Evolutionary and biogeographic history of bees from the tribe Emphorini (Hymenoptera: Apidae)

Emphorines are solitary ground-nesting bees restricted to the Western Hemisphere with an antitropical distribution, i.e. they are present in North and South America, but there are fewer representatives in the tropics (Freitas et al., 2022). This tribe comprises 107 described species in nine genera, and shows its higher diversity in dry regions of South America (Roig-Alsina, 1998). One of their most distinctive features is their strong floral specialization, primarily visiting plants from the families Malvaceae, Convolvulaceae, Cactaceae, Zygophyllaceae, Portulacaceae, and Onagraceae (Roig Alsina 1998, Sipes & Tepedino 2005). While previous studies have suggested a South American origin for the tribe and at least four dispersal events into North America (Freitas et al., 2022), their limited taxon sampling has left important gaps in our understanding of their evolutionary history. In this study, we aimed to test whether patterns of diversification and biogeography are related to their specialized pollen diets. We reconstructed the most comprehensive phylogeny of the group to date using ultra-conserved elements (UCEs) from 85 species. Our results provide new insights into divergence times and biogeographic patterns of these highly specialized bees and contribute to a deeper understanding of their evolutionary history.