Jeong Choongwon, Alkorta-Aranburu Gorka, Basnyat Buddha, Neupane Maniraj, Witonsky David B, Pritchard Jonathan K, Beall Cynthia M, Di Rienzo Anna
Department of Human Genetics, University of Chicago, Chicago, Illinois 60637, USA.
Oxford University Clinical Research Unit, Patan Hospital, Lal Durbar marg, GPO Box 3596, Kathmandu, Nepal.
Nat Commun. 2014;5:3281. doi: 10.1038/ncomms4281.
Admixture is recognized as a widespread feature of human populations, renewing interest in the possibility that genetic exchange can facilitate adaptations to new environments. Studies of Tibetans revealed candidates for high-altitude adaptations in the EGLN1 and EPAS1 genes, associated with lower haemoglobin concentration. However, the history of these variants or that of Tibetans remains poorly understood. Here we analyse genotype data for the Nepalese Sherpa, and find that Tibetans are a mixture of ancestral populations related to the Sherpa and Han Chinese. EGLN1 and EPAS1 genes show a striking enrichment of high-altitude ancestry in the Tibetan genome, indicating that migrants from low altitude acquired adaptive alleles from the highlanders. Accordingly, the Sherpa and Tibetans share adaptive haemoglobin traits. This admixture-mediated adaptation shares important features with adaptive introgression. Therefore, we identify a novel mechanism, beyond selection on new mutations or on standing variation, through which populations can adapt to local environments.
基因混合被认为是人类群体的一个普遍特征，这重新引发了人们对基因交换是否能够促进对新环境适应的兴趣。对藏族人的研究揭示了与较低血红蛋白浓度相关的EGLN1和EPAS1基因中高海拔适应的候选基因。然而，这些变异的历史或藏族人的历史仍然知之甚少。在这里，我们分析了尼泊尔夏尔巴人的基因型数据，发现藏族人是与夏尔巴人和汉族相关的祖先群体的混合体。EGLN1和EPAS1基因在藏族基因组中显示出高海拔祖先的显著富集，表明来自低海拔的移民从高海拔人群中获得了适应性等位基因。因此，夏尔巴人和藏族人具有共同的适应性血红蛋白特征。这种混合介导的适应与适应性基因渗入具有重要的共同特征。因此，我们确定了一种新的机制，超越了对新突变或现有变异的选择，通过这种机制，群体可以适应当地环境。
