Patterns of molecular evolution in caenorhabditis preclude ancient origins of selfing
Patterns of molecular evolution in caenorhabditis preclude ancient origins of selfing
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DOI：
10.1534/genetics.107.085787
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发表时间：
2008-04-01
期刊：
影响因子：
3.3
通讯作者：
Washington, Nicole L.
中科院分区：
文献类型：
--
作者：
Cutter, Asher D.;Wasmuth, James D.;Washington, Nicole L.
自花受精的进化可以介导基因组的显著变化，作为有效种群规模急剧减少的副产品，以及伴随的遗传漂变造成的轻微有害突变的积累。在线虫属小杆线虫中，高度自交的生活方式已经独立地进化了两次，从而允许有机会在基因组尺度上测试繁殖模式对分子进化模式的影响。在这里，我们对比率的核苷酸取代和密码子使用的偏见之间的数千个orthopathic组的基因在六种小杆线虫，包括经典的模式生物秀丽隐杆线虫。尽管有证据表明，弱选择同义密码子的使用是普遍存在于本属的所有物种的历史，我们发现物种之间的密码子使用偏好的模式，并在复制位点取代的差异不大。应用密码子使用的松弛选择模型对C.和秀丽隐杆线虫C. briggsae谱系表明，自花受精的进化不太可能超过400万年前，这是不到四分之一的时间，因为他们有一个共同的祖先与异交物种。我们的结论是，交配行为，生理和发育机制的深刻变化，伴随着从专性异交到主要的自交繁殖模式的转变，在不太遥远的进化。
The evolution of self-fertilization can mediate pronounced changes in genomes as a by-product of a drastic reduction in effective population size and the concomitant accumulation of slightly deleterious mutations by genetic drift. In the nematode genus Caenorhabditis, a highly selfing lifestyle has evolved twice independently, thus permitting an opportunity to test for the effects of mode of reproduction on patterns of molecular evolution on a genomic scale. Here we contrast rates of nucleotide substitution and codon usage bias among thousands of orthologous groups of genes in six species of Caenorhabditis, including the classic model organism Caenorhabditis elegans. Despite evidence that weak selection on synonymous codon usage is pervasive in the history of all species in this genus, we find little difference among species in the patterns of codon usage bias and in replacement-site substitution. Applying a model of relaxed selection on codon usage to the C. elegans and C. briggsae lineages suggests that self-fertilization is unlikely to have evolved more than similar to 4 million years ago, which is less than a quarter of the time since they shared a common ancestor with outcrossing species. We conclude that the profound changes in mating behavior, physiology, and developmental mechanisms that accompanied the transition from an obligately outcrossing to a primarily selfing mode of reproduction evolved in the not-too-distant