Ant genotype, not fungus genotype, predicts aggression in the asexual fungus-farming ant, Mycocepurus smithii

Hamilton's rule specifies that the relatedness of two individuals will have a large bearing on whether an altruistic action is performed; however, it says little with regards to whether individuals are able to discern that relatedness. In this study we examine whether the fungus-farming ant Mycocepurus smithii uses genotypic information to decide whether to attack an introduced queen or if it utilizes environmental cues from the fungus that they cultivate. We performed 180 blind trials in which we introduced queens to queenless mesocosms and recorded and scored aggression behavior directed towards the queen. We find strong evidence that M. smithii uses genotype to mediate aggression, but find no support that fungal cultivar plays any role in recognition. These results serve to support Hamilton's notion that relatedness acts as a gateway to altruism.