COS 80-1 - Cultural transmission, competition for prey, and the evolution of cooperative hunting

Abstract: Although cooperative hunting (CH) is widespread among animals, its benefits are unclear. When rare, CH may allow predators to escape competition and access big prey. However, a lone CH predator cannot such catch food. Cultural transmission may allow CH to spread fast enough that cooperators can find hunting partners, but competition for big prey may increase. We construct a one-predator, two-prey model in which the predators either learn to hunt small prey alone or learn to hunt big prey cooperatively. The predators first learn vertically and then choose partners from which they learn horizontally with probability H. CH predators only catch the big prey if their partner is cooperative. We find that without horizontal learning, CH cannot evolve when initially rare. Together, a high probability of horizontal learning and competition for the small prey allow CH to evolve. However, CH can only fix in the predator population if the big prey is very abundant. Furthermore, a mutant that increases horizontal learning can invade whenever CH is present but not fixed, because horizontal learning allows predators to match their strategies, avoiding the situation in which a cooperator cannot find a partner. While competition for prey is important for determining the degree of CH that evolves, it is not enough for CH to emerge and spread; horizontal cultural transmission is essential. Future models may explore factors that control how horizontal transmission influences cooperative predation, and vice versa. Lessons from our model may be useful in conservation efforts and wildlife reintroduction programs.