Bowcock A M, Kidd J R, Mountain J L, Hebert J M, Carotenuto L, Kidd K K, Cavalli-Sforza L L
Department of Genetics, Stanford University, CA 94305.
Proc Natl Acad Sci U S A. 1991 Feb 1;88(3):839-43. doi: 10.1073/pnas.88.3.839.
Accuracy of evolutionary analysis of populations within a species requires the testing of a large number of genetic polymorphisms belonging to many loci. We report here a reconstruction of human differentiation based on 100 DNA polymorphisms tested in five populations from four continents. The results agree with earlier conclusions based on other classes of genetic markers but reveal that Europeans do not fit a simple model of independently evolving populations with equal evolutionary rates. Evolutionary models involving early admixture are compatible with the data. Taking one such model into account, we examined through simulation whether random genetic drift alone might explain the variation among gene frequencies across populations and genes. A measure of variation among populations was calculated for each polymorphism, and its distribution for the 100 polymorphisms was compared with that expected for a drift-only hypothesis. At least two-thirds of the polymorphisms appear to be selectively neutral, but there are significant deviations at the two ends of the observed distribution of the measure of variation: a slight excess of polymorphisms with low variation and a greater excess with high variation. This indicates that a few DNA polymorphisms are affected by natural selection, rarely heterotic, and more often disruptive, while most are selectively neutral.
对一个物种内的种群进行进化分析的准确性，需要检测属于多个基因座的大量遗传多态性。我们在此报告基于在来自四大洲的五个种群中检测的100个DNA多态性对人类分化的重构。结果与基于其他类遗传标记的早期结论一致，但揭示出欧洲人并不符合具有相等进化速率的独立进化种群的简单模型。涉及早期混合的进化模型与数据相符。考虑到这样一个模型，我们通过模拟研究了仅随机遗传漂变是否可能解释不同种群和基因间基因频率的差异。针对每个多态性计算了种群间差异的一个度量，并将其在100个多态性中的分布与仅漂变假说预期的分布进行了比较。至少三分之二的多态性似乎是选择中性的，但在差异度量的观察分布两端存在显著偏差：变异低的多态性略有过量，变异高的多态性过量更多。这表明少数DNA多态性受自然选择影响，很少是杂种优势的，且更常是破坏的（注：原文disruptive此处翻译可能不准确，需结合更多专业知识确定更准确含义），而大多数是选择中性的。
