Item

Abstract

The emergence and mechanism of cooperation in social dilemmas have always been fundamental issues in evolutionary game theory. In this paper, we study the snowdrift game, in which individuals in a stronger position can gain additional benefits in cooperation with weaker individuals due to differences in status. Meanwhile, innocuous-type strong individuals will not harm their partners’ interests, while harmful-type ones will. In a mixed population, the strong individuals in these two asymmetric snowdrift games are more inclined to cooperate, but the weaker ones are more willing to choose defection. The average cooperation frequency is not lower than in symmetric populations. In structured populations, on the other hand, asymmetry promotes the formation of a configuration with a cooperator cluster with a core of strong cooperators, thereby promoting cooperation among individuals. However, only within a small range of parameters the frequency of cooperation will be slightly reduced. Harmful-type strong individuals can be more conducive to promoting cooperation than innocuous-type ones in some cases. The existence of harmful and strong individuals in the snowdrift game further helps to solve the social loafing effect.