James Ananthu, Jain Kavita
Theoretical Sciences Unit Jawaharlal Nehru Centre for Advanced Scientific Research Jakkur PO Bangalore 560064 India.
Ecol Evol. 2016 Jan 11;6(3):755-64. doi: 10.1002/ece3.1932. eCollection 2016 Feb.
Although mutations drive the evolutionary process, the rates at which the mutations occur are themselves subject to evolutionary forces. Our purpose here is to understand the role of selection and random genetic drift in the evolution of mutation rates, and we address this question in asexual populations at mutation-selection equilibrium neglecting selective sweeps. Using a multitype branching process, we calculate the fixation probability of a rare nonmutator in a large asexual population of mutators and find that a nonmutator is more likely to fix when the deleterious mutation rate of the mutator population is high. Compensatory mutations in the mutator population are found to decrease the fixation probability of a nonmutator when the selection coefficient is large. But, surprisingly, the fixation probability changes nonmonotonically with increasing compensatory mutation rate when the selection is mild. Using these results for the fixation probability and a drift-barrier argument, we find a novel relationship between the mutation rates and the population size. We also discuss the time to fix the nonmutator in an adapted population of asexual mutators, and compare our results with experiments.
虽然突变驱动着进化过程，但突变发生的速率本身也受到进化力量的影响。我们在此的目的是了解选择和随机遗传漂变在突变率进化中的作用，并且我们在忽略选择性清除的情况下，在处于突变 - 选择平衡的无性种群中探讨这个问题。使用多类型分支过程，我们计算了在一个大型无性突变体种群中一个罕见的非突变体的固定概率，发现当突变体种群的有害突变率较高时，非突变体更有可能固定下来。当选择系数较大时，发现突变体种群中的补偿性突变会降低非突变体的固定概率。但是，令人惊讶的是，当选择作用较弱时，固定概率会随着补偿性突变率的增加而非单调变化。利用这些关于固定概率的结果和一个漂移障碍论点，我们发现了突变率与种群大小之间的一种新关系。我们还讨论了在一个适应的无性突变体种群中固定非突变体所需时间，并将我们的结果与实验进行比较。
