SRA

The genus Nomada Scopoli (Hymenoptera: Apidae) is the largest genus of brood parasitic bees with nearly 800 species found across the globe and in nearly all biogeographic realms except Oceania and Antarctica. There is no previous molecular phylogeny focused on Nomada despite their high species abundance nor is there an official biogeography. Using ultraconserved element (UCE) phylogenomic data, we constructed the first molecular phylogeny for the genus Nomada and tested the previously established 16 species groups. We also estimated divergence dates using fossil calibration points and inferred the origin and diversification of this genus around the globe. Our phylogeny provided support for 14 of the 16 previously established species groups; two species groups were suggested to be one unified group while another group was found to be paraphyletic. All remaining species groups were found to be monophyletic. Historical biogeographic reconstruction indicates that Nomada originated in the Holarctic, but most likely in the Palearctic ~65 Mya. Geodispersal into the southern hemisphere occurred three times; once during the Eocene into the Afrotropics, once during the Oligocene into the Neotropics, and once during the Miocene into Australasia. Geodispersal across the Holarctic was most frequent and occurred repeatedly throughout the Cenozoic era, using the De Geer, Thulean, and the Bering Land Bridges. This is the first instance of a bee using both the Thulean and De Geer land bridges and has implications of how early bee species dispersed throughout the Palearctic in the late Cretaceous and early Paleogene.