IUCN SSC Phylogenetic Diversity Specialist Group

More about the Task Force

The IUCN SSC Phylogenetic Diversity Task Force (‘PDTF’) aims to provide leadership and guidance on the inclusion of phylogenetic diversity (PD) in conservation strategies. 

Conserving the Tree of Life and our evolutionary heritage: Phylogenetic diversity (PD) measures the evolutionary history captured by a set of species and therefore describes a fundamental aspect of biodiversity; the diversity of features produced by the course of evolution (Faith 1992). The evolutionary tree of life is a storehouse of benefits for humanity, including potential and unexpected future benefits. By conserving PD, we conserve feature diversity (broadly, the full range of different evolutionary features of a set of species) and thus options for humanity. As well as providing potential future benefits (biodiversity option value), the benefits and values of PD may include (but are not limited to) intrinsic value, existence value, proxy value, and insurance value. Yet, existing conservation action is insufficient to safeguard the million species estimated to be threatened with extinction, so it is essential to consider how we can effectively direct our limited resources to ensure we are truly conserving the diversity of life. Although there is a growth in the application of PD in conservation, and IUCN Resolution 19 (2012) calls for “halting the loss of evolutionarily distinct lineages”, there is a need to improve the general understanding of PD in the wider community. 

Phylogenetic Diversity approaches: The PDTF recognises that there are a wide range of PD approaches to conservation prioritisation provided by various PD-based calculations and is particularly engaged with two high-profile applications of PD: the expected loss of PD (ExpPDloss); and the EDGE (Evolutionarily Distinct and Globally Endangered) approach. ExpPDloss is used by IPBES as a key indicator for Nature’s Contributions to People and represents the maintenance of options from biodiversity for future humanity and nature, for present and future generations. The EDGE approach represents the current primary practical methodology to apply PD to conservation. The EDGE lists produced by the Zoological Society of London, identify priority EDGE species that are threatened with extinction with few or no close relatives on the tree of life. EDGE species are those which disproportionately represent threatened phylogenetic diversity and represent opportunities to avert the loss of entire branches of the tree of life by prioritising their conservation. In particular, the expertise and guidance provided by the PDTF will be essential in conveying the importance of conserving phylogenetic diversity and consequently the tree of life to major conventions (starting with the CBD but also CITES, CMS, Ramsar), governments, and the public.