Physiological flexibility and acclimation to food shortage in a heterothermic primate

Abstract

SUMMARYAs ecosystems undergo changes worldwide, physiological flexibility is likely to be an important adaptive response to increased climate instability. Extreme weather fluctuations impose energetical constraints such as unpredictable food shortage. We tested how grey mouse lemurs (Microcebus murinus) could adjust their daily heterothermy and locomotor activity to these 'energetic accidents' with a food restriction experiment. The experimental design consisted of acute calorie restriction (2weeks, 80% restriction) in the middle of winter, after a fattening season with low (11weeks, 40% restriction) versus high (ad libitum) food availability. This design aimed at simulating the combined effects of the quality of the fattening season (acclimation effect) and a sudden, severe food shortage during the lean season. Hour of start and duration of torpor were the most flexible components of energy savings, increasing in response to the acute food shortage with facilitation by chronic restriction (acclimation effect). Modulations of locomotor activity did not support the hypothesis of energy savings, as total locomotor activity was not reduced. Nonetheless, acutely restricted individuals modified their temporal pattern of locomotor activity according to former food availability. We provide the first experimental evidence of different temporal levels of flexibility of energy-saving mechanisms in a heterotherm exposed to food shortage. The acclimation effect of past food scarcity suggests that heterothermic organisms are better able to respond to unpredicted food scarcity during the lean season. The flexible control of energy expenditure conferred by heterothermy may facilitate the plastic response of heterothermic species to more frequent climatic hazards. Supplementary material available online at

The flexible clock: predictive and reactive homeostasis, energy balance and the circadian regulation of sleep–wake timing

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When to initiate torpor use? Food availability times the transition to winter phenotype in a tropical heterotherm

“…Grey mouse lemurs prepare in advance to this unfavourable season by a suite of physiological modifications (e.g. Génin and Perret 2003;Giroud et al 2008Giroud et al , 2009Canale et al 2011), including fat deposition (Perret and Aujard 2001;Schmid 2001). Internal energy storage is complemented with torpor-based energy saving to maintain a favourable energy balance.…”

Quantifying seasonal fallback on invertebrates, pith, and bromeliad leaves by white‐faced capuchin monkeys (Cebus capucinus) in a tropical dry forest

“…They are typically of high nutritive value, require little processing effort, are patchy in time and space, and favor adaptations that maximize harvesting return, typified by ripe fruit for most primates (Marshall et al, 2009). Primates adjust to decreases in preferred food abundance by resting more, shifting their ranging behaviors to relocate preferred foods, or by changing their diet (Harrison, 1985;Gursky, 2000;Altmann, 2009;Lee-Thorp et al, 2010;Canale et al, 2011;Blumenthal et al, 2012;Sato, 2013;Campos et al, 2014). The study of dietary ecology, specifically the pursuit of fallback foods (FBFs) that are eaten when preferred foods are less abundant, generates useful insights into primate dietary adaptations and evolution (Foley, 1993;Vrba, 1995;Potts, 1998;Teaford and Ungar, 2000;Ungar, 2004).…”