Organisms living in high altitudes are exposed to multiple stresses such as low temperature, hypoxia, high UV radiation and other extreme environmental factors. Understanding how high-altitude species cope with the combined effects of environmental factors can provide important insights into the process of adaptive evolution. Mitochondria are the energy factory in cells, and more than 95% of the energy in cells is produced by the mitochondrial oxidative phosphorylation (OXPHOS). Therefore, mitochondria likely plays an important role in the process of high-altitude adaptation. Lizard species of the genus Phrynocephalus
(Squamata, Agamidae) are widespread in central Asia and cross a large elevational range from 1000 m to 5300 m. Using two high-altitude and six low-altitude Phrynocephalus
species, the role of mitochondrial genome in high-altitude adaptation of ectotherms were tested in this study. The branch model analyses revealed that Phrynocephalus theobaldi
had the largest ω value among species, followed by P. vlangalii
. Among different genes, ATP8 had the largest ω value, and in P. theobaldi
it was greater than 1, suggesting that ATP8 had experienced positive selection. In the branch-site model analyses, we found evidence of positive selection in ATP8 gene on the P. theobaldi
<0.05). Amino-acid residue sites 5 and 40 of the ATP8 genes were inferred as positively selected sites with posterior probabilities greater than 95%. Our results suggested that the changes of mitochondrial genes likely played a critical role during the adaptation process to high altitudes for P. theobaldi
. Surprisingly, no evidence for positive selection was detected in P. vlangalii
, suggesting that species might use different molecular mechanisms in high-altitude adaptation.
2015,34(6): 810-816 收稿日期：2015-05-07
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