Department of Theoretical Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany.
PLoS Comput Biol. 2023 Sep 1;19(9):e1011387. doi: 10.1371/journal.pcbi.1011387. eCollection 2023 Sep.
Evolutionary dynamics in spatially structured populations has been studied for a long time. More recently, the focus has been to construct structures that amplify selection by fixing beneficial mutations with higher probability than the well-mixed population and lower probability of fixation for deleterious mutations. It has been shown that for a structure to substantially amplify selection, self-loops are necessary when mutants appear predominately in nodes that change often. As a result, for low mutation rates, self-looped amplifiers attain higher steady-state average fitness in the mutation-selection balance than well-mixed populations. But what happens when the mutation rate increases such that fixation probabilities alone no longer describe the dynamics? We show that self-loops effects are detrimental outside the low mutation rate regime. In the intermediate and high mutation rate regime, amplifiers of selection attain lower steady-state average fitness than the complete graph and suppressors of selection. We also provide an estimate of the mutation rate beyond which the mutation-selection dynamics on a graph deviates from the weak mutation rate approximation. It involves computing average fixation time scaling with respect to the population sizes for several graphs.
长期以来，人们一直在研究具有空间结构的种群的进化动态。最近，人们的关注点集中在构建能够通过更高的概率固定有益突变，同时降低有害突变固定概率的结构上，从而放大选择的力度。已经表明，当突变体主要出现在经常变化的节点时，自我循环是必要的，以便结构能够显著放大选择。因此，在低突变率下，自我循环放大器在突变-选择平衡中达到比混合种群更高的稳态平均适应度。但是，当突变率增加到仅固定概率不再描述动力学时会发生什么？我们表明，在低突变率范围之外，自我循环的影响是有害的。在中高突变率范围内，选择放大器的稳态平均适应度低于完全图和选择抑制剂。我们还提供了一个突变率的估计值，超过该值后，图上的突变-选择动力学将偏离弱突变率近似值。这涉及到计算几个图的平均固定时间与种群大小的关系。
