Dissertation Research: Evolution in Socially-Structured Populations

9701057种群居哺乳动物通常被细分为半隔离的繁殖群体，由行为障碍维持扩散。这种社会中介的对遗传交换的限制已经被提出，以增加随机漂移的幅度(基因变异频率从一代到下一代的随机波动)和育种群体之间的遗传差异，从而提高进化变化的速度。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内独立运行，具有足够的规模，足以压倒种群内和种群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上一种高度社会化的哺乳动物--短鼻果蝠(Cynopterus Shinx)在自然种群中的遗传变异分布，来验证这一预测。种群内和种群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在三个等级细分的内部和之间的分布来检验：个人、后宫社会群体和地理人口。这种嵌套的层次结构为研究交配、扩散和新的社会群体形成模式影响种群遗传结构的方式提供了一个框架。

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.