Abstract
ObjectivesThere are large populations of indigenous horse (Equus caballus) in China and some other parts of East Asia. However, their matrilineal genetic diversity and origin remained poorly understood. Using a combination of mitochondrial DNA (mtDNA) and hypervariable region (HVR-1) sequences, we aim to investigate the origin of matrilineal inheritance in these domestic horses.MethodsTo investigate patterns of matrilineal inheritance in domestic horses, we conducted a phylogenetic study using 31 de novo mtDNA genomes together with 317 others from the GenBank. In terms of the updated phylogeny, a total of 5,180 horse mitochondrial HVR-1 sequences were analyzed.ResultsEightteen haplogroups (Aw-Rw) were uncovered from the analysis of the whole mitochondrial genomes. Most of which have a divergence time before the earliest domestication of wild horses (about 5,800 years ago) and during the Upper Paleolithic (35–10 KYA). The distribution of some haplogroups shows geographic patterns. The Lw haplogroup contained a significantly higher proportion of European horses than the horses from other regions, while haplogroups Jw, Rw, and some maternal lineages of Cw, have a higher frequency in the horses from East Asia. The 5,180 sequences of horse mitochondrial HVR-1 form nine major haplogroups (A-I). We revealed a corresponding relationship between the haplotypes of HVR-1 and those of whole mitochondrial DNA sequences. The data of the HVR-1 sequences also suggests that Jw, Rw, and some haplotypes of Cw may have originated in East Asia while Lw probably formed in Europe.ConclusionsOur study supports the hypothesis of the multiple origins of the maternal lineage of domestic horses and some maternal lineages of domestic horses may have originated from East Asia.
Highlights
Domestication of horses has always attracted scientific interests as the animals played an important role in the civilization of humans in ancient times
Our study supports the hypothesis of the multiple origins of the maternal lineage of domestic horses and some maternal lineages of domestic horses may have originated from East Asia
Some studies (e.g., Lei & Su, 2009; Yang & Zhu, 2017) proposed that certain horse lineages may have origins outside of the Eurasian Steppe. This suggests that subsequent domestication occurred after the first domestication event, which is supported by the fact that modern horses possess rich maternal lineages, referring to multiple origins of maternal lineages of the domesticated horses
Summary
Domestication of horses has always attracted scientific interests as the animals played an important role in the civilization of humans in ancient times. Attributed to rapid molecular evolution and maternal inheritance, mitochondrial DNA (mtDNA) has been widely employed in phylogenetic studies of domestic horses, which revealed some valuable clues about the origins of modern horses (Lippold & Matzke, 2011; Achilli & Olivieri, 2012). Some studies (e.g., Lei & Su, 2009; Yang & Zhu, 2017) proposed that certain horse lineages may have origins outside of the Eurasian Steppe. This suggests that subsequent domestication occurred after the first domestication event, which is supported by the fact that modern horses possess rich maternal lineages, referring to multiple origins of maternal lineages of the domesticated horses.
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