Advancing EDGE Zones: spatial priorities for the conservation of tetrapod evolutionary history

Abstract The biodiversity crisis is set to prune the Tree of Life in a way that threatens billions of years of evolutionary history. To secure this evolutionary heritage along with the benefits it provides to humanity, there is a need to understand where in space the greatest losses are predicted to occur. We therefore present threatened evolutionary history mapped for all tetrapod groups, globally and within Biodiversity Hotspots, and identify priority regions of Evolutionarily Distinct and Globally Endangered (EDGE) species at both a grid cell and national level. We find that threatened evolutionary history peaks in Cameroon, whilst EDGE species richness peaks in Madagascar. We refined and advanced the 2013 EDGE Zone concept for spatially prioritising phylogenetic diversity using a novel complementarity procedure with uncertainty incorporated for 33,628 tetrapod species. This involved using extinction risk, phylogenetic, and spatial data to iteratively select areas with the highest accumulated threatened evolutionary history driven by unique species compositions. We identify 25 priority EDGE Zones, which are insufficiently protected and disproportionately exposed to high levels of human pressure. Together, the 25 EDGE Zones occupy 0.723% of the world’s surface but harbour one-third of the world’s threatened evolutionary history, half of which is endemic to these grid cells. They also contain part of the distribution of 918 EDGE tetrapod species, representing near one-third of all EDGE species, with 480 being endemic. Our tetrapod EDGE Zones highlight areas of immediate concern for researchers, practitioners, policymakers, and communicators looking to safeguard the Tree of Life.