Meeting Abstract
The relationship between animals and their thermal environment has been gaining prominence in the fields of ecology and physiology with the increasing concern over climate change. Yet, despite a large body of knowledge on the thermoregulation of temperate and cold-climate endotherms, our functional knowledge of endotherms in the tropics remains incredibly scarce. As part of a long-term project investigating the effects of high ambient temperatures on small mammals in the tropical rainforests of Sarawak, Borneo, we recorded the body temperatures of free-ranging large treeshrews (Tupaia tana, order Scandentia). We also measured resting metabolic rates over a range of ambient temperatures to measure the thermoregulatory characteristics of this species. As well as showing some of the highest circadian body temperature variations (~5°C) of any small eutherian mammal, these animals had surprisingly high active body temperatures (~40°C), some of the highest recorded for an animal of their body mass (250-300g). We hypothesize that their high body temperatures would allow them to maintain a large enough gradient between ambient temperatures and body temperatures to allow passive heat dissipation, important in a high humidity environment where opportunities for evaporative cooling are few. A better understanding of the thermoregulation of this species, as well as that of tropical mammals in general will not only enlarge our understanding of endothermic temperature regulation, but will aid in the creation of accurate mechanistic models for predicting the effects of changes in global climates.
