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.
