Temnothorax unifasciatus

Temnothorax unifasciatus exhibit the altruistic behavior of social withdrawal, or “altruistic self-removal” whilst on the brink of death. Dying ants will leave their nest hours or in some cases days before their death. The behavior is exhibited both in the presence of fungal infection as well as when experimentally exposed to 95% CO2, causing the ants to die in the absence of an acting pathogen. This indicates that the ants are in fact behaving in an altruistic manner, rather than experiencing behavioral manipulation as a result of pathogen influence. The action is altruistic because it reduces the risk of infecting other ants in the colony. This in turn minimizes the risk of transferring the infection to kin and thus likely results in a higher inclusive fitness for the socially withdrawing individuals. Ant colonies exhibit altruistic behavior through the suppression of selfish egg-laying behavior on behalf of worker ants by means of “policing;” this is accomplished either through aggression or through direct disposal of the eggs. In a study entitled Policing Effectiveness Depends on Relatedness and Group Size, researchers found the efficacy of colony policing to improve under conditions of decreased relatedness and decreased group size. …