Department of Organismic and Evolutionary Biology and The Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
Philos Trans R Soc Lond B Biol Sci. 2010 Aug 27;365(1552):2439-50. doi: 10.1098/rstb.2010.0104.
Convergence--the independent evolution of the same trait by two or more taxa--has long been of interest to evolutionary biologists, but only recently has the molecular basis of phenotypic convergence been identified. Here, we highlight studies of rapid evolution of cryptic coloration in vertebrates to demonstrate that phenotypic convergence can occur at multiple levels: mutations, genes and gene function. We first show that different genes can be responsible for convergent phenotypes even among closely related populations, for example, in the pale beach mice inhabiting Florida's Gulf and Atlantic coasts. By contrast, the exact same mutation can create similar phenotypes in distantly related species such as mice and mammoths. Next, we show that different mutations in the same gene need not be functionally equivalent to produce similar phenotypes. For example, separate mutations produce divergent protein function but convergent pale coloration in two lizard species. Similarly, mutations that alter the expression of a gene in different ways can, nevertheless, result in similar phenotypes, as demonstrated by sister species of deer mice. Together these studies underscore the importance of identifying not only the genes, but also the precise mutations and their effects on protein function, that contribute to adaptation and highlight how convergence can occur at different genetic levels.
趋同进化——两个或更多分类单元独立进化出相同特征——一直以来都是进化生物学家感兴趣的话题，但直到最近，表型趋同的分子基础才被确定。在这里，我们强调了对脊椎动物隐性颜色快速进化的研究，以证明表型趋同可以在多个层次上发生：突变、基因和基因功能。我们首先表明，即使在密切相关的种群中，不同的基因也可能导致趋同表型，例如，在栖息于佛罗里达州墨西哥湾和大西洋沿岸的浅色海滩鼠中。相比之下，完全相同的突变可以在远缘物种（如老鼠和猛犸象）中产生类似的表型。其次，我们表明，同一基因中的不同突变不一定具有相同的功能等效性，也能产生相似的表型。例如，两种蜥蜴的不同突变产生了不同的蛋白质功能，但却产生了趋同的浅色。同样，以不同方式改变基因表达的突变，尽管如此，也会导致类似的表型，这正如鹿鼠的姐妹种所证明的那样。这些研究强调了不仅要识别出导致适应的基因，还要确定导致适应的精确突变及其对蛋白质功能的影响，同时也突出了趋同如何在不同的遗传水平上发生。
