Mitochondrial DNA analyses revealed distinct lineages in an alpine
mammal, Siberian ibex (Capra sibirica) in Xinjiang, China
Maternal lineages of mitochondrial DNA (mtDNA) are recognized as
important components of intra- and inter-specific biodiversity and help
us to disclose the phylogeny and divergence times of many taxa. Species
of the genus Capra are canonical mountain dwellers. Among these
is the Siberian ibex (Capra sibirica), which is regarded as a
relic species whose intra-specific classification has been 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 estimate 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 genetic 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.