Centre National de la Recherche Scientifique (CNRS), UMI 3614, Evolutionary Biology and Ecology of Algae, Roscoff, 29688 France.
Sorbonne Universités, UPMC Université Paris VI, Roscoff, 29680 France.
Genetics. 2017 Dec;207(4):1561-1575. doi: 10.1534/genetics.117.300346. Epub 2017 Oct 2.
Different factors can influence the evolution of the mutation rate of a species: costs associated with DNA replication fidelity, indirect selection caused by the mutations produced (that should generally favor lower mutation rates, given that most mutations affecting fitness are deleterious), and genetic drift, which may render selection acting on weak mutators inefficient. In this paper, we use a two-locus model to compute the strength of indirect selection acting on a modifier locus that affects the mutation rate toward a deleterious allele at a second, linked, locus, in a population undergoing partial selfing or partial clonality. The results show that uniparental reproduction increases the effect of indirect selection for lower mutation rates. Extrapolating to the case of a whole genome with many deleterious alleles, and introducing a direct cost to DNA replication fidelity, the results can be used to compute the evolutionarily stable mutation rate, In the absence of mutational bias toward higher , the analytical prediction fits well with individual-based, multilocus simulation results. When such a bias is added into the simulations, however, genetic drift may lead to the maintenance of higher mutation rates, and this effect may be amplified in highly selfing or highly clonal populations due to their reduced effective population size.
与 DNA 复制保真度相关的成本、突变产生的间接选择（通常应该有利于较低的突变率，因为大多数影响适应性的突变都是有害的），以及遗传漂变，它可能使对弱突变体的选择效率降低。在本文中，我们使用双基因座模型来计算在经历部分自交或部分克隆的种群中，一个修饰基因座对第二个连锁基因座上的有害等位基因的突变率的间接选择强度，该修饰基因座会影响突变率。结果表明，单亲繁殖会增加对较低突变率的间接选择的影响。将结果外推到具有许多有害等位基因的整个基因组，并引入对 DNA 复制保真度的直接成本，可以用来计算进化稳定的突变率。在没有向更高突变率的突变偏向的情况下，分析预测与基于个体的多基因座模拟结果非常吻合。然而，当在模拟中添加这种偏向时，遗传漂变可能导致更高的突变率得以维持，并且由于其有效种群规模较小，这种效应在高度自交或高度克隆的种群中可能会放大。
