Effects of Beneficial Mutations in pykF Gene Vary over Time and across Replicate Populations in a Long-Term Experiment with Bacteria.
Effects of Beneficial Mutations in pykF Gene Vary over Time and across Replicate Populations in a Long-Term Experiment with Bacteria.
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DOI：
10.1093/molbev/msx279
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发表时间：
2018-01-01
影响因子：
10.7
通讯作者：
Cooper TF
中科院分区：
文献类型：
--
作者：
Peng F;Widmann S;Wünsche A;Duan K;Donovan KA;Dobson RCJ;Lenski RE;Cooper TF
突变的适应性效应可能取决于它们发生的遗传背景，从而影响进化种群的未来机会。特别是，在群体中固定的突变可能会改变后续突变的选择性利益，从而产生历史偶然性。我们通过关注一个关键代谢基因pykF的突变来研究这些影响，该基因在12个大肠杆菌种群的长期进化实验中独立出现。八种不同的进化非同义突变在转移到祖先中时赋予了近似10%的适应性益处，并且这些益处大于缺失突变所赋予的益处。相比之下，相同的突变具有高度可变的适应性效应，范围从10%到25%，在20,000代的种群中分离出的进化克隆中。将两个突变移入这些进化的克隆中，在给定的克隆中赋予了相似的适应性效应，但克隆之间的效应不同，表明进化的pykF等位基因与每个进化的克隆中积累的其他突变之间的上位相互作用。我们还测量了6个进化的pykF等位基因在它们固定的相同种群中的适应性效应，但在0到50，000代之间的7个时间点。在中间的时间点，健身效果的变化是高的，并下降到一个低水平，在50,000代，当平均健身效果是最低的。我们的研究结果表明，遗传背景的重要性，在确定不同的有益突变的健身效果，即使在同一个基因。
The fitness effects of mutations can depend on the genetic backgrounds in which they occur and thereby influence future opportunities for evolving populations. In particular, mutations that fix in a population might change the selective benefit of subsequent mutations, giving rise to historical contingency. We examine these effects by focusing on mutations in a key metabolic gene, pykF, that arose independently early in the history of 12 Escherichia coli populations during a long-term evolution experiment. Eight different evolved nonsynonymous mutations conferred similar fitness benefits of ∼10% when transferred into the ancestor, and these benefits were greater than the one conferred by a deletion mutation. In contrast, the same mutations had highly variable fitness effects, ranging from ∼0% to 25%, in evolved clones isolated from the populations at 20,000 generations. Two mutations that were moved into these evolved clones conferred similar fitness effects in a given clone, but different effects between the clones, indicating epistatic interactions between the evolved pykF alleles and the other mutations that had accumulated in each evolved clone. We also measured the fitness effects of six evolved pykF alleles in the same populations in which they had fixed, but at seven time points between 0 and 50,000 generations. Variation in fitness effects was high at intermediate time points, and declined to a low level at 50,000 generations, when the mean fitness effect was lowest. Our results demonstrate the importance of genetic context in determining the fitness effects of different beneficial mutations even within the same gene.
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影响因子：
10.7
作者：
Flynn WF;Haldane A;Torbett BE;Levy RM
通讯作者：
Levy RM
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