Data from: Variable postzygotic isolation in Drosophila melanogaster/D. simulans hybrids

The study of hybrid inviability reveals cryptic divergence between the genetic interactions that maintain stable phenotypes in the pure species. We characterized the effects of natural variation on the penetrance of hybrid inviability phenotypes in crosses between Drosophila melanogaster and two species of the D. simulans subcomplex, D. simulans and D. sechellia. Using a panel of wild-caught lines, we studied the levels of genetic variance present in D. simulans and D. sechellia affecting prezygotic and postzygotic isolation in hybridizations with D. melanogaster females. We observed extensive variability in the viability of hybrid individuals, dependent on the genotype of the parents, suggesting that intraspecific natural variation manifests directly in hybrid phenotypes. Furthermore, we found that genetic background significantly affects the penetrance of a well studied determinant of hybrid inviability: the interaction between Hmrmel–Lhrsim. Our results suggest that hybrid inviability—and reproductive isolation generally—can be modified by polymorphisms at multiple loci segregating within the parental species. Just as the penetrance of most mutant phenotypes can be modified by the genetic background within the pure species, the penetrance of hybrid inviability phenotypes is highly influenced by the parental genotypes.

针对杂种致死（hybrid inviability）的研究，揭示了纯种物种内维持稳定表型的遗传互作网络中存在隐秘分化。本研究以黑腹果蝇（Drosophila melanogaster）与拟暗果蝇亚组（D. simulans subcomplex）的两个物种——拟暗果蝇（D. simulans）和塞氏果蝇（D. sechellia）——的杂交组合为研究对象，解析了自然变异对杂种致死表型外显率（penetrance）的影响。我们借助一组野生捕获品系，探究了拟暗果蝇与塞氏果蝇中，影响其与黑腹果蝇雌性交配时合子前生殖隔离（prezygotic isolation）与合子后生殖隔离（postzygotic isolation）的遗传变异水平。研究发现，杂种个体的存活力存在广泛变异，且该变异取决于亲本基因型，这表明种内自然变异可直接体现在杂种表型中。此外，我们还发现遗传背景可显著影响一个已被广泛研究的杂种致死决定因子——Hmrmel与Lhrsim的互作——的外显率。本研究结果表明，杂种致死——以及广义上的生殖隔离——可被亲本物种内多个分离位点的多态性所修饰。正如多数突变表型的外显率可被纯种物种内的遗传背景所修饰，杂种致死表型的外显率也极大程度上受亲本基因型的影响。