Genome-wide SNP analysis unveils genetic structure and phylogeographic history of snow sheep (Ovis nivicola) populations inhabiting the Verkhoyansk Mountains and Momsky Ridge (northeastern Siberia)

Abstract

Insights into the genetic characteristics of a species provide important informationfor wildlife conservation programs. Here, we used the OvineSNP50 BeadChip developed for domestic sheep to examine population structure and evaluate genetic diversity of snow sheep (Ovis nivicola) inhabiting Verkhoyansk Range and MomskyRidge. A total of 1,121 polymorphic SNPs were used to test 80 specimens representing five populations, including four populations of the Verkhoyansk Mountain chain:Kharaulakh Ridge-Tiksi Bay (TIK, n = 22), Orulgan Ridge (ORU, n = 22), the centralpart of Verkhoyansk Range (VER, n = 15), Suntar-Khayata Ridge (SKH, n = 13), andMomsky Ridge (MOM, n = 8). We showed that the studied populations were genetically structured according to a geographic pattern. Pairwise FST values ranged from0.044 to 0.205. Admixture analysis identified K = 2 as the most likely number of ancestral populations. A Neighbor-Net tree showed that TIK was an isolated group related to the main network through ORU. TreeMix analysis revealed that TIK andMOM originated from two different ancestral populations and detected gene flowfrom MOM to ORU. This was supported by the f3 statistic, which showed that ORUis an admixed population with TIK and MOM/SKH heritage. Genetic diversity in thestudied groups was increasing southward. Minimum values of observed (Ho) and expected (He) heterozygosity and allelic richness (Ar) were observed in the most northern population-TIK, and maximum values were observed in the most southernpopulation-SKH. Thus, our results revealed clear genetic structure in the studiedpopulations of snow sheep and showed that TIK has a different origin from MOM,SKH, and VER even though they are conventionally considered a single subspeciesknown as Yakut snow sheep (Ovis nivicola lydekkeri). Most likely, TIK was an isolatedgroup during the Late Pleistocene glaciations of Verkhoyansk Range.