Document Detail

A comparative analysis of thermogenic capacity and cold tolerance in small birds.
MedLine Citation:
PMID:  16424096     Owner:  NLM     Status:  MEDLINE    
Small birds showing marked seasonal changes in cold tolerance also exhibit winter increases in summit metabolic rate (Msum=maximum cold-induced thermogenesis or thermogenic capacity) relative to summer birds. However, some birds show modest seasonal changes in cold tolerance without winter increases in Msum and others exhibit large seasonal changes in cold tolerance with only minor changes in Msum. Thus, the degree of correlation between cold tolerance and Msum is uncertain and no interspecific study has directly addressed this question. In this study, we measured cold tolerance and Msum in summer- (21 species) and winter- (11 species) acclimatized birds from southeastern South Dakota. Msum was measured as the maximum oxygen consumption attained during exposure of individual birds to a declining series of temperatures in 79% helium/21% oxygen (helox). Cold tolerance was measured as the temperature at cold limit (TCL), which is the helox temperature that induced hypothermia in individual birds. Residuals from allometric regressions of logMsum and logTCL were significantly and negatively related for summer (R2=0.34, P=0.006) and winter (R2=0.40, P=0.037) birds. Data were also subjected to a comparative analyses with phylogenetically independent contrasts to remove potential confounding effects of phylogeny, and results were similar to the non-phylogenetic analyses, with significant negative correlations in both summer (R2=0.47, P<0.001) and winter (R2=0.40, P=0.049). Thus, birds with high Msum tended to show reduced TCL (i.e. high cold tolerance), suggesting that cold tolerance and summit metabolism are phenotypically linked in small birds.
David L Swanson; Eric T Liknes
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  209     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2006-01-20     Completed Date:  2006-05-17     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  466-74     Citation Subset:  IM    
Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD 57069, USA.
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MeSH Terms
Adaptation, Physiological / physiology
Birds / genetics,  metabolism*,  physiology
Body Size / physiology*
Body Temperature Regulation / physiology*
Cold Temperature*
Genetic Variation
Oxygen Consumption
Species Specificity

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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