Hitchhiking and epistasis give rise to cohort dynamics in adapting populations
Hitchhiking and epistasis give rise to cohort dynamics in adapting populations
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DOI：
10.1073/pnas.1702314114
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发表时间：
2017-08-01
影响因子：
11.1
通讯作者：
Lang, Gregory I.
中科院分区：
文献类型：
--
作者：
Buskirk, Sean W.;Peace, Ryan Emily;Lang, Gregory I.
有益的突变是适应性进化的驱动力。在无性群体中，有益等位基因的鉴定被遗传连锁的搭便车突变的存在所混淆。平行进化实验使得能够识别选择的共同靶标;然而这些靶标固有地富集大靶标大小的基因和大效应的突变。对单个突变的全面研究对于创建有益突变的进化显著谱的现实画面是必要的。在这里，我们使用批量分离的方法来确定实验进化的酵母菌群的11个谱系的有益突变。我们报告说，近80%的检测到的突变没有明显的影响健身和不到1%是有害的。我们确定了31个突变队列中驱动突变和搭便车突变的分布，这些突变组从低频率同步出现，并且彼此紧密跟踪。令人惊讶的是，我们发现三分之一的队列缺乏可识别的驱动突变。此外，我们发现hsl 7和kel 1等位基因之间存在着股内协同上位性，这两个等位基因在一个低频率谱系中共同出现。
Beneficial mutations are the driving force of adaptive evolution. In asexual populations, the identification of beneficial alleles is confounded by the presence of genetically linked hitchhiker mutations. Parallel evolution experiments enable the recognition of common targets of selection; yet these targets are inherently enriched for genes of large target size and mutations of large effect. A comprehensive study of individual mutations is necessary to create a realistic picture of the evolutionarily significant spectrum of beneficial mutations. Here we use a bulk-segregant approach to identify the beneficial mutations across 11 lineages of experimentally evolved yeast populations. We report that nearly 80% of detected mutations have no discernible effects on fitness and less than 1% are deleterious. We determine the distribution of driver and hitchhiker mutations in 31 mutational cohorts, groups of mutations that arise synchronously from low frequency and track tightly with one another. Surprisingly, we find that one-third of cohorts lack identifiable driver mutations. In addition, we identify intracohort synergistic epistasis between alleles of hsl7 and kel1, which arose together in a low-frequency lineage.