Correlates of extinction risk in Australian squamate reptiles

Aim: Identification of particular traits that predispose species to elevated extinction risk is an important component of proactive conservation. We capitalise on a recent strategic extinction risk assessment of all Australian squamate reptiles to identify intrinsic life history traits and extrinsic threats that correlate with extinction risk. We further assess whether extinction risk correlates differ between species impacted by different threatening processes (habitat loss vs. invasive species). Location: Australia. Taxon: Squamate reptiles. Methods: We used the IUCN Red List data for Australian squamates, and publicly available datasets for 14 intrinsic and extrinsic traits. We used phylogenetically controlled Bayesian inference to test hypotheses regarding relationships between extinction risk and species traits, environment, and threat measures. Results: We found that intrinsic characteristics (habitat specialisation, small range size and large body size), as well as extrinsic factors (high human footprint, accessibility from human population centres, cold temperatures and high rainfall), predispose a species to extinction. Similar predictors were important in threat-specific analyses, although relationships were generally more uncertain. Conclusions: Our results largely accord with those of global and regional studies of extinction risk in reptiles and of terrestrial vertebrates more broadly. Our findings illustrate that there is no single pathway to extinction among Australian squamates.