The genetic legacy of aridification: Climate cycling fostered lizard diversification in Australian montane refugia and left low-lying deserts genetically depauperate

► We examine genetic patterns of geckos distributed in mountain and desert biomes. ► Genetic diversity is generally higher in mountain regions than in low-lying deserts. ► Taxa in mountain regions have older coalescent histories than desert taxa. ► Mountain ranges enabled long-term persistence and diversification of taxa. ► Intensifying aridification during the Pleistocene left little genetic diversity in desert organisms.