The Evolution of Collective Behaviour

The feedback between the behavioral phenotypes of individuals, the collective behaviors that these phenotypes produce, and individual-level fitness consequences has made it challenging to study how complex collective behaviors evolve. Many species, including fish and birds, form groups in which members have low genetic relatedness, which implies that kin selection alone cannot explain the evolution of collective behavior. Moreover, while natural selection acts on the behavioral phenotypes of selfish individuals, collective behaviors are group-level, or perhaps even population-level, properties rather than heritable individual phenotypes. To understand how collective behaviors evolve, then, one must first understand the mapping between individual phenotypes and collective behavior, and between collective behavior and individual fitness.