EVAPORATIVE WATER LOSS OF SOME HABITAT-RESTRICTED MEXICAN LIZARD SPECIES

Water relations of terrestrial ectotherms are influenced by a number of environmental factors and physiological constraints. Whereas macroenvironment undoubtedly plays a role in determining such relations, microenvironmental conditions are likely to be of even greater importance for habitat specialist species. The aim of this study was to examine the habitat-and size-related patterns of evaporative water loss (EWL) of eight Mexican endemic lizards: Anolis barkeri (Barker's Anole), A. gadovii (Gadow's Anole), Lepidophyma gaigeae (Gaige's Tropical Night Lizard), L. inagoi (Tierra Colorada Tropical Night Lizard), L. pajapanense (Pajapan Tropical Night Lizard), Phyllodactylus delcampoi (Del Campo's Leaf-toed Gecko), Sceloporus stejnegeri (Stejneger's Blackcollar Spiny Lizard), and Xenosaurus newmanorum (Newman's Knob-scaled Lizard), all of which are restricted to humid habitats or microhabitats. The species studied exhibited considerably high rates of EWL, even in comparison to other mesic environment squamates. Although the relationship between EWL and habitat aridity was not very strong, this pattern might be influenced by the highly specialized and secretive habits of some of these lizards. Based on these results, we argue that the marked habitat specificity of the species studied can be explained, at least partially, by their high EWL rates, suggesting that microenvironmental conditions are of major importance for the water relations of these lizards.