Hamilton's rule and kin competition in a finite kin population

Kin selection means that individuals can increase their own inclusive fitness through displaying more altruistically toward their relatives. So, Hamilton's rule says kin selection will work if the coefficient of relatedness exceeds the cost-to-benefit ratio of the altruistic act. However, some studies have shown that the kin competition due to the altruism among relatives can reduce, and even totally negate, the kinselected benefits of altruism toward relatives. In order to understand how the evolution of cooperation is influenced by both kin selection and kin competition under a general theoretical framework, we here consider the evolutionary dynamics of cooperation in a finite kin population, where kin competition is incorporated into a simple Prisoner's Dilemma game between relatives. Differently from the previous studies, we emphasize that the difference between the effects of mutually and unilaterally altruistic acts on kin competition may play an important role for the evolution of cooperation. The main results not only show the conditions that Hamilton's rule still works under the kin competition but also reveal the evolutionary biological mechanism driving the evolution of cooperation in a finite kin population. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the evolutionary dynamics of cooperation in a finite kin population, considering both kin selection and kin competition. The results show the conditions under which Hamilton's rule still applies in the presence of kin competition, as well as the biological mechanism driving the evolution of cooperation in a limited kin population.