Genomic diversity and post-admixture adaptation in the Uyghurs

Abstract

Population admixture results in genome-wide combinations of genetic variants derived from different ancestral populations of distinct ancestry, thus providing a unique opportunity for understanding the genetic determinants of phenotypic variation in humans. Here, we used whole-genome sequencing of 92 individuals with high coverage (30-60×) to systematically investigate genomic diversity in the Uyghurs living in Xinjiang, China (XJU), an admixed population of both European-like and East-Asian-like ancestry. The XJU population shows greater genetic diversity, especially a higher proportion of rare variants, compared with their ancestral source populations, corresponding to greater phenotypic diversity of XJU. Admixture-induced functional variants in <i>EDAR</i> were associated with the diversity of facial morphology in XJU. Interestingly, the interaction of functional variants between <i>SLC24A5</i> and <i>OCA2</i> likely influences the diversity of skin pigmentation. Notably, selection has seemingly been relaxed or canceled in several genes with significantly biased ancestry, such as <i>HERC2</i>-<i>OCA2</i>. Moreover, signatures of post-admixture adaptation in XJU were identified, including genes related to metabolism (e.g. <i>CYP2D6</i>), digestion (e.g. <i>COL11A1</i>), olfactory perception (e.g. <i>ANO2</i>) and immunity (e.g. <i>HLA</i>). Our results demonstrated population admixture as a driving force, locally or globally, in shaping human genetic and phenotypic diversity as well as in adaptive evolution.