Genetic signature of natural selection in first Americans
Genetic signature of natural selection in first Americans
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DOI：
10.1073/pnas.1620541114
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发表时间：
2017-02-28
影响因子：
11.1
通讯作者：
Hunemeier, Tabita
中科院分区：
文献类型：
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作者：
Amorim, Carlos Eduardo G.;Nunes, Kelly;Hunemeier, Tabita
当人类在18，000年前从亚洲向美洲迁移并最终定居在新世界时，他们遇到了一个具有极端气候条件和独特饮食资源的新环境。这些环境和饮食压力可能导致遗传适应的情况下，影响现存的美洲原住民人口的表型变异的潜力。这类事件的一个例子是脂肪酸去饱和酶（FADS）基因的进化，该基因被认为是因努伊特人适应寒冷的格陵兰北极气候和富含蛋白质的饮食而产生的积极选择信号。因为有证据表明，在这个遗传区域存在洲际变异，并有迹象表明其变异体存在正选择，我们决定将因纽特人的发现与其他美洲原住民的数据进行比较。在这里，我们使用几条证据来表明，FADS阳性选择的信号并不局限于北极，而是在整个美洲广泛观察到。生活在如此多样化环境中的种群之间的共同选择特征可能是由于在进入新世界之前，共同祖先种群发生了单一而强烈的地方适应。这些第一批美国人居住在整个大陆，并将这种适应性变体传播到各种环境中。
When humans moved from Asia toward the Americas over 18,000 y ago and eventually peopled the New World they encountered a new environment with extreme climate conditions and distinct dietary resources. These environmental and dietary pressures may have led to instances of genetic adaptation with the potential to influence the phenotypic variation in extant Native American populations. An example of such an event is the evolution of the fatty acid desaturases (FADS) genes, which have been claimed to harbor signals of positive selection in Inuit populations due to adaptation to the cold Greenland Arctic climate and to a proteinrich diet. Because there was evidence of intercontinental variation in this genetic region, with indications of positive selection for its variants, we decided to compare the Inuit findings with other Native American data. Here, we use several lines of evidence to show that the signal of FADS-positive selection is not restricted to the Arctic but instead is broadly observed throughout the Americas. The shared signature of selection among populations living in such a diverse range of environments is likely due to a single and strong instance of local adaptation that took place in the common ancestral population before their entrance into the New World. These first Americans peopled the whole continent and spread this adaptive variant across a diverse set of environments.