Figure 1.

Hydric physiology variables and predictions for this study on G. sila. Variables related to hydric physiology (a) include plasma osmolality, CEWL and body condition. VPD (b) quantifies the drying power of the air as a function of both air temperature and humidity. High VPD is desiccating to organisms. We predict that when environmental VPD is low (c), such as in early spring when G. sila are emerging from hibernation, they should be able to maintain relatively good hydration, measured as low plasma osmolality and high body condition. Because lizards are hydrated, CEWL should be unrestricted (c). Conversely, we predict that when VPD is high (d), such as during the summer, G. sila should become relatively dehydrated, measured as higher plasma osmolality and lower body condition compared to when they are not exposed to desiccating conditions. Because lizards are dehydrated, CEWL should be reduced to aid in water conservation (d). Artwork of G. sila by S. Mieko Temple.