Poikilothermic traits in Mashona mole-rat (Fukomys darlingi). Reality or myth?

• Published in: Journal of thermal biology 2012-11, Vol.37 (7), p.485-489
• Main Authors: ZemanovA!, Milada, ANBumbera, Radim, Okrouhlik, Jan
• Format: Article
• Language: English
• Subjects: Adaptation; Adults; Ambient temperature; Arid regions; Bathyergidae; Biology; Body temperature; Mammals; Poikilothermy; Resting metabolic rate; Subterranean rodent; Thermoregulation
• ISSN: 0306-4565; 1879-0992
• DOI: 10.1016/j.jtherbio.2012.04.001

The African mole-rats (Bathyergidae, Rodentia) is a mammalian family well known for a variety of ecophysiological adaptations for strictly belowground life. The smallest bathyergid, the hairless naked mole-rat from arid areas in Eastern Africa, is even famous as the only truly poikilothermic mammal. Another bathyergid, the Mashona mole-rat (Fukomys darlingi) from Zimbabwe, is supposed to have strong poikilothermic traits, because it is not able to maintain a stable body temperature at ambient temperatures below 20°C. This is surprising because, compared to the naked mole-rat, this species, together with all congenerics, is larger, haired, and living in more seasonal environment. In addition, other Fukomys mole-rats show typical mammalian pattern in resting metabolic rates. In our study, we measured resting metabolic rate and body temperature of Mashona mole-rats from Malawi across a gradient of ambient temperatures to test its poikilothermic traits. We found that the adult mass specific resting metabolic rate was 0.76±0.20mlO2g−1h−1 and body temperature 34.8±1.1°C in the thermoneutral zone (27–34°C). Body temperature was stable (33.0±0.5°C) at ambient temperatures from 10 to 25°C. We thus cannot confirm poikilothermic traits in this species, at least for its Malawian population. Factors potentially explaining the observed discrepancy in Mashona mole-rat energetics are discussed. [Display omitted] ► We measured metabolic rate of Mashona mole-rat (Fukomys darlingi, Bathyergidae). ► Body temperature (33°C) of F. darlingi was stable even at low ambient temperatures. ► Previously reported poikilothermic traits of F. darlingi were not confirmed. ► Thermoneutral zone of F. darlingi was determined to be from 27 to 34°C. ► Resting metabolic rate of F. darlingi is 0.76mlO2g−1h−1 within thermoneutral zone.