TY - JOUR A1 - Dammhahn, Melanie A1 - Landry-Cuerrier, Manuelle A1 - Reale, Denis A1 - Garant, Dany A1 - Humphries, Murray M. T1 - Individual variation in energy-saving heterothermy affects survival and reproductive success JF - Functional ecology : an official journal of the British Ecological Society N2 - 1. Given fundamental energetic trade-offs among growth, maintenance and reproduction, individual differences in energy saving should have consequences for survival and reproductive success. Many endotherms use periodic heterothermy to reduce energy and water requirements and individual variation in heterothermy should have fitness consequences. However, attempts to disentangle individual- and population-level variation in heterothermy are scarce. 2. Here, we quantified patterns of heterothermy of 55 free-ranging eastern chipmunks (Tamias striatus), food-hoarding hibernators. Over five hibernation periods, we obtained a total of 7108 daily individual heterothermy indices (median: 118 per individual). 3. Based on an individual reaction norm approach, we found that the use of heterothermy was repeatable and varied among individuals of the same population under similar environmental conditions. This among-individual variation had consequences for winter survival and reproductive success. Individuals using less heterothermy at the beginning of the winter had decreased survival in resource-rich but not in resource-poor years and higher reproductive success in the subsequent breeding season. 4. These results support the hypothesis that fluctuating selection maintains heterothermic diversity and suggest that individualized ecophysiology can contribute to a more thorough understanding of the evolution of energy-saving strategies in endotherms. KW - fitness consequences KW - hibernation KW - individual differences KW - individual reaction norm KW - Tamias striatus KW - torpor Y1 - 2017 U6 - https://doi.org/10.1111/1365-2435.12797 SN - 0269-8463 SN - 1365-2435 VL - 31 SP - 866 EP - 875 PB - Wiley CY - Hoboken ER -