The complete mitochondrial genome of a blue sheep (Pseudois nayaur szechuanensis) from Gongga mountains of Sichuan, China

Abstract

The blue sheep (Pseudois nayaur) belongs to the subfamily Caprinae. Here, we report the complete mitochondrial genome of a blue sheep subspecies (Pseudois nayaur szechuanensis) from Gongga Mountains of Sichuan, China. The genome (GenBank accession number MH719216) has a length of 16,664 bp and exhibits the typical structure of mammalian mitochondrial genomes. Phylogenetically, the newly generated mitochondrial genome is nested within the genus Pseudois group and formed a strongly supported (100% bootstrap) sister lineage to the previously reported P. n. szechuanensis (GenBank accession number, KJ784494). These results provide more molecular data for the genetic diversity conservation of this rare species.

Keywords:

• Blue sheep
• Gongga mountains
• mitochondrial DNA
• phylogenetic analysis
• Pseudois nayaur

The blue sheep (Pseudois nayaur) belongs to the subfamily Caprinae within the Cetartiodactyla and is found on the Tibetan Plateau and peripheral mountains through Central Asia (Shadel and Clayton 1997). It is categorized as two subspecies: Pseudois nayaur nayaur and Pseudois nayaur szechuanensis. This species is found in Bhutan, China (Gansu, Ningxia-Inner Mongolia border, Qinghai, Sichuan, Tibet, southeastern Xinjiang, and northern Yunnan), northern India, northern Myanmar, Nepal, and northern Pakistan. Pseudois nayaur is listed into a Class II protected species under China’s National Wildlife Law (Harris 2014). So far, there are only a few reports on the complete mitochondrial genome of the blue sheep (Jiang et al. 2015a, 2015b; Deng et al. 2016), thus more molecular data need to be provided for the genetic diversity conservation of this rare species.

We report here on the sequencing of the mitochondrial genome of a blue sheep subspecies (P. n. szechuanensis) from Hailuogou Glacier (N29°36′30″, E102°04′7″), Gongga Mountains of Sichuan, China, where was potential refugium for blue sheep during the Quaternary period with a high degree of genetic diversity (Hewitt 1996; 2000). The muscle tissue of P. n. szechuanensis was sampled from an illegal hunting individual captured by forest police, and it was kept in the laboratory of zoology, Sichuan agricultural university, China. Total genomic DNA was extracted by using the methods of standard phenol-chloroform (Sambrook and Russell 2001). Seventeen pairs of primers were used to amplify the overlapping segments of its mitochondrial genome based on the polymerase chain reaction (PCR).

The newly generated mitochondrial genome sequence had a total length of 16,664 bp (GenBank accession number MH719216). The overall base composition of the P. n. szechuanensis mitogenome was biased toward A + T (59.75%), and 33.42% A, 26.33% T, 26.97% C, and 13.27% G. It includes 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and the control region in the order typically found in mammals (Anderson et al. 1981). Compared with the previously reported P. n. szechuanensis (GenBank accession number KJ784494), the newly generated mitochondrial genome has 64 variable sites in total and 75 deletion in D-loop region.

Phylogenetic analysis included the complete mitochondrial genomes of three blue sheep, one dwarf blue sheep (Pseudois schaeferithe), and other nine Caprinae species, using the water buffalo (Bubalus bubalis) of Bovinae as an outgroup. A maximum-likelihood tree (with 1000 bootstrap replicates) was generated in MEGA6 (Tamura et al. 2013). On the phylogenetic tree (Figure 1), the newly generated mitochondrial genome is nested within the genus Pseudois group and formed a strongly supported (100% bootstrap) sister lineage to the previously reported P. n. szechuanensis (GenBank accession number, KJ784494). Additionally, P. schaeferi is nested in the Pseudois nayaur, indicating that P. schaeferi may be a subspecies of Pseudois nayaur, which is consistent with the previously reported results (Zeng et al. 2008; Tan et al. 2012). The complete mitochondrial genome sequence provides more molecular data for the genetic diversity conservation of this rare species.

Figure 1. Maximum likelihood (ML) phylogenetic tree of three blue sheep, one dwarf blue sheep (Pseudois schaeferithe), and other nine Caprinae species, using the water buffalo (Bubalus bubalis) of Bovinae as an outgroup. The number at each node indicates the ML bootstrap support values. The solid circle represents the sequence in this study. GenBank accession numbers are given after the species name.

Acknowledgements

We thank Qian Su, Xue Liu, Pu Zhao and Yuhan Wu for their assistance in the laboratory, and the Tianquan County Forest Security Bureau of Sichuan, China, for their support of the sampling activities.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [31370407] .