Centre for the Study of Evolution, School of Life Sciences, University of Sussex, Brighton, United Kingdom.
Mol Biol Evol. 2010 Aug;27(8):1822-32. doi: 10.1093/molbev/msq079. Epub 2010 Mar 18.
The relative contribution of advantageous and neutral mutations to the evolutionary process is a central problem in evolutionary biology. Current estimates suggest that whereas Drosophila, mice, and bacteria have undergone extensive adaptive evolution, hominids show little or no evidence of adaptive evolution in protein-coding sequences. This may be a consequence of differences in effective population size. To study the matter further, we have investigated whether plants show evidence of adaptive evolution using an extension of the McDonald-Kreitman test that explicitly models slightly deleterious mutations by estimating the distribution of fitness effects of new mutations. We apply this method to data from nine pairs of species. Altogether more than 2,400 loci with an average length of approximately 280 nucleotides were analyzed. We observe very similar results in all species; we find little evidence of adaptive amino acid substitution in any comparison except sunflowers. This may be because many plant species have modest effective population sizes.
有利突变和中性突变对进化过程的相对贡献是进化生物学中的一个核心问题。目前的估计表明，果蝇、老鼠和细菌经历了广泛的适应性进化，而人类在蛋白质编码序列中几乎没有表现出适应性进化的证据。这可能是由于有效种群大小的差异造成的。为了进一步研究这个问题，我们使用麦当劳-克里坦测试的扩展来研究植物是否表现出适应性进化的证据，该扩展通过估计新突变的适应度效应分布来明确地对轻微有害突变进行建模。我们将这种方法应用于来自九对物种的数据。总共分析了超过 2400 个平均长度约为 280 个核苷酸的基因座。我们在所有物种中都观察到非常相似的结果；除了向日葵外，在任何比较中，我们几乎没有发现适应性氨基酸替换的证据。这可能是因为许多植物物种的有效种群大小适中。
