Different maternal lineages revealed by ancient mitochondrial genome of Camelus bactrianus from China

Abstract

Domestic Bactrian camel (Camelus bactrianus) used to be one of the most important livestock species in Chinese history, as well as the major transport carrier on the ancient Silk Road. However, archeological studies on Chinese C. bactrianus are still limited, and molecular biology research on this species is mainly focused on modern specimens. In this study, we retrieved the complete mitochondrial genome from a C. bactrianus specimen, which was excavated from northwestern China and dated at 1290–1180 cal. years before present (yBP). Phylogenetic analyses using 18 mitochondrial genomes indicated that the C. bactrianus clade was divided into two maternal lineages. The majority of samples originating from Iran to Japan and Mongolia belong to subclade A1, while our sample together with two Mongolian individuals formed the much smaller subclade A2. Furthermore, the divergence time of these two maternal lineages was estimated as 165 Kya (95% credibility interval 117–222 Kya), this might indicate that several different evolutionary lineages were incorporated into the domestic gene pool during the initial domestication process. Bayesian skyline plot (BSP) analysis suggest a slow increase in female effective population size of C. bactrianus from 5000 years ago, which corresponds to the beginning of domestication of C. bactrianus. The present study also revealed that there were extensive exchanges of genetic information among C. bactrianus populations in regions along the Silk Road.

Keywords:

• Camelus bactrianus
• mitochondrial genome
• ancient DNA
• phylogeny
• maternal lineages

Acknowledgments

We appreciate Yuyang Zhang at China University of Geosciences for his help in the experiments of this research.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Data availability

Project Information: NCBI BioProject Accession: PRJNA515177

Sample Information: NCBI BioSample Accession: SAMN10743616

Reads alignments (bam format): NCBI Accession: SRR8442720

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Nos. 41472014; 41672017) and Social Science Foundation of Shaanxi Province, China (Nos. 2015H012).

This work was supported by the National Natural Science Foundation of China (Nos. 41472014; 41672017) and Social Science Foundation of Shaanxi Province, China (Nos. 2015H012).