Meeting Abstract

S9-5  Sunday, Jan. 8 10:00 - 10:30  Not all partners are equal: A role for identity signaling in generating differential cooperative behavior. SHEEHAN, Michael J; Cornell University

The evolution of stable cooperation requires discrimination among potential recipients – either those with shared genotypes or also show cooperative behavior. Discrimination requires diversity in appearance, smell or vocalizations within a population. Thus, the mechanisms that maintain diversity in traits used for recognition are central to understanding the maintenance of costly cooperative behaviors. Paradoxically, models of recognition trait evolution have argued that cooperation leads to positive frequency-dependent selection and the loss of diversity in recognition traits, eroding cooperation. As a result, authors have appealed to balancing selection on traits for reasons other than recognition (e.g. immune selection on MHC) to explain the maintenance of recognition. Here, I challenge this view by first presenting evidence that recognition traits used to mediate cooperation are themselves under negative frequency-dependent selection as a result of social interactions. Second, I present a novel model showing that learning recognition templates is sufficient to maintain diversity in recognition traits used for cooperation. Importantly, this model predicts a positive feedback whereby cooperation maintains diversity, which in turn favors higher investment in cooperation, leading to greater diversity, etc.