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Biodiversity hotspots for conservation priorities
Norman Myers*, Russell A. Mittermeier², Cristina G. Mittermeier², Gustavo A. B. da Fonseca³ & Jennifer Kent§
* Green College, Oxford University, Upper Meadow, Old Road, Headington, Oxford OX3 8SZ, UK ² Conservation International, 2501 M Street NW, Washington, DC 20037, USA ³ Centre for Applied Biodiversity Science, ConservationInternational, 2501 M Street NW, Washington, DC 20037, USA § 35 Dorchester Close, Headington, Oxford OX3 8SS, UK

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Conservationistsare 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 fourvertebrate groups are con®ned 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 setto 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 asystematic 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 populationsand even ecological processes are not important manifestations 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 de®ned above. Concentrating a large proportion of conservation support on these areas would go far to stem themass 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 ®ts 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. Muchthe same applies to `ecological islands' in clearly de®ned continental units such as the Cape

Figure 1 The 25 hotspots. The hotspot expanses comprise 30±3% of the red areas.
NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com

© 2000 Macmillan Magazines Ltd

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Floristic Province, the Eastern Arc and Coastal Forests of Tanzania/ Kenya (hereafter abbreviated to `EasternArc'), southwestern Australia and Caucasus. In other areas the de®nition 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 de®nition re¯ects a best-judgement opinion from experts in the ®eld. Were larger hotspots, for example, the Tropical Andes,...