Meeting Abstract
Increases in temperature and changes in the timing and quantity of rainfall in desert habitats due to climate change may pose a threat to desert lizard species by restricting the area of thermally suitable habitat and altering water needs. In common chuckwallas, Sauromalus ater, seasonal increases in temperature do not appear to restrict activity. However, water loss rates in this species have not been widely investigated in the context of changing climate. Investigating how water needs vary with body mass and temperature is important to assess how chuckwallas may be impacted by climate change. Total evaporative water losses (EWL) of chuckwallas (body mass: S. ater 20-240g; S. varius 500-1000g) acclimated to 15°C, 25°C, and 35°C, were measured using a flow-through respirometry system. Standard metabolic rates were also measured since rates of oxygen consumption (VO2) and carbon dioxide production (VCO2) can be obtained using flow-through respirometry. Preliminary results indicate that total evaporative water loss increased with body mass as predicted by the surface area to volume ratio. However, the effects of temperature on water loss rates were unclear and require additional measurements. Scaling exponents for standard metabolic rates at the three temperatures were 1.31 and 0.80 for VO2 and VCO2, respectively. These metabolic rates were not significantly different (p<0.05) from metabolic rates obtained at the same three temperatures in a previous study by Pirtle and Todd. It is possible that chuckwallas may have mechanisms to modify either respiratory or cutaneous water loss to maintain overall water loss rates when temperature changes.
