Contrasting dynamics of a mutator allele in asexual populations of differing size.
Contrasting dynamics of a mutator allele in asexual populations of differing size.
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不同大小的无性群体中突变等位基因的动态对比。
DOI：
10.1111/j.1558-5646.2011.01577.x
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Sniegowski,PaulD
中科院分区：
文献类型：
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作者：
Raynes,Yevgeniy;Gazzara,MatthewR;Sniegowski,PaulD
当突变子亚群的预期有益突变供应率NUb（对于大小为N和有益突变率Ub的亚群）超过野生型亚群时，突变子已被证明在无性群体中搭便车。在这里，我们研究了总人口规模的影响，在无性实验群体ofSaccharomycescerevisiae的突变动力学。虽然在较小的群体中，突变体迅速搭便车固定，但随着群体规模的增加，突变体固定需要越来越多的时间;这种观察到的突变体搭便车的延迟与克隆干扰的预期效果一致。有趣的是，尽管它们的有益突变供应率较高，但在非常大的人群中，突变体被野生型取代。我们假设，这种惊人的逆转增变动力学是由克隆干扰，增变基因等位基因的健身成本之间的相互作用，并在我们的实验人群中罕见的大效应有益的突变。因此，我们的工作确定了一组潜在的情况下，可以抑制自然无性种群中的突变体搭便车，尽管最近的理论预测，这样的人口应该有一个净趋势，进化越来越高的基因组突变率。
Mutators have been shown to hitchhike in asexual populations when the anticipated beneficial mutation supply rate of the mutator subpopulation,NUb(for subpopulation of sizeNand beneficial mutation rateUb) exceeds that of the wild-type subpopulation. Here, we examine the effect of total population size on mutator dynamics in asexual experimental populations ofSaccharomyces cerevisiae. Although mutators quickly hitchhike to fixation in smaller populations, mutator fixation requires more and more time as population size increases; this observed delay in mutator hitchhiking is consistent with the expected effect of clonal interference. Interestingly, despite their higher beneficial mutation supply rate, mutators are supplanted by the wild type in very large populations. We postulate that this striking reversal in mutator dynamics is caused by an interaction between clonal interference, the fitness cost of the mutator allele, and infrequent large-effect beneficial mutations in our experimental populations. Our work thus identifies a potential set of circumstances under which mutator hitchhiking can be inhibited in natural asexual populations, despite recent theoretical predictions that such populations should have a net tendency to evolve ever-higher genomic mutation rates.