Rich maternal and paternal genetic diversity and divergent lineage composition in wild yak (Bos mutus)

Wild yak (Bos mutus) is a vulnerable bovine species on the Qinghai-Tibetan Plateau. So far, most studies on the molecular genetic diversity of wild yak have focused on autosomal and mtDNA variations based on the small number of samples. In this study, we analyzed 84 D-loop and 24 whole mitogenome sequences of wild yak to further comprehensively explore its maternal genetic diversity and lineage composition. Meanwhile, using six yak Y-specific polymorphic markers (i.e., SRY4, USP9Y, UTY19, AMELY3, OFD1Y10 and INRA189), we assessed the paternal genetic diversity and lineage composition based on eight wild yak. Our results showed that wild yak exhibited abundant maternal genetic diversity with haplotype diversities of 0.9621 ± 0.0078 and 0.9928 ± 0.0144 in the D-loop and whole mitogenome sequences, respectively. Maternal phylogenetic analysis of wild yak uncovered three defined lineages (mt-I, mt-II and mt-III). Similarly, profuse paternal genetic diversity was observed in wild yak with Y-haplotype diversity at 0.8214 ± 0.1007. Two Y-haplogroups (Y1 and Y2) and four Y-haplotypes (yH1-yH4) were identified in paternal phylogenetic analysis, indicating wild yak to be of two paternal lineages. The present study of genetic diversity and lineage composition of wild yak would provide useful information for the genetic resource conservation and utilization of this vulnerable wild species.