Metabolism and thermoregulation in the Cabrera vole (Rodentia: Microtus cabrerae).

Metabolism and thermoregulation were studied for the first time in the Cabrera vole (Microtus cabrerae), an endemic and threatened rodent of the Iberian Peninsula. Low values of resting metabolic rate (RMR) were registered (1.13 mlO(2) g(-1) h(-1)) at the lower limit of the thermoneutral zone (TNZ) (around 33.5 degrees C). Body temperature increased near the TNZ up to 37.3 degrees C but remained stable, around 36 degrees C, at ambient temperatures below 25 degrees C. Values of thermal conductance remained quite stable at ambient temperatures of 10-25 degrees C (0.144-0.160 mlO(2) g(-1) h(-1) degrees C) and increased to 0.301 mlO(2) g(-1) h(-1) degrees C at 33.5 degrees C. Data revealed that M. cabrerae developed a highly adaptive ability of conserving energy and lowering the metabolic cost of thermoregulation at high ambient temperatures, allowing the body temperature to approximate that of the environment and exhibiting low resting metabolic rate and high conductance.