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隔离的繁殖群体，这些群体通过行为障碍来维持扩散。这种社会介导的对遗传交换的限制被认为是为了增加随机漂移（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分歧，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，独立运作的行为隔离的育种群体内，是足够的规模压倒了遗传交换的种群内和种群之间的遗传效应。本研究的目的是测试这种预测，通过分析自然种群的高度社会性哺乳动物，短鼻果蝠（Cynopterus斯芬克斯），在印度半岛的遗传变异的分布。将根据（2）核基因组编码的基因变异频率和（2）线粒体DNA序列的频率和谱系来评估种群内和种群间的遗传细分程度。社会结构的遗传后果将通过评估遗传变异在三个层次的细分内和之间的分布进行检查：个人，后宫社会群体和地理种群。这种嵌套的层次结构提供了一个框架，研究交配，传播和新的社会群体形成的模式影响人口遗传结构的方式。

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.