Cecilia F. Fiorini , Eric de Camargo Smidt, L. Lacey Knowles, Eduardo Leite Borba

Genetic data shows that cryptic hybrids are more common than previously thought and that hybridization and introgression are widespread processes in nature. Regardless of this, studies on hybridization are scarce for the highly speciose Bulbophyllum. The genus presents more than 2,200 species and many examples of recent radiations, in which hybridization is expected to be frequent. Currently, only four natural Bulbophyllum hybrids are recognized, all of them recently described based on morphological evidence. Here we test whether genomic evidence supports the hybrid status of two Neotropical Bulbophyllum species, while also evaluating the impact of this phenomenon on the genomes of the putative parental species. We also evaluate if there is evidence of hybridization among B. involutum and B. exaltatum, sister species that diverged recently. We leverage the power of next-generation sequence data, associated with model-based analysis, for three putative parental species pairs belonging to the Neotropical Bulbophyllum clade. We found evidence of hybridization in all studied systems. Despite the occurrence of hybridization, there are no signs of backcrossing. Because of the high propensity of hybridization across many taxa, the common occurrence of hybridization during the evolutionary history of B. sect. Didactyle means it is time to account for and examine in detail hybridization's evolutionary role in the diversification of these orchids.