Scientists at the University of Illinois have conducted a genetic analysis of vespid wasps that revises the vespid family tree and challenges long-held views about how the wasps social behaviors evolved.
In the study, published in the Feb. 21 Proceedings of the National Academy of Sciences, the researchers found genetic evidence that eusociality (the reproductive specialization seen in some insects and other animals) evolved independently in two groups of vespid wasps.
These findings contradict an earlier model of vespid wasp evolution, which placed the groups together in a single lineage with a common ancestor.
Eusocial behavior is quite rare, and generally involves the breeding of different reproductive classes within a colony. The sterile members of the group perform tasks that support their fertile counterparts. Eusociality occurs in only a few species of insects, rodents, crustaceans and other arthropods.
The evolution of eusociality in wasps has long been a source of debate, said U. of I. entomology graduate student Heather Hines and entomology professor Sydney Cameron, who is the principal investigator of the study. A prior model of vespid wasp evolution placed three subfamilies of wasps the Polistinae, Vespinae and Stenogastrinae together in a single evolutionary group with a common ancestor. This model did not rely on a genetic analysis of the wasps, but instead classified them according to several physical and behavioral traits.
Camerons team included University of Missouri biology professor James H. Hunt, an expert on the evolution of social behavior in the vespid wasps. Hunt observed that many behavioral characteristics of the vespid wasps contradicted this model of the vespid family tree.
Hunts observations, along with those of other behavioral experts in the field, prompted the new analysis.