Data from: An evaluation of the hybrid speciation hypothesis for Xiphophorus clemenciae based on whole genome sequences

Once thought rare in animal taxa, hybridization has been increasingly recognized as an important and common force in animal evolution. In the past decade, a number of studies have suggested that hybridization has driven speciation in some animal groups. We investigate the signature of hybridization in the genome of a putative hybrid species, Xiphophorus clemenciae, through whole genome sequencing of this species and its hypothesized progenitors. Based on analysis of this data, we find that X. clemenciae is unlikely to have been derived from admixture between its proposed parental species. However, we find significant evidence for recent gene flow between Xiphophorus species. Though we detect genetic exchange in two pairs of species analyzed, the proportion of genomic regions that can be attributed to hybrid origin is small, suggesting that strong behavioral pre-mating isolation prevents frequent hybridization in Xiphophorus. The direction of gene flow between species supports a role for sexual selection in mediating hybridization.曾被认为在动物分类类群中较为罕见的杂交（hybridization）现象，如今愈发被视为动物演化进程中一种重要且普遍的驱动力。在过去十年间，多项研究表明杂交曾推动了部分动物类群的物种形成。本研究通过对推定杂交物种剑尾鱼Xiphophorus clemenciae及其推测亲本物种开展全基因组测序，探究其基因组中留存的杂交信号。基于上述数据分析，我们发现X. clemenciae不太可能由其推定亲本物种的遗传混合演化而来。但我们却找到了剑尾鱼属（Xiphophorus）物种间近期发生基因流的显著证据。尽管我们在分析的两对物种中检测到了遗传交换，但可归因于杂交起源的基因组区域占比极低，这表明剑尾鱼属物种间存在较强的行为型交配前隔离机制，从而阻止了频繁的杂交事件。物种间的基因流方向，也佐证了性选择在介导杂交过程中发挥的作用。