Uncovering signals of positive selection in peruvian populations from three ecological regions

Abstract

Peru hosts extremely diverse ecosystems which can be broadly classified into the following three major ecoregions: the Pacific desert coast, the Andean highlands, and the Amazon rainforest. Since its initial peopling approximately 12,000 years ago, the populations inhabiting such ecoregions might have differentially adapted to their contrasting environmental pressures. Previous studies have described several candidate genes underlying adaptation to hypobaric hypoxia among Andean highlanders. However, the adaptive genetic diversity of coastal and rainforest populations has been less studied. Here, we gathered genome-wide single-nucleotide polymorphism-array data from 286 Peruvians living across the three ecoregions and analyzed signals of recent positive selection through population differentiation and haplotype-based selection scans. Among highland populations, we identify candidate genes related to cardiovascular function (TLL1, DUSP27, TBX5, PLXNA4, SGCD), to the Hypoxia-Inducible Factor pathway (TGFA, APIP), to skin pigmentation (MITF), as well as to glucose (GLIS3) and glycogen metabolism (PPP1R3C, GANC). In contrast, most signatures of adaptation in coastal and rainforest populations comprise candidate genes related to the immune system (including SIGLEC8, TRIM21, CD44, and ICAM1 in the coast; CBLB and PRDM1 in the rainforest; and BRD2, HLA-DOA, HLA-DPA1 regions in both), possibly as a result of strong pathogen-driven selection. This study identifies candidate genes related to human adaptation to the diverse environments of South America.

This work was supported by the Ministerio de Ciencia e Innovación and the Agencia Estatal de Investigación (AEI) (PID2019-110933GB-I00/AEI/10.13039/501100011033 to E.B.); the Unidad de Excelencia María de Maeztu funded by the Ministerio de Ciencia e Innovación and the Agencia Estatal de Investigación (DOI: 10.13039/501100011033; ref: CEX2018-000792-M to E.B. and R.C.-C.); the National Science Foundation (NSF) SBE (Postdoctoral Research Fellowship Award No. 1711982 to M.A.N.-C.), NSF-BCS (BCS-0242958 to A.C.S.) and NSF-Research Experience for Undergraduates (BCS-0242958 to A.C.S.); the Mexican National Council for Science and Technology (CONACYT) (FONCICYT/50/2016 to A.M.-E.); and the International Center for Genetic Engineering and Biotechnology (ICGEB, Italy) (CRP/MEX15-04_EC to A.M.-E.). The PEGEN-BC study was supported by the National Cancer Institute at the National Institutes of Health (R01CA204797 to L.F.) and the Instituto Nacional de Enfermedades Neoplásicas in Lima, Peru.