Comeault Aaron A
Biology Department University of North Carolina Chapel Hill NC USA.
Ecol Evol. 2018 Feb 14;8(5):2926-2937. doi: 10.1002/ece3.3872. eCollection 2018 Mar.
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.
尽管存在同倍体杂交物种的实例，但描述我们预期同倍体杂交物种形成的时间、地点和方式的理论研究仍然相对较少。在这里，我探讨了在不同的选择和遗传情景下，由于“对称不相容性”导致同倍体杂交物种形成的可能性。通过模拟，我测试了基因结构以及作用于本身不会产生不相容性的性状的选择如何相互作用，以影响杂种与其亲本物种进化出对称不相容性的概率。不出所料，在与产生不相容性的位点连锁的“适应性”位点上对混合的选择往往会降低进化出对称不相容性的概率。相比之下，在适应性位点上有利于混合基因型的选择可以促进对称不相容性的进化。这些结果的程度受到选择强度、基因结构方面（如连锁关系和位点沿染色体的线性排列）以及杂交区域形成后的杂交量的影响。这些结果凸显了理解选择的本质、影响适应性的性状的遗传方面以及杂交类群之间生殖隔离的强度如何都可用于判断我们何时预期会观察到由于对称不相容性导致的同倍体杂交物种形成。
