Abstract
BackgroundOn the Qinghai–Tibet Plateau, known as the roof ridge of the world, the yak is a precious cattle species that has been indispensable to the human beings living in this high-altitude area. However, the origin of domestication, dispersal route, and the divergence of domestic yaks from different areas are poorly understood.ResultsHere, we resequenced the genome of 91 domestic yak individuals from 31 populations and 1 wild yaks throughout China. Using a population genomics approach, we observed considerable genetic variation. Phylogenetic analysis suggested that the earliest domestications of yak occurred in the south-eastern QTP, followed by dispersal to the west QTP and northeast to SiChuang, Gansu, and Qinghai by two routes. Interestingly, we also found potential associations between the distribution of some breeds and historical trade routes such as the Silk Road and Tang-Tibet Ancient Road. Selective analysis identified 11 genes showing differentiation between domesticated and wild yaks and the potentially positively selected genes in each group were identified and compared among domesticated groups. We also detected an unbalanced pattern of introgression among domestic yak, wild yak, and Tibetan cattle.ConclusionsOur research revealed population genetic evidence for three groups of domestic yaks. In addition to providing genomic evidence for the domestication history of yaks, we identified potential selected genes and introgression, which provide a theoretical basis and resources for the selective breeding of superior characters and high-quality yak.
Highlights
On the Qinghai–Tibet Plateau, known as the roof ridge of the world, the yak is a precious cattle species that has been indispensable to the human beings living in this high-altitude area
We found the introgression from wild yaks into domestic yaks was far less than that from domestic yaks into wild yaks, this was related to the selective breeding of domestic yaks, the small population of wild yaks, the poorer living environment, and the bottleneck effect [36] could lead to lower retention of introgression in wild yaks
We identified 11 genes related to metabolism and immunity that showed significant selection between domestic yak and wild yak
Summary
On the Qinghai–Tibet Plateau, known as the roof ridge of the world, the yak is a precious cattle species that has been indispensable to the human beings living in this high-altitude area. The origin of domestica‐ tion, dispersal route, and the divergence of domestic yaks from different areas are poorly understood. On the Qinghai–Tibet Plateau (QTP), known as the roof ridge of the world, the average altitude is over 4000 m, where most plants and animals cannot survive because of the harsh climate, hypoxia, and low atmospheric pressure [2, 3]. The origin of domestication of yaks and their dispersal route is an important strand of evidence for the history of human migration, exploitation, and development on the QTP. The detection of genomic differences among domestic yaks may help elucidate the underlying mechanisms of adaptation and facilitate selective breeding
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