Coexistence of competing strategies through contact-based dynamics in structured populations

Studies of complex networks has provided new grounds to the understanding of evolutionary dynamics [1, 2]. Models for evolutionary games have traditionally assumed that players imitate their successful neighbours by comparison of payoffs [3, 4]. In this paper for two-strategy evolutionary games in structured populations, we follow a different approach, bypassing the requirement for explicit knowledge about the exact payoffs, by encoding the payoffs into the willingness of any player to switch from her current strategy to the competing one. Theoretical computations and numerical simulations show that the evolutionary dynamics are intrinsically regulated by contact relationships specified by the network topologies of the populations. In particular, when each player plays simultaneously against all her nearest neighbors, competing strategies can easily coexist even when one strategy dominates the other in each base game. More interestingly, the results further reveals that the frequencies of the coexisting strategies can be calculated analytically. This provides new insight into why and how different strategies coexist in large populations