Research Interests

For thirty years, the motivating central theme of my research program has been to unravel the natural selection foundations of the evolution of insect sociality, with particular emphasis on the wasp family Vespidae. In 2003-04 I was a Fellow of the Wissenschaftskolleg zu Berlin (www.wiko-berlin.de), and during that time I wrote a book that summarizes my work and places it in context amidst the large literature of the field. 

W. D. Hamilton's 3/4-relatedness hypothesis is false, and kin selection as a general paradigm is uninformative with regard to either the phylogenetic history or mechanisms of social evolution. Rejecting behavioral ecology approaches in favor of pursuing mechanisms, I have emphasized a "nutritional scenario" for the evolution of vespid sociality. Components of the scenario include: the nutrient richness of the trophallactic saliva that vespid larvae produce as an appeasement to forestall cannibalism by their mother or other colony adults during times of low colony-level nourishment; differential nourishment of vespid larvae during development, which profoundly affects reproductive potential and, hence, caste differentiation; and the role of haplodiploidy in biasing early brood away from males, which do not work. General features of the evolution of insect sociality include nest sharing by related individuals other than a mated pair, unequal nourishment among nestmates, unequal reproductive competence as a correlate of differential nourishment, and allo-parental brood care ("work") by low nourishment non-reproductives. 

The most important breakthrough in my understanding of the evolution of vespid sociality came during the writing of The Evolution of Social Wasps (more...). I realized that the worker and gyne castes among the brood of a Polistes colony are based on the underlying physiology of non-diapause and diapause as is found widely among insects. The import of this insight is that early brood workers are reproductively active, whereas later brood gynes - commonly called the reproductives - are in reproductive diapause. This means that Polistes offspring do not "choose" to work in order to maximize their inclusive fitness. Instead they are products of their ontogeny combined with the social context into which they emerge, and their behaviors have the consequence of enhancing the fitness of the colony queen that laid the eggs that now are the larvae they care for. Inclusive fitness had nothing whatsoever to do with the origin of such sociality. However, kin selection (in Maynard Smith's original sense - the sense of Darwin's family level selection) is the means whereby adaptive variations among non-reproducing workers can increase in frequency in a population of already-social wasps.

Research collaborations on Polistes metricus are under way with Dr. Gro V. Amdam of Arizona State University, Dr. Gene E. Robinson and his student Dr. Amy Toth of the University of Illinois at Champaign-Urbana, and Dr. Michael Henshaw of McKendree College. In an additional collaboration, Dr. Sydney A. Cameron and her student Heather Hines (and colleagues) have recently completed a molecular phylogeny that includes representatives of all major internal clades of Vespidae. The results are unambiguous: social behavior in wasps currently called Vespidae evolved twice - once in the common ancestor of Polistinae+Vespinae and once in the very distantly related Stenogastrinae.
 


Synoeca septentrionalis  -  Honduras
Photo by James H. Hunt