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Female Polistes paper wasps can initiate colonies either solitarily or in cooperative groups. Reproduction is often distributed unequally in groups, even to the point of complete monopolization of breeding by the dominant group member. Transactional models of reproductive skew predict the degree of reproductive partitioning, assuming that the dominant controls group membership and will yield a proportion of reproduction to a subordinate as an incentive to stay peacefully in the group. Using a combination of demographic, genetic and morphological data from a population of P. dominulus, we test predictions of ‘classical’ two-person skew models as well as more complex ‘N-person’ models. This is the most comprehensive study of skew in this species to date, and the results generally do not support transactional models. We found no relationship between skew and relatedness for dyads, and complete skew was observed in unrelated groups despite the prediction for this population that such groups should not occur. In contrast to N-person model predictions, group size tended to increase with relatedness. Although we did find the predicted positive correlation between group size and skew for groups of nonrelatives, this relationship was weak. The zone of conflict between the predicted minimum and maximum staying incentives often spans the entire possible range of reproductive skew, suggesting that a ‘tug-of-war’ scenario may be more appropriate than a transactional framework for understanding within-colony dynamics. Overall, our results demonstrate that transactional skew models have little predictive power and are therefore unlikely to yield further insight into Polistes wasp societies. |
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