The population genetics of ecological specialization in evolving Escherichia coli populations
The population genetics of ecological specialization in evolving Escherichia coli populations
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DOI：
10.1038/35037572
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发表时间：
2000-10-12
期刊：
影响因子：
64.8
通讯作者：
Lenski, RE
中科院分区：
文献类型：
--
作者：
Cooper, VS;Lenski, RE
当生物在遗传上适应一种环境时，它们可能会在其他环境中失去适应性（1-4）。两种不同的群体遗传过程可以产生生态特化-突变积累和拮抗多效性（5-8）。在突变积累中，突变通过基因中的遗传漂变而固定，而这些基因不是通过选择来维持的;对一种环境的适应和对另一种环境的适应的丧失是由不同的突变引起的。拮抗多效性来自权衡，例如在一种环境中有益的相同突变在另一种环境中是有害的。一般来说，很难区分这些过程（5-8）。我们分析了在葡萄糖上繁殖20，000代的12个大肠杆菌系中未使用的分解代谢功能的衰减（9，10）。在此期间，几个品系进化出高突变率（11）。如果突变累积是重要的，则它们未使用的功能应该比其他线衰减得更多，但没有观察到显著差异。此外，大多数分解代谢损失发生在实验早期，此时有益突变正在迅速固定，这是拮抗多效性预测的模式。因此，拮抗多效性似乎更重要的是比突变积累的衰变未使用的分解代谢功能，在这些人口。
When organisms adapt genetically to one environment, they may lose fitness in other environments(1-4). Two distinct population genetic processes can produce ecological specialization-mutation accumulation and antagonistic pleiotropy(5-8). In mutation accumulation, mutations become fixed by genetic drift in genes that are not maintained by selection; adaptation to one environment and loss of adaptation to another are caused by different mutations. Antagonistic pleiotropy arises from trade-offs, such that the same mutations that are beneficial in one environment are detrimental in another. In general, it is difficult to distinguish between these processes(5-8). We analysed the decay of unused catabolic functions in 12 lines of Escherichia coli propagated on glucose for 20,000 generations(9,10). During that time, several lines evolved high mutation rates(11). If mutation accumulation is important, their unused functions should decay more than the other lines, but no significant difference was observed. Moreover, most catabolic losses occurred early in the experiment when beneficial mutations were being rapidly fixed, a pattern predicted by antagonistic pleiotropy. Thus, antagonistic pleiotropy appears more important than mutation accumulation for the decay of unused catabolic functions in these populations.