Comparative physiology of thermoregulation in rodents: adaptations to arid and mesic environments

Metabolic and thermoregulatory variables of six rodent species inhabiting a desert environment were compared with those of six species inhabiting mesic environments. The results of such a comparison show that species originating in deserts are more efficient in conserving energy and presumably water when compared with those species originating in mesic habitats. Reduced resting metabolic rates (RMR) which characterize desert species are an important adaptation. However, the ability to inhabit mesic or very cold environments by such species is achieved through different morphological, physiological or behavioural adaptations, and not by an increase in RMR values. Non-shivering thermogenesis (NST) seems to be an important physiological adaptation in such desert rodents. The relatively high values of NST capacity found in desert species seem to compensate for their low RMR values.