Thermoregulatory differences in African mole-rat species from disparate habitats: Responses and limitations.

Abstract

Individuals and populations possess physiological adaptations to survive local environmental conditions. To occur in different regions where ambient temperature varies, animals must adopt appropriate thermoregulatory mechanisms. Failure to adjust to environmental challenges may result in species distributional range shifts or decreased viability. African mole-rats (Bathyergidae) occupy various habitats in sub-Saharan Africa from deserts to montane regions to mesic coastal areas. We examined thermoregulatory characteristics of three African mole-rat species originating from disparate (montane, savannah, and arid/semi-arid) habitats. Animals were exposed to various ambient temperatures, whilst core body temperature and the surface temperature of different body parts were measured. Oxygen consumption was determined as a measure of heat production. Core body temperatures of Natal (montane) mole-rats (Cryptomys hottentotus natalensis) increased significantly at ambient temperatures >24.5°C, while those of the highveld (Cryptomys hottentotus pretoriae) (savannah) and Damaraland (Fukomys damarensis) (arid/semi-arid) mole-rats remained within narrower ranges. In terms of surface temperature variation, while pedal surfaces were important in regulating heat loss in Natal and Damaraland mole-rats at high ambient temperatures, the ventral surface was important for heat dissipation in Damaraland and highveld mole-rats. This study provides evidence of the variation and limitations of thermo-physiological mechanisms for threemole-rat species relative to their habitats. Information on physiological adaptations to particular habitats may inform predictive modelling of species movements, declines, and extinctions in response to a changing environment, such as climate change.