Meeting Abstract

P1.135  Tuesday, Jan. 4  Life stage affects water loss in the Gila monster, a desert dwelling lizard MOELLER, KT*; DENARDO, DF; Arizona State University karla.moeller@asu.edu

Juveniles often experience the same environmental conditions as intraspecific adults, but may have different limitations due to decreased body size (and related increase in surface area-to-volume ratio) or physiological differences. Consequently, sensitivity to environmental challenges may vary across life stages. Adult Gila monsters use a variety of physiological and behavioral strategies to mitigate water loss during seasonal drought, yet the extent to which juvenile Gila monsters utilize the same strategies is unknown. Previous studies have shown that in a laboratory setting, Gila monsters have high rates of evaporative water loss in comparison with other lizards of similar size. This intensifies the challenge they face in conserving water through the dry, hot summer in the wild. Thus, tolerance of dehydration is a critical physiological strategy for this species. To identify differences in physiological challenges and strategies between life stages, we compared sensitivity to hydric losses between adults and juveniles, focusing on the rate of water loss and tolerance of dehydration. Mass-corrected total evaporative water loss was significantly greater in juveniles, but transcutaneous evaporative water loss across a given area did not differ significantly between groups. The influences of surface area and epidermal composition on these findings were also explored. To determine ecologically relevant effects of this relative increase in water loss, we also monitored rate and tolerance of dehydration in adults and juveniles held under laboratory conditions that mimicked a seasonal drought. Juvenile Gila monsters showed clinical signs of dehydration after a shorter duration than adults, suggesting that juveniles are more vulnerable to the hydric challenges presented by life in the desert.