Climate change from an ectotherm perspective: evolutionary consequences and demographic change in amphibian and reptilian populations

Abstract Understanding how natural populations will respond to contemporary changes in climate is becoming increasingly urgent and of fundamental importance for the preservation of future biodiversity. Among vertebrates, amphibians and reptiles are more sensitive to environmental perturbations than endotherms and ectotherm diversity will likely be disproportionally impacted by climate change. Notwithstanding concerns surrounding the climate change resilience of ectotherm populations, accurately predicting future population trajectories based on contemporary ecological and physiological data alone remains challenging and much can be learnt by studying how populations have responded to climate change in the past. Genomic approaches can now assay the genetic diversity of contemporary population at an unprecedented scale but to date have been relatively underutilised when studying the demographic history of amphibians and reptiles. In this review, we first summarise how changing climatic conditions may influence the ectotherm phenotype and how this can translate to changes in fitness and population dynamics. We then discuss how the relative role of past climate in shaping ectotherm diversity has traditionally been approached in a phylogeographic context and how expanding genomic resources for ectotherm species can be leveraged to improve the study of past demography for many amphibian and reptilian groups. An integrative approach that links known proximate effects on phenotype due to climate change, with past changes in demographic trajectories will ultimately enable us to generate more accurate models of future population change and improve our ability to assess climate change resilience for many ectotherm groups.