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Flexibility, variability and constraint in energy management patterns across vertebrate taxa revealed by long‐term heart rate measurements.

Halsey, Lewis G. and Green, Jonathan A. and Twiss, Sean D. and Arnold, Walter and Burthe, Sarah J. and Butler, Patrick J. and Cooke, Steven J. and Grémillet, David and Ruf, Thomas and Hicks, Olivia and Minta, Katarzyna J. and Prystay, Tanya S. and Wascher, Claudia A. F. and Careau, Vincent (2019) 'Flexibility, variability and constraint in energy management patterns across vertebrate taxa revealed by long‐term heart rate measurements.', Functional ecology., 33 (2). pp. 260-272.


1. Animals are expected to be judicious in the use of the energy they gain due to the costs and limits associated with its intake. The management of energy expenditure (EE) exhibited by animals has previously been considered in terms of three patterns: the constrained, independent and performance patterns of energy management. These patterns can be interpreted by regressing daily EE against maintenance EE measured over extended periods. From the multiple studies on this topic, there is equivocal evidence about the existence of universal patterns in certain aspects of energy management. 2. The implicit assumption that animals exhibit specifically one of three discrete energy management patterns, and without variation, seems simplistic. We suggest that animals can exhibit gradations of different energy management patterns and that the exact pattern will fluctuate as their environmental context changes. 3. To investigate these ideas, and for possible large‐scale patterns in energy management, we analysed long‐term heart rate data—a strong proxy for EE—across and within individuals in 16 species of birds, mammals and fish. 4. Our analyses of 292 individuals representing 46,539 observation‐days suggest that vertebrates typically exhibit predominantly the independent or performance energy patterns at the across‐individual level, and that the pattern does not associate with taxonomic group. Within individuals, however, animals generally exhibit some degree of energy constraint. Together, these findings indicate that across diverse species, some individuals supply more energy to all aspects of their life than do others, however all individuals must trade‐off deployment of their available energy between competing functions. This demonstrates that within‐individual analyses are essential for the interpretation of energy management patterns. 5. We also found that species do not necessarily exhibit a fixed energy management pattern but rather temporal variation in their energy management over the year. Animals’ energy management exhibited stronger energy constraint during periods of higher EE, which typically coincided with clear and key life cycle events such as reproduction, suggesting an adaptive plasticity to respond to fluctuating energy demands.

Item Type:Article
Full text:Publisher-imposed embargo
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Publisher statement:This is the accepted version of the following article: Halsey, Lewis G., Green, Jonathan A., Twiss, Sean D., Arnold, Walter, Burthe, Sarah J., Butler, Patrick J., Cooke, Steven J., Grémillet, David, Ruf, Thomas, Hicks, Olivia, Minta, Katarzyna J., Prystay, Tanya S., Wascher, Claudia A. F. & Careau, Vincent (2019). Flexibility, variability and constraint in energy management patterns across vertebrate taxa revealed by long‐term heart rate measurements. Functional Ecology 33(2): 260-272 which has been published in final form at This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Date accepted:28 November 2018
Date deposited:07 February 2019
Date of first online publication:16 December 2018
Date first made open access:No date available

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