Ultraconserved element phylogenomics and biogeography of the agriculturally important mason bee subgenus Osmia (Osmia)

One of the most important non-Apis groups of bees for agriculture is the mason bee subgenus Osmia Panzer (Osmia), or Osmia s.s. (Hymenoptera: Megachilidae). Out of the 29 known species, four have been developed as managed pollinators of orchards. In addition, the group is important as a source of non-native pollinators, given that several species have been introduced into new areas. Osmia s.s. occurs naturally throughout the northern temperate zone with greatest species richness in Europe and Asia. Here, we integrate phylogenomic data from ultraconserved elements (UCEs), near complete taxon sampling, and a diversity of analytical approaches to infer the phylogeny, divergence times and biogeographic history of Osmia s.s. We also demonstrate how mitochondrial sequence data can be extracted from ultraconserved element data and combined with sequences from public repositories in order to test the phylogeny, examine species boundaries and identify specimen-associated, non-bee DNA. We resolve the phylogeny of Osmia s.s. and show strong support that Nearctic Osmia ribifloris is the sister group to the rest of the subgenus. Biogeographic analyses indicate that the group originated during the Late Miocene in the West Nearctic plus East Palearctic region following dispersal from the East Palearctic to the West Nearctic across the Bering land bridge prior to its closure 5.5–4.8 Ma. The mitochondrial DNA results reveal potential taxonomic synonymies involving Osmia yanbianensis and Osmia opima, and Osmia rufina, Osmia rufinoides and Osmia taurus.