Prioritising Functionally Distinct and Globally Endangered (FuDGE) sharks for conservation action

Abstract

Robust species-level methods for quantifying ecological differences have yet to be incorporated into conservation strategies. Here, we describe a new approach to measure the unique contribution of species to overall functional diversity and incorporate it into an actionable conservation metric. The Functionally Distinct and Globally Endangered (FuDGE) metric directs conservation action to species whose extinction would result in significant losses of irreplaceable functional diversity. We apply FuDGE to the world’s sharks and compare it with the phylogeny-based Evolutionarily Distinct and Globally Endangered (EDGE) metric to highlight shared and divergent priorities for conservation. Identifying threatened species revealed that functionally distinct species are disproportionately threatened, with 17-24% of extant shark trait space at risk of extinction. We show that exploitation by humans threatens to disproportionately erode shark trait space, with 70% of trait space at risk. We hope our FuDGE metric will be used to guide the conservation of functionally irreplaceable species in the face of human impacts.