Gillespie J H
Genetics. 1986 Aug;113(4):1077-91. doi: 10.1093/genetics/113.4.1077.
A statistical analysis of DNA sequences from four nuclear loci and five mitochondrial loci from different orders of mammals is described. A major aim of the study is to describe the variation in the rate of molecular evolution of proteins and DNA. A measure of rate variability is the statistic R, the ratio of the variance in the number of substitutions to the mean number. For proteins, R is found to be in the range 0.16 less than R less than 35.55, thus extending in both directions the values seen in previous studies. An analysis of codons shows that there is a highly significant excess of double substitutions in the first and second positions, but not in the second and third or first and third positions. The analysis of the dynamics of nucleotide evolution showed that the ergodic Markov chain models that are the basis of most published formulas for correcting for multiple substitutions are incompatible with the data. A bootstrap procedure was used to show that the evolution of the individual nucleotides, even the third positions, show the same variation in rates as seen in the proteins. It is argued that protein and silent DNA evolution are uncoupled, with the evolution at both levels showing patterns that are better explained by the action of natural selection than by neutrality. This conclusion is based primarily on a comparison of the nuclear and mitochondrial results.
本文描述了对来自不同目哺乳动物的四个核基因座和五个线粒体基因座的DNA序列进行的统计分析。该研究的一个主要目的是描述蛋白质和DNA分子进化速率的变化。速率变异性的一个衡量指标是统计量R，即替换数方差与平均数的比值。对于蛋白质，发现R的范围是0.16 < R < 35.55，从而在两个方向上扩展了先前研究中看到的值。对密码子的分析表明，第一和第二位存在极显著的双替换过量，但第二和第三位或第一和第三位则没有。核苷酸进化动力学分析表明，作为大多数已发表的多重替换校正公式基础的遍历马尔可夫链模型与数据不兼容。使用自助法表明，单个核苷酸的进化，即使是第三位，也显示出与蛋白质中相同的速率变化。有人认为蛋白质和沉默DNA的进化是不相关的，两个水平上的进化所呈现的模式用自然选择的作用比用中性理论能更好地解释。这一结论主要基于对核基因和线粒体结果的比较。
