title: Detecting signatures of selection within the Tibetan sheep mitochondrial genome.
abstract: Tibetan sheep, a Chinese indigenous breed, are mainly distributed in plateau and mountain-valley areas at a terrestrial elevation between 2260 and 4100 m. The herd is genetically distinct from the other domestic sheep and undergoes acclimatization to adapt to the hypoxic environment. To date, whether the mitochondrial DNA modification of Tibetan sheep shares the same feature as the other domestic breed remains unknown. In this study, we compared the whole mitogenome sequences from 32 Tibetan sheep, 22 domestic sheep and 24 commercial sheep to identify the selection signatures of hypoxic-tolerant in Tibetan sheep. Nucleotide diversity analysis using the sliding window method showed that the highest level of nucleotide diversity was observed in the control region with a peak value of π = 0.05215, while the lowest π value was detected in the tRNAs region. qPCR results showed that the relative mtDNA copy number in Tibetan sheep was significantly lower than that in Suffolk sheep. None of the mutations in 12S rRNA were fixed in Tibetan sheep, which indicated that there has been less artificial selection in this herd than the other domestic and commercial breeds. Although one site (1277G) might undergo the purifying selection, it was not identified as the breed-specific allele in Tibetan sheep. We proposed that nature selection was the main drive during the domestication of Tibetan sheep and single mutation (or locus) could not reveal the signature of selection as for the high diversity in the mitogenome of Tibetan sheep.
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Lili
authors.initials: L
authors.lastname: Niu
authors.affiliation: b Institute of Animal Science and Veterinary of Hebei Province , Baoding , China.
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Chen
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Ping
authors.initials: P
authors.lastname: Xiao
authors.affiliation: c CAAS-ILRI Joint Laboratory on Livestock and Forage Genetic Resources , Institute of Animal Science, Chinese Academy of Agricultural Sciences , Beijing , China.
authors.forename: Qianjun
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Jingxuan
authors.initials: J
authors.lastname: Zhou
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Jiangtao
authors.initials: J
authors.lastname: Hu
authors.affiliation: b Institute of Animal Science and Veterinary of Hebei Province , Baoding , China.
authors.forename: Hongxin
authors.initials: H
authors.lastname: Sun
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Jiazhong
authors.initials: J
authors.lastname: Guo
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Linjie
authors.initials: L
authors.lastname: Wang
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Hongping
authors.initials: H
authors.lastname: Zhang
authors.affiliation: a Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology , Sichuan Agricultural University , Chengdu , China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhong
mesh_terms: D000818:Animals; D001947:Breeding; D019143:Evolution, Molecular; D014644:Genetic Variation; D054629:Genome, Mitochondrial; D010802:Phylogeny; D012641:Selection, Genetic; D034561:Sheep, Domestic / Q000235:genetics*; D018609:Tibet
keywords: Copy number; Tibetan sheep; high altitude; mitochondrial DNA; selection signature