Range restriction, climate variability and human-related risks imperil lizards world-wide

Aims: Identifying major reasons for species imperilment is a necessary step for conservation, but the degree to which we can generalize is hard for species-rich yet less-studied taxa, such as lizards. Here, we aim to bridge the gap by providing comprehensive analyses of the correlates and processes of species extinction and threats for global lizards. Location: Global. Time period: Current. Major taxa studied: Lizards. Methods: We compiled a dataset comprising extinction risk status, six intrinsic traits and seven extrinsic factors for 5256 lizard species. We carried out binomial distribution tests for 43 families and seven realms to check the non-randomness in species extinction risk and used phylogenetic linear regressions to identify the key factors that relate to the extinction proneness of lizards and species subgroups. Based on the International Union for Conservation of Nature (IUCN) threat assessment, we identified major threats for global lizards and for major families and regions. Results: We found strong evidence of taxonomic and geographical non-randomness in the extinction risk of lizards. Geographical range size, human footprint and density, insular endemism, temperature and precipitation seasonality, and body size were key predictors of extinction risk, and the first three factors were also important across families and realms. Moreover, newly described species were more likely to have a restricted range size and a higher extinction risk. Globally, the most detrimental threat was habitat destruction, while overexploitation, species invasion and climate change varied widely in importance among species groups. Main conclusions: Overall, we highlight the detrimental influences of range restriction, climate variability and anthropogenic threats to species persistence. We suggest that lizards are potentially at high risk of extinction owing to widespread human disturbance and that species with extinction-prone traits require conservation prioritization. Moreover, lizards of different families and regions require different management strategies because of variation in extinction-risk correlates and threats.