Policing and dominance behaviour in the parthenogenetic ant Platythyrea punctata

Abstract

In the parthenogenetic ant Platythyrea punctata policing behaviour is not expected on relatedness grounds as workers are normally clonemates and thus equally related to all offspring in the colony. Nevertheless, colonies usually contain only a single reproductive and other workers that begin to lay eggs are attacked by their nestmates (‘policing’). We found that those individuals that most actively engaged in policing later themselves had activated ovaries when the old reproductive was removed from the colonies. This suggests that police workers, through attacking and eliminating others, increase their own chances of becoming reproductive themselves. Because regular parthenogenesis leads to a clonal colony structure, individuals are not expected to invest energy in dominance and policing. On the assumption that physical dominance reflects an individual's reproductive potential, aggression among workers might ensure that the most fecund individual becomes the next reproductive, which would benefit the colony as a whole. Furthermore, aggression among nestmates may be maintained in this species despite predominant clonality, because infrequent sex, recombination or the adoption of alien workers may introduce genetic heterogeneity into the colony.