PT  - JOURNAL ARTICLE
AU  - Darveau, Charles-A.
AU  - Hochachka, Peter W.
AU  - Welch, Kenneth C.
AU  - Roubik, David W.
AU  - Suarez, Raul K.
TI  - Allometric scaling of flight energetics in Panamanian orchid bees: a comparative phylogenetic approach
AID  - 10.1242/jeb.01776
DP  - 2005 Sep 15
TA  - Journal of Experimental Biology
PG  - 3581--3591
VI  - 208
IP  - 18
4099  - http://jeb.biologists.org/content/208/18/3581.short
4100  - http://jeb.biologists.org/content/208/18/3581.full
SO  - J. Exp. Biol.2005 Sep 15; 208
AB  - The relationship between body size and flight energetics was studied in the clade of tropical orchid bees, in order to investigate energy metabolism and evolution. Body mass, which varied from 47 to 1065 mg, was found to strongly affect hovering flight mass-specific metabolic rates, which ranged from 114 ml CO2 h-1 g-1 in small species to 37 ml CO2 h-1 g-1 in large species. Similar variation of wingbeat frequency in hovering flight occurred among small to large species, and ranged from 250 to 86 Hz. The direct relationship between such traits was studied by the comparative method of phylogenetically independent contrasts (PIC), using a new molecular phylogeny generated from the cytochrome b gene partial sequences. We found wingbeat frequency variation is satisfactorily explained by variation in wing loading, after corrections for body mass and phylogeny. The correlated evolution of mass-specific metabolic rate, wingbeat frequency and wing loading was also revealed after correcting for phylogeny and body mass. Further, the effect of body size on flight energetics can be understood in terms of a relationship between wing form and kinematics, which directly influence and explain the scaling of metabolic rate in this group of bees.