Dissertation Research: Evolution in Socially-Structured Populations

9701057 Kunz群居哺乳动物的种群通常被细分为半孤立的繁殖群体，这些群体通过行为障碍来维持传播。有人提出，这种社会介导的基因交换限制增加了随机漂变（基因变异频率从一代到下一代的偶然波动）和繁殖群体之间的遗传分化的幅度，从而提高了进化变化的速度。根据这一假设，随机漂移的多样化影响，在行为隔离的繁殖群体中独立运作，足以压倒群体内部和群体之间遗传交换的同质化效应。本研究的目的是通过分析印度半岛高度社会化哺乳动物短鼻果蝠（Cynopterus sphinx）自然种群的遗传变异分布来验证这一预测。种群内部和种群之间的遗传细分程度将根据(2)核基因组编码的基因变异的频率和(2)线粒体DNA序列的频率和谱系来评估。社会结构的遗传后果将通过评估遗传变异的分布内部和之间的三个等级细分：个人，后宫社会群体和地理种群。这种嵌套的层次结构为研究交配、分散和新社会群体形成模式对种群遗传结构的影响提供了一个框架。

9701057 Kunz Populations of social mammals typically are subdivided into semi-isolated breeding groups maintained by behavioral impediments to dispersal. Such socially-mediated constraints on genetic exchange have been proposed to increase the magnitude of random drift (chance fluctuations in the frequencies of gene variants from one generation to the next) and genetic divergence among breeding groups, thereby enhancing rates of evolutionary change. According to this hypothesis, the diversifying influence of random drift, operating independently within behaviorally-segregated breeding groups, is of sufficient magnitude to overpower the homogenizing effect of genetic exchange within and among populations. The objective of the present study is to test this prediction by analyzing the distribution of genetic variation in natural populations of a highly social mammal, the short nosed fruit bat (Cynopterus sphinx), in peninsular India. The degree of genetic subdivision within and among populations will be assessed in terms of (2) the frequencies of gene variants encoded by the nuclear genome and (2) the frequencies and genealogies of mitochondrial DNA sequences. The genetic consequences of social structure will be examined by assessing the distribution of genetic variation within and among three levels of hierarchical subdivision: individuals, harem social groups, and geographic populations. This nested hierarchy provides a framework for examining the way in which patterns of mating, dispersal, and new social group formation influence population-genetic structure.