Effect of Thermal Acclimation on Locomotor Energetics and Locomotor Performance in a Tropical Salamander, Bolitoglossa subpalmata

Abstract

Bolitoglossa subpalmata, a plethodontid salamander from Costa Rica, was found to resemble many other tropical amphibians in undergoing no significant thermal acclimation of the standard rate of oxygen consumption (standard Ṁo2). To determine whether any deficit in locomotor performance was associated with this absence of acclimation, the Ṁo2 of Bolitoglossa acclimated at 5, 13, and 21 C was measured in an exercise wheel (A) at 13 C while the animals walked at various speeds and (B) at 21 C while the animals walked at a single speed (22 cm · min⁻¹) until exhausted. When data for all acclimation treatments were pooled in experiment A, the maximum sustainable speed and the routine Ṁo2 were correlated with the Ṁo2 during activity at 13 C. During exercise at this temperature in experiment A, acclimation temperature did not affect the Ṁo2. By contrast, in a temperate-zone species (Desmognathus ochrophaeus) that does undergo acclimation of the standard Ṁo2, acclimation of the Ṁo2 during activity paralleled acclimation of the standard Ṁo2. In neither species did acclimation affect the maximum sustainable speed at 13 C. In experiment B, acclimation to 5 C reduced both the Ṁo2 and locomotor stamina despite the absence of any acclimation of the standard Ṁo2. In contrast to initial expectations, these and other inconsistencies suggest that acclimation of activity metabolism and locomotor performance are poorly related, if at all, to acclimation of the standard Ṁo2.