Dataset Information

Differentiated demographic histories and local adaptations between Sherpas and Tibetans.

ABSTRACT: The genetic relationships reported by recent studies between Sherpas and Tibetans are controversial. To gain insights into the population history and the genetic basis of high-altitude adaptation of the two groups, we analyzed genome-wide data in 111 Sherpas (Tibet and Nepal) and 177 Tibetans (Tibet and Qinghai), together with available data from present-day human populations.Sherpas and Tibetans show considerable genetic differences and can be distinguished as two distinct groups, even though the divergence between them (~3200-11,300 years ago) is much later than that between Han Chinese and either of the two groups (~6200-16,000 years ago). Sub-population structures exist in both Sherpas and Tibetans, corresponding to geographical or linguistic groups. Differentiation of genetic variants between Sherpas and Tibetans associated with adaptation to either high-altitude or ultraviolet radiation were identified and validated by genotyping additional Sherpa and Tibetan samples.Our analyses indicate that both Sherpas and Tibetans are admixed populations, but the findings do not support the previous hypothesis that Tibetans derive their ancestry from Sherpas and Han Chinese. Compared to Tibetans, Sherpas show higher levels of South Asian ancestry, while Tibetans show higher levels of East Asian and Central Asian/Siberian ancestry. We propose a new model to elucidate the differentiated demographic histories and local adaptations of Sherpas and Tibetans.

SUBMITTER: Zhang C

PROVIDER: S-EPMC5472941 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Differentiated demographic histories and local adaptations between Sherpas and Tibetans.

Zhang Chao C Lu Yan Y Feng Qidi Q Wang Xiaoji X Lou Haiyi H Liu Jiaojiao J Ning Zhilin Z Yuan Kai K Wang Yuchen Y Zhou Ying Y Deng Lian L Liu Lijun L Yang Yajun Y Li Shilin S Ma Lifeng L Zhang Zhiying Z Jin Li L Su Bing B Kang Longli L Xu Shuhua S

Genome biology 20170615 1

<h4>Background</h4>The genetic relationships reported by recent studies between Sherpas and Tibetans are controversial. To gain insights into the population history and the genetic basis of high-altitude adaptation of the two groups, we analyzed genome-wide data in 111 Sherpas (Tibet and Nepal) and 177 Tibetans (Tibet and Qinghai), together with available data from present-day human populations.<h4>Results</h4>Sherpas and Tibetans show considerable genetic differences and can be distinguished as ...[more]

PMID: 28619099

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Project description:BackgroundRevealing the past and present demographic history of populations is of high importance to evaluate the conservation status of species. Demographic data can be obtained by direct monitoring or by analysing data of historical and recent collections. Although these methods provide the most detailed information they are very time consuming. Another alternative way is to make use of the information accumulated in the species' DNA over its history. Recent development of the coalescent theory makes it possible to reconstruct the demographic history of species using nucleotide polymorphism data. To separate the effect of natural selection and demography, multilocus analysis is needed because these two forces can produce similar patterns of polymorphisms. In this study we investigated the amount and pattern of sequence variability of a Europe wide sample set of two peat moss species (Sphagnum fimbriatum and S. squarrosum) with similar distributions and mating systems but presumably contrasting historical demographies using 3 regions of the nuclear genome (appr. 3000 bps). We aimed to draw inferences concerning demographic, and phylogeographic histories of the species.ResultsAll three nuclear regions supported the presence of an Atlantic and Non-Atlantic clade of S. fimbriatum suggesting glacial survival of the species along the Atlantic coast of Europe. Contrarily, S. squarrosum haplotypes showed three clades but no geographic structure at all. Maximum likelihood, mismatch and Bayesian analyses supported a severe historical bottleneck and a relatively recent demographic expansion of the Non-Atlantic clade of S. fimbriatum, whereas size of S. squarrosum populations has probably decreased in the past. Species wide molecular diversity of the two species was nearly the same with an excess of replacement mutations in S. fimbriatum. Similar levels of molecular diversity, contrasting phylogeographic patterns and excess of replacement mutations in S. fimbriatum compared to S. squarrosum mirror unexpected differences in the demography and population history of the species.ConclusionThis study represents the first detailed European wide phylodemographic investigation on bryophytes and shows how pattern of nucleotide polymorphism can reveal unexpected differences in the population history of haploid plants with seemingly similar characteristics.

Dataset Information

Differentiated demographic histories and local adaptations between Sherpas and Tibetans.

Publications

Differentiated demographic histories and local adaptations between Sherpas and Tibetans.

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