Closely related Amazonian whiptail lizards show contrasting responses to climate change

Abstract

Different approaches can be used to forecast species range shifts in future climate change scenarios. Among these, hybrid species distribution models achieve greater accuracy than purely mechanistic or correlative models by incorporating physiological mechanisms into a correlative framework. Despite the observation that tropical ectotherms are among the most threatened organisms by climate change, hybrid modeling was not used to date to infer vulnerability and extinction risks across organisms in open Amazonian ecosystems. Here, we forecast the impacts of climate change on Amazonian whiptail lizards by incorporating estimates of thermal performance and hours of activity on hybrid species distribution models. We estimate local extinction risks for two species, the bisexual Cnemidophorus lemniscatus and the parthenogenetic C. cryptus, for 2060 and 2100 in two carbon emission scenarios and discuss the variation between species and sites (including the congener C. aff. gramivagus) in ecophysiological thermal traits. Our models predicted a 20 % increase in C. lemniscatus range and a 44 % decrease in C. cryptus range under the most severe scenario for the year 2100. Our results suggest that the parthenogenetic species will be more affected by climate change than the bisexual one, likely due to differences in their activity periods, which are shaped by their thermal needs and tolerances. These results show that regions with lower future climatic suitability are at the transition between the Amazonian rainforest and Cerrado savannas, a region highly altered by human land use and climate change, which raises concerns about the survival of populations from the Amazonian C. lemniscatus group. Moreover, the contrasting results between closely related species demonstrate that climate change can cause distinct impacts even within related taxonomic groups. This shows the difficulty of identifying model species to predict responses to current environmental changes.