NEIGHBORHOOD DENSITY AND REPRODUCTIVE POTENTIAL IN HARVESTER ANTS

When neighbors compete for resources, the characteristics of a neighbo rhood may affect fitness. We examined the relationship between reprodu ctive success and the density and size/age characteristics of neighbor s in a population of the seed-eating ant, Pogonomyrmex barbatus, in wh ich the ages of all colonies were known. Reproductive success was esti mated by trapping and counting the number of alate, reproductive ants emerging from the nest for the annual mating flight. Alate production was negatively related to neighborhood density. Decreased production o f alates by more crowded colonies may be due to competition for food w ith surrounding colonies. Neighbor size/age was unrelated to alate pro duction. If alate production is correlated with lifetime reproductive success, these results suggest that selection favors colonies that mon opolize more space, whatever the size of neighboring colonies.