It has been suggested that species with few close relatives (i.e. high ED) are ‘relicts’ or ‘living fossils’ that have limited ability to generate novel diversity. This view implies that conservation efforts should instead be focused on recent radiations containing species with low ED scores (e.g. murid rodents), which represent ‘cradles’ rather than ‘museums’ of diversity [e.g. 16], [42]. However, the assumption that we are able to predict future evolutionary potential is dubious and no general relationships between phylogeny and diversity over geological time have yet been established [43], [44]. Furthermore, phylogenetic diversity is clearly related to character diversity [30], and so ED may be a useful predictor of divergent properties and hence potential utilitarian value [14]. Moreover, because species with low ED scores tend to suffer from low levels of extinction risk, phylogenetic cradles of mammalian diversity are likely to survive the current extinction crisis even without specific interventions. Focusing on lower risk species, at the expense of EDGE priorities, would therefore result in a severe pruning of major branches of the Tree of Life comparable to that seen in previous mass extinction events [45], [46].
The top 100 EDGE species span all the major mammalian clades [being distributed among 18 orders and 52 families recognised by ref 35] and display a comparable range of morphological and ecological disparity, including the largest and smallest mammals, most of the world's freshwater cetaceans, an oviparous mammal and the only species capable of injecting venom using their teeth. However, around three-quarters of species-based mammal conservation projects are specifically aimed at charismatic megafauna [47], so conventional priority-setting tools may not be sufficient to protect high priority EDGE species. This concern is supported by two additional lines of evidence. First, we found that species not found in protected areas [‘gap species’ defined by ref 48] tended to have higher EDGE scores than those found inside protected areas (logistic regression: χ2 1,3994 = 69.46, p<0.0001). Second, an assessment of published conservation strategies and recommendations (including IUCN Specialist Group Conservation Action Plans, captive breeding protocols and the wider scientific literature listed in the 1978–2005 Zoological Record database) reveals that no species-specific conservation actions have even been suggested for 42 of the top 100 EDGE species. Most of these species are from poorly known regions or taxonomic groups and until now have rarely been highlighted as conservation priorities. Little conservation action is actually being implemented for many other top EDGE species, despite frequent recommendations in the conservation literature. Indeed, the top-scoring EDGE species, the Yangtze River dolphin (Lipotes vexillifer), is now possibly the world's most threatened mammal despite two decades of debate over a potential ex situ breeding programme, and may number fewer than 13 surviving individuals [49]. The lack of conservation attention for priority EDGE species is a serious problem for mammalian biodiversity and suggests that large amounts of evolutionary history are likely to be lost in the near future. This phenomenon of diversity slipping quietly towards extinction is likely to be much more severe in less charismatic groups than mammals.
The approach described in this paper can be used for conservation in a number of ways. First, conservation managers with limited resources at their disposal typically need to conserve populations of several threatened species. If all other factors were equal, the management of the most evolutionarily distinct species should be prioritized. Second, a list of high-priority species requiring urgent conservation action can be generated easily. In this paper, we have selected the 100 highest-ranking species, but one might equally choose all threatened (Vulnerable and above) species with above average ED. This would result in a list of 521 (using median) or 630 (using geometric mean) ‘EDGE species’ that are both evolutionarily distinct and globally endangered. Third, EDGE scores could also be used to weight species' importance in selecting reserve networks, building on previous studies that have used phylogenetic diversity [50]–[52] or threatened species [11] to identify priority areas for conservation. The statistical properties of EDGE scores (they are both normally-distributed and bounded at zero) make them especially suitable for these kinds of analysis. In this way, the EDGE approach is not an alternative to existing conservation frameworks [e.g. 6] but complements them.
Extract only the main points for the information given above
- There is a debate about focusing conservation efforts on species with high evolutionary distinctiveness (ED) or low ED.
- It is uncertain whether we can accurately predict future evolutionary potential and there is no established relationship between phylogeny and diversity over time.
- ED can be a useful predictor of divergent properties and potential utilitarian value.
- Species with low ED scores tend to have low extinction risk and may survive the current extinction crisis without specific interventions.
- Focusing on lower risk species instead of high priority EDGE (Evolutionarily Distinct and Globally Endangered) species would result in a loss of major branches of the Tree of Life.
- Most mammalian conservation projects are aimed at charismatic megafauna and may not be sufficient to protect high priority EDGE species.
- Species not found in protected areas tend to have higher EDGE scores than those found inside protected areas.
- Many of the top 100 EDGE species have not had any species-specific conservation actions recommended for them.
- The lack of conservation attention for high priority EDGE species is a serious problem and suggests that a significant amount of evolutionary history may be lost.
- The approach described in this paper can be used for conservation in several ways, including prioritizing the management of the most evolutionarily distinct species, generating lists of high-priority species for urgent conservation action, and weighting species' importance in selecting reserve networks.
1. The idea that species with few close relatives have limited ability to generate novel diversity is questionable and not supported by established relationships between phylogeny and diversity over time.
2. Phylogenetic diversity is related to character diversity and can be a useful predictor of utilitarian value.
3. Species with low phylogenetic diversity tend to have lower extinction risk and are likely to survive without specific interventions.
4. Focusing on lower risk species instead of EDGE (Evolutionarily Distinct and Globally Endangered) priorities would result in loss of major branches of the Tree of Life.
5. The top 100 EDGE species span all major mammalian clades and have diverse morphological and ecological characteristics.
6. Most mammal conservation projects prioritize charismatic megafauna, which may not be sufficient to protect high priority EDGE species.
7. Species not found in protected areas tend to have higher EDGE scores.
8. Many of the top 100 EDGE species have not been the subject of species-specific conservation actions.
9. The lack of conservation attention for priority EDGE species is a serious problem and risks losing a significant amount of evolutionary history.
10. The approach described in the paper can be used to prioritize species for conservation, generate lists of high-priority species, and guide the selection of reserve networks.
1. The concept of Evolutionary Distinctiveness (ED) suggests that species with few close relatives are "living fossils" and have limited ability to generate new diversity.
2. This view implies that conservation efforts should focus on recent radiations containing species with low ED scores, which represent "cradles" of diversity.
3. The assumption that we can predict future evolutionary potential is doubtful, and no general relationships between phylogeny and diversity over time have been established.
4. Phylogenetic diversity is related to character diversity, so ED may be a useful predictor of divergent properties and potential utility.
5. Species with low ED scores tend to have low extinction risk, so focusing on them would risk pruning major branches of the Tree of Life.
6. The top 100 EDGE (Evolutionarily Distinct and Globally Endangered) species span all major mammalian clades and display a range of morphological and ecological disparity.
7. Most mammal conservation projects focus on charismatic megafauna, so conventional tools may not be enough to protect high priority EDGE species.
8. Species not found in protected areas tend to have higher EDGE scores than those found inside protected areas, indicating the need for conservation attention.
9. Many top EDGE species have not been the subject of species-specific conservation actions, despite recommendations in the literature.
10. The lack of conservation attention for priority EDGE species suggests that significant amounts of evolutionary history may be lost in the near future.
11. The approach described in the paper can be used to prioritize conservation efforts, generate lists of high-priority species, and guide the selection of reserve networks.
12. EDGE scores are suitable for this type of analysis and complement existing conservation frameworks.