Heat transfer in a microvascular network: The effect of heart rate on heating and cooling in reptiles (Pogona barbata and Varanus varius)

Seebacher, Frank (2000) Heat transfer in a microvascular network: The effect of heart rate on heating and cooling in reptiles (Pogona barbata and Varanus varius). Journal of Theoretical Biology, 203 2: 97-109. doi:10.1006/jtbi.1999.1067


Author Seebacher, Frank
Title Heat transfer in a microvascular network: The effect of heart rate on heating and cooling in reptiles (Pogona barbata and Varanus varius)
Formatted title
Heat transfer in a microvascular network: The effect of heart rate on heating and cooling in reptiles (Pogona barbata and Varanus varius)
Journal name Journal of Theoretical Biology   Check publisher's open access policy
ISSN 0022-5193
1095-8541
Publication date 2000-03-21
Sub-type Article (original research)
DOI 10.1006/jtbi.1999.1067
Volume 203
Issue 2
Start page 97
End page 109
Total pages 13
Editor J. Tyson
L. Wolpert
Place of publication London, U.K.
Publisher Academic Press
Collection year 2000
Language eng
Subject C1
270604 Comparative Physiology
780105 Biological sciences
Formatted abstract
Thermally-induced changes in heart rate and blood flow in reptiles are believed to be of selective advantage by allowing animal to exert some control over rates of heating and cooling. This notion has become one of the principal paradigms in reptilian thermal physiology. However, the functional significance of changes in heart rate is unclear, because the effect of heart rate and blood flow on total animal heat transfer is not known. I used heat transfer theory to determine the importance of heat transfer by blood flow relative to conduction. I validated theoretical predictions by comparing them with field data from two species of lizard, bearded dragons (Pogona barbata) and lace monitors (Varanus varius). Heart rates measured in free-ranging lizards in the field were significantly higher during heating than during cooling, and heart rates decreased with body mass. Convective heat transfer by blood flow increased with heart rate. Rates of heat transfer by both blood flow and conduction decreased with mass, but the mass scaling exponents were different. Hence, rate of conductive heat transfer decreased more rapidly with increasing mass than did heat transfer by blood flow, so that the relative importance of blood flow in total animal heat transfer increased with mass. The functional significance of changes in heart rate and, hence, rates of heat transfer, in response to heating and cooling in lizards was quantified. For example, by increasing heart rate when entering a heating environment in the morning, and decreasing heart rate when the environment cools in the evening a Pogona can spend up to 44 min longer per day with body temperature within its preferred range. It was concluded that changes in heart rate in response to heating and cooling confer a selective advantage at least on reptiles of mass similar to that of the study animals (0.21–5.6 kg).
© 2000 Academic Press
Keyword Biology
Model
Capillary
Lengths
Animals
Flow
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
 
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Created: Tue, 10 Jun 2008, 11:42:49 EST