The relative strength of selection on modifiers of genetic architecture under migration load

Gene flow between populations adapting to differing local environmental conditions creates a \"migration load\" because individuals might disperse to habitats where their survival is low or because they might reproduce with locally maladapted individuals. The amount by which the mean relative population fitness is kept below one creates an opportunity for modifiers of the genetic architecture to spread due to selection. Prior work that separately considered modifiers changing dispersal or recombination rates, or altering dominance or epistasis, has typically focused on the direction of selection rather than its absolute magnitude. We here develop methods to determine the strength of selection on modifiers of the genetic architecture, including modifiers of the dispersal rate, after populations evolved local adaptation. We consider scenarios with up to five loci contributing to local adaptation and derive a matrix model for the deterministic spread of modifiers. We find that selection for ...针对不同局部环境条件产生适应性分化的种群间的基因流（Gene flow）会形成迁移负荷（migration load）：一方面，个体可能扩散至自身存活率较低的生境；另一方面，它们可能与局部适应性欠佳的个体进行交配繁殖。种群平均相对适合度被压制在1以下的程度，为遗传架构（genetic architecture）修饰因子通过选择实现传播创造了契机。以往研究中，针对改变扩散率（dispersal rate）、重组率（recombination rates），或调控显性（dominance）与上位性（epistasis）的修饰因子所开展的分析，通常仅聚焦于选择的作用方向，而非其绝对强度。本文提出了一套方法，用以确定种群完成局部适应性演化后，遗传架构修饰因子所受的选择强度，其中涵盖扩散速率修饰因子。我们构建了至多包含5个参与局部适应性分化的基因座（loci）的研究场景，并推导了修饰因子确定性传播的矩阵模型（matrix model）。研究发现，针对……的选择作用……