Data from: 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)

Insights into the genetic characteristics of a species provide important information for 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 Momsky Ridge. A total of 1121 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 central part of Verkhoyansk Range (VER, n = 15), Suntar-Khayata Ridge (SKH, n = 13), and Momsky Ridge (MOM, n = 8). We showed that the studied populations were genetically structured according to a geographical pattern. Pairwise FST values ranged from 0.044 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 and MOM originated from two different ancestral populations and detected gene flow from MOM to ORU. This was supported by the f3 statistic, which showed that ORU is an admixed population with TIK and MOM/SKH heritage. Genetic diversity in the studied 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 southern population–SKH. Thus, our results revealed clear genetic structure in the studied populations of snow sheep and showed that TIK has a different origin from MOM, SKH and VER even though they are conventionally considered a single subspecies known as Yakut snow sheep (Ovis nivicola lydekkeri). Most likely, TIK was an isolated group during the late Pleistocene glaciations of Verkhoyansk Range.对某一物种遗传特征的深入解析，可为野生动物保护计划提供关键科学依据。本研究使用针对家羊开发的OvineSNP50基因芯片（OvineSNP50 BeadChip），对栖息于维尔霍扬斯克山脉（Verkhoyansk Range）与莫姆斯基岭（Momsky Ridge）的雪羊（Ovis nivicola）开展群体结构分析与遗传多样性评估。研究共采用1121个多态性单核苷酸多态性（Single Nucleotide Polymorphism, SNP，文中简称SNPs）位点，对代表5个群体的80份样本进行基因分型；其中4个群体隶属于维尔霍扬斯克山系，分别为卡拉拉赫岭-季克西湾群体（TIK, n=22）、奥卢尔甘岭群体（ORU, n=22）、维尔霍扬斯克山脉中部群体（VER, n=15）、孙塔尔-哈亚塔岭群体（SKH, n=13），以及莫姆斯基岭群体（MOM, n=8）。分析结果显示，本次研究的雪羊群体遗传结构呈现显著的地理分化模式。群体间的两两固定指数（Fixation Index, FST）取值范围为0.044至0.205。群体混合分析（Admixture analysis）结果表明，最可信的祖先群体数目为K=2。邻接网（Neighbor-Net）系统发育树显示，TIK群体为独立分支，仅通过ORU群体与主系统发育网络相连。TreeMix群体历史分析显示，TIK与MOM起源于两个不同的祖先群体，且检测到MOM向ORU的基因流事件。f3统计量（f3 statistic）分析进一步验证了这一结论：ORU群体为混合群体，其遗传组分同时继承自TIK与MOM/SKH群体。研究群体的遗传多样性随纬度降低（向南）逐渐升高：观测杂合度（Observed Heterozygosity, Ho）、期望杂合度（Expected Heterozygosity, He）以及等位基因丰富度（Allelic Richness, Ar）的最低值均出现在最北端的TIK群体，而最高值则出现在最南端的SKH群体。综上，本研究结果明确揭示了雪羊研究群体的遗传结构特征，同时发现尽管传统分类中将上述群体均归为雅库特雪羊（Ovis nivicola lydekkeri）这一亚种，但TIK群体的起源与MOM、SKH及VER群体存在显著差异。推测在维尔霍扬斯克山脉晚更新世冰期期间，TIK群体便已处于长期地理隔离状态。