Molecular Ecology Group, Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou, Gansu, China.
Mol Biol Evol. 2011 May;28(5):1553-6. doi: 10.1093/molbev/msq336. Epub 2010 Dec 14.
Wild yaks roaming in the high-altitude Qinghai-Tibetan plateau have to maintain high metabolic efficiency. However, domestic yaks do not require such high efficiency because of their limited activity. Hence, domestication may have caused the relaxation of selective constraints on the yak mitochondrial genome because mitochondrial mutations are extremely sensitive to energy-related selective pressures. We have tested this hypothesis by analyzing the mitochondrial genomes of 51 domestic yaks and 21 wild yaks. The results show that the ratio of nonsynonymous/synonymous substitutions in mitochondrial protein-coding genes is significantly higher in domestic yak lineages than those of wild yaks. This genetic difference suggests that the relaxation of selective constraints following the domestication in addition to bottlenecks has allowed faster accumulation of nonsilent substitutions in the yak mitochondrial genome, despite its short domestication history.
野生牦牛在高海拔的青藏高原上漫游，必须保持较高的代谢效率。然而，由于活动范围有限，家养牦牛不需要如此高的效率。因此，驯化可能导致牦牛线粒体基因组的选择压力放松，因为线粒体突变对与能量相关的选择压力非常敏感。我们通过分析 51 头家养牦牛和 21 头野生牦牛的线粒体基因组来验证这一假说。结果表明，在家养牦牛谱系中，线粒体蛋白编码基因的非同义/同义替换率明显高于野生牦牛。这种遗传差异表明，除瓶颈效应外，驯化后的选择压力放松使得牦牛线粒体基因组中沉默突变的积累速度更快，尽管其驯化历史较短。
