QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online December 1, 2006
Journal of Experimental Biology 209, 4869-4877 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02585

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Glanville, E. J. Articles by Seebacher, F. Search for Related Content PubMed PubMed Citation Articles by Glanville, E. J. Articles by Seebacher, F.

Compensation for environmental change by complementary shifts of thermal sensitivity and thermoregulatory behaviour in an ectotherm

E. J. Glanville and F. Seebacher^*

School of Biological Sciences A08, University of Sydney, NSW 2006, Australia

^* Author for correspondence (e-mail: fseebach{at}bio.usyd.edu.au)

Accepted 5 October 2006

Thermoregulating animals are thought to have evolved a preferred body temperature at which thermally sensitive performance is optimised. Even during thermoregulation, however, many animals experience pronounced variability in body temperature, and may regulate to different body temperatures depending on environmental conditions. Here we test the hypothesis that there is a trade-off between regulating to lower body temperatures in cooler conditions and locomotory and metabolic performance. Animals (estuarine crocodiles, Crocodylus porosus) acclimated to cold (N=8) conditions had significantly lower maximum and mean daily body temperatures after 33 days than warm-acclimated animals (N=9), despite performing characteristic thermoregulatory behaviours. Concomitant with behavioural changes, maximum sustained swimming speed (U_crit) shifted to the respective mean body temperatures during acclimation (cold=20°C, warm=29°C), but there was no difference in the maxima between acclimation groups. Mitochondrial oxygen consumption changed significantly during acclimation, and maximum respiratory control ratios coincided with mean body temperatures in liver, muscle and heart tissues. There were significant changes in the activities of regulatory metabolic enzymes (lactate dehydrogenase, citrate synthase, cytochrome c oxidase) and these were tissue specific. The extraordinary shift in behaviour and locomotory and metabolic performance shows that within individuals, behaviour and physiology covary to maximise performance in different environments.

Key words: phenotypic plasticity, thermal reaction norm, mitochondria, metabolism, reptile, acclimation

This article has been cited by other articles:

				F. Seebacher and R. S. James Plasticity of muscle function in a thermoregulating ectotherm (Crocodylus porosus): biomechanics and metabolism Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2008; 294(3): R1024 - R1032. [Abstract] [Full Text] [PDF]