Whole-Genome Resequencing Reveals Population Genetic Structure and Selection Signatures in the Golden Wild Yak

The wild yak (Bos mutus) is a flagship species on the Qinghai–Tibet Plateau, possessing significant ecological functions and conservation value. Using single-nucleotide polymorphism markers from whole-genome resequencing, we systematically analyzed golden wild yak (n = 37), common wild yak (n = 106), and domestic yak (Bos grunniens) (n = 20) to characterize the population genetic structure and adaptive selection signals in the golden wild yak. Genetic diversity analyses revealed that the golden wild yak had the lowest nucleotide diversity (π = 0.00148) and the highest inbreeding coefficient (FHom = 0.043). Population structure analyses integrating principal component analysis, phylogenetic tree, and ancestral component clustering indicated that the golden wild yak formed a relatively independent evolutionary lineage. However, its genetic differentiation from sympatric common wild yak population was limited (fixation index = 0.031). Selective sweep analysis identified a set of candidate positively selected genes in the golden wild yak genome associated with key traits and physiological functions, including coat color (TYRP1), hypoxia adaptation (MYH11, POLQ), reproductive function (SLC9C1, SPAG16, CFAP97D1), and immune response (CASP8, PGGT1B, BIRC6). Overall, our study reveals a distinct genetic background and selection signatures in the golden wild yak and provides genomic insights to inform the conservation and management of the wild yak.