Current Biology has just published what is surely among the most significant papers this year on insect evolutionary relationships:
The importance of the paper derives from a combination of hitting a controversial topic with a much-needed phylogeny, and doing so with a staggering amount of information. The 300 or so genes employed to create the genomic tree is orders of magnitude more data than that used in any previous effort, and the result finally brings clarity to a question that’s been nagging a lot of Hymenopterists: what are the closest relatives of ants?
Probably, bees and spheciform wasps.
That’s not necessarily the relationship I would have guessed, but it holds under multiple modes of analysis.
Here’s the abstract (emphasis mine):
Eusocial behavior has arisen in few animal groups, most notably in the aculeate Hymenoptera, a clade comprising ants, bees, and stinging wasps. Phylogeny is crucial to understanding the evolution of the salient features of these insects, including eusociality. Yet the phylogenetic relationships among the major lineages of aculeate Hymenoptera remain contentious. We address this problem here by generating and analyzing genomic data for a representative series of taxa. We obtain a single well-resolved and strongly supported tree, robust to multiple methods of phylogenetic inference. Apoidea (spheciform wasps and bees) and ants are sister groups, a novel finding that contradicts earlier views that ants are closer to ectoparasitoid wasps. Vespid wasps (paper wasps, yellow jackets, and relatives) are sister to all other aculeates except chrysidoids. Thus, all eusocial species of Hymenoptera are contained within two major groups, characterized by transport of larval provisions and nest construction, likely prerequisites for the evolution of eusociality. These two lineages are interpolated among three other clades of wasps whose species are predominantly ectoparasitoids on concealed hosts, the inferred ancestral condition for aculeates. This phylogeny provides a new framework for exploring the evolution of nesting, feeding, and social behavior within the stinging Hymenoptera.
Source: Brian R. Johnson, Marek L. Borowiec, Joanna C. Chiu, Ernest K. Lee, Joel Atallah, Philip S. Ward (2013) Phylogenomics Resolves Evolutionary Relationships among Ants, Bees, and Wasps. Current Biology, Available online 3 October 2013. http://dx.doi.org/10.1016/j.cub.2013.08.050