Tetrapods on the EDGE: Overcoming data limitations to identify phylogenetic conservation priorities

Abstract

The scale of the ongoing biodiversity crisis requires both effective conservation prioritisation and urgent action. The EDGE metric, which prioritises species based on their Evolutionary Distinctiveness (ED) and Global Endangerment (GE), relies on adequate phylogenetic and extinction risk data to generate meaningful priorities for conservation. However, comprehensive phylogenetic analyses of large clades are extremely rare and, even when available, become quickly out-of-date due to the rapid rate of species descriptions and taxonomic revisions. Thus, it is important that conservationists can use the available data to incorporate evolutionary history into conservation prioritisation. We compared published and new methods to impute ED for species missing from a phylogeny whilst simultaneously correcting the ED scores of their close taxonomic relatives. We found that following artificial removal of species from a phylogeny, the new method provided the closest estimates of their \"true\" score, differing from the true ED score by an average of less than 1%, compared to the 31% and 38% difference of the previous imputation methods. Previous methods also substantially under- and over-estimated scores as more species were artificially removed from a phylogeny. We therefore used the new method to estimate ED scores for all tetrapods. From these scores we updated EDGE prioritisation rankings for all tetrapod species with IUCN Red List assessments, including the first EDGE prioritisation for reptiles. Further, we identified criteria to identify robust priority species in an effort to further inform conservation action whilst limiting uncertainty and anticipating future phylogenetic advances.