Positive effects of multiple gene control on the spread of altruism by group selection.

The origin of altruistic behavior has long been a challenge for students of evolutionary biology. The populations with altruistic individuals do better than those without altruists; however, the altruists within a population do worse than the non-altruists and their prevalence in the population decreases due to individual selection. Under certain conditions, the strength of group selection, i.e., the selection driven by competition between populations, can surpass the strength of individual selection; however, such conditions seem to be relatively strict and probably do not hold in many natural systems where the altruistic behavior was observed. It was suggested recently that chances for altruistic behavior to spread highly increase when it is controlled not by a single gene but by multiple independent genes substitutable in their effects on the phenotype of the individual. Here we confirm the original verbal model by numerical modeling of the spread of altruistic/selfish alleles in a metapopulation consisting of partly isolated groups of organisms (demes) interconnected by migration. We have shown that altruistic behavior coded by multiple substitutable genes can stably coexist with selfish behavior, even under relatively high mutation and migration rates, i.e., under such conditions where altruistic behavior coded by a single gene is quickly outcompeted in a metapopulation.