PHYSIOLOGICAL ADAPTATION TO ARIDITY IN THE BUSHVELD GERBIL, TATERA LEUCOGASTER

Oxygen consumption, rectal temperature, thermal conductance, and evapo rative water loss (EWL) were determined in resting captive Tatera leuc ogaster at ambient temperatures of between 14 and 38 degrees C. Basal metabolic rate (BMR) was 0.86 ml 0(2).min(-1) (S.D. = 0.15, n = 6), 45 % of that expected for a rodent of the same body mass (106.2 g). Minim um wet thermal conductance was 0.21 ml O-2.min(-1).degrees C-1 (S.D. = 0.01, n = 6), 113% of that expected for a mammal of the same body mas s. Wet thermal conductance increased exponentially at temperatures gre ater than 32 degrees C. Mean rectal temperature was 35.3 degrees C bel ow 35 degrees C (S.D. = 0.5, n = 6) and 39.3 (S.D. = 0.6, n = 5) at 38 degrees C. Mean resting EWL was 1.43 mg.min(-1) (S.D. = 0.14, n = 6) between 15 and 32 degrees C and increased dramatically at temperatures above 32 degrees C. Combining our data with data from the literature suggests that gerbils (Family Muridae; subfamily Gerbillinae) have, on average, low BMR and average minimum wet thermal conductance when com pared to other rodents and other mammals, respectively, of the same bo dy mass. Similarly, rodents (including gerbils) from arid habitats hav e, on average, levier rates of EWL when at rest below thermo-neutralit y than do other rodents of the same body mass from mesic habitats.