Prof. Raghavendra Gadagkar
INSA SN Bose Research Professor and JC Bose National Fellow, Centre for Ecological Sciences, and Chairman, Centre for Contemporary Studies, IISc, Bangalore; Evolutionary and Organismic Biology Unit Honorary Professor, JNCASR, bangalore http://ces.iisc.ern

In social insect colonies one or a small group of individuals (queen/s) monopolize reproduction and the remaining (workers) perform various tasks required for the welfare of the colony and successful reproduction by the queens. The evolution by natural selection of such altruist behaviour on the part of workers remains a major unsolved problem in Evolutionary Biology. Hamilton's rule (inclusive fitness or kin selection theory) provides a powerful conceptual framework for investigations of this phenomena. Primitively eusocial polistine wasps provide an equally powerful model system for empirical investigations. Theoretical and empirical studies using the primitively eusocial wasp Ropalidia marginata suggests a weak role for asymmetries in genetic relatedness but strong roles for ecological, physiological and demographic factors in the evolution of cooperative nesting and altruism. We also have evidence now that genetic relatedness plays no role when wasps choose their queens. A simultaneous consideration of genetic, ecological, physiological and demographic factors that influence the inclusive fitnesses of solitary nest foundresses and workers, permits the prediction that only about 5.1% of the individuals in a population should prefer the solitary nesting strategy. In striking confirmation of this prediction, empirical investigations demonstrate that 4.6 to 5.7% of R. marginata females choose to initiate single foundress nests and 92.5 to 94% choose to nest in groups. So we think we understand why the wasps nest in groups and why most of them behave altruistically. But of course there is more to it than that…