Akashi H
Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence 66045-2201, USA.
Gene. 1999 Sep 30;238(1):39-51. doi: 10.1016/s0378-1119(99)00294-2.
Extensive DNA data emerging from genome-sequencing projects have revitalized interest in the mechanisms of molecular evolution. Although the contribution of natural selection at the molecular level has been debated for over 30 years, the relevant data and appropriate statistical methods to address this issue have only begun to emerge. This paper will first present the predominant models of neutral, nearly neutral, and adaptive molecular evolution. Then, a method to identify the role of natural selection in molecular evolution by comparing within- and between-species DNA sequence variation will be presented. Computer simulations show that such methods are powerful for detecting even very weak selection. Examination of DNA variation data within and between Drosophila species suggests that 'silent' sites evolve under a balance between weak selection and genetic drift. Simulated data also show that sequence comparisons are a powerful method to detect adaptive protein evolution, even when selection is weak or affects a small fraction of nucleotide sites. In the Drosophila data examined, positive selection appears to be a predominant force in protein evolution.
来自基因组测序项目的大量DNA数据重新激发了人们对分子进化机制的兴趣。尽管分子水平上自然选择的作用已经争论了30多年，但解决这一问题的相关数据和合适的统计方法才刚刚开始出现。本文将首先介绍中性、近中性和适应性分子进化的主要模型。然后，将介绍一种通过比较种内和种间DNA序列变异来确定自然选择在分子进化中作用的方法。计算机模拟表明，这些方法对于检测即使非常微弱的选择也很有效。对果蝇种内和种间DNA变异数据的研究表明，“沉默”位点在弱选择和遗传漂变之间的平衡下进化。模拟数据还表明，序列比较是检测适应性蛋白质进化的有力方法，即使选择很弱或只影响一小部分核苷酸位点。在所研究的果蝇数据中，正选择似乎是蛋白质进化中的主要力量。
