NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com 853 articles Biodiversity hotspots for conservation priorities Norman Myers*, Russell A. Mittermeier��, Cristina G. Mittermeier��, Gustavo A. B. da Fonseca��� & Jennifer Kent�� * Green College, Oxford University, Upper Meadow, Old Road, Headington, Oxford OX3 8SZ, UK �� Conservation International, 2501 M Street NW, Washington, DC 20037, USA ��� Centre for Applied Biodiversity Science, Conservation International, 2501 M Street NW, Washington, DC 20037, USA �� 35 Dorchester Close, Headington, Oxford OX3 8SS, UK ............................................................................................................................................................................................................................................................................ Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify ���biodiversity hotspots��� where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a ���silver bullet��� strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world���s species at risk. The number of species threatened with extinction far outstrips available conservation resources, and the situation looks set to become rapidly worse1���4. This places a premium on identifying priorities. How can we protect the most species per dollar invested? This key question is at the forefront of conservation planning, and forms the focus of this article. By concentrating on areas where there is greatest need and where the payoff from safeguard measures would also be greatest, conservationists can engage in a systematic response to the challenge of large-scale extinctions ahead. A promising approach is to identify ���hotspots���, or areas featuring exceptional concentrations of endemic species and experiencing exceptional loss of habitat5���9. Here we focus on species, rather than populations or other taxa, as the most prominent and readily recognizable form of biodiversity. This is not to suggest that populations and even ecological processes are not important mani- festations of biodiversity, but they do not belong in this assessment. There are other types of hotspot10,11, featuring richness of, for example, rare12,13 or taxonomically unusual species14,15. This article considers only hotspots as defined above. Concentrating a large proportion of conservation support on these areas would go far to stem the mass extinction of species that is now underway. The hotspots��� boundaries have been determined by ���biological commonalities���. Each of the areas features a separate biota or community of species that fits together as a biogeographic unit. This is apparent in the case of islands or island groups such as New Caledonia, New Zealand, the Caribbean, Polynesia/Micronesia, Madagascar and the Philippines. Much the same applies to ���eco- logical islands��� in clearly defined continental units such as the Cape Figure 1 The 25 hotspots. The hotspot expanses comprise 30���3% of the red areas. �� 2000 Macmillan Magazines Ltd

Floristic Province, the Eastern Arc and Coastal Forests of Tanzania/ Kenya (hereafter abbreviated to ���Eastern Arc���), southwestern Aus- tralia and Caucasus. In other areas the definition of a hotspot���s boundaries derives from recognized divisions such as Wallace���s line between Sundaland and Wallacea, or the Kangar���Pattani line between Indo-Burma and Sundaland. In still other areas, the definition reflects a best-judgement opinion from experts in the field. Were larger hotspots, for example, the Tropical Andes, Mesoamerica, Indo-Burma and Sundaland to be subdivided into areas the size of the smaller hotspots, they would still meet the criterion of biological commonalities and the result would be a far larger number of mini-hotspots, making for a much more compli- cated assessment and diffusing the essential strategy of just 25 hotspots designated for priority conservation. This article is a qualitative as well as a quantitative advance on a preliminary effort5,6, which limited itself to vascular plants in 18 hotspots. The number of hotspots has been increased to 25. More importantly, the expanded criteria require that a hotspot contains endemic plant species comprising at least 0.5% of all plant species world-wide. Here we include four categories of vertebrate species, bringing the number of endemics to almost three times more than in the earlier papers. We analyse key questions of species/area ratios and congruence among taxa. Finally, we present a way to determine the hottest hotspots and thus to pinpoint super priorities. Analytic methods The basic analysis is driven by two criteria: species endemism and degree of threat. The main source of data for both plants and vertebrates has been more than 100 scientists with abundant experience in countries concerned and around 800 references in the professional literature (see Supplementary Information). Additional details are available in ref. 16 supplementary sources on plants include refs 17���19. The species dimension is based in the first instance on vascular plants (comprising around 90% of all plants, and hereafter referred to as ���plants���), as they are essential to virtually all forms of animal life and are fairly well known scien- tifically. To qualify as a hotspot, an area must contain at least 0.5% or 1,500 of the world���s 300,000 plant species20 as endemics. In fact, 15 of the 25 hotspots contain at least 2,500 endemic plant species, and 10 of them at least 5,000. The four vertebrate groups, mammals, birds, reptiles and am- phibians, comprise 27,298 species, consisting of 4,809 mammals21, 9,881 birds22, 7,828 reptiles23 and 4,780 amphibians24. The other vertebrate group, fishes, is excluded because data are generally poor (there could well be at least 5,000 species waiting to be discovered25, or more than all mammals). Hereafter ���vertebrates��� refers to all vertebrates except fishes. Vertebrates do not serve as an alternative determinant of hotspot status, nor do their endemics have to comprise 0.5% of global totals. If an area qualifies by the 0.5% plants criterion (and the habitat threat criterion), it makes the list. Vertebrates serve as back-up support, and also to determine con- gruence and to facilitate other comparisons among the hotspots. The analysis omits invertebrates, which are largely undocumen- ted but probably make up at least 95% of all species, the bulk of them insects. To the extent that the five categories of endemic species assessed are sometimes matched by similar concentrations of endemic insect species, the hotspots thesis can be applied to invertebrates as well. In any case, if we were to lose, say, half of endemic plant species, we could well lose a large and perhaps similar proportion of insect species. The fig genus, for example, being the most widespread of plant genera in the tropics, comprises more than 900 species, each of which is pollinated by a single wasp species conversely, the wasps depend on the figs��� ovaries as sites for their larvae to develop26. Although the plant/insect connection is variable in general application27���30, it is supported by the many pollination, herbivory and other relationships between plants and insects. The endemism data tend to be minimalist for two reasons. One is the lack of recent documentation in the form of, for example, modern floras. For instance, there is no up-to-date account of Brazil���s plant species even though the country is believed to harbour the Earth���s richest flora, at least 50,000 species or one-sixth of the planetary total. Second, and more importantly, endemism data almost always relate only to individual countries or parts of countries, whereas 12 of the hotspots extend across two or more countries and six across four or more countries. In these cases, it has been difficult to compute regional totals for hotspot-wide endemics, articles 854 NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com Table 1 The 25 hotspots Hotspot Original extent of primary vegetation (km2) Remaining primary vegetation (km2) (% of original extent) Area protected (km2) (% of hotspot) Plant species Endemic plants (% of global plants, 300,000) Vertebrate species Endemic vertebrates (% of global vertebrates, 27,298) Tropical Andes 1,258,000 314,500 (25.0) 79,687 (25.3) 45,000 20,000 (6.7%) 3,389 1,567 (5.7%) Mesoamerica 1,155,000 231,000 (20.0) 138,437 (59.9) 24,000 5,000 (1.7%) 2,859 1,159 (4.2%) Caribbean 263,500 29,840 (11.3) 29,840 (100.0) 12,000 7,000 (2.3%) 1,518 779 (2.9%) Brazil���s Atlantic Forest 1,227,600 91,930 (7.5) 33,084 (35.9) 20,000 8,000 (2.7%) 1,361 567 (2.1%) Choc/Darien/Western Ecuador 260,600 63,000 (24.2) 16,471 (26.1) 9,000 2,250 (0.8%) 1,625 418 (1.5%) Brazil���s Cerrado 1,783,200 356,630 (20.0) 22,000 (6.2) 10,000 4,400 (1.5%) 1,268 117 (0.4%) Central Chile 300,000 90,000 (30.0) 9,167 (10.2) 3,429 1,605 (0.5%) 335 61 (0.2%) California Floristic Province 324,000 80,000 (24.7) 31,443 (39.3) 4,426 2,125 (0.7%) 584 71 (0.3%) Madagascar* 594,150 59,038 (9.9) 11,548 (19.6) 12,000 9,704 (3.2%) 987 771 (2.8%) Eastern Arc and Coastal Forests of Tanzania/Kenya 30,000 2,000 (6.7) 2,000 (100.0) 4,000 1,500 (0.5%) 1,019 121 (0.4%) Western African Forests 1,265,000 126,500 (10.0) 20,324 (16.1) 9,000 2,250 (0.8%) 1,320 270 (1.0%) Cape Floristic Province 74,000 18,000 (24.3) 14,060 (78.1) 8,200 5,682 (1.9%) 562 53 (0.2%) Succulent Karoo 112,000 30,000 (26.8) 2,352 (7.8) 4,849 1,940 (0.6%) 472 45 (0.2%) Mediterranean Basin 2,362,000 110,000 (4.7) 42,123 (38.3) 25,000 13,000 (4.3%) 770 235 (0.9%) Caucasus 500,000 50,000 (10.0) 14,050 (28.1) 6,300 1,600 (0.5%) 632 59 (0.2%) Sundaland 1,600,000 125,000 (7.8) 90,000 (72.0) 25,000 15,000 (5.0%) 1,800 701 (2.6%) Wallacea 347,000 52,020 (15.0) 20,415 (39.2) 10,000 1,500 (0.5%) 1,142 529 (1.9%) Philippines 300,800 9,023 (3.0) 3,910 (43.3) 7,620 5,832 (1.9%) 1,093 518 (1.9%) Indo-Burma 2,060,000 100,000 (4.9) 100,000 (100.0) 13,500 7,000 (2.3%) 2,185 528 (1.9%) South-Central China 800,000 64,000 (8.0) 16,562 (25.9) 12,000 3,500 (1.2%) 1,141 178 (0.7%) Western Ghats/Sri Lanka 182,500 12,450 (6.8) 12,450 (100.0) 4,780 2,180 (0.7%) 1,073 355 (1.3%) SW Australia 309,850 33,336 (10.8) 33,336 (100.0) 5,469 4,331 (1.4%) 456 100 (0.4%) New Caledonia 18,600 5,200 (28.0) 526.7 (10.1) 3,332 2,551 (0.9%) 190 84 (0.3%) New Zealand 270,500 59,400 (22.0) 52,068 (87.7) 2,300 1,865 (0.6%) 217 136 (0.5%) Polynesia/Micronesia 46,000 10,024 (21.8) 4,913 (49.0) 6,557 3,334 (1.1%) 342 223 (0.8%) Totals 17,444,300 2,122,891 (12.2) 800,767 (37.7) �� 133,149 (44%) �� 9,645 (35%) ................................................................................................................................................................................................................................................................................................................................................................... Documentation of plant and vertebrate species and endemism can be found in Supplementary Information. * Madagascar includes the nearby islands of Mauritius, Reunion, Seychelles and Comores. �� These totals cannot be summed owing to overlapping between hotspots. �� 2000 Macmillan Magazines Ltd