Phylogeny and social evolution of the bee-tribe Halictini (Hymenoptera: Halictidae)

The bee-family Halictidae has enormous behavioural diversity, including multiple origins of eusociality, cleptoparasitism, and multiple reversals to solitary behaviour. We use a phylogenetic approach to examine social evolution in the Halictini, which is the largest and most behaviourally diverse tribe. We report results from two datasets; a dataset of seven genes was used to examine the tribal relationships within the Halictidae; and a four gene dataset with over 200 included species was used to examine the relationships within the Halictini. Both parsimony-based and model-based ancestral state reconstruction was used to map the evolution of eusociality onto the phylogeny of the Halictini. The possibility of a single origin of eusocial behaviour in the common ancestor of Halictus and Lasioglossum is discussed.