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. As extinction is non-random across the tree of life, it is important to prioritise threatened species which represent large amounts of evolutionary history. The EDGE metric prioritises species based on their Evolutionary Distinctiveness (ED), which measures the relative contribution of a species to the total evolutionary history of their taxonomic group, and Global Endangerment (GE), or extinction risk. EDGE prioritisations rely on adequate phylogenetic and extinction risk data to generate meaningful priorities for conservation. However, comprehensive phylogenetic trees of large taxonomic groups are extremely rare and, even when available, become quickly out-of-date due to the rapid rate of species descriptions and taxonomic revisions.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 estimate missing ED scores for species absent from a phylogenetic tree whilst simultaneously correcting the ED scores of their close taxonomic relatives. We found that following artificial removal of species from a phylogenetic tree, the new method provided the closest estimates of their “true” ED score, differing from the true ED score by an average of less than 1%, compared to the 31% and 38% difference of the previous methods. The previous methods also substantially under- and over-estimated scores as more species were artificially removed from a phylogenetic tree. 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.

Extinction risk and threats to plants and fungi

“…EDGE ranks species by combining their extinction risk with their evolutionary distinctiveness, determined from their position in a phylogenetic tree and number of close relatives. This approach has been applied to numerous animal groups (Gumbs, Gray, Wearn, & Owen, 2018;Isaac, Redding, Meredith, & Safi, 2012;Stein et al, 2018), but few plant groups and no fungi to date (Forest et al, 2018;Hills, Bachman, Forest, Moat, & Wilkin, 2019;Li, Gale, Kumar, Zhang, & Fischer, 2018;Yessoufou, Daru, Tafirei, Elansary, & Rampedi, 2017). Further metrics, inspired by EDGE, integrate evolution and extinction risks for conservation of species and areas (Farooq et al, 2020;Nunes, Turvey, & Rosindell, 2015;Pearse et al, 2015;Pimiento et al, 2020).…”

Conceptual Framework for Biodiversity Assessments in Global Value Chains

“…Intact ecosystems with a high proportion of endemic species form the basis for High Biodiversity Wilderness Areas. EDGE areas show critical areas where phylogenetically unique and globally threatened species occur [49,50,105].…”

“…Whereas most of the proactive schemes only focus on low vulnerability and do not account for any irreplaceability measures, except from the High Biodiversity Wilderness Areas (HBWA) [43,84]. Furthermore, in order to meet the requirement concerning the different levels of biodiversity, conservation schemes are included into the risk map that highlight areas that harbor phylogenetically different species [49,50,105] or species with an important gene pool [51]. [34,35,44,68,69,86,88].…”

Species characteristics of felids and canids, and the number of articles published for each species between 2013 and 2017

“…Taxonomic uniqueness was listed for each species, by deriving Evolutionary Distinctiveness (ED) scores and Evolutionary Distinct and Globally Endangered (EDGE) scores [12] ; the higher the score, the higher a species’ conservation priority ( Table 4 ). We also predicted taxonomic uniqueness by counting the number of species per genus; a monotypic genus, which consists of only one representative, has a higher conservation priority Table 5 .…”