The genomic and ecological context of hybridization affects the probability that symmetrical incompatibilities drive hybrid speciation

Despite examples of homoploid hybrid species, theoretical work describing when, where, and how we expect homoploid hybrid speciation to occur remains relatively rare. Here, I explore the probability of homoploid hybrid speciation due to “symmetrical incompatibilities” under different selective and genetic scenarios. Through simulation, I test how genetic architecture and selection acting on traits that do not themselves generate incompatibilities interact to affect the probability that hybrids evolve symmetrical incompatibilities with their parent species. Unsurprisingly, selection against admixture at “adaptive” loci that are linked to loci that generate incompatibilities tends to reduce the probability of evolving symmetrical incompatibilities. By contrast, selection that favors admixed genotypes at adaptive loci can promote the evolution of symmetrical incompatibilities. The magnitude of these outcomes is affected by the strength of selection, aspects of genetic architecture such as ...尽管已存在同倍体杂交物种（homoploid hybrid species）的相关实例，但阐释同倍体杂交物种形成（homoploid hybrid speciation）发生的时机、场景与机制的理论研究仍相对匮乏。本文探究了在不同选择与遗传场景下，由“对称不相容性（symmetrical incompatibilities）”引发的同倍体杂交物种形成概率。通过模拟实验，本文检验了遗传架构（genetic architecture）以及作用于本身不会产生不相容性的性状的选择，如何共同影响杂交种群演化出与亲本物种对称不相容性的概率。不出所料，对与产生不相容性的位点连锁的“适应性位点（adaptive loci）”处的基因渗入（admixture）施加选择抑制，往往会降低杂交种群演化出对称不相容性的概率。与之相反，对适应性位点处的混杂基因型施加选择偏好，则可推动对称不相容性的演化。这些效应的强弱受选择强度、遗传架构的相关特征（如……）影响。