THERMOREGULATION AND SPATIAL DISTRIBUTION OF LIZARDS IN THE SOUTHWESTERN USA: ADAPTATION TO A CHANGING CLIAMTE

Caleb Loughran, University of New Mexico - Main Campus

Abstract

Lizards rely heavily on environmental temperatures to thermoregulate and maintain a body temperature (T_b) that optimizes physiological function and maximizes surface activity time. While early research noted the propensity for lizards to thermoregulate by shuttling between different thermal environments, it was long assumed that evaporative cooling via panting was an ineffective means of thermoregulation. However, evaporative cooling can potentially lower a lizard’s T_b significantly below air temperature, and thus allow lizards to extend activity periods during prolonged heat exposure. In this dissertation, I explore the varying abilities of lizards to thermoregulate while panting. I describe the metabolic and evaporative water costs of panting for lizards. Finally, I employ the mechanistic niche model ‘NicheMapR’ to explore the ecological consequences and evolutionary implications of thermoregulatory panting in lizards. Results from these studies indicate that panting is a highly important thermoregulation mechanism for lizards and may significantly affect how species cope with an increasingly warmer world.