Statistical studies on protein polymorphism in natural populations. I. Distribution of single locus heterozygosity.
Statistical studies on protein polymorphism in natural populations. I. Distribution of single locus heterozygosity.
复制标题
自然群体蛋白质多态性的统计研究。
作者：
Paul A. Fuerst;Ranajit Chakraborty;Masatoshi Nei
在查阅文献的基础上，研究了95种脊椎动物和34种无脊椎动物蛋白质位点间单位点杂合性的频率分布，以检验突变漂移假说的有效性。当用Kolmogorov-Smirnov拟合优度统计检验时，这种分布与在突变漂变假设下所期望的任何物种的分布都没有显著差异。观察到的杂合性基因座间方差与其理论期望的吻合也令人满意。有迹象表明，基因座间突变率的变化扩大了杂合性的基因座间变异。对同一同源位点的杂合性在不同种间的变异进行了研究。尽管在某些果蝇种群中存在显著差异，但这种差异总体上与理论值非常吻合。观察到的平均杂合度与多态位点比例的关系与理论关系吻合较好。结果表明，就杂合性的分布模式而言，大多数蛋白质多态性数据符合突变漂移假说。在考察了涉及选择的其他可能的解释之后，得出的结论是，如果不考虑随机遗传漂变的巨大影响，无论是否存在选择，目前的数据都无法充分解释。
Surveying the literature, the frequency distribution of single-locus heterozygosity among protein loci was examined in 95 vertebrate and 34 invertebrate species with the aim of testing the validity of the mutation-drift hypothesis. This distribution did not differ significantly from that expected under the mutation-drift hypothesis for any of the species examined when tested by the Kolmogorov-Smirnov goodness-of-fit statistic. The agreement between the observed interlocus variance of heterozygosity and its theoretical expectation was also satisfactory. There was an indication that variation in the mutation rate among loci inflates the interlocus variance of heterozygosity. The variance of heterozygosity for a homologous locus among different species was also studied. This variance generally agreed with the theoretical value very well, though in some groups of Drosophila species there was a significant discrepancy. The observed relationship between average heterozygosity and the proportion of polymorphic loci was in good agreement with the theoretical relationship. It was concluded that, with respect to the pattern of distribution of heterozygosity, the majority of data on protein polymorphisms are consistent with the mutation-drift hypothesis. After examining alternative possible explanations involving selection, it was concluded that the present data cannot be explained adequately without considering a large effect of random genetic drift, whether there is selection or not.