Data from: Genomic regions with a history of divergent selection affect fitness of hybrids between two butterfly species

Speciation is the process by which reproductively isolated lineages arise, and is one of the fundamental means by which the diversity of life increases. Whereas numerous studies have documented an association between ecological divergence and reproductive isolation, relatively little is known about the role of natural selection in genome divergence during the process of speciation. Here we use genome-wide DNA sequences and Bayesian models to test the hypothesis that loci under divergent selection between two butterfly species (Lycaeides idas and L. melissa) also affect fitness in an admixed population. Locus-specific measures of genetic differentiation between L. idas and L. melissa and genomic introgression in hybrids varied across the genome. The most differentiated genetic regions were characterized by elevated L. idas ancestry in the admixed population, which occurs in L. idas-like habitat, consistent with the hypothesis that local adaptation contributes to speciation. Moreover, locus-specific measures of genetic differentiation (a metric of divergent selection) were positively associated with extreme genomic introgression (a metric of hybrid fitness). Interestingly, concordance of differentiation and introgression was only partial. We discuss multiple, complementary explanations for this partial concordance.物种形成（Speciation）是指生殖隔离类群产生的过程，亦是生命多样性提升的核心途径之一。尽管已有诸多研究证实生态分化与生殖隔离之间存在关联，但学界对于自然选择在物种形成过程中推动基因组分化的作用仍所知有限。本研究采用全基因组DNA序列（genome-wide DNA sequences）与贝叶斯模型（Bayesian models），检验如下假说：两种蝴蝶——灰蝶属Lycaeides idas与L. melissa之间受趋异选择的基因座，在杂交种群中同样会影响个体适合度。Lycaeides idas与L. melissa之间的基因座特异性遗传分化指标，以及杂种的基因组渐渗（genomic introgression）水平在全基因组范围内存在异质性。分化程度最高的遗传区域，在该杂交种群中呈现出更高的Lycaeides idas祖先组分占比；该杂交种群生存于类似Lycaeides idas的生境中，这与“局部适应促进物种形成”的假说相符。此外，基因座特异性遗传分化指标（趋异选择的量化指标）与极端基因组渐渗水平（杂交适合度的量化指标）呈显著正相关。值得注意的是，遗传分化与基因组渐渗的一致性仅为部分程度。针对这一部分一致性现象，本研究探讨了多种互补性解释。