Metabolism, thermoregulation and evaporative water loss in the Chaotung Vole (Eothenomys olitor) in Yunnan-Kweichow Plateau in summer

Abstract

Proper adjustment of thermoregulatory mechanisms ensures the survival of mammals when they are subjected to seasonal changes in their natural environment. To understand the physiological and ecological adaptations of Eothenomys olitor, we measured their metabolic rate, thermal conductance, body temperature (Tb) and evaporative water loss at a temperature range of 5–30°C in summer. The thermal neutral zone (TNZ) of E. olitor was 20–27.5°C, and the mean body temperature was 35.81±0.15°C. Basal metabolic rate (BMR) was 2.81±0.11mlO2/gh and mean minimum thermal conductance (Cm) was 0.18±0.01mlO2/gh°C. Evaporative water loss (EWL) in E. olitor increased when the ambient temperature increased. The maximal evaporative water loss was 6.74±0.19mgH2O/gh at 30°C. These results indicated that E. olitor have relatively high BMR, low body temperature, low lower critical temperature, and normal thermal conductance. EWL plays an inportant role in temperature regulation. These characteristics are closely related to the living habitat of the species, and represent its adaptive strategy to the climate of the Yunnan-Kweichow Plateau, a low-latitude, high-altitude region where annual temperature fluctuations are small, but daily temperature fluctuations are greater.