Why hunter-gatherer populations do not show signs of Pleistocene demographic expansions
Why hunter-gatherer populations do not show signs of Pleistocene demographic expansions
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DOI：
10.1073/pnas.96.19.10597
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发表时间：
1999-09-14
影响因子：
11.1
通讯作者：
Schneider, S
中科院分区：
文献类型：
--
作者：
Excoffier, L;Schneider, S
对62个人类群体样本的线粒体DNA多样性进行了检测，以寻找群体扩张的潜在信号。通过考虑位点间突变率的异质性来估算逐步扩张的时间。假设线粒体DNA每百万年的分歧率为33%，大多数群体在非洲和亚洲约7万年前、美洲约5.5万年前、欧洲和中东约4万年前显示出更新世扩张的信号，而最古老扩张的痕迹在东非发现（图尔卡纳人在11万年前）。两组群体（大多数美洲印第安人群体和现今的狩猎采集者群体）的遗传多样性无法用简单的逐步扩张模型来解释。对61个群体间遗传距离的多变量分析表明，没有经历人口扩张的群体与其他群体的遗传距离增加，这证实了群体的人口统计学特征强烈影响所观察到的遗传亲缘关系。现今狩猎采集者群体中没有更新世扩张的痕迹，这似乎最好用这些群体近期发生过瓶颈效应来解释，这意味着更新世（约180万年前至1万年前）和全新世（1万年前至今）狩猎采集者的人口统计学特征存在差异，这种差异发生在其他群体的新石器时代扩张之后，并且可能是对其的一种反应。
The mitochondrial DNA diversity of 62 human population samples was examined for potential signals of population expansions, Stepwise expansion times were estimated by taking into account heterogeneity of mutation rates among sites. Assuming an mtDNA divergence rate of 33% per million years, most populations show signals of Pleistocene expansions at around 70,000 years (70 KY) ago in Africa and Asia, 55 KY ago in America, and 40 KY ago in Europe and the Middle East, whereas the traces of the oldest expansions are found in East Africa (110 KY ago for the Turkana). The genetic diversity of two groups of populations (most Amerindian populations and present-day hunter-gatherers) cannot be explained by a simple stepwise expansion model. A multivariate analysis of the genetic distances among 61 populations reveals that populations that did not undergo demographic expansions show increased genetic distances from other populations, confirming that the demography of the populations strongly affects observed genetic affinities. The absence of traces of Pleistocene expansions in present-day hunter-gatherers seems best explained by the occurrence of recent bottlenecks in those populations, implying a difference between Pleistocene (approximate to 1,800 KY to 10 KY ago) and Holocene (10 KY to present) hunter-gatherers demographies, a difference that occurred after, and probably in response to, the Neolithic expansions of the other populations.