Metabolism and evaporative water loss of Western Australian geckos (Reptilia : Sauria : Gekkonomorpha)

Resting metabolic rate (RMR) and evaporative water loss (EWL) were measured , and resistance (R) to evaporative water loss and water use index (WUI = E WL/RMR) were calculated, for 22 species of Western Australian gecko. For al l available gecko data, body mass and temperature explained 85% of the vari ability in RMR (=14.5 x mass(0.833) x 10(0.0398 Ta) mu L h(-1)), and 70% of the variability in EWL (=0.126 x mass(0.539) x 10(0.049) (Ta) mg h(-1)). F or Western Australian geckos, RMR and EWL were significantly influenced by body mass, using conventional regression and phylogenetic analyses. Resista nce to evaporative water loss (R) was not significantly affected by body ma ss. Water use index was inversely related to body mass: WUI = 21.9 M-0.344 mg mL O-2(-1). There were significant differences between species for R and for standardised residuals of RMR, EWL and WUI. R was not correlated with phylogeny, and was significantly higher (P = 0.020) for saxicolous geckos ( 1467 s cm(-1)) than terrestrial geckos (797 s cm(-1)); arboreal geckos had an intermediate R (977 s cm(-1)). Species that ate termites had lower stand ardised linear regression residuals (P = 0.003) for RMR than did species th at ate more general diets. Standardised residuals for EWL were almost signi ficantly related to microhabitat (P = 0.053). Standardised residuals for WU I were significantly related to microhabitat (P = 0.016); saxicolous specie s had lower WUI than terrestrial species. Standardised linear regression re siduals of the residuals from autoregression (which should be independent o f both mass and phylogeny effects) still significantly correlated RMR and d iet, but not EWL or WUI with microhabitat.