Phylogeny of the carpenter bees (Apidae: Xylocopinae) highlights repeated evolution of sociality. Xylocopinae

The carpenter bees, subfamily Xylocopinae, are a diverse clade including over 1000 species distributed around the world. These bees exhibit a wide range of social behaviours, from solitary life to obligate eusociality with distinct morphological castes, making them ideal focal taxa in studying the evolution of sociality. We used ultraconserved element data to generate a broadly-sampled phylogeny of the Xylocopinae, including several newly sequenced species. We then conducted ancestral state reconstructions on the evolutionary history of sociality in this group under multiple coding models. Our results indicate solitary origins for the Xylocopinae with at least three transitions to sociality across the tree and up to five reversals, demonstrating the lability and dynamic nature of social evolution in carpenter bees. Ultimately, this work clarifies the evolutionary history of the Xylocopinae, and expands our understanding of independent origins and gains and losses of social complexity across the social insects.