ADAPTIVE PROTEIN EVOLUTION AT THE ADH LOCUS IN DROSOPHILA
ADAPTIVE PROTEIN EVOLUTION AT THE ADH LOCUS IN DROSOPHILA
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DOI：
10.1038/351652a0
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发表时间：
1991-06-20
期刊：
影响因子：
64.8
通讯作者：
KREITMAN, M
中科院分区：
文献类型：
--
作者：
MCDONALD, JH;KREITMAN, M
蛋白质的氨基酸序列在不同物种间往往不同。 这种差异是通过随机漂移的中性突变积累、选择的适应性突变固定或两者的混合而进化的。 在这里，我们提出了一个简单的统计测试的中性蛋白质进化假说的基础上比较的氨基酸置换取代的同义取代的编码区中的一个基因座的数量。 如果观察到的取代是中性的，物种之间的取代与同义固定差异的比率应该与物种内的取代与同义多态性的比率相同。 在黑腹果蝇物种亚组的三个物种中，Adh基因座（编码乙醇脱氢酶，EC 1.1.1.1）的DNA序列数据不符合这一预期;相反，物种之间的固定替代差异比预期的要多。 我们认为，这些过量的替代取代的选择性有利的突变的适应性固定的结果。
PROTEINS often differ in amino-acid sequence across species. This difference has evolved by the accumulation of neutral mutations by random drift, the fixation of adaptive mutations by selection, or a mixture of the two. Here we propose a simple statistical test of the neutral protein evolution hypothesis based on a comparison of the number of amino-acid replacement substitutions to synonymous substitutions in the coding region of a locus. If the observed substitutions are neutral, the ratio of replacement to synonymous fixed differences between species should be the same as the ratio of replacement to synonymous polymorphisms within species. DNA sequence data on the Adh locus (encoding alcohol dehydrogenase, EC 1.1.1.1) in three species in the Drosophila melanogaster species subgroup do not fit this expectation; instead, there are more fixed replacement differences between species than expected. We suggest that these excess replacement substitutions result from adaptive fixation of selectively advantageous mutations.