The selective advantage of low relatedness

Relatedness within colonies of social Hymenoptera is often significantly lo wer than the outbred population maximum of 0.75, Several hypotheses address the widespread occurrence of Low relatedness, but none have measured the c ovariation of colony fitness and relatedness. In a polyandrous harvester an t, Pogonomyrmex occidentalis, average within-colony relatedness in the popu lation is Low but highly variable among colonies, and relatedness is negati vely correlated with colony growth rate. Differences in growth rate strongl y influence survival and the onset of reproduction, leading to a 35-fold in crease in fitness of fast-growing colonies, Benefits of a genetically diver se worker population may favor polyandry in this species.