FIGURE 5.

Flexibility of heterothermy in captive Microcebus murinus. (A) Captive mouse lemurs adjust the depth and duration of torpor bouts depending on food supply (control CTL vs. 30% caloric restriction CR) and ambient temperature (25 vs. 12°C); (B) Example of thermographic image of a mouse lemur acclimated to 12°C; the surface temperature is maintained very low, witnessing the insulating capacity of the animal, except at the inter-capsular region where brown adipose tissue is present; (C) Graph showing the relationship between minimal core temperature and energy expenditure during the resting phase recorded in animals acclimated to 25 and 12°C; the data clearly demonstrate the existence of an inter-individual variability in the response to cold (either maintenance of normothermia or deep torpor bouts); (D) Data showing the rise of surface temperature (heat dissipation mostly through hands and feet) following the injection of isoproterenol, a chemical that stimulates non-shivering thermogenesis.