Adaptations to Climate-Mediated Selective Pressures in Humans

Humans inhabit a remarkably diverse range of environments, and adaptation through natural selection has likely played a central role in the capacity to survive and thrive in extreme climates. Unlike numerous studies that used only population genetic data to search for evidence of selection, here we scan the human genome for selection signals by identifying the SNPs with the strongest correlations between allele frequencies and climate across 61 worldwide populations. We find a striking enrichment of genic and nonsynonymous SNPs relative to non-genic SNPs among those that are strongly correlated with these climate variables. Among the most extreme signals, several overlap with those from GWAS, including SNPs associated with pigmentation and autoimmune diseases. Further, we find an enrichment of strong signals in gene sets related to UV radiation, infection and immunity, and cancer. Our results imply that adaptations to climate shaped the spatial distribution of variation in humans.人类生存于极为多样的环境之中，经由自然选择的适应性演化，极有可能在人类适应极端气候、实现存续与繁荣的能力中发挥了核心作用。相较于诸多仅依托群体遗传数据搜寻选择证据的研究，本研究通过在全球61个人群中筛选出等位基因频率与气候变量间相关性最强的单核苷酸多态性（Single Nucleotide Polymorphisms, SNPs），以此扫描人类基因组中的选择信号。我们发现，在与这些气候变量强相关的位点中，基因区域及非同义单核苷酸多态性的富集程度显著高于非基因区域的单核苷酸多态性。在最为显著的选择信号中，有部分与全基因组关联研究（Genome-Wide Association Study, GWAS）所得信号存在重叠，其中包括与色素沉着及自身免疫性疾病相关的单核苷酸多态性位点。此外，我们还发现，与紫外线辐射、感染免疫及癌症相关的基因集内，强选择信号存在显著富集现象。本研究结果表明，针对气候的适应性演化塑造了人类遗传变异的空间分布格局。