Keinan Alon, Mullikin James C, Patterson Nick, Reich David
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Nat Genet. 2009 Jan;41(1):66-70. doi: 10.1038/ng.303. Epub 2008 Dec 21.
Comparisons of chromosome X and the autosomes can illuminate differences in the histories of males and females as well as shed light on the forces of natural selection. We compared the patterns of variation in these parts of the genome using two datasets that we assembled for this study that are both genomic in scale. Three independent analyses show that around the time of the dispersal of modern humans out of Africa, chromosome X experienced much more genetic drift than is expected from the pattern on the autosomes. This is not predicted by known episodes of demographic history, and we found no similar patterns associated with the dispersals into East Asia and Europe. We conclude that a sex-biased process that reduced the female effective population size, or an episode of natural selection unusually affecting chromosome X, was associated with the founding of non-African populations.
对X染色体和常染色体的比较能够阐明男性和女性历史的差异，同时也有助于揭示自然选择的力量。我们使用为这项研究收集的两个基因组规模的数据集，比较了基因组这些部分的变异模式。三项独立分析表明，在现代人类走出非洲之时，X染色体经历的遗传漂变比常染色体模式预期的要多得多。这并非已知人口历史事件所能预测，而且我们没有发现与向东亚和欧洲迁徙相关的类似模式。我们得出结论，一个降低女性有效种群大小的性别偏向过程，或者一个异常影响X染色体的自然选择事件，与非洲以外人群的形成有关。
