Phylogeny, antiquity, and niche occupancy of Trinomia (Hymenoptera: Halictidae), an Afrotropical endemic genus of Nomiinae.

Abstract

The Afrotropical region is home to many endemic bee groups, yet almost none have been studied from an integrated, holistic perspective. Among them, the halictid subfamily Nomiinae contains exceptional African diversity with variable distributions and life histories. Here, we combine phylogenomics, molecular dating, and distributional modelling to explore the evolutionary ecology of the genus Trinomia. We analyzed a matrix of 59 species of Nomiinae using ultraconserved element (UCE) and whole genome data, including all six species of Trinomia, and estimated divergence times for the subfamily. We then generated distribution models for all six species of Trinomia using Maximum Entropy models (MaxEnt) and 671 spatial data points. From these methods, we discovered a monophyletic Trinomia with an unexpected sister group relationship to the Asian-endemic genus Gnathonomia, as well as a recent origin of Trinomia in the late Miocene (∼5.8 million years ago). From our results, we found hints of phylogenetic conservatism in distribution among sister-groups of Trinomia, however, our results also highlight the need for additional efforts inventorying, identifying, and sharing data on African bees. This study represents an exemplary first step into studying bee spatial phylogenomics of African endemic bees.