Compensatory Evolution and the Origins of Innovations
Compensatory Evolution and the Origins of Innovations
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DOI：
10.1534/genetics.112.148627
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发表时间：
2013-04-01
期刊：
影响因子：
3.3
通讯作者：
Masel, Joanna
中科院分区：
文献类型：
--
作者：
Rajon, Etienne;Masel, Joanna
隐藏的遗传序列对表型的影响减弱。在经典的观点中，宽松的选择允许隐藏的遗传多样性在种群中的个体之间建立，提供等位基因，这些等位基因后来可能有助于适应，例如，在突变之后，从低的、减弱的基线增加表达。这个观点可以用一个比喻来描述，即一个种群在基因型空间中的一个中性网络中的传播。作为另一种观点，考虑大多数表型性状受多个序列影响的事实，包括隐藏的序列。即使在一个严格的克隆群体中，不同基因座上的隐性序列的共同选择也可能产生不同的表型效应，并为群体提供多种适应可能性。在这里，我们模拟的数量表型字符编码的隐藏序列的进化和比较的相对贡献的遗传多样性和变异的跨站点的表型潜力的人口。我们表明，大多数的表型变异，通过选择性将存在，即使在人口没有多态性。这是可能的补偿性进化的历史，其中一个位点的隐性突变的表型效应被基因组中其他地方的突变所平衡，导致不同位点而不是不同个体的隐性效应大小的多样性。隐藏序列可能会加速适应和促进大的表型变化，即使在缺乏遗传多样性，传统上定义的替代等位基因。
Cryptic genetic sequences have attenuated effects on phenotypes. In the classic view, relaxed selection allows cryptic genetic diversity to build up across individuals in a population, providing alleles that may later contribute to adaptation when co-opted-e.g., following a mutation increasing expression from a low, attenuated baseline. This view is described, for example, by the metaphor of the spread of a population across a neutral network in genotype space. As an alternative view, consider the fact that most phenotypic traits are affected by multiple sequences, including cryptic ones. Even in a strictly clonal population, the co-option of cryptic sequences at different loci may have different phenotypic effects and offer the population multiple adaptive possibilities. Here, we model the evolution of quantitative phenotypic characters encoded by cryptic sequences and compare the relative contributions of genetic diversity and of variation across sites to the phenotypic potential of a population. We show that most of the phenotypic variation accessible through co-option would exist even in populations with no polymorphism. This is made possible by a history of compensatory evolution, whereby the phenotypic effect of a cryptic mutation at one site was balanced by mutations elsewhere in the genome, leading to a diversity of cryptic effect sizes across sites rather than across individuals. Cryptic sequences might accelerate adaptation and facilitate large phenotypic changes even in the absence of genetic diversity, as traditionally defined in terms of alternative alleles.