title: A dispersive morph in the naked mole-rat.
abstract: Close inbreeding is known for a variety of small mammal species for which a high probability of mortality during dispersal makes helping and delayed maturation a relatively secure fitness option. Prolonged inbreeding, however, is usually associated with lowered fitness, and it has been shown that most highly inbred small mammals and social insects have inbreeding-avoidance mechanisms that promote some degree of outbreeding. However, previous field and laboratory research on the naked mole-rat (Heterocephalus glaber) suggested that this cooperatively breeding rodent is highly inbred, with new colonies forming by fission. Here we report the discovery of a dispersal phenotype that may occasionally promote outbreeding in naked mole-rats. These dispersers are morphologically, physiologically and behaviourally distinct from other colony members. They are laden with fat, exhibit elevated levels of luteinizing hormone, have a strong urge to disperse, and only solicit matings with non-colony members. These findings suggest that, although rare, a dispersive morph exists within naked mole-rat colonies.
authors.affiliation: Department of Zoology, University of Cape Town, Rondebosch, South Africa.
authors.forename: M J
authors.initials: MJ
authors.lastname: O'Riain
authors.forename: J U
authors.initials: JU
authors.lastname: Jarvis
authors.forename: C G
authors.initials: CG
authors.lastname: Faulkes
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005260:Female; D007178:Inbreeding; D008297:Male; D011859:Radiography; D012098:Reproduction; D012377:Rodentia / Q000033:anatomy & histology / Q000502:physiology; D012726:Sexual Behavior, Animal