Ohta T
National Institute of Genetics, Mishima, Japan.
Proc Natl Acad Sci U S A. 1993 May 15;90(10):4548-51. doi: 10.1073/pnas.90.10.4548.
The number of amino acid replacement substitutions and that of synonymous substitutions are examined by using DNA sequences of the Adh locus of Drosophila. The ratio of replacement to synonymous substitutions is higher in sequence comparisons between species than in polymorphisms within species. The ratio for the between-species comparisons is highest in the Hawaiian group and lowest in the obscura group. These observations suggest that amino acid substitutions are facilitated by small population size. The result is in accord with the nearly neutral theory of molecular evolution.
利用果蝇乙醇脱氢酶(Adh)基因座的DNA序列,研究氨基酸替换取代的数量和同义取代的数量。物种间序列比较中替换取代与同义取代的比率高于物种内多态性中的该比率。物种间比较的比率在夏威夷种群中最高,在果蝇暗果蝇种群中最低。这些观察结果表明,小种群规模促进了氨基酸替换。这一结果与分子进化的近中性理论相符。