Department of Ecology, Evolution and Natural Resources, Rutgers University, Cook Campus, USA.
Mol Biol Evol. 2010 May;27(5):1173-80. doi: 10.1093/molbev/msq009. Epub 2010 Jan 18.
The rate of genome evolution varies significantly between species. Evidence is growing that at least some of this variation is associated with species characteristics, such as body size, diversification rate, or population size. One of the strongest correlates of the rate of molecular evolution in vertebrates is generation time (GT): Species with faster generation turnover tend to have higher rates of molecular evolution, presumably because their genomes are copied more frequently and therefore collect more DNA replication errors per unit time. But the GT effect has never been tested for nonvertebrate animals. Here, we present the first general test of the GT effect in invertebrates, using 15 genes from 143 species spread across the major eumetazoan superphyla (including arthropods, nematodes, molluscs, annelids, platyhelminthes, cnidarians, echinoderms, and urochordates). We find significant evidence that rates of molecular evolution are correlated with GT in invertebrates and that this effect applies consistently across genes and taxonomic groups. Furthermore, the GT effect is evident in nonsynonymous substitutions, whereas theory predicts (and most previous evidence has supported) a relationship only in synonymous changes. We discuss both the practical and theoretical implications of these findings.
物种间的基因组进化速度差异显著。越来越多的证据表明，这种差异至少与某些物种特征有关，如体型、多样化率或种群规模。在脊椎动物中，与分子进化速度相关性最强的因素之一是世代时间（GT）：世代更替较快的物种往往具有较高的分子进化速度，这可能是因为它们的基因组复制得更频繁，因此在单位时间内积累了更多的 DNA 复制错误。但 GT 效应从未在非脊椎动物中进行过测试。在这里，我们使用来自 143 个物种的 15 个基因（分布在主要后生动物超门中，包括节肢动物、线虫、软体动物、环节动物、扁形动物、刺胞动物、棘皮动物和尾索动物），首次对无脊椎动物中的 GT 效应进行了一般性检验。我们发现有确凿的证据表明，无脊椎动物的分子进化速度与 GT 相关，而且这种效应在基因和分类群中普遍适用。此外，GT 效应在非同义替换中明显存在，而理论预测（并且大多数先前的证据也支持）仅在同义变化中存在这种关系。我们讨论了这些发现的实际和理论意义。
