Cooperation with and without genetic relatedness in Polistes wasps
Some of the major evolutionary transitions have occurred through selection for cooperative alliances. Those based on cooperation among relatives are quite different from those based on cooperation among unrelated entities, pointing to the overriding importance of genetic structure. The paper wasp, Polistes dominulus, is very unusual in having groups founded cooperatively both by relatives and by non-relatives. It therefore provides an excellent system for studying how kinship, or the lack of it, affects the evolution of cooperation.
The study employs a combination of field work and assessment of genetic structure using seven DNA microsatellite loci. We propose to ask and answer three principal questions about the evolution of cooperation in Polistes dominulus. First, since unrelated subordinate foundresses do not gain indirect inclusive fitness benefits, what kinds of direct reproductive benefits do they obtain? Second, how does kinship alter the nature of cooperation in foundress associations; that is, how do associations of related foundresses differ from those of unrelated foundresses? We will test hypotheses that they differ in the partitioning of direct reproduction, in the degree of fighting, and in the degree of cooperation. Third, we will determine the effects of having unrelated subordinates on the subsequent genetic structure of the colony, and test how this altered genetic structure affects conflicts of interests over queen succession and the laying of male eggs.
Besides providing unique results on the effect of kinship on cooperation, these studies will also address questions of reproductive control that are crucial to understanding the functioning of cooperative societies. The comparison of reproductive partitioning in related and unrelated foundresses groups provides a critical test of two control alternatives for small societies: Does the dominant foundress completely control the association or is it a tug-of-war among the foundresses? The studies of queen succession and laying of male eggs will provide unusually strong tests of who controls reproduction in larger groups. Specifically, they will test whether the largest group, the workers, can collaborate to exercise collective control.