Meeting Abstract
Current climate change models predict increases in operative temperatures and changes to the timing and quality of precipitation events within desert habitats. Increased operative temperatures and prolonged periods of water deprivation may pose a threat to herbivorous lizards by restricting water quantities in habitats and food sources thus, requiring lizards to modify behavior in order to conserve water. Various species of snakes and insectivorous lizards are known to reduce preferred temperature (Tpref) when deprived of water, and change thermoregulatory shuttling behaviors by expanding the range of temperatures voluntarily tolerated (i.e. expanding Tpref range). However this interaction is known to be species-specific and has not been studied in herbivorous lizards. We predicted that thermoregulatory behaviors and Tpref would be modified more as the time lizards are deprived of water lengthens. Desert iguanas (Dipsosaurus dorsalis) and chuckwallas (Sauromalus ater(=obesus)) were deprived of water for 1-4 weeks. During this time, shuttling behaviors and Tpref were assessed using a shuttle box and thermal gradient. Blood osmolality was measured at the onset of thermal measurements to determine hydration status. Preliminary results for D. dorsalis suggest that shuttling behaviors and Tpref changed as the duration of water deprivation increased. However, Tpref of D. dorsalis after only three days was not significantly different from fully hydrated lizards. Sample size for S. ater is as yet, too small for any patterns to be clear. Overall, these results suggest that D. dorsalis has a high tolerance to prolonged periods of water deprivation and therefore may be buffered against changes in climate better than other lizard species.
