The evolution of cooperation: an evolutionary advantage of individuals impedes the evolution of the population

Range expansion is a universal process in biological systems, and therefore plays a part in biological evolution. Using a quantitative individual-based method based on the stochastic process, we identify that enhancing the inherent self-proliferation advantage of cooperators relative to defectors is a more effective channel to promote the evolution of cooperation in range expansion than weakening the benefit acquisition of defectors from cooperators. With this self-proliferation advantage, cooperators can rapidly colonize virgin space and establish spatial segregation more readily, which acts like a protective shield to further promote the evolution of cooperation in return. We also show that lower cell density and migration rate have a positive effect on the competition of cooperators with defectors. Biological evolution is based on competition between individuals and should therefore favor selfish behaviors. However, we observe a counterintuitive phenomenon that the evolution of a population is impeded by the fitness-enhancing chemotactic movement of individuals. This highlights a conflict between the interests of the individual and the population. The short-sighted selfish behavior of individuals may not be that favored in the competition between populations. Such information provides important implications for the handling of cooperation.