Rate variation between mitochondrial domains and adaptive evolution in humans
Rate variation between mitochondrial domains and adaptive evolution in humans
复制标题
DOI：
10.1093/hmg/ddm180
复制
发表时间：
2007-10-01
影响因子：
3.5
通讯作者：
Gyllensten, Ulf
中科院分区：
文献类型：
--
作者：
Ingman, Max;Gyllensten, Ulf
有人提出，由于人类适应不同气候，线粒体基因受到自然选择的影响。为了进一步研究人类线粒体 DNA 的选择压力，我们分析了四个地理区域的基因、结构域和核苷酸位点水平的多态性。相对于其他线粒体基因，北亚的 ATP6、非洲的 ND3 和欧洲的 cytb 的非同义相对于同义替代的比率较高。此外，非同义替换在核心功能域之外出现的频率是功能域内的近五倍。因此，线粒体基因之间的速率变化很大一部分可以通过功能域长度相对于基因长度的差异来解释。来自北亚的序列中 ATP6 基因中非同义取代的积累是数千年来的渐进过程，这与宽松的纯化选择而不是最近的强选择性扫描一致。当最简洁的解释是宽松的纯化选择和遗传漂变的作用时，没有必要援引适应性选择来解释线粒体基因的多态性模式。
It has been proposed that as a result of human adaptation to different climates, mitochondrial genes have been affected by natural selection. To further study the selective pressure on human mitochondrial DNA, we have analysed polymorphism at the gene, domain and nucleotide site level in four geographic regions. The ratio of non-synonymous relative to synonymous substitutions is elevated for ATP6 in North Asia, ND3 in Africa and cytb in Europe relative to other mitochondrial genes. In addition, non-synonymous substitutions appear nearly five times more frequently outside core functional domains as compared with within functional domains. Therefore, a large part of the rate variation between mitochondrial genes is explained by differences in the length of the functional domain relative to the length of the gene. The accumulation of non-synonymous substitutions in the ATP6 gene among sequences from North Asia has been a gradual process over many thousands of years, consistent with relaxed purifying selection rather than recent strong selective sweeps. It is not necessary to invoke adaptive selection to explain the pattern of polymorphism in mitochondrial genes, when the most parsimonious explanation is relaxed purifying selection and the action of genetic drift.