Environmental Audit Committee: written evidence for inquiry into biodiversity and ecosystems from On the EDGE Conservation

Who we are:

On the EDGE Conservation (OTEC) is a charitable foundation, supporting conservation, science and storytelling for often-overlooked Evolutionarily Distinct and Globally Endangered (EDGE) species. EDGE species are an irreplaceable part of the world’s evolutionary heritage - with no or few close relatives, they represent an entire branch of the Tree of Life. Yet, the majority are little-known and nine out of ten priority EDGE species are not receiving sufficient conservation attention. OTEC also hosts the IUCN Species Survival Commission Phylogenetic Diversity Task Force, the global expert group providing expertise and guidance on the incorporation of phylogenetic diversity and evolutionary heritage into conservation.


Evidence for selected questions for EAC inquiry into biodiversity:

Co-ordination of UK environmental policy:


Executive Summary




Our global biodiversity is in crisis, with a million species at risk of extinction[1]; a 68% reduction in wildlife populations since 1970[2]; and under current human impacts, we stand to lose more than 50 billion years of evolutionary history across terrestrial vertebrates[3]. We need biodiversity for a healthy and liveable planet, for human well-being now and in the future. However, our current approaches to biodiversity conservation are limited – we typically focus on a relatively small number of unrepresentative species[4], often because they are perceived as more appealing[5]; and with an increasing emphasis on ecosystem service provision rather than biodiversity itself. Biodiversity means the variety of life on earth, in all its forms – yet existing conservation action is insufficient to safeguard so many threatened species.


Conservation action has effectively averted species extinctions in recent years[6], and analyses show that it will be possible to bend the curve on biodiversity loss into the future through ambitious conservation efforts[7]. However, it is essential to consider how can we effectively direct our limited resources to ensure we are truly conserving the diversity of life and hence the diversity of nature’s contributions to people, now and for the future. In 2019 the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services1 (IPBES) recognised the concept of nature’s contributions to people, encompassing all the benefits and values provided by biodiversity and ecosystem services, but which are deteriorating worldwide.


The upcoming Convention on Biological Diversity Conference of the Parties (COP 15), sets out a Vision for 2050 which calls not only for halting the loss of biodiversity but also recognising its value. However, many of the Aichi Biodiversity Targets for 2020 are likely to be missed - the UK report to the CBD in 2019 found insufficient progress was being made on 14 of the 19 targets[8], identified continuing pressures on biodiversity, and that significant work is still required to address invasive species, species declines and engaging the public on the value of biodiversity. Globally, commitments to genuine monitoring and implementation of biodiversity conservation will be essential. The CBD COP 15 presents a historic opportunity to achieve global transformative change, and the UK has an opportunity to lead in supporting a stronger global commitment to biodiversity in the post-2020 global biodiversity framework, especially aspects that have been neglected to date.

Phylogenetic Diversity

A critical and often overlooked aspect of biodiversity is the evolutionary heritage represented by a set of species on the tree of life, called Phylogenetic Diversity[9] (PD). By conserving PD globally, we conserve the variety of different evolutionary features of species, and so options for humanity and nature. This global option value of biodiversity is essential if we are to capture the full value of biodiversity for humanity[10]. PD is already used by IPBES as an indicator for nature’s contributions to people: for maintenance of options (NCP 18) and as relevant to medicinal, biochemical and genetic resources (NCP 14)1. For example, PD strongly predicts current pharmaceutical and agricultural uses of the Cape floras[11], although it is important to note that medicinal, biochemical and genetic resources are but one component of the options we maintain when we conserve PD.

Evolutionarily Distinct and Globally Endangered (EDGE) species

A practical methodology to apply the concept of PD to conservation is embodied in the EDGE lists produced by the Zoological Society of London (ZSL)[12]. With few or no close relatives, EDGE (Evolutionarily Distinct and Globally Endangered) species collectively represent billions of years of threatened evolutionary history3, meaning not only the major opportunities to avert loss of PD and maintenance of options, but also their heritage and existence values as highly distinctive species[13]. The tree of life is a storehouse of potential benefits for humanity, and EDGE species make significant unique contributions to this variety of life and its promise of future benefits.

Their uniqueness means that the loss of one EDGE species can mean the loss of an entire branch of the tree of life, yet the majority are little-known and receiving insufficient conservation attention. Reflecting this, in 2012, IUCN adopted a resolution[14] that recognised the importance of conserving threatened evolutionarily distinct lineages.


Protecting EDGE species provides an opportunity to more effectively conserve the breadth of global biodiversity: EDGE species lists are a ready-made biodiversity prioritisation scheme which can be used to help direct limited resources, identifying approximately 10% of species that represent much of the threatened evolutionary heritage present in each assessed taxonomic group11. Out of 36,715 vertebrates (mammals[15], amphibians[16], birds[17], reptiles[18], sharks and rays[19]), gymnosperms[20] (conifers and cycads), and reef-building scleractinian corals[21], 3,147 EDGE species have been identified for conservation prioritisation.


Conservation efforts since the inception of the CBD in 1993 have been shown to have averted species extinctions6, including for highly threatened EDGE species such as the California condor, Javan rhino and pygmy hog, demonstrating the importance of prioritising these species for conservation action to avert the loss of millions of years of evolutionary history. The UK continues to be instrumental in EDGE species conservation overseas, such as in the reintroduction of the Northern bald ibis back into Europe[22], and bringing the Mauritian Round Island keel-scaled boa back from the brink of extinction[23], as well as supporting a range of EDGE species conservation projects through Darwin Initiative funding[24]. The UK’s own resident EDGE species, the angelshark Squatina squatina, is already recognised and protected under UK legislation and is the focus of conservation attention by a collaboration of NGOs and the Welsh Government[25].

Proposed indicators for the CBD post-2020 framework

The IUCN Species Survival Commission Phylogenetic Diversity Task Force has proposed two indicators for the CBD post-2020 biodiversity framework to meet the drafted goals, elements and targets[26]. These indicators explicitly and uniquely interlink Goal A (preventing extinctions and improving conservation status) and Goal B (valuing nature’s contributions to people).

1.       Expected loss of Phylogenetic Diversity: already used by IPBES as an indicator for the maintenance of options (NCP 18), and noting that this includes benefits under NCP 14 (medicinal, biochemical and genetic resources) and NCP 15 (learning).

2.       Changing status of Evolutionarily Distinct and Globally Endangered species (EDGE Index): a newly developed indicator which adds value to existing broader species measures, as this set of species represents billions of years of evolutionary history, and thus options for humanity. This indicator can be applied to trends in conservation status, extinctions, and recovery.


These indicators fill an important current gap in the draft monitoring framework relating to Nature’s Contributions to People, as well as the lack of linkages with IPBES’s work to date. IPBES highlighted how this loss of species, and therefore biodiversity (in the sense of variety), means also a loss of nature’s contributions to people. Our indicators therefore link the conservation of PD, including EDGE species, to the bigger picture of biodiversity’s value to humanity, as an effective mechanism to address the CBD Vision’s dual challenges to better appreciate the value of biodiversity and to halt its loss.


This integration of PD as an indicator of biodiversity value also serves the recent recognition that “A composite scale that combined species, genetic and ecosystem diversity would allow the public to follow and understand, to vote and to lobby for biodiversity conservation.”[27]



An explicit focus on EDGE species in biodiversity conservation represents an opportunity for policy action to avert the impending loss of billions of years of evolutionary history. The UK Government can support the adoption of PD and EDGE focused indicators into the post-2020 Global Biodiversity framework. These indicators capture different important aspects of the changing status of phylogenetic diversity: expected PD loss reflects the loss of biodiversity and its value; while the change in status of EDGE species reflects our success or failure in conserving our evolutionary heritage; enabling conservation, measurement and monitoring into the future.






[1] IPBES 2019 Summary for policymakers of the global assessment report on biodiversity and ecosystem services. Diaz, S. et al. (eds).

[2] WWF 2020 Living Planet Report 2020 - Bending the curve of biodiversity loss. Almond et al. (eds). WWF, Gland, Switzerland.

[3] Gumbs et al. 2020 Global priorities for conservation of reptilian phylogenetic diversity in the face of human impacts. NatComms 11:2616

[4] Sitas et al. 2009 What are we saving? Developing a standardized approach for conservation action Anim. Cons. 12(3)231-237

[5] Verissimo et al. 2017 Increased conservation marketing effort has major fundraising benefits for even the least popular species Biol. Cons. 211(A)95-101

[6] Bolam et al. 2020. How many bird and mammal extinctions has recent conservation action prevented? Cons. Letters  

[7] Leclère et al. 2020. Bending the curve of terrestrial biodiversity needs an integrated strategy Nature 447

[8] JNCC 2019 Sixth National Report to the United Nations Convention on Biological Diversity: United Kingdom of Great Britain and Northern Ireland.

[9] Faith 1992 Conservation evaluation and phylogenetic diversity. Biol Cons 61, 1–10.

[10] Faith 2018 Avoiding paradigm drifts in IPBES. Ecology and Society 23(2):40 

[11] Forest et al. 2007 Preserving the evolutionary potential of floras in biodiversity hotspots. Nature, 445(7129), 757–760

[12] ZSL EDGE of Existence programme www.edgeofexistence.org

[13] Owen et al. (2019) Global conservation of phylogenetic diversity captures more than just functional diversity. NatComms 10:859

[14] IUCN Resolution WCC-2012-Res-019-EN: Halting the loss of evolutionarily distinct lineages

[15] Collen et al. 2011 Investing in evolutionary history: implementing a phylogenetic approach for mammal conservation. Phil Trans Royal Soc B 366(1578)

[16] Isaac et al. 2012 Phylogenetically-Informed Priorities for Amphibian Conservation. PLoS One 7(8)

[17] Jetz et al. 2014 Global Distribution and Conservation of Evolutionary Distinctness in Birds. Curr Biol 24(9) 919-930

[18] Gumbs et al. 2018 Tetrapods on the EDGE: Overcoming data limitations to identify phylogenetic conservation priorities. PLoS One 13(4)

[19] Stein et al. 2018 Global priorities for conserving the evolutionary history of sharks, rays and chimaeras. Nat Eco Evo 2:288-298

[20] Forest et al. 2018 Gymnosperms on the EDGE. Sci Reports 8(6053)

[21] Curnick et al. 2014 Setting evolutionarybased conservation priorities for a phylogenetically datapoor taxonomic group (Scleractinia) Anim Cons 18(4):303-312

[22] https://www.zsl.org/zsl-london-zoo/news/into-the-wild

[23] https://www.durrell.org/wildlife/species-index/round-island-boa/timeline/#myCarousel

[24] https://www.darwininitiative.org.uk/project/

[25] Angelshark Project Wales

[26] IUCN SSC Phylogenetic Diversity Task Force submission to the CBD SBSTTA

[27] CBD/WG2020/1/5


September 2020