High-resolution mapping reveals hundreds of genetic incompatibilities in hybridizing fish species

Hybridization is increasingly being recognized as a common process in both animal and plant species. Negative epistatic interactions between genes with different parental ancestry decrease the fitness of hybrids and can limit gene flow between species. However, little is known about the number and genome-wide distribution of genetic incompatibilities separating species. To detect interacting genes, we perform a detailed genome scan for linkage disequilibrium between unlinked genomic regions in naturally occurring hybrid populations of swordtail fish. We estimate that hundreds of pairs of genomic regions contribute to reproductive isolation between these species, despite them being recently diverged. Many of these incompatibilities are likely the result of natural or sexual selection on hybrids, since intrinsic isolation is known to be weak. Patterns of genomic divergence at these regions imply that genetic incompatibilities play a significant role in limiting gene flow even in young sp...

杂交（Hybridization）正日益被公认为动植物类群中普遍存在的演化过程。来自不同亲本血统的基因间所产生的负向上位性互作，会降低杂交个体的适合度，并可限制物种间的基因交流。然而，目前学界对分隔不同物种的遗传不相容性的数量及其全基因组分布格局仍所知甚少。为了检测存在互作的基因，我们针对剑尾鱼（swordtail fish）自然杂交种群中未连锁基因组区域间的连锁不平衡（linkage disequilibrium）开展了精细全基因组扫描。尽管这些物种的分化时间较近，我们估算仍有数百对基因组区域参与了这两个物种间的生殖隔离形成。由于已知这两个物种的内在生殖隔离强度较弱，因此这类遗传不相容性大多可能是杂交个体经受自然选择或性选择后的演化结果。这些区域的基因组分化模式表明，即便在分化较新的物种类群中，遗传不相容性也对阻碍基因交流发挥着重要作用。