Data from: 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 linkage relationships and the linear arrangement of loci along a chromosome, and the amount of hybridization following the formation of a hybrid zone. These results highlight how understanding the nature of selection, aspects of the genetics of traits affecting fitness, and the strength of reproductive isolation between hybridizing taxa can all be used to inform when we expect to observe homoploid hybrid speciation due to symmetrical incompatibilities.

尽管已有同倍体杂交物种（homoploid hybrid species）的相关报道，但阐明同倍体杂交物种形成（homoploid hybrid speciation）的发生时机、场景与机制的理论研究仍相对匮乏。本文探讨了不同选择与遗传情境下，由“对称不相容性（symmetrical incompatibilities）”引发的同倍体杂交物种形成概率。本研究通过模拟实验，探究了遗传架构（genetic architecture）与作用于非不相容性产生性状的选择二者如何交互，影响杂种与其亲本物种演化出对称不相容性的概率。不出所料，对与不相容性产生位点连锁的适应性位点（adaptive loci）处的基因渗入施加选择抑制，往往会降低演化出对称不相容性的概率。与之相反，对适应性位点处的杂交基因型施加选择偏好，则可促进对称不相容性的演化。上述效应的强度受选择强度、遗传架构的相关特征（如连锁关系与位点在染色体上的线性排布），以及杂交带（hybrid zone）形成后的杂交总量所影响。本研究结果表明，明晰选择的本质、影响适合度（fitness）的性状遗传学特征，以及杂交类群间的生殖隔离（reproductive isolation）强度，均可用于预判对称不相容性引发的同倍体杂交物种形成的观测时机。