标题： 死亡-出生更新图上的选择增强器和固定减少器 显示英文标题

标题： Transient amplifiers of selection and reducers of fixation for death-Birth updating on graphs

摘要： 进化种群的空间结构影响哪些突变会被固定。 一些结构会增强选择作用，增加有益突变被固定的可能，而有害突变则不会。 其他结构会抑制选择作用，降低适应度差异的影响，并增加随机性的作用。 这一现象可以通过将空间结构表示为图来建模，其中个体占据顶点。 出生和死亡是按照指定的更新规则以随机方式发生的。 我们研究的是死亡-出生更新：一个个体被选中死亡，然后其邻居竞争在空位上繁殖。 之前的数值实验表明，对于这个过程的选择增强器要么很少，要么不存在。 我们为弱选择条件下的这个问题引入了一种微扰方法，即突变具有较小的适应度效应。 我们证明，在弱选择下，固定概率可以表示为随机游走的共轭时间。 这一结果自然地引出了有效种群大小的新定义。 利用这种方法和其他方法，我们发现了死亡-出生过程中已知的第一个瞬时选择增强器的例子（在特定适应度值范围内增强选择的图）。 我们还展示了新的“固定减少者”家族，这些家族会降低所有突变的固定概率，无论是有益还是有害的。 显示英文摘要

摘要： The spatial structure of an evolving population affects which mutations become fixed. Some structures amplify selection, increasing the likelihood that beneficial mutations become fixed while deleterious mutations do not. Other structures suppress selection, reducing the effect of fitness differences and increasing the role of random chance. This phenomenon can be modeled by representing spatial structure as a graph, with individuals occupying vertices. Births and deaths occur stochastically, according to a specified update rule. We study death-Birth updating: An individual is chosen to die and then its neighbors compete to reproduce into the vacant spot. Previous numerical experiments suggested that amplifiers of selection for this process are either rare or nonexistent. We introduce a perturbative method for this problem for weak selection regime, meaning that mutations have small fitness effects. We show that fixation probability under weak selection can be calculated in terms of the coalescence times of random walks. This result leads naturally to a new definition of effective population size. Using this and other methods, we uncover the first known examples of transient amplifiers of selection (graphs that amplify selection for a particular range of fitness values) for the death-Birth process. We also exhibit new families of "reducers of fixation", which decrease the fixation probability of all mutations, whether beneficial or deleterious.