Title: Evolutionary dynamics of cooperation in neutral populations,
Abstract: Cooperation is a difficult proposition in the face of Darwinian selection.
Those that defect have an evolutionary advantage over cooperators who should
therefore die out. However, spatial structure enables cooperators to survive
through the formation of homogeneous clusters, which is the hallmark of network
reciprocity. Here we go beyond this traditional setup and study the
spatiotemporal dynamics of cooperation in a population of populations. We use
the prisoner's dilemma game as the mathematical model and show that considering
several populations simultaneously give rise to fascinating spatiotemporal
dynamics and pattern formation. Even the simplest assumption that strategies
between different populations are payoff-neutral with one another results in
the spontaneous emergence of cyclic dominance, where defectors of one
population become prey of cooperators in the other population, and vice versa.
Moreover, if social interactions within different populations are characterized
by significantly different temptations to defect, we observe that defectors in
the population with the largest temptation counterintuitively vanish the
fastest, while cooperators that hang on eventually take over the whole
available space. Our results reveal that considering the simultaneous presence
of different populations significantly expands the complexity of evolutionary
dynamics in structured populations, and it allow us to understand the stability
of cooperation under adverse conditions that could never be bridged by network
reciprocity alone.