Evidence that two main bottleneck events shaped modern human genetic diversity
Evidence that two main bottleneck events shaped modern human genetic diversity
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DOI：
10.1098/rspb.2009.1473
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发表时间：
2010-01-07
影响因子：
4.7
通讯作者：
Hoffman, J. I.
中科院分区：
文献类型：
--
作者：
Amos, W.;Hoffman, J. I.
有一个强烈的共识，即现代人类起源于非洲，并在大约5万年前移居到世界各地。在扩展过程中，变异性消失了，形成了随着离非洲距离的增加而减少的线性梯度。然而，这一损失发生的确切方式仍然有些不清楚：它是否涉及一个、几个或一系列连续的人口瓶颈？我们解决了这个问题，通过分析一个大型的数据集发表的783个微卫星位点基因分型在53个世界各地的人口，使用程序'BOTTLENeck'。在种群数量急剧下降之后，稀有等位基因的丢失速度比杂合性更快，造成相对于等位基因数量的杂合性短暂过剩，这是BOTTLENECK用来推断历史事件的特征。我们发现了两个主要事件的证据，一个是“走出非洲”，另一个是在白令海峡附近，那里有一座古老的陆桥，可以通往美洲。这些发现与世界上最大的创始人事件可能已经预期的地区一致，但与当前杂合性与非洲距离作图时所揭示的明显平滑的变异梯度形成对比。
There is a strong consensus that modern humans originated in Africa and moved out to colonize the world approximately 50 000 years ago. During the process of expansion, variability was lost, creating a linear gradient of decreasing diversity with increasing distance from Africa. However, the exact way in which this loss occurred remains somewhat unclear: did it involve one, a few or a continuous series of population bottlenecks? We addressed this by analysing a large published dataset of 783 microsatellite loci genotyped in 53 worldwide populations, using the program 'BOTTLENECK'. Immediately following a sharp population decline, rare alleles are lost faster than heterozygosity, creating a transient excess of heterozygosity relative to allele number, a feature that is used by BOTTLENECK to infer historical events. We find evidence of two primary events, one 'out of Africa' and one placed around the Bering Strait, where an ancient land bridge allowed passage into the Americas. These findings agree well with the regions of the world where the largest founder events might have been expected, but contrast with the apparently smooth gradient of variability that is revealed when current heterozygosity is plotted against distance from Africa.