The evolution of recombination in a heterogeneous environment.
The evolution of recombination in a heterogeneous environment.
复制标题
异质环境中重组的演变。
作者：
T. Lenormand;S. Otto
大多数描述重组进化的模型都集中在单一种群的情况下，隐含地假设所有个体都有同样的交配可能性，并且选择中不存在空间异质性。在这些模型中，重组的进化是由上位选择或漂变产生的连锁不平衡驱动的。基于上位性选择的模型表明，如果上位性与定向选择相比是负的和弱的，并且如果重组修饰基因座与所选择的基因座紧密连锁，则重组可以是有利的。在这篇文章中，我们研究了选择和上位性的空间异质性对重组进化的联合影响。在一个模型中，两个补丁，每个受到不同的选择制度，我们考虑的情况下，突变选择和迁移选择的平衡，以及传播的有益等位基因。我们发现，包括空间异质性扩大了上位性的范围，重组可以得到青睐。事实上，重组可以是有利的，没有上位性，负上位性，甚至正上位性取决于环境条件。作用在重组修饰基因座上的选择压力往往随着空间异质性而增强，甚至松散连锁的修饰基因和自由连锁也可能进化。在每种情况下，预测重组是否有利需要了解环境异质性和上位性的类型，因为单独这些因素都不足以预测结果。
Most models describing the evolution of recombination have focused on the case of a single population, implicitly assuming that all individuals are equally likely to mate and that spatial heterogeneity in selection is absent. In these models, the evolution of recombination is driven by linkage disequilibria generated either by epistatic selection or drift. Models based on epistatic selection show that recombination can be favored if epistasis is negative and weak compared to directional selection and if the recombination modifier locus is tightly linked to the selected loci. In this article, we examine the joint effects of spatial heterogeneity in selection and epistasis on the evolution of recombination. In a model with two patches, each subject to different selection regimes, we consider the cases of mutation-selection and migration-selection balance as well as the spread of beneficial alleles. We find that including spatial heterogeneity extends the range of epistasis over which recombination can be favored. Indeed, recombination can be favored without epistasis, with negative and even with positive epistasis depending on environmental circumstances. The selection pressure acting on recombination-modifier loci is often much stronger with spatial heterogeneity, and even loosely linked modifiers and free linkage may evolve. In each case, predicting whether recombination is favored requires knowledge of both the type of environmental heterogeneity and epistasis, as none of these factors alone is sufficient to predict the outcome.