Competition for resources may reinforce the evolution of altruism in spatially structured populations.

Spatial structure is known to affect the evolution of social behaviour, but little is known on how this evolution depends on simultaneous competition for resources. In simple models, competition for resources tends to counteract altruism, but ecologically more realistic models suggest that competition for resources might actually reinforce altruism. Here we set up a probabilistic cellular automaton (PCA) model and analyse it using the Correlation Dynamics (CD) approach, to study how competition for resources affects the evolution of altruism. If the resource diffuses across space, spatiallyseparateclustersofrelativesmaystillcompeteforresources, thuscreatingalargercompetitive kernelthantheimmediateneighbourhood. Thisincreasestheseparationofclustersofrelativesandthus reinforces the selection of altruistic behaviour.