The complete mitochondrial genome sequence analysis of Tibetan argali (Ovis ammon hodgsoni): Implications of Tibetan argali and Gansu argali as the same subspecies

The genus Ovis (Bovidae, Artiodactyla) includes six species, i.e. Ovis ammon, Ovis aries, Ovis canadensis, Ovis dalli, Ovis nivicola and Ovis vignei. Based on morphology, geographical location, habitat, etc., the species O. ammon is divided into nine subspecies. The near threatened Tibetan argali is distributed across the Tibetan Plateau and its peripheral mountains, and believed to be one of the O. ammon subspecies (O. a. hodgsoni). However, considering its morphological features and distributions, a question has been proposed by some researchers about the subspecies status of Tibetan argali. In this study, we employed complete mitochondrial DNA (mtDNA) to explore the phylogenetic relationship and population genetic structure of Tibetan argali. The results revealed that the nucleotide composition, gene arrangement and codon usage pattern of the mitochondrial genome of Tibetan argali are similar to those of other caprines. Phylogenetic analyses showed that Tibetan argali was clustered with O. ammon. Interestingly, five Tibetan argali individuals and one of the three Gansu argali (O. a. dalailamae) individuals were clustered in the same branch, which is a sister group to other two Gansu argali individuals. Together with morphological characteristics, our results suggested that Tibetan argali and Gansu argali may belong to the same subspecies (O. a. hodgsoni) of O. ammon, rather than two different subspecies.