176:. 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.
1063:
122:
623:
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
484:
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
129:, species A has a higher ED score than either species B or C — it represents a branch rather than a twig on the tree of life. If species A were to go extinct, there would be no similar species left on the planet and a larger amount of unique evolutionary history would be lost forever.
92:
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. The programme lists key supporters as the
Fondation Franklinia, On the EDGE, and
17:
485:
EDGE rankings. These species are conserved by 'EDGE Fellows', who collect data on these species and develop conservation action plans. Fellows have previously collaborated with institutions like
National Geographic and The Disney Conservation Fund.
459:
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.
467:
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
454:
661:
1072:
853:
108:
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.
189:
98:
141:
originated only recently and have many close relatives. Species uniqueness can be measured as an 'Evolutionary
Distinctiveness' (ED) score, using a
1108:
1098:
340:
102:
334:
The EDGE score of a species is derived from its scores for
Evolutionary Distinctness (ED) and for Globally Endangered status (GE) as follows:
1113:
149:
of species descended from a common ancestor. The three clades for which the EDGE of
Existence Programme has calculated scores are all
878:
964:
590:
529:
237:
81:, are highly threatened yet remain poorly understood, and are frequently overlooked by existing conservation frameworks.
973:
585:
133:
Some species are more distinct than others because they represent a larger amount of unique evolution. Species like the
85:
46:. The extinction of such species would therefore represent a disproportionate loss of unique evolutionary history and
1103:
1032:
169:
89:
38:. Distinctive species have few closely related species, and EDGE species are often the only surviving member of their
780:
Pipins, Sebastian; Baillie, Jonathan E. M.; Bowmer, Alex; Pollock, Laura J.; Owen, Nisha; Gumbs, Rikki (2024-09-03).
662:"Anthropologist Paul Barnes: 'The conservation of species depends almost exclusively on philanthropy and goodwill'"
137:
have few close relatives and have been evolving independently for many millions of years. Others like the domestic
502:
633:
573:
1093:
563:
65:, are well-known and already receive considerable conservation attention, but many others, such as the
172:
at the root, all the current species as the leaves, and intermediate nodes at each point of branching
1022:
710:
684:
1047:
782:"Advancing EDGE Zones to identify spatial conservation priorities of tetrapod evolutionary history"
224:
198:
185:
78:
31:
854:"Meet the 10 Species ZSL EDGE of Existence and National Geographic Are Working to Protect in Asia"
1027:
612:
607:
541:
464:
263:
250:
173:
1014:
957:
801:
738:
687:. (2012). National Oceanographic and Atmospheric Administration Office of Protected Resources.
126:
94:
985:
809:
793:
728:
718:
595:
497:
1062:
519:
276:
150:
814:
714:
1067:
1042:
733:
698:
637:
625:
469:
302:
43:
27:
16:
1087:
1004:
781:
616:
473:
315:
289:
74:
1036:
950:
47:
829:
723:
507:
942:
797:
628:(125.1). Examples of Critically Endangered species with very low ED scores are
999:
524:
211:
905:
805:
699:"Mammals on the EDGE: conservation priorities based on threat and phylogeny"
629:
546:
449:{\displaystyle {\text{EDGE}}=\ln(1+{\text{ED}})+{\text{GE}}\cdot \ln(2)=\ln}
158:
142:
58:
879:"The Disney Conservation Fund Names the Recipients of its 2016-2017 Grants"
742:
756:
551:
134:
70:
568:
66:
51:
685:
Gulf of
California Harbor Porpoise/ Vaquita/ Cochito/ (Phocoena sinus)
463:
EDGE species are species which have an above average ED score and are
121:
993:
154:
488:
Top 3 ranked species in each taxonomic group, as of
September 2024:
162:
146:
120:
62:
39:
35:
932:
697:
Isaac, N. J. B.; Turvey, S. T.; Collen, B.; Waterman, C. (2007).
946:
145:, or evolutionary tree. ED scores are calculated relative to a
105:, and numerous non-governmental organisations and foundations.
981:
138:
30:
which have a high 'EDGE score', a metric combining endangered
15:
77:(arguably the world's smallest mammal) and the egg-laying l
24:
Evolutionarily
Distinct and Globally Endangered (EDGE)
937:
343:
1013:
980:
34:with the genetic distinctiveness of the particular
448:
192:with more endangered species having a higher GE:
190:International Union for Conservation of Nature
958:
8:
184:GE is a number corresponding to a species'
965:
951:
943:
813:
732:
722:
437:
422:
378:
367:
344:
342:
938:ZSL−Zoological Society of London website
194:
649:
7:
900:
898:
655:
653:
14:
1061:
1109:Species by conservation status
1099:Animals by conservation status
660:Sánchez, Esther (2024-01-21).
443:
427:
413:
410:
398:
392:
372:
358:
168:The phylogenetic tree has the
1:
591:Central American river turtle
530:New Caledonian owlet-nightjar
1114:Zoological Society of London
974:Zoological Society of London
724:10.1371/journal.pone.0000296
586:Madagascar big-headed turtle
103:US Fish and Wildlife Service
86:Zoological Society of London
1033:EDGE of Existence programme
858:news.nationalgeographic.org
170:most recent common ancestor
90:EDGE of Existence Programme
57:Some EDGE species, such as
1130:
798:10.1038/s41467-024-51992-5
1056:
933:EDGE of Existence website
503:Chinese giant salamander
883:The Walt Disney Company
112:Calculating EDGE Scores
50:. The EDGE logo is the
634:mountainous star coral
450:
130:
20:
786:Nature Communications
564:Mountain pygmy possum
552:Moseleya latistellata
547:Poritipora paliformis
451:
238:Critically endangered
124:
97:. Donors include the
19:
1023:Institute of Zoology
877:Bruce (2017-04-20).
341:
69:(the world's rarest
1048:Living Planet Index
715:2007PLoSO...2..296I
574:Leadbeater's possum
225:Extinct in the wild
199:Conservation status
186:conservation status
79:ong-beaked echidnas
32:conservation status
1104:Endangered animals
1068:Animals portal
1028:Journal of Zoology
613:Smalltooth sawfish
608:Largetooth sawfish
542:Siderastrea glynni
446:
131:
21:
1081:
1080:
910:EDGE of Existence
834:EDGE of Existence
761:EDGE of Existence
630:porites pukoensis
440:
425:
381:
370:
347:
327:
326:
188:according to the
127:phylogenetic tree
95:Darwin Initiative
1121:
1066:
1065:
967:
960:
953:
944:
920:
919:
917:
916:
902:
893:
892:
890:
889:
874:
868:
867:
865:
864:
850:
844:
843:
841:
840:
826:
820:
819:
817:
777:
771:
770:
768:
767:
753:
747:
746:
736:
726:
694:
688:
682:
676:
675:
673:
672:
657:
624:(149.7) and the
596:Pig-nosed turtle
455:
453:
452:
447:
442:
441:
438:
426:
423:
382:
379:
371:
368:
348:
345:
195:
1129:
1128:
1124:
1123:
1122:
1120:
1119:
1118:
1084:
1083:
1082:
1077:
1060:
1052:
1009:
976:
971:
929:
924:
923:
914:
912:
904:
903:
896:
887:
885:
876:
875:
871:
862:
860:
852:
851:
847:
838:
836:
830:"Focal Species"
828:
827:
823:
779:
778:
774:
765:
763:
755:
754:
750:
696:
695:
691:
683:
679:
670:
668:
666:EL PAÍS English
659:
658:
651:
646:
604:
602:Sharks and Rays
582:
560:
538:
520:Plains-wanderer
516:
494:
482:
433:
339:
338:
332:
277:Near threatened
182:
119:
114:
42:or even higher
12:
11:
5:
1127:
1125:
1117:
1116:
1111:
1106:
1101:
1096:
1086:
1085:
1079:
1078:
1076:
1075:
1073:Fellows of ZSL
1070:
1057:
1054:
1053:
1051:
1050:
1045:
1043:Red List Index
1040:
1030:
1025:
1019:
1017:
1011:
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1008:
1007:
1002:
997:
990:
988:
978:
977:
972:
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969:
962:
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947:
941:
940:
935:
928:
927:External links
925:
922:
921:
894:
869:
845:
821:
772:
748:
689:
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645:
642:
638:magenta petrel
626:narrow sawfish
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470:data deficient
457:
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303:Data deficient
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44:taxonomic rank
28:animal species
13:
10:
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2:
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1038:
1034:
1031:
1029:
1026:
1024:
1021:
1020:
1018:
1016:
1012:
1006:
1005:Whipsnade Zoo
1003:
1001:
998:
995:
992:
991:
989:
987:
983:
979:
975:
968:
963:
961:
956:
954:
949:
948:
945:
939:
936:
934:
931:
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926:
911:
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901:
899:
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835:
831:
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762:
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667:
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635:
631:
627:
618:
617:green sawfish
614:
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584:
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531:
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513:
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504:
501:
499:
498:Archey's frog
496:
495:
491:
489:
486:
480:Focal species
479:
477:
475:
474:not evaluated
471:
466:
461:
434:
430:
419:
416:
407:
404:
401:
395:
389:
386:
383:
375:
364:
361:
355:
352:
349:
337:
336:
335:
329:
322:
319:
317:
316:Not evaluated
314:
313:
309:
306:
304:
301:
300:
296:
293:
291:
290:Least concern
288:
287:
283:
280:
278:
275:
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270:
267:
265:
262:
261:
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252:
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144:
140:
136:
128:
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116:
111:
109:
106:
104:
100:
96:
91:
88:launched the
87:
82:
80:
76:
75:bumblebee bat
72:
68:
64:
60:
55:
53:
49:
45:
41:
37:
33:
29:
25:
18:
1094:EDGE species
1037:EDGE Species
913:. Retrieved
909:
906:"EDGE Lists"
886:. Retrieved
882:
872:
861:. Retrieved
857:
848:
837:. Retrieved
833:
824:
789:
785:
775:
764:. Retrieved
760:
757:"Supporters"
751:
706:
702:
692:
680:
669:. Retrieved
665:
622:
487:
483:
462:
458:
333:
183:
167:
132:
107:
83:
56:
48:biodiversitz
26:species are
23:
22:
996:(Cancelled)
792:(1): 7672.
709:(3): e296.
508:Purple frog
1088:Categories
1000:London Zoo
915:2024-09-17
888:2024-09-17
863:2024-09-17
839:2019-12-12
766:2024-09-17
671:2024-09-17
644:References
636:, and the
525:Giant ibis
492:Amphibians
465:threatened
264:Vulnerable
251:Endangered
174:divergence
159:amphibians
806:2041-1723
431:⋅
408:
390:
384:⋅
356:
206:GE score
153:, namely
143:phylogeny
59:elephants
1015:Research
815:11377708
743:17375184
703:PLOS ONE
580:Reptiles
135:aardvark
125:In this
71:cetacean
986:aquaria
734:1808424
711:Bibcode
569:Aye-aye
558:Mammals
212:Extinct
155:mammals
151:classes
67:vaquita
52:echidna
994:Biota!
812:
804:
741:
731:
536:Corals
163:corals
161:, and
73:) the
63:pandas
619:(tie)
514:Birds
147:clade
40:genus
36:taxon
984:and
982:Zoos
802:ISSN
739:PMID
615:and
346:EDGE
330:EDGE
203:Code
99:IUCN
84:The
61:and
810:PMC
794:doi
729:PMC
719:doi
476:).
472:or
165:.
139:dog
1090::
908:.
897:^
881:.
856:.
832:.
808:.
800:.
790:15
788:.
784:.
759:.
737:.
727:.
717:.
705:.
701:.
664:.
652:^
640:.
632:,
439:GE
424:ED
405:ln
387:ln
380:GE
369:ED
353:ln
323:—
320:NE
310:—
307:DD
297:0
294:LC
284:1
281:NT
271:2
268:VU
258:3
255:EN
245:4
242:CR
232:—
229:EW
219:—
216:EX
180:GE
157:,
117:ED
101:,
54:.
1039:)
1035:(
966:e
959:t
952:v
918:.
891:.
866:.
842:.
818:.
796::
769:.
745:.
721::
713::
707:2
674:.
468:(
444:]
435:2
428:)
420:+
417:1
414:(
411:[
402:=
399:)
396:2
393:(
376:+
373:)
365:+
362:1
359:(
350:=
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