Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Q Rev Biol. 2010 Dec;85(4):419-45. doi: 10.1086/656902.
Adaptive evolution can cause a species to gain, lose, or modify a function; therefore, it is of basic interest to determine whether any of these modes dominates the evolutionary process under particular circumstances. Because mutation occurs at the molecular level, it is necessary to examine the molecular changes produced by the underlying mutation in order to assess whether a given adaptation is best considered as a gain, loss, or modification of function. Although that was once impossible, the advance of molecular biology in the past half century has made it feasible. In this paper, I review molecular changes underlying some adaptations, with a particular emphasis on evolutionary experiments with microbes conducted over the past four decades. I show that by far the most common adaptive changes seen in those examples are due to the loss or modification of a pre-existing molecular function, and I discuss the possible reasons for the prominence of such mutations.
适应进化可以导致一个物种获得、失去或改变某种功能；因此，确定在特定情况下这些模式中的哪一种主导进化过程是非常重要的。由于突变发生在分子水平上，因此有必要检查潜在突变产生的分子变化，以评估给定的适应是否最好被视为功能的获得、丧失或改变。尽管曾经不可能，但过去半个世纪分子生物学的进步使得这成为可能。在本文中，我回顾了一些适应进化的分子变化，特别强调了过去四十年中对微生物进行的进化实验。我表明，到目前为止，在这些例子中看到的最常见的适应性变化是由于预先存在的分子功能的丧失或改变，我还讨论了这种突变如此突出的可能原因。
