Bivoltinism as an antecedent to eusociality in the paper wasp genus Polistes

To learn the evolutionary trajectories of caste differentiation in eusocial spe-cies is a major goal of sociobiology. We present an explanatory framework for caste evolution in the eusocial wasp genus Polistes (Vespidae), which is a model system for insect eusocial evolution. We hypothesize that Polistes worker and gyne castes stem from two developmental pathways that characterized the bivoltine life cycle of a solitary ancestor. Through individual-based simu-lations, we show that our mechanistic framework can reproduce colony-level characteristics of Polistes and, thereby, that social castes can emerge from solitary regulatory pathways. Our explanatory framework illustrates, by spe-cific example, a changed perspective for understanding insect social evolution. The essence of eusociality in Polistes wasps is the differentiation of female offspring into two castes: nonreproductive females that work in their natal colony and reproductive gynes that found colonies in the next nesting cycle (1)