Phylotaxonomic position of Tianzhu white yak (Poephagus grunniens) based on nucleotide sequences of multiple subunits of cytochrome c oxidase

Abstract

To estimate the phylotaxonomic position of Tianzhu white yak (Poephagus grunniens), multiple subunit genes of cytochrome c oxidase (cox) were sequenced: 1545 bp of cox1 (JF946751), 684 bp of cox2 (JN008944) and 781 bp of cox3 (JF946752). Sequence divergences of cox genes between yaks and cattle/zebus (5.7% in cox1, 7.7% in cox2 and 6.45% in cox3) were higher than those between yaks and American bisons (2.4% in cox1, 3.0% in cox2 and 2.1% in cox3). Molecular phylogenetic analysis with these genes also found that yaks and American bisons firstly clustered in one clade, indicating there was higher genetic comparability than that of cattle/zebus. The findings sustained the idea that in the choice of nomenclature yaks belong to the subgenus of Poephagus. According to the nucleotide substitution rate of cox genes among species of Bovinae, the speculated divergence time of yaks from cattle/zebus, American bisons, European bisons, Asian buffaloes/African buffaloes was 1.05–1.50 million years ago (MYA), 2.85–3.89 MYA, 2.90–3.70 MYA, 6.85–7.50 MYA, respectively. The sequential evolution of Bovinae members could be predicted that buffaloes were first to be domesticated during the end of Miocene and the early of Pliocene. In the end of Pliocene, the Bovinae genera were evolved to Bos, Bison and Poephagus. Poephagus was the latest evolved genera among the species of Bovinae.

Keywords:

• cytochrome c oxidase (cox) genes
• taxonomy
• phylogenetic relationship
• divergence time
• Bovinae species
• Tianzhu white yak

Funding

The work was partially financed by the project of National Natural Science Foundation of China, NSFC [grant number 31260533] and the Programme for Changjiang Scholars and Innovative Research Team in University of Ministry of Education, China [grant number IRT13091].

Additional information

Funding

Funding: The work was partially financed by the project of National Natural Science Foundation of China, NSFC [grant number 31260533] and the Programme for Changjiang Scholars and Innovative Research Team in University of Ministry of Education, China [grant number IRT13091].