Data from: Genetic divergence and the number of hybridizing species affect the path to homoploid hybrid speciation

Hybridization is often maladaptive, and in some instances has led to the loss of biodiversity. However, hybridization can also promote speciation, such as during homoploid hybrid speciation, thereby generating biodiversity. Despite examples of homoploid hybrid species, the importance of hybridization as a speciation mechanism is still widely debated, and we lack a general understanding of the conditions most likely to generate homoploid hybrid species. Here we show that the level of genetic divergence between hybridizing species has a large effect on the probability that their hybrids evolve reproductive isolation. We find that populations of hybrids formed by parental species with intermediate levels of divergence were more likely to mate assortatively, and discriminate against their parental species, than those generated from weakly or strongly diverged parental species. Reproductive isolation was also found between hybrid populations, suggesting differential sorting of parental traits across populations. Finally, hybrid populations derived from three species were more likely to evolve reproductive isolation than those derived from two, supporting arguments that hybridization-supplied genetic diversity can lead to the evolution of novel "adaptive systems" and promote speciation. Our results illustrate when we expect hybridization and admixture to promote hybrid speciation. Whether homoploid hybrid speciation is a common speciation mechanism in general, remains an outstanding empirical question.Dataset_S1-mate_countsData table listing the parental species used to generate a population of hybrids and the number of males that received matings during mate-choice experiments conducted en masse. The column "hyb_mate" gives the number of hybrid males from the same population as the females in a given experiment that females mated with. Each row reports the matings of a single hybrid population of females at 10 generations after the initial cross. Additional columns report results from statistical tests reported in the main text.Dataset_S1.csvDataset_S2-hybrid-v-hybrid-mate-countsMate counts for populations of admixed Drosophila given the choice to mate with males of their parental species, males from their same population, or males from an independent population derived from the same parental cross. Integers given in columns labeled "hybrid_1" and "hybrid_2" are used as identifiers of the hybrid population used in a given mate-choice experiment. Each row represents a single mate-choice experiment conducted en masse. Data are presented in Figure 2 of the main text.Dataset_S2.txtDataset_S3-tri-parental-mate-choiceMate counts for populations of admixed Drosophila produced by crossing three parental species. This data table reports the number matings occurring between hybrid females produced by crossing three parental species ("sp_1", "sp_2", and "sp_3") and each of the three parental male genotypes and hybrid male genotypes. Mating experiments were conducted 10 generations after the initial tri-parental cross. Each line reports mate choices of females from the same population of hybrids. Data are presented in Figure 3 of the main text.Dataset_S3.tx