Responses to Dehydration in Anolis Lizards Sampled along Altitudinal Transects

Rates of dehydration and vital limits of dehydration were measured for six populations of Anolis roquet and three populations of Anolis cybotes sampled along altitudinal transects. After 10 days of laboratory acclimation (25 C, 12L:12D), rates of dehydration varied slightly among samples of A. cybotes, but not in A. roquet. Vital limits did not differ among samples of either species. The data suggest that the frequent basking behavior observed in high altitude populations of these species may induce selection for water conservation that is nearly as effective as that observed in their lowland populations. These two species exhibited much less altitudinal variation of dehydration rates than did a non-basking, dense forest species, Anolis gundlachi. Rates of dehydration were negatively rank correlated with the body weights of animals in all samples. Differences in body weights of experimental animals have markedly influenced the measurement of the characters associated with dehydration in Anolis lizards, but previous researchers generally have not recognized this effect.