰岛素样生长因子-1（IGF-1）是一种激素，主要参与促进生长和生殖，以及缩短寿命。 因此，IGF-1系统的分化可以解释湖岸与草甸种群的生长和繁殖增加和生存减少。这一假设将通过检查野生和实验室中蛇的IGF-1系统的多个水平来进行测试，以便区分环境和遗传效应。 IGF-1属于在进化过程中高度保守的胰岛素样信号分子家族，在脊椎动物和无脊椎动物的生理学中发挥关键作用。因此，这项研究将对动物类群产生重要影响。 此外，它将大大有助于我们对爬行动物生态学、生活史和种群动态的了解，这对成功管理自然种群至关重要，并将增加我们对与人类衰老和健康有关的长寿的生理和遗传决定因素的理解。

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