Phylogenetic relationships of yellowjackets inferred from nine loci (Hymenoptera: Vespidae, Vespinae, Vespula and Dolichovespula).

Eusociality has arisen repeatedly and independently in the history of insects, often leading to evolutionary success and ecological dominance. Eusocial wasps of the genera Vespula and Dolichovespula, or yellowjackets, have developed advanced social traits in a relatively small number of species. The origin of traits such as effective paternity and colony size has been interpreted with reference to an established phylogenetic hypothesis that is based on phenotypic data, while the application of molecular evidence to phylogenetic analysis within yellowjackets has been limited. Here, we investigate the evolutionary history of yellowjackets on the basis of mitochondrial and nuclear markers (nuclear: 28S, EF1α, Pol II, and wg; mitochondrial: 12S, 16S, COI, COII, and Cytb). We use these data to test the monophyly of yellowjackets and species groups, and resolve species-level relationships within each genus using parsimony and Bayesian inference. Our results indicate that a yellowjacket clade is either weakly supported (parsimony) or rejected (Bayesian inference). However, the monophyly of each yellowjacket genus as well as species groups are strongly supported and concordant between methods. Our results agree with previous studies regarding the monophyly of the Vespula vulgaris group and the sister relationship between the V. rufa and V. squamosa groups. This suggests convergence of large colony size and high effective paternity in the vulgaris group and V. squamosa, or a single origin of both traits in the most recent common ancestor of all Vespula species and their evolutionary reversal in the rufa group.