|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online September 9, 2005
Journal of Experimental Biology 208, 3593-3602 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01777
Allometric scaling of flight energetics in orchid bees: evolution of flux capacities and flux rates
,*
1 Department of Zoology, University of British Columbia, Vancouver, BC,
Canada V6T 1Z4
2 Smithsonian Tropical Research Institute, Balboa, Republic of
Panama
3 Department of Ecology, Evolution and Marine Biology, University of
California Santa Barbara, Santa Barbara, CA 93106-9610, USA
* Author for correspondence (e-mail: darveau{at}zoology.ubc.ca)
Accepted 6 July 2005
The evolution of metabolic pathways involved in energy production was studied in the flight muscles of 28 species of orchid bees. Previous work revealed that wingbeat frequencies and mass-specific metabolic rates decline in parallel by threefold as body mass increases interspecifically over a 20-fold range. We investigated the correlated evolution of metabolic rates during hovering flight and the flux capacities, i.e. Vmax values, of flight muscle enzymes involved in substrate catabolism, the Krebs cycle and the electron transport chain. Vmax at the hexokinase (HK) step scales allometrically with an exponent almost identical to those obtained for wingbeat frequency and mass-specific metabolic rate. Analysis of this relationship using phylogenetically independent contrasts supports the hypothesis of correlated evolution between HK activity and mass-specific metabolic rate. Although other enzymes scale allometrically with respect to body mass, e.g. trehalase, glycogen phosphorylase and citrate synthase, no other enzyme activities were correlated with metabolic rate after controlling for phylogenetic relatedness. Pathway flux rates were used with enzyme Vmax values to estimate fractional velocities (fraction of Vmax at which enzymes operate) for various reactions to gain insights into enzyme function and how this varies with body mass. Fractional velocity is highly conserved across species at the HK step, but varied at all other steps examined. These results are discussed in the context of the regulation and evolution of pathways of energy metabolism.
Key words: enzyme activity, metabolic rate, evolution, allometry, insect flight, orchid bee
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
Related articles in JEB:
This article has been cited by other articles:
|
|
 |
|
  W. F. Eanes, T. J. S. Merritt, J. M. Flowers, S. Kumagai, E. Sezgin, and C.-T. Zhu Flux control and excess capacity in the enzymes of glycolysis and their relationship to flight metabolism in Drosophila melanogaster PNAS, December 19, 2006; 103(51): 19413 - 19418. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. van Bergen BUSY BEES J. Exp. Biol., September 15, 2005; 208(18): i - i. [Full Text] [PDF]
|
|
|
|
|
|
R. K. Suarez, C.-A. Darveau, K. C. Welch Jr., D. M. O'Brien, D. W. Roubik, and P. W. Hochachka Energy metabolism in orchid bee flight muscles: carbohydrate fuels all J. Exp. Biol., September 15, 2005; 208(18): 3573 - 3579. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C.-A. Darveau, P. W. Hochachka, K. C. Welch Jr, D. W. Roubik, and R. K. Suarez Allometric scaling of flight energetics in Panamanian orchid bees: a comparative phylogenetic approach J. Exp. Biol., September 15, 2005; 208(18): 3581 - 3591. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. K. Suarez, C.-A. Darveau, and P. W. Hochachka Roles of hierarchical and metabolic regulation in the allometric scaling of metabolism in Panamanian orchid bees J. Exp. Biol., September 15, 2005; 208(18): 3603 - 3607. [Abstract] [Full Text] [PDF]
|
|
