Insights into the phylogeny and biogeography of the cleptoparasitic bee genus Nomada

The cleptoparasitic bee genus Nomada (Hymenoptera: Apidae) is the most diverse lineage of cleptoparasitic bees and is found on every continent except Antarctica. Previous morphological work of the genus established 16 distinct species groups, however the validity of these groups has not been confirmed using molecular data. Additionally, there are two competing hypotheses regarding the biogeography of the Nomada: one suggesting an origin in South America and another suggesting a South African origin. Neither of these hypotheses have been formally tested. Using molecular techniques, we 1) tested the validity of the previously established 16 species groups, 2) use fossil calibration points to establish the age, and 3) use ancestral state reconstruction to infer the biogeography of Nomada. Ultraconserved elements (UCEs) are used to construct a phylogenetic tree representing each of the 16 species group and cover every ecoregion for biogeographic analyses. These data support 15 of the 16 formerly established species groups and suggests the need for revision of the remaining group. Here we present the first molecular phylogeny and historical biogeography for the Nomada. These results provide an important foundation for understanding their diversification and will be invaluable for future studies examining host-parasite relationships.