BUFFENSTEIN, Rochelle; SALTON, Justine; City University of New York; City University of New York: Field thermoregulatory profiles in tenrecs from the rainforest and dryforest of Madagascar

Although the Tenrecidae is as an ancient eutherian lineage, with more than 26 species living in a diverse range of habitats. We asked if closely-related tenrecids from the arid regions showed similar thermoregulatory responses to those from the rainforest. The lowland streaked tenrec (Hemicentetes semispinosus, N=14) were captured in the rainforest at Analamazaotra, and the lesser hedgehog tenrec (Echinops telfairi, N=14) from the arid regions at Beza Mahafaly. Upon capture, we measured body temperature, mass resting oxygen consumption, blood glucose and hematocrit levels. Maximum oxygen consumption was induced by exercise on an auromated treadmill with an attached respirometer. In addition we monitored body temperature over two 24 hour periods. The two species are approximately the same size (E. telfairi 96+14g; H. semispinosus 73+32g) yet pronounced differences in thermoregulatory profiles were evident. Both species had lower resting metabolic rates at 32oC than predicted by mass for typical eutherians. Resting metabolic rates of the arid-dwelling species were considerably lower than those of rain forest inhabitants. Aerobic scope from arid dwelling species were however similar to those from the rainforest. While the lowland streaked tenrec exhibited pronounced thermolability over a 24h period, the lesser hedgehog appeared to exhibit a daily torpor arousing in the early evening to feed. These differences in physiological profile are most likely habitat-based, reflecting seasonal differences in food availability in the these climatic zones.