Individual and sibling-group variation in metabolism of lizards: The aerobic capacity model for the origin of endothermy

Abstract

1. 1. We measured standard, resting and exercise metabolism of 28 Chaicides ocellatus (Scincidae). Individual lizards consistently showed statistically significant differences in mass-independent rates of standard and exercise metabolism during three replicates of the experiments at weekly intervals. 2. 2. Metabolic differences were also detected among groups of siblings. 3. 3. Mass-independent resting metabolic rates were closely correlated with standard rates, but there was no correlation of metabolic rates during forced activity with either standard or resting rates. 4. 4. These data suggest a heritable component of metabolism for lizards, but they do not support the “aerobic capacity model” of the origin of endothermy, which proposes that initial selection for high resting metabolic rates operated via selection for high rates of aerobic metabolism during exercise.