Ancient mitogenomes reveal a high maternal genetic diversity of Pleistocene woolly rhinoceros in Northern China.

BACKGROUND: Woolly rhinoceros (Coelodonta antiquitatis) is a typical indicator of cold-stage climate that was widely distributed in Northern Hemisphere during the Middle-Late Pleistocene. Although a plethora of fossils have been excavated from Northern China, their phylogenetic status, intraspecific diversity and phylogeographical structure are still vague. RESULTS: In the present study, we generated four mitogenomes from Late Pleistocene woolly rhinoceros in Northern China and compared them with published data. Bayesian and network analyses indicate that the analyzed individuals contain at least four maternal haplogroups, and Chinese samples fall in three of them. One of our samples belongs to a previously unidentified early diverging clade (haplogroup D), which separated from other woolly rhinoceros around 0.57 Ma (95% CI: 0.76-0.41 Ma). The timing of this clade's origin coincides with the first occurrence of woolly rhinoceros, which are thought to have evolved in Europe. Our other three samples cluster in haplogroup C, previously only identified from one specimen from Wrangel Island (ND030) and initially considered to be an isolated clade. Herein, our findings suggest that ND030 is likely descended from a northward dispersal of the individuals carrying haplogroup C from Northern China. Additionally, Chinese woolly rhinoceros specimens exhibit higher nucleotide diversity than those from Siberia. CONCLUSION: Our findings highlight Northern China as a possible refugium and a key evolution center of the Pleistocene woolly rhinoceros.

Ancient Mitogenomes Provide New Insights into the Origin and Early Introduction of Chinese Domestic Donkeys.

Both molecular data and archaeological evidence strongly support an African origin for the domestic donkey. Recent genetic studies further suggest that there were two distinct maternal lineages involved in its initial domestication. However, the exact introduction time and the dispersal process of domestic donkeys into ancient China are still unresolved. To address these questions, we retrieved three near-complete mitochondrial genomes from donkey specimens excavated from Gaoling County, Shaanxi Province, and Linxia Basin, Gansu Province, China, dated at 2,349-2,301, 469-311, and 2,160-2,004 cal. BP, respectively. Maximum-likelihood and Bayesian phylogenetic analyses reveal that the two older samples fall into the two different main lineages (i.e., clade Ⅰ and clade Ⅱ) of the domestic donkey, suggesting that the two donkey maternal lineages had been introduced into Midwestern China at least at the opening of Silk Road (approximately the first century BC). Bayesian analysis shows that the split of the two donkey maternal lineages is dated at 0.323 Ma (95% CI: 0.583-0.191 Ma) using root-tip dating calibrations based on near-complete mitogenomes, supporting the hypothesis that modern domestic donkeys go back to at least two independent domestication events. Moreover, Bayesian skyline plot analyses indicate an apparent female population increase between 5,000 and 2,500 years ago for clade I followed by a stable population size to the present day. In contrast, clade II keeps a relatively stable population size over the past 5,000 years. Overall, our study provides new insights into the early domestication history of Chinese domestic donkeys.