What is a Naked Mole rat?
The Naked Mole-Rat (Heterocephalus glaber) is one of the only known eusocial mammals. Living in massive colonies under subsaharan desert sand, their lifestyle is famously similar to the eusocial arthropods. A queen functions as the sole reproductive member of the colony, with several reproductive males assisting in this labor. Colony members are capable of recognizing a large number of individuals using scent and possibly vocal cues (Clarke and Faulkes, 1999; Cooney and Bennett, 2000; Mateo 2003; Holmes and Mateo, 2007). Colonies are maintained by prosocial contributions from weaned members, with effort expended on cooperative tasks divided among individuals and varying by caste (Lacey and Sherman, 1991). Prosocial contributions include behaviors such as food-source recruitment, territorial defense, co-resting or huddling, substrate movement and tunnel excavation (Yahav and Buffenstein, 1991; Judd and Sherman, 1995; O’Riain and Jarvis, 1998). By definition, the most unique contributions to the colony are made by the queen, by which the colony is defined and created (e.g. Alexander et al., 1991; Lacey and Sherman, 1991).
Social Caste and Rescue Speed
in Experimentally Trapped Naked Mole Rats
in Experimentally Trapped Naked Mole Rats
A captive colony of naked mole-rats (Heterocephalus glaber) implanted with subcutaneous RFID tags permits microsecond resolution information about the movements of this incredibly unusual fossorial mammal. The eusocial system exhibited by H. glaber is almost unique among vertebrates. Colonies are stratified by social type, with worker, soldier, breeding male, and queen castes.
By experimentally “trapping” colony members with an artificial cave-in, we examine the effects of caste difference and social contributions on speed of rescue by other members of the colony. eusocial Naked Mole-Rat (Heterocephalus glaber). Using two small colonies (N = 4, N = 5) and an experimental cave-in scenario, we show that queens spend less time in excavation of experimentally trapped colony members than do workers, and that the individuals most likely to initiate rescue behavior are also the individuals that spend the greatest amount of time performing rescue behavior. This research also demonstrated preferential excavation of tubes in which colony members were trapped, as compared with empty tubes featuring the same obstacle. While further study of this topic using larger sample sizes is necessary, it represents not only a continuation of rescue studies in rodents (Ben-Ami Bartal et al. 2011), but also an important step in investigating the role of caste in social contribution by a eusocial mammal. In many cases contribution to the maintenance of the colony by eusocial animals, and particularly H. glaber (among the only euoscial mammals) has centered on routine behaviors such as foraging, alloparental care, and nest/tunnel construction (e.g. Lacey and Sherman 1991; Beshers and Fewell 2001). In this case, we test for a stochastic form of contribution: response to the physical isolation of a colony member. A "rescuer" removes the cork trapping a colony member. |