Postexercise thermoregulatory behavior and recovery from exercise in desert iguanas.
Desert iguanas (Dipsosaurus dorsalis) undergo respiratory recovery more rapidly and incur lower energetic costs when they recover from 40 degrees C burst activity at 20 degrees C than when they recover at 40 degrees C. However, a body temperature of 20 degrees C falls well outside the preferred activity temperature range of this species, and imposes several physiological and behavioral liabilities. To determine if exhausted animals would favor a thermal regimen that allows for rapid and inexpensive respiratory recovery, we exercised lizards to exhaustion and allowed them to recover in a laboratory thermal gradient for 180 min. Recovering animals allowed their body temperatures to cool significantly to a mean temperature of 33.5 degrees C during the first 60 min of recovery, and subsequently rewarmed themselves to an average temperature of 38 degrees C for the remainder of their recovery period. Control animals maintained a constant body temperature of 37.7 degrees C throughout the 180-min recovery period. We then exercised animals to exhaustion at 40 degrees C and allowed them to recover for 180 min under a thermal regimen that mimicked that selected by exhausted animals in the previous experiment. Animals recovering under this thermal regimen returned to rates of O2 consumption, removed exercise-generated blood lactate, and incurred energetic costs that were more similar to data previously collected for animals recovering from exercise at a constant 40 degrees C than to data from animals recovering at 20 degrees C. These results suggested that the energetic benefits associated with recovery at 20 degrees C are not of sufficient biological importance to cause a major shift in thermoregulatory behavior.
Wagner
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Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder 80309-0334, USA. wagnerel@spot.colorado.edu
Gleeson
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D000064:Acclimatization / Q000502:physiology; D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D003889:Desert Climate; D004734:Energy Metabolism / Q000502:physiology; D007076:Iguanas / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*
D019344:Lactic Acid