Kinship and incompatibility between colonies of the acacia ant Pseudomyrmex ferruginea

Summary The effect of kinship on incompatibility between colonies of the acacia-ant Pseudomyrmex ferruginea was examined. Colonies were reared on a clone of Acacia hindsii in a standard environment. A slight but significant reduction in intercolony incompatibility was obtained within two inbred lineages, compared with the observed frequency of rejection for unrelated colonies. These results indicate that the relevant odor differences between colonies are probably not determined at a single gene locus. The gestalt model for recognition pheromones does not apply to P. ferrugnea, since nestmates are often treated differently upon introduction to a second colony. However, the resulting intermediate rejection frequencies (30–100%) fail to converge on the 50% level predicted by single locus models for recognition pheromones.