BUFFENSTEIN, Rochelle; SALTON, Justine; City University of New York; City University of New York: Microhabitat and taxon-based thermoregulatory profiles in six Malagasy rainforest tenrecid species

The Tenrecidae includes a diverse array of terrestrial, semi-aquatic, arboreal and subterranean species, isolated on Madagascar since the mid-Miocene. Tenrecids are prime examples of mammalian adaptive radiation, yet they are also considered primitive relative to other eutherians. We questioned if rainforest species employ microhabitat-specific thermoregulationsimilar to that of other eutherians. We examined field metabolism of six rainforest species (Hemicentetes semispinosus; Oryzorictes hova; and four species of shrew tenrec,Microgale sp.). We compared these to the introduced musk shrew. Upon capture, we measured body temperature, mass, resting metabolic rate, blood glucose and hematocrit. Maximum oxygen consumption was induced by exercise on an auromated treadmill with an attached respirometer. The largest species, (H. semispinosus, showed pronounced thermolability. The other species regulated body temperature. Resting metabolic rates of all tenrecids were considerably lower than predicted by mass and approximately 66% of that of the shrew. Hematocrit values varied with microhabitat; the subterranean rice tenrec exhibited the highest hematocrit while the terrestrial species had similar hematocrit values to that of the musk shrew. While tenrecids display primitive characteristics of physiology, they also reveal a number of microhabitat-specific adaptations that define species-based thermogenic profiles.