In modern societies, individuals often have a large degree of freedom and anonymity. This allows them to get away not only with free-riding on the efforts of others, but also with opting out from participating in cooperative enterprises altogether. While many studies in the biological and social sciences have contributed to understanding the enduring conundrum of how cooperation can emerge and be maintained in the presence of free-riders, only a handful of studies have studied the role of voluntary participation. These studies investigated a classical Public Goods game in which individuals could cooperate, defect, or opt not to participate in the game altogether. The evolutionary dynamics of these three pure strategies can resemble the “rock-scissors-paper” cycle known from evolutionary game theory, and thus prevent populations from ending up with 100% defection. While this can explain why a significant number of cooperators may be present in a population, it does not explain how the three pure strategies under consideration emerged in the first place. To overcome this limitation, we will consider a model in which individuals are characterized by two continuously varying traits describing their cooperative investment and participation rate in a Public Goods game in which payoffs depend nonlinearly on a group’s total cooperative investment. The resultant coevolutionary dynamics, including the potential for evolutionary branching in two or three directions, will be explored using adaptive dynamics techniques and through an individual-based model in which many of the otherwise needed simplifying assumptions can be relaxed.
Last edited: 24 March 2016
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