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First published online December 14, 2006
Journal of Experimental Biology 210, 97-106 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02615
Phenotypic flexibility in the basal metabolic rate of laughing doves: responses to short-term thermal acclimation
1 DST/NRF Centre of Excellence at the Percy FitzPatrick Institute,
University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South
Africa
2 School of Animal, Plant and Environmental Sciences, University of the
Witwatersrand, Private Bag 3, Wits, 2050, South Africa, University of
KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
3 School of Biological and Conservation Sciences, University of
KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
* Author for correspondence (e-mail: mckechnie{at}gecko.wits.ac.za)
Accepted 24 October 2006
Many birds exhibit considerable phenotypic flexibility in maintenance energy requirements, and up- or downregulate basal metabolic rate (BMR) over time scales of days to weeks during thermal acclimation. However, the extent to which individual birds can reverse the direction of BMR adjustments over short time scales remains unknown. In this study, we examined metabolic responses to short-term thermal acclimation in laughing doves Streptopelia senegalensis. In 30 wild-caught doves (mean body mass=92.6 g) divided into three experimental groups of 10 birds each, initial BMR averaged 0.760±0.036 W. Thereafter, each group was acclimated to one of three acclimation air temperatures (Tacc=10, 22 or 35°C) for 21 days, during which time the doves were housed in individual cages. Following the first acclimation period (acclimation I), BMR (W) was significantly lower and was negatively and linearly related to Tacc [BMR=0.714-0.005Tacc]. Acclimation I BMR varied from 0.546±0.039 W in doves acclimated to Tacc=35°C to 0.665±0.058 W at Tacc=10°C. A second acclimation period of a further 21 days (acclimation II) revealed that the direction of BMR adjustments could be reversed within individuals, with acclimation II BMR again negatively and linearly related to Tacc. The slope of the relationship between BMR and Tacc following acclimation II was not significantly different to that following acclimation I. BMR exhibited consistent inter-individual variation, with a low but significant repeatability of 0.113. The within-individual BMR variation of up to 26% that we observed in laughing doves reveals that BMR is a highly flexible trait in this species, and reiterates the need to take phenotypic plasticity into account in comparative analyses of avian energetic parameters.
Key words: acclimation, basal metabolic rate, phenotypic flexibility, thermoregulation, repeatability
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