The development of endothermy during pouch life in the eastern barred bandicoot (Perameles gunnii), a marsupial.
Marsupials are born ectothermic and gradually become endothermic during pouch occupancy. In order to study the timing of this transition, we measured the metabolic rates of eight pouch-young eastern barred bandicoots (Perameles gunnii) at 25 degrees C (the thermoneutral zone of adults), at 35 degrees C (pouch temperature), and after injection with norepinephrine. From 5 to 7 wk of age, oxygen consumption (VO(2)) was higher at 35 degrees C than at 25 degrees C. At 8 wk, VO(2) was significantly higher at 25 degrees C than at 35 degrees C. Norepinephrine administration at 5 and 6 wk had no effect on metabolic rate, but at 8 wk, near pouch vacation, it resulted in a significant increase in metabolic rate. Our results indicate that signs of thermoregulation for P. gunnii begin at 7 wk, and at 8 wk the species is endothermic, that is, able to increase heat production in response to both cold and norepinephrine. The appearance of fur, first seen at the age of 6 wk and fully developed at 8 wk, coincides with the onset of endothermy.
Ikonomopoulou
Maria P
MP
School of Zoology, University of Tasmania, Hobart, Australia.
Rose
Randy W
RW
D000367:Age Factors; D000818:Animals; D001481:Basal Metabolism / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D008297:Male; D008394:Marsupialia / Q000378:metabolism / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010101:Oxygen Consumption / Q000502:physiology; D012044:Regression Analysis; D013648:Tasmania
D009638:Norepinephrine