Intracolony aggression in the eusocial naked mole-rat, Heterocephalus glaber

In colonies of the eusocial naked mole-rat, breeding is monopolized by one dominant female (the 'queen') and one to three males. Aggression in the form of shoving (prolonged pushes involving nose to nose contact) is frequently observed in captive colonies and is principally initiated by breeders. It has been suggested that shoving by queens functions primarily to suppress reproduction in subordinates (threat reduction hypothesis) or to incite work activity in nonbreeding 'helpers' (work conflict hypothesis). We tested predictions of both hypotheses by examining shoving in five captive colonies before and after removing breeders. Shoving was strongly associated with reproductive status. The vast majority of shoves were carried out by the queen, and to a lesser extent breeding males, and the onset of reproductive activity coincided with the onset, or greatly increased rates, of shoving. No evidence for the work conflict hypothesis was found. Queens shoved high-ranking and large colony members most, a finding that does not allow discrimination between hypotheses. Those males that posed the greatest threat to the queen's reproductive dominance, namely future breeding males, were shoved most, providing some support for the threat reduction hypothesis. However, evidence that queens targeted those females that posed the greatest threat, females that were to succeed them, was equivocal. Queen shoving may have several functions, depending on social context, in inhibiting reproduction in subordinates of both sexes, maintaining social order, and in inciting work-related behaviours in colony members, all of which ultimately increase the reproductive success of queens. (C) 2001 The Association for the Study of Animal Behaviour.