Evaporative Water Loss in Nine Insular Populations of the LizardAnolis cristatellusGroup in the British Virgin Islands

We studied water loss in eight insular populations of the lizardAnolis cristatellus wileyaeand in one population ofA. ernestwilliamsiin the British Virgin Islands. We found a strong negative correlation between habitat aridity and total and cutaneous water loss rate (ranging from 1.5–10.3 mg g−1h−l) and a strong positive correlation between habitat aridity and integument resistance to water loss (28.5−199.0 s cm−1). Water loss and integumentary resistance ofA. ernestwilliamsiwere similar to what would be predicted forA. cristatellusliving in the same habitat. The Guana Island population ofA. cristatelluswas significantly different from all other populations. We believe two processes are responsible; phenotypic plasticity explains most of the observed variability, but genetic differentiation may be responsible for the distinction of lizards from Guana.