Phylogenomic analysis of yellowjackets and hornets (Hymenoptera, Vespidae)

The Vespidae is a family of wasps exhibiting solitary and social phenotypes and thus a useful system for studying genes that might have evolved novel roles linked to sociality. Within the Vespidae, hornets and yellowjackets are all social and show considerable diversity in their behavior. According to the traditional phylogenetic hypothesis, the yellowjackets are monophyletic and sister to the hornets. Recent genetic evidence, however, contradicts or fails to support the traditional phylogenetic hypothesis. Here, we test for the first time the genus-level relationships of hornets and yellowjackets using a phylogenomic approach. We sampled six species and sequenced their transcriptomes to conduct a phylogenetic analysis. Moreover, we included three additional hymenopteran transcriptomes from a published data set. We identified 1000 putative orthologs present in all nine taxa. Orthologs were concatenated into a supermatrix (596,004 aligned sites) and analyzed using ML. Our results robustly reject the traditional view and instead place hornets within yellowjackets, rendering the latter paraphyletic. The results of this phylogenomic study will be the foundation for future studies of molecular evolution across solitary and social lifestyles in the Vespidae.