  Evolution of cooperation in the prisoner's dilemma and the public goods game
is studied, where initially players belong to two independent structured
populations. Simultaneously with the strategy evolution, players whose current
utility exceeds a threshold are rewarded by an external link to a player
belonging to the other population. Yet as soon as the utility drops below the
threshold, the external link is terminated. The rewarding of current
evolutionary fitness thus introduces a time-varying interdependence between the
two populations. We show that, regardless of the details of the evolutionary
game and the interaction structure, the self-organization of fitness and reward
gives rise to distinguished players that act as strong catalysts of cooperative
behavior. However, there also exist critical utility thresholds beyond which
distinguished players are no longer able to percolate. The interdependence
between the two populations then vanishes, and cooperators are forced to rely
on traditional network reciprocity alone. We thus demonstrate that a simple
strategy-independent form of rewarding may significantly expand the scope of
cooperation on structured populations. The formation of links outside the
immediate community seems particularly applicable in human societies, where an
individual is typically member in many different social networks.
