UC Davis

Aim: Habitat modification is causing widespread declines in biodiversity and the homogenization of biotas. Amphibians are especially threatened by habitat modification, yet we know little about why some species persist or thrive in the face of this threat whereas others decline. Our aim was to identify intrinsic factors that explain variation among amphibians in their sensitivity to habitat modification (SHM), factors that could help target groups of species for conservation. Location: Global. Time period: 1986–2015. Major taxon studied: Amphibians. Methods: We quantified SHM using species abundances in natural and altered habitats as reported in published field surveys. We first examined associations between local SHM and range-wide threatened status, population trends and invasiveness. We then evaluated the importance of intrinsic and extrinsic variables in explaining species SHM using multiple comparative methods. Our analyses included over 200 species that could be ranked with confidence from 47 studies across five continents. Results: Amphibians species varied considerably in local SHM. High SHM was associated with elevated range-wide extinction risk and declining population trends. Species that were tolerant of habitat modification were most likely to be invasive outside their native range. Geographical range size was the most important intrinsic predictor and was negatively associated with SHM. Larval habitat was also an important predictor, but was tightly coupled with phylogenetic position. Main conclusions: Narrowly distributed species whose larvae develop on land or in lotic habitats are most sensitive to habitat modification. However, other unmeasured, phylogenetically constrained traits could underlie the effect of larval habitat. Species range size is frequently correlated with global extinction risk in vertebrates, and our analysis extends this macroecological pattern to the sensitivity of amphibians to local habitat loss, a proximate driver of extinction. These general patterns of SHM should help identify those groups of amphibians most at risk in an era of rapid habitat loss and scarce conservation resources.