Theory of Cooperation

Abstract

Abstract Cooperation is defined as any adaptation that has evolved, at least in part, to increase the reproductive success of the actor's social partners. Inclusive fitness theory reveals that cooperation can be favoured by natural selection owing to either direct fitness benefits (mutually beneficial cooperation) or indirect fitness benefits (altruistic cooperation). Direct fitness benefits can arise as a simple by‐product of cooperation, or else owing to the existence of enforcement mechanisms, which may be fixed or conditioned according to the individual's cooperative behaviour. Indirect fitness benefits can arise when cooperation occurs between genetically similar individuals, as a consequence of limited dispersal, kin discrimination or greenbeard mechanisms. These theoretical mechanisms are illustrated with empirical examples, from laboratory experiments to field studies. Key Concepts The function of Darwinian adaptation is to maximise the organism's inclusive fitness. Inclusive fitness describes how well an organism transmits copies of its genes to future generations. Direct fitness is the part of inclusive fitness that comes from the organism's own reproductive success. Indirect fitness is the part of inclusive fitness that comes from the reproductive success of the organism's genetic relatives. Cooperation is any adaptation whose function is, at least in part, to increase the reproductive success of a social partner. Cooperation is mutually beneficial if the actor also benefits and altruistic if the actor suffers a net loss of reproductive success. Mutually beneficial cooperation is favoured by direct fitness benefits. Direct fitness benefits can arise as a by‐product or owing to enforcement mechanisms. Altruistic cooperation is favoured by indirect fitness benefits. Indirect fitness benefits can arise as a consequence of limited dispersal, kin discrimination or greenbeard mechanisms.