The EDGE of Existence programme is a research and conservation initiative that focuses on species deemed to be the world's most Evolutionarily Distinct and Globally Endangered (EDGE) species. Developed by the Zoological Society of London (ZSL), the programme aims to raise awareness of these species, implement targeted research and conservation actions to halt their decline, and to train in-country conservationists (called EDGE Fellows) to protect them.
EDGE species are animal species which have a high 'EDGE score', a metric combining endangered conservation status with the genetic distinctiveness of the particular taxon. Distinctive species have few closely related species, and EDGE species are often the only surviving member of their genus or even higher taxonomic rank. The extinction of such species would therefore represent a disproportionate loss of unique evolutionary history and biodiversity. The EDGE logo is the echidna. [1]
Some EDGE species, such as elephants and pandas, are well-known and already receive considerable conservation attention, but many others, such as the vaquita (the world's rarest cetacean) [2] [3] the bumblebee bat (arguably the world's smallest mammal) and the egg-laying long-beaked echidnas, are highly threatened yet remain poorly understood, and are frequently overlooked by existing conservation frameworks. [3]
The Zoological Society of London launched the EDGE of Existence Programme in 2007 to raise awareness and funds for the conservation of these species. As of 2024, the programme has awarded fellows funds to help conserve 157 different species in 47 countries. [1] The programme lists key supporters as the Fondation Franklinia, On the EDGE, and Darwin Initiative. Donors include the IUCN, US Fish and Wildlife Service, and numerous non-governmental organisations and foundations. [4]
In 2024, researchers at the programme identified EDGE Zones that make up 0.7% of Earth's surface but are home to one-third of the world's four-legged EDGE species. [5]
The EDGE of Existence programme is centred on an interactive website that features information on the top 100 EDGE mammals, reptiles, birds, amphibians and top 25 EDGE corals, detailing their specific conservation requirements. Each of the top 100 species is given an 'EDGE-ometer' rating according to the degree of conservation attention they are currently receiving, as well as its perceived rarity in its natural environment. 70% of the mammals which have been chosen are receiving little or no conservation attention according to the inventors. [6]
EDGE research and conservation is carried out by ZSL researchers, a network of partner organizations and local scientists. An important part of the EDGE programme is a fellowship scheme which provides funding and support to local scientists. EDGE Fellows participate in all phases of a research project. Each project is focused on delivering a conservation action plan. Once the action plan is completed, a meeting is held to make additions and corrections to the document.
Some species are more distinct than others because they represent a larger amount of unique evolution. Species like the aardvark have few close relatives and have been evolving independently for many millions of years. Others like the domestic dog originated only recently and have many close relatives. Species uniqueness can be measured as an 'Evolutionary Distinctiveness' (ED) score, using a phylogeny, or evolutionary tree. ED scores are calculated relative to a clade of species descended from a common ancestor. The three clades for which the EDGE of Existence Programme has calculated scores are all classes, namely mammals, amphibians, and corals.
The phylogenetic tree has the most recent common ancestor at the root, all the current species as the leaves, and intermediate nodes at each point of branching divergence. The branches are divided into segments (between one node and another node, a leaf, or the root). Each segment is assigned an ED score defined as the timespan it covers (in millions of years) divided by the number of species at the end of the subtree it forms. The ED of a species is the sum of the ED of the segments connecting it to the root. Thus, a long branch which produces few species will have a high ED, as the corresponding species are relatively distinctive, with few close relatives. ED metrics are not exact, because of uncertainties in both the ordering of nodes and the length of segments.
GE is a number corresponding to a species' conservation status according to the International Union for Conservation of Nature with more endangered species having a higher GE:
Conservation status | Code | GE score |
---|---|---|
Extinct | EX | — |
Extinct in the wild | EW | — |
Critically endangered | CR | 4 |
Endangered | EN | 3 |
Vulnerable | VU | 2 |
Near threatened | NT | 1 |
Least concern | LC | 0 |
Data deficient | DD | — |
Not evaluated | NE | — |
The EDGE score of a species is derived from its scores for Evolutionary Distinctness (ED) and for Globally Endangered status (GE) as follows:
This means that a doubling in ED affects the EDGE score almost as much as increasing the threat level by one (e.g. from 'vulnerable' to 'endangered'). EDGE scores are an estimate of the expected loss of evolutionary history per unit time.
EDGE species are species which have an above average ED score and are threatened with extinction (critically endangered, endangered or vulnerable). There are currently 564 EDGE mammal species (≈12% of the total). Potential EDGE species are those with high ED scores but whose conservation status is unclear (data deficient or not evaluated).
Focal species are typically selected from the priority EDGE species —the top 100 amphibians, birds, mammals and reptiles, top 50 sharks and rays, and top 25 corals— however, they also prioritise species outside these rankings. Such species can also have a very high ED but fall outside the top 100 EDGE rankings. These species are conserved by 'EDGE Fellows', who collect data on these species and develop conservation action plans. [7] Fellows have previously collaborated with institutions like National Geographic and The Disney Conservation Fund. [8] [9]
Top 3 ranked species in each taxonomic group, as of September 2024: [10]
The species with an EDGE score of 20 or higher are the mountain pygmy possum (25.1) and aye-aye (20.1). Only mammals have and EDGE score of 8 or higher. The non-mammal species with the highest EDGE score is the largetooth sawfish (7.4). The species with the highest ED scores are the pig-nosed turtle (149.7) and the narrow sawfish (125.1). Examples of Critically Endangered species with very low ED scores are porites pukoensis, mountainous star coral, and the magenta petrel. [10]
Porpoises are small dolphin-like cetaceans classified under the family Phocoenidae. Although similar in appearance to dolphins, they are more closely related to narwhals and belugas than to the true dolphins. There are eight extant species of porpoise, all among the smallest of the toothed whales. Porpoises are distinguished from dolphins by their flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and lack of a pronounced beak, although some dolphins also lack a pronounced beak. Porpoises, and other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates.
London Zoo, previously known as ZSL London Zoo or London Zoological Gardens and sometimes called Regent's Park Zoo, is the world's oldest scientific zoo. It was opened in London on 27 April 1828, and was originally intended to be used as a collection for scientific study. In 1831 or 1832, the animals of the Tower of London menagerie were transferred to the zoo's collection. It was opened to the public in 1847. As of December 2022, it houses a collection of 14,926 individuals, making it one of the largest collections in the United Kingdom.
Bristol Zoo was a zoo in the city of Bristol in South West England. The zoo's stated mission was to "maintain and defend" biodiversity through breeding endangered species, conserving threatened species and habitats and promoting a wider understanding of the natural world".
The vaquita is a species of porpoise endemic to the northern end of the Gulf of California in Baja California, Mexico. Reaching a maximum body length of 150 cm (4.9 ft) (females) or 140 cm (4.6 ft) (males), it is the smallest of all living cetaceans.
Sawfish, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish, with some species reaching lengths of about 7–7.6 m (23–25 ft). They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes. All species are critically endangered.
Wildlife conservation refers to the practice of protecting wild species and their habitats in order to maintain healthy wildlife species or populations and to restore, protect or enhance natural ecosystems. Major threats to wildlife include habitat destruction, degradation, fragmentation, overexploitation, poaching, pollution, climate change, and the illegal wildlife trade. The IUCN estimates that 42,100 species of the ones assessed are at risk for extinction. Expanding to all existing species, a 2019 UN report on biodiversity put this estimate even higher at a million species. It is also being acknowledged that an increasing number of ecosystems on Earth containing endangered species are disappearing. To address these issues, there have been both national and international governmental efforts to preserve Earth's wildlife. Prominent conservation agreements include the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and the 1992 Convention on Biological Diversity (CBD). There are also numerous nongovernmental organizations (NGO's) dedicated to conservation such as the Nature Conservancy, World Wildlife Fund, and Conservation International.
Threatened fauna of Australia are those species and subspecies of birds, fish, frogs, insects, mammals, molluscs, crustaceans, and reptiles to be found in Australia that are in danger of becoming extinct. This article lists species classified as threatened species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
Marine conservation, also known as ocean conservation, is the protection and preservation of ecosystems in oceans and seas through planned management in order to prevent the over-exploitation of these marine resources. Marine conservation is informed by the study of marine plants and animal resources and ecosystem functions and is driven by response to the manifested negative effects seen in the environment such as species loss, habitat degradation and changes in ecosystem functions and focuses on limiting human-caused damage to marine ecosystems, restoring damaged marine ecosystems, and preserving vulnerable species and ecosystems of the marine life. Marine conservation is a relatively new discipline which has developed as a response to biological issues such as extinction and marine habitats change.
The Hispaniolan solenodon, also known as the agouta, is a small, furry, shrew-like mammal endemic to the Caribbean island of Hispaniola. Like other solenodons, it is a venomous, insect-eating animal that lives in burrows and is active at night. It is an elusive animal and was only first described in 1833; its numbers are stable in protected forests but it remains the focus of conservation efforts.
The largetooth sawfish is a species of sawfish in the family Pristidae. It is found worldwide in tropical and subtropical coastal regions, but also enters freshwater. It has declined drastically and is now critically endangered.
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The longcomb sawfish, narrowsnout sawfish or green sawfish is a species of sawfish in the family Pristidae, found in tropical and subtropical waters of the Indo-West Pacific. It has declined drastically and is now considered a critically endangered species.
The Madagascan big-headed turtle is a turtle native to the waters of permanent slow moving rivers and lakes in western Madagascar. These turtles are critically endangered and have been evaluated to be the most endangered turtle in the world by a 2018 review. Due to its ancient origins and threatened status, it is ranked as #1 on the EDGE of Existence programme's list of priority reptiles.
The Mary River turtle is an endangered species of short-necked turtle in the family Chelidae. The species is endemic to the Mary River in south-east Queensland, Australia. Although this turtle was known to inhabit the Mary River for nearly 30 years, it was not until 1994 that it was recognised as a new species. There has been a dramatic decrease in its population due to low reproduction rates and an increase of depredation on nests.
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The Swiss Cetacean Society or Swiss Society for the Study and Protection of Cetaceans is a Swiss nonprofit organization dedicated to the conservation of marine mammals and other endangered marine species in their natural habitat. Founded in 1997, its headquarters are in Lausanne in Switzerland.