Meeting Abstract
In many species, animals can behave pro-socially by helping their neighbors survive or reproduce. Simple evolutionary models of these scenarios use the “prisoner’s dilemma” from game theory and predict that helping strategies either invade and fix in a population or are entirely excluded by non-helping strategies. Classic presentations of Hamilton’s rule produce this kind of prediction where populations evolve to be helpful if the fitness benefits of helping times genetic relatedness outweigh the fitness costs. However, individual-level variation in helping behaviors is common and likely to have fitness consequences, which requires studying helping in the context of two additional scenarios from game theory, the hawk-dove game and the stag-hunt game; behavioral variation can be maintained within populations in a hawk-dove game and between populations in a stag-hunt game. Recent theoretical analyses of the evolution of helping behaviors show that demographic, ecological, and behavioral factors can determine whether helping occurs in the context of a prisoner’s dilemma, hawk-dove, or stag-hunt game. For example, ecological synergies in the production of benefits from helping determine whether the helping scenario starts with a prisoner’s dilemma or a stag-hunt game at low levels of population structure. Increases in population structure (e.g., due to increases in relatedness) in turn can shift a prisoner’s dilemma game to a hawk-dove game or a stag-hunt game to a mutualism game. Behavioral plasticity in the form of reciprocity can alter the fitness costs of helping and induce additional changes in the game structure towards more cooperative outcomes. By reviewing the sum of these effects, we can better understand how demographic, ecological, and behavioral factors shape selection for or against individual-level variation in helping behaviors.
