45.5 Saturday, Jan. 5 Torpor-based compensation of energy shortage: a review of evidences from field experiments VUARIN, P*; DAMMHAHN, M; HENRY, PY; UMR 7179 CNRS-MNHN, Muséum National d’Histoire Naturelle, France; Behavioral Ecology & Sociobiology Unit, German Primate Center, Germany; UMR 7179 CNRS-MNHN, Muséum National d’Histoire Naturelle, France email@example.com
Hibernation and daily torpor are considered to be adaptations to seasonal energy shortage and environmental uncertainty. Although energy availability is commonly assumed to determine heterothermy patterns, few field data support this hypothesis. Yet, as climate and habitats change, energy availability is expected to become more variable, i.e. less predictable, in time, space and substrate. Recent literature suggests that hibernating mammals optimize the use of torpor expression according to energy availability, so that the trade-off between benefits (reduction of energy requirements, enhancement of survival) and costs (somatic damage, reduced immunocompetence) of torpor remains favorable. Most studies focused on species from temperate and boreal climates, exposed to severe winter conditions, however heterotherms from tropical climates may be exposed to different energetic constraints. In this study, we review published evidences from field experiments on the role of energy availability in determining torpor use. In addition, we present results of the first field experimental test based on food supplementation in a heterothermic tropical primate, the grey mouse lemur (Microcebus murinus ). The nutritional content of the available food, like the composition in fatty acids or in anti-nutrients, also likely constrains the efficiency of torpor at compensating energy shortage. We outline what field experimental data are still missing and which alternative mechanisms need to be tested to achieve a robust understanding of the role of energy and nutrient availability as the proximate cues for fine-tuning torpor use.