Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich 8057, Switzerland.
Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK.
Genetics. 2022 Jan 4;220(1). doi: 10.1093/genetics/iyab205.
Both pleiotropic connectivity and mutational correlations can restrict the decoupling of traits under divergent selection, but it is unknown which is more important in trait evolution. To address this question, we create a model that permits within-population variation in both pleiotropic connectivity and mutational correlation, and compare their relative importance to trait evolution. Specifically, we developed an individual-based stochastic model where mutations can affect whether a locus affects a trait and the extent of mutational correlations in a population. We find that traits can decouple whether there is evolution in pleiotropic connectivity or mutational correlation, but when both can evolve, then evolution in pleiotropic connectivity is more likely to allow for decoupling to occur. The most common genotype found in this case is characterized by having one locus that maintains connectivity to all traits and another that loses connectivity to the traits under stabilizing selection (subfunctionalization). This genotype is favored because it allows the subfunctionalized locus to accumulate greater effect size alleles, contributing to increasingly divergent trait values in the traits under divergent selection without changing the trait values of the other traits (genetic modularization). These results provide evidence that partial subfunctionalization of pleiotropic loci may be a common mechanism of trait decoupling under regimes of corridor selection.
无论是多效性连接还是突变相关都可以限制在分歧选择下的性状解耦，但哪种因素在性状进化中更重要尚不清楚。为了解决这个问题，我们创建了一个模型，允许在种群内同时存在多效性连接和突变相关的变化，并比较它们对性状进化的相对重要性。具体来说，我们开发了一种基于个体的随机模型，其中突变可以影响一个基因座是否影响一个性状以及群体中突变相关的程度。我们发现，无论多效性连接还是突变相关发生进化，性状都可以解耦，但当两者都可以进化时，多效性连接的进化更有可能允许解耦发生。在这种情况下，最常见的基因型特征是具有一个维持与所有性状连接的基因座和另一个失去与稳定选择下的性状连接的基因座（亚功能化）。这种基因型是有利的，因为它允许亚功能化的基因座积累更大的效应等位基因，导致在分歧选择下的性状值越来越发散，而不改变其他性状的性状值（遗传模块化）。这些结果提供了证据表明，多效性基因座的部分亚功能化可能是走廊选择下性状解耦的一种常见机制。
