Exome Sequencing Provides Evidence of Polygenic Adaptation to a Fat-Rich Animal Diet in Indigenous Siberian Populations

• Published in: Molecular Biology and Evolution
• Main Authors: Hsieh, PingHsun, Hallmark, Brian, Watkins, Joseph, Karafet, Tatiana M., Osipova, Ludmila P., Gutenkunst, Ryan N., Hammer, Michael F.
• Other Authors: Univ Arizona, Dept Ecol & Evolutionary Biol, Univ Arizona, Interdisciplinary Program Stat, Univ Arizona, Dept Math, Univ Arizona, ARL Div Biotechnol, Univ Arizona, Dept Mol & Cellular Biol
• Format: Article in Journal/Newspaper
• Language: English
• Published: OXFORD UNIV PRESS 2017
• Subjects: adaptation; diet; Siberia; extreme climates; polygenic selection; Nganasan*; Yakuts
• Online Access: http://hdl.handle.net/10150/627857; https://doi.org/10.1093/molbev/msx226

Siberia is one of the coldest environments on Earth and has great seasonal temperature variation. Long-term settlement in northern Siberia undoubtedly required biological adaptation to severe cold stress, dramatic variation in photoperiod, and limited food resources. In addition, recent archeological studies show that humans first occupied Siberia at least 45,000 years ago; yet our understanding of the demographic history of modern indigenous Siberians remains incomplete. In this study, we use whole-exome sequencing data from the Nganasans and Yakuts to infer the evolutionary history of these two indigenous Siberian populations. Recognizing the complexity of the adaptive process, we designed a model-based test to systematically search for signatures of polygenic selection. Our approach accounts for stochasticity in the demographic process and the hitchhiking effect of classic selective sweeps, as well as potential biases resulting from recombination rate and mutation rate heterogeneity. Our demographic inference shows that the Nganasans and Yakuts diverged similar to 12,000-13,000 years ago from East-Asian ancestors in a process involving continuous gene flow. Our polygenic selection scan identifies seven candidate gene sets with Siberian-specific signals. Three of these gene sets are related to diet, especially to fat metabolism, consistent with the hypothesis of adaptation to a fat-rich animal diet. Additional testing rejects the effect of hitchhiking and favors a model in which selection yields small allele frequency changes at multiple unlinked genes. National Science Foundation [PLR-1203874, DEB-1146074]; State Research Project [0324-2016-0002] 12 month embargo; published online: 12 September 2017 This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [e-mail].