Divergent behavioural responses to acute hypoxia between individuals and groups of naked mole rats

Abstract

Most small rodents reduce energy demand in hypoxia via behavioural strategies. For example, animals may reduce their activity, and/or move to colder environments or alter huddling strategies to take advantage of anapyretical energy savings. Naked mole rats (NMRs) are among the most hypoxia tolerant mammals and are highly social; social interactions also have a significant impact on behaviour. Therefore, this species offers a fascinating model in which to study trade-offs between social interactions and energy conservation in hypoxia. We hypothesized that the need to conserve energy in hypoxia supersedes the impetus of sociality in this species and predicted that, in hypoxia, behaviour would not differ between individuals or groups of NMRs. To test this hypothesis, we placed awake, freely behaving NMRs, alone or in groups of 2 or 4, into a temperature-controlled apparatus and measured behavioural activity during 1 h each of normoxia (21% O₂), acute hypoxia (7% O₂), and normoxic recovery. We found that in normoxia, groups of 4 NMRs were significantly more active in all temperatures than were groups of 1-2 NMRs. When exposed to hypoxia, individual NMRs were ~50% less active and their speed was reduced relative to normoxic levels. Conversely, groups of 2 or 4 NMRs exhibited minor or insignificant decreases in time spent active and speed in hypoxia and huddling behaviour was not altered. Our findings suggest that social interactions influence behavioural strategies employed by NMRs in hypoxia.

Keywords: Anapyrexia; Behavioural thermoregulation; Huddling behaviour; Hypoxia tolerance.