Mitochondrial DNA analyses revealed distinct lineages of Siberian ibex ( Capra sibirica ) in Xinjiang, China

Maternal lineages of mitochondrion DNA (mtDNA) are conceived as important components of intra- and inter-specific biodiversity and help us to disclose phylogeny and divergence time of many taxa. Species of the genus Capra are canonical mountain dwellers. Among these is Siberian ibex ( Capra sibirica ) that is regarded as a relic species and its intra-specific classification is controversial so far. We collected 54 samples in Xinjiang, China, and analyzed the mtDNA genes to shed light on the intra-specific relationships of the C. sibirica populations and estimated the divergence time. Intriguingly, we found that the mtDNA sequences of C. sibirica split into two main lineages in both phylogenetic and network analyses: the southern lineage, sister to C. falconeri , consisting of samples from India, Ulugqat, and Kagilik in Xinjiang; and the northern lineage further divided into four monophyletic clades A–D corresponding to their geographic origins. Samples from Urumqi, Sawan and Arturk formed a distinct monophyletic clade C within the northern lineage. The genetic distance between the C. sibirica clades ranges from 3 to 8.6 percent, with values of FST between 0.72 and 0.95, indicating notable differentiation. The split of the genus Capra occurred approximately 6.75 Mya during the late Miocene. The northern lineage diverged around 5.88 Mya, following the divergence of Clades A–D from 3.3 Mya to 1.9 Mya during the late Pliocene and early Pleistocene. The radiation between the southern lineage and C. falconeri occurred at 2.29 Mya during the early Pleistocene. Our results highlight the importance of extensive sampling when relating to genetic studies of alpine mammals and call for further genomic studies to draw definitive conclusions.