The Shape of Water: Physiological Adaptations to Habitat Aridity in the Ornate Tree Lizard (Urosaurus ornatus).

This article investigates how intrinsic physiology and climatic factors influence water loss in populations of the ornate tree lizard (Urosaurus ornatus) across a 1400 km latitudinal gradient in the western United States. The study found significant differences among populations in thermal traits such as critical thermal minimum (CTmin), critical thermal maximum (CTmax), body temperature (Tb), and thermal breadth (Tbr), with CTmin decreasing and CTmax increasing with latitude. However, water loss was not correlated with these physiological traits or body mass but was strongly associated with climatic variables, particularly mean diurnal temperature range and mean temperature of the coldest quarter. Additionally, water loss measured at the throat correlated with overall water loss, suggesting a potential role in thermoregulation. The findings highlight the importance of climatic niche over intrinsic physiology in influencing water loss and underscore the vulnerability of U. ornatus to climate change, recommending further research on microclimatic effects and behavioral adaptations.