Dehydration Alters Behavioral Thermoregulation and the Geography of Climatic Vulnerability in Amazonian Lizards

Abstract

Since high temperatures and low water availability often strike organisms in parallel, observing how they behaviorally thermohydroregulate may help us to better understand their climatic vulnerability. This understanding is especially important for tropical lizards, purportedly under greater climatic risk. We observed the influence of hydration level on the Voluntary Thermal Maximum (VTM) of two small amazonian lizard species: Loxopholis ferreirai (semiaquatic and scansorial) and Loxopholis percarinatum (leaf litter parthenogenetic dweller), accounting for several sources of variation (turn, body weight, start temperature and heating rate). Then, we used two modelling approaches (simple mapping of thermal margins and NicheMapR), to examine the effects of dehydration, decrease in rainfall, ability to burrow, and tree cover availability, on the geography of climatic vulnerability. Dehydration decreased the VTM in both species, which also reacted to start temperature and heating rates. Our two modelling approaches show that dehydration, changes the intensity, extent and duration of thermal risk across the Amazon basin. Based on our results and previous studies, we identify new evidence needed to better understand thermohydroregulation and model the geography of climatic risk, more realistically.