Extreme individual flexibility of heterothermy in free-ranging Malagasy mouse lemurs (Microcebus griseorufus)
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Flexibility in physiological processes is essential to adequately respond to changes in environmental conditions. Madagascar is a particularly challenging environment because climatic conditions seem less predictable than in comparative ecosystems in other parts of the world. We used the reddish-gray mouse lemur (Microcebus griseorufus) from the most unpredictable environment in Madagascar as a model to investigate the flexibility of energy saving strategies to cope with the unpredictability of their habitat. For this we measured T sk of free-ranging mouse lemurs throughout the year using temperature data loggers. M. griseorufus showed a very strong seasonal as well as an individual flexibility in thermoregulation. During the rainy season all M. griseorufus remained normothermic. At the beginning of the dry season individuals started to exhibit different energy saving strategies: irregular short torpor bouts, regular daily torpor, prolonged torpor of a few days, and hibernation over several weeks. The accumulation of sufficient seasonal body fat was the crucial factor determining the thermal behavior of individuals. The observed intraspecific and sex independent variation in thermoregulatory patterns within one population inhabiting the same small geographical area is exceptional and gives M. griseorufus the ability to respond to current environmental as well as individual conditions. This thermal plasticity might be seen as a key to success and survival for M. griseorufus in an extremely unpredictable environment.
KeywordsThermoregulation Individual plasticity Hibernation Prolonged torpor Daily torpor
The study has been conducted under the Accord de Collaboration between the Université d’Antananarivo (Département de Biologie Animale), MNP and Hamburg University. We also thank D. Rakotomalala and J. Rakotomalala (MNP Toliara) for their hospitality and support while working in Tsimanampetsotsa. P. Giertz and J. Rakotondranary supported the field project in numerous ways. The studies were supported by the DFG (Ga 342/14-1, 15-1), BMZ/GTZ, WWF Germany and WWF Madagascar. All experiments comply with the current laws of the country where they were performed.
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