NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com 853
articles
Biodiversity hotspots for
conservation priorities
Norman Myers*, Russell A. Mittermeier
²
, Cristina G. Mittermeier
²
, Gustavo A. B. da Fonseca
³
& 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, 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 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 set to
become rapidly worse
1±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 habitat
5±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 hotspot
10,11
, featuring richness of, for
example, rare
12,13
or taxonomically unusual species
14,15
. This article
considers only hotspots as de®ned above. Concentrating a large
proportion of conservation support on these areas would go far to
stem 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 ®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. Much the same applies to `eco-
logical 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.
© 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 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,
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 effort
5,6
, 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
®rst 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-
ti®cally. To qualify as a hotspot, an area must contain at least 0.5%
or 1,500 of the world's 300,000 plant species
20
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 mammals
21
,
9,881 birds
22
, 7,828 reptiles
23
and 4,780 amphibians
24
. The other
vertebrate group, ®shes, is excluded because data are generally poor
(there could well be at least 5,000 species waiting to be discovered
25
,
or more than all mammals). Hereafter `vertebrates' refers to all
vertebrates except ®shes. 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 quali®es 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 ®ve 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 ®g 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 ®gs' ovaries as sites for their
larvae to develop
26
. Although the plant/insect connection is variable
in general application
27±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 ¯oras. 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 ¯ora, 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 dif®cult 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
(km
2
)
Remaining primary
vegetation (km
2
)
(% of original extent)
Area protected (km
2
)
(% 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) ² 133,149 (44%) ² 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.
² These totals cannot be summed owing to overlapping between hotspots.
© 2000 Macmillan Magazines Ltd

and we have often had to depend on best-judgement estimates by
over 100 scientists with abundant experience in the countries
concerned. In a few instances, we have had to accept a simple
summation of country-by-country totals, which surely under-
estimates regional totals. To this extent, many of the endemism
estimates are distinctly conservative.
A second determinant of hotspot status, applied only after an area
has met the `plants' criterion, is the degree of threat through habitat
loss. To qualify, a hotspot should have lost 70% or more of its
primary vegetation, this being the form of habitat that usually
contains the most species, especially endemics. Eleven hotspots have
already lost at least 90% and three have lost 95%. The 70% cutoff is
justi®ed on the grounds that most large-scale concentrations of
endemic plant species occur within the 25 hotspots as delineated.
Other concentrations of plant endemics with perhaps another 15%
of the Earth's plant species occur in three regions designated as
`major tropical forest wilderness areas', each retaining 75% of its
primary vegetation (see below). There are few other areas with
comparable concentrations. Moreover, were the 70% cutoff to be
replaced with 60%, this would admit hardly any other hotspots,
whereas a 90% cutoff would exclude 11 of the hotspots.
Finally, the analysis is limited to the terrestrial realm (Conserva-
tion International is preparing an analysis of marine species and
conservation priorities).
The area-by-area ®ndings are presented in Tables 1±6 and Fig. 1.
For further information regarding the sources of our statistics, see
the list of references and experts in Supplementary Information.
There is variability in the precision and accuracy of data. This is to
be expected given the range of areas and the degree of documenta-
tion available. In many instances, the statistical information is
considered to be accurate to within 5%. In most others, it is
suf®ciently accurate to rank as sound support for working esti-
mates. For example, the Tropical Andes is believed to contain at least
20,000 known plant endemics, this being a rounded ®gure (many
more species, probably thousands, remain to be discovered there).
Another 14 such totals are rounded. The Cape Floristic Province, by
contrast, is considered to contain exactly 5,682 known plant
endemics; the same precision applies to another nine hotspots.
Similar considerations apply to vertebrate data and to estimates of
remaining primary vegetation.
This overall approach, uneven as it is, is justi®ed for an analysis
that seeks to convert a profound problem into a ®ne opportunity.
After all, to decide that a potential hotspot should not be evaluated
because it lacks a conventional degree of accurate data is effectively
to decide that its conservation needs cannot be evaluated either, in
which case its cause tends to go by default. Uncertainty can cut both
ways.
Chief ®ndings
The 25 hotspots contain the remaining habitats of 133,149 plant
species (44% of all plant species world-wide; Table 1) and 9,645
vertebrate species (35%; Table 2). These endemics are con®ned to an
aggregate expanse of 2.1 million square kilometres, or 1.4% of the
Earth's land surface. They formerly occupied 17.4 million square
kilometres or 11.8% of the Earth's land surface. They are so
threatened that, having already lost an aggregate of 88% of their
primary vegetation, they all seem likely, in the absence of greatly
increased conservation efforts, to lose much if not most of their
remaining primary vegetation within the foreseeable future.
The 25 hotspots feature several habitat types at global scale.
Predominant are tropical forests, appearing in 15 hotspots, and
Mediterranean-type zones, in ®ve. Nine are mainly or completely
made up of islands; almost all tropical islands fall into one or
another hotspot. Sixteen hotspots are in the tropics, which largely
means developing countries where threats are greatest and con-
servation resources are scarcest.
Leading hotspots
Some hotspots are much richer than others in terms of their
numbers of endemics (Table 3). (Three other modes of comparison
are presented below.) Each of ®ve hotspotsÐthe Tropical Andes,
Sundaland, Madagascar, Brazil's Atlantic Forest and the Carib-
beanÐcontains endemic plants and vertebrates amounting to at
least 2% of total species world-wide. Together, they comprise 20%
and 16%, respectively, of all plants and vertebrates, and 45% of all
the hotspots' endemic plants and vertebrates alike, but they com-
prise a mere 0.4% of the Earth's land surface. At the same time, they
feature some of the most depleted habitats: the Caribbean retains
only 11.3% of its primary vegetation, Madagascar 9.9%, Sundaland
7.8% and Brazil's Atlantic Forest 7.5%. These ®ve hotspots, with
articles
NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com 855
Table 2 Vertebrate species and endemism
Hotspot Bird species
and endemism
Mammal species
and endemism
Reptile species
and endemism
Amphibian species
and endemism
Total species
and endemism
Tropical Andes 1,666 677 414 68 479 218 830 604 3,389 1,567
Mesoamerica 1,193 251 521 210 685 391 460 307 2,859 1,159
Caribbean 668 148 164 49 497 418 189 164 1,518 779
Brazil's Atlantic Forest 620 181 261 73 200 60 280 253 1,361 567
Choco/Darien/W. Ecuador 830 85 235 60 210 63 350 210 1,625 418
Brazil's Cerrado 837 29 161 19 120 24 150 45 1,268 117
Central Chile 198 4 56 9 55 34 26 14 335 61
California Floristic Province 341 8 145 30 61 16 37 17 584 71
Madagascar 359 199 112 84 327 301 189 187 987 771
Eastern Arc and Coastal Forests
of Tanzania/Kenya
585 22 183 16 188 50 63 33 1,019 121
West African Forests 514 90 551 45 139 46 116 89 1,320 270
Cape Floristic Province 288 6 127 9 109 19 38 19 562 53
Succulent Karoo 269 1 78 4 115 36 10 4 472 45
Mediterranean Basin 345 47 184 46 179 110 62 32 770 235
Caucasus 389 3 152 32 76 21 15 3 632 59
Sundaland 815 139 328 115 431 268 226 179 1,800 701
Wallacea 697 249 201 123 188 122 56 35 1,142 529
Philippines 556 183 201 111 252 159 84 65 1,093 518
Indo-Burma 1,170 140 329 73 484 201 202 114 2,185 528
South Central China 686 36 300 75 70 16 85 51 1,141 178
Western Ghats/Sri Lanka 528 40 140 38 259 161 146 116 1,073 355
SW Australia 181 19 54 7 191 50 30 24 456 100
New Caledonia 116 22 9 6 65 56 0 0 190 84
New Zealand 149 68 3 3 61 61 4 4 217 136
Polynesia/Micronesia 254 174 16 9 69 37 3 3 342 223
Total endemics and % of
global total
* 2,821
28.5%
* 1,314
27.3%
* 2,938
37.5%
* 2,572
53.8%
9,645
35.3%
...................................................................................................................................................................................................................................................................................................................................................................
* These totals cannot be summed owing to overlapping between hotspots.
© 2000 Macmillan Magazines Ltd

four others, contain endemics amounting to 30.1% and 25.0% of
the global totals for plant and vertebrate species, respectively, in
0.7% of the Earth's land surface.
Some hotspots are likewise signi®cant in having their endemic
species concentrated in exceptionally small areas (Table 4). The
Eastern Arc contains 1,500 endemic plants in 2,000 square kilo-
metres, giving a ratio of 75 species to 100 square kilometres,
represented as 75:1, and 121 endemic vertebrates for a ratio of
6.1:1, both ratios topping the lists for all hotspots. Similarly, New
Caledonia, with 5,200 square kilometres, works out at 49:1 and
1.6:1, and the Philippines with 9,023 square kilometres at 64.7:1 and
5.7:1. The rest range from 33.3:1 to 1.2:1 for plants and 2.9:1 to
0.03:1 for vertebrates.
Congruence among species categories
In several hotspots there is species congruence insofar as high
counts for endemic plants are matched by high counts for endemic
vertebrates (Table 5). (For analysis of congruence in other areas, see
refs 12 and 31.) This factor reinforces the conservation priority
thesis, especially in those hotspots with the most endemic species
(Table 3). There can also be high congruence in areas with lower
species counts, for example, 80% in the Eastern Arc with 0.5% of
plant species and 0.4% of vertebrate species.
Endemic plants in the Tropical Andes comprise 6.7% of all plant
species world-wide, and its endemic vertebrates 5.7%, with 85%
congruence; Madagascar's species comprise 3.2% and 2.8%, respec-
tively, with 88% congruence; and the Caribbean's 2.3% and 2.9%,
with 79%. (The ®rst is a large area where one could expect high
congruence; the other two are only one-®fth and one-tenth as big,
respectively.) In contrast, Cape Floristic Province possesses 1.9% of
all plants but only 0.2% of all vertebrates, for 11% congruence, and
the Mediterranean Basin possesses 4.3% of all plants but only 0.9%
of all vertebrates, for 21%. Congruence tends to be high in tropical
forest hotspots, and generally low in Mediterranean-type hotspots
and other drier areas with their meagre counts for endemic
vertebrates.
The hottest hotspots
The analysis so far has considered ®ve key factors: numbers of
endemics and endemic species/area ratios for both plants and
vertebrates, and habitat loss. These factors do not carry equal
weight, so they cannot be combined into a single quantitative
ranking. For comparative purposes in qualitative fashion, Table 6
lists the eight `hottest hotspots', which appear at least three times
in the top ten listings for each factor. The leaders are Madagascar,
the Philippines and Sundaland, appearing for all ®ve factors,
followed by Brazil's Atlantic Forest and the Caribbean, appearing
for four. Three of these hotspots, Madagascar, the Philippines and
the Caribbean, have small areas, which further highlights their
importance.
Two additional hotspots, the Tropical Andes and the Mediterra-
nean Basin, should be considered as hyper-hot candidates for
conservation support in light of their exceptional totals of endemic
plants: 20,000 and 13,000, respectively. The Tropical Andes is at the
top for endemic vertebrates too, and the Mediterranean third after
Sundaland for endemic plants, with 34% more than the fourth
hotspot. But they do not rank in more than two of the ®ve factor
listings. Similarly, Mesoamerica is second for endemic vertebrates
(49% more than the third highest), but it scores only tenth for
endemic plants.
Higher taxa assessment
The analysis can be complemented by an assessment of endemism
among higher taxa such as families and genera. Madagascar
(including nearby Indian Ocean islands) possesses 11 endemic
families and 310 endemic genera of plants, 5 endemic families
and 14 endemic genera of primates, and 5 endemic families and 35
endemic genera of birds. Cape Floristic Province has 6 endemic
families and 198 endemic genera of plants; and New Caledonia has 5
endemic families and 112 endemic genera of plants, and 1 endemic
family and 3 endemic genera of birds. In contrast, the United States
and Canada, with an expanse 8.8 times larger than the 25 hotspots
combined, have only two endemic families of plants. Moreover,
plant family richness can often serve as a predictor of species
richness for certain animal taxa such as mammals, amphibians
and reptiles
32
.
Action responses
In sum, the 25 hotspots contain the sole remaining habitats of 44%
of the Earth's plant species and 35% of its vertebrate species, and
these habitats face a high risk of elimination. Many of the hotspots
could well contain sizeable proportions of endemic invertebrates. It
is often supposed
1±4
that, were the present mass extinction of species
to proceed virtually unchecked, between one-third and two-thirds
of all species would be likely to disappear within the foreseeable
future. The hotspots analysis indicates that much of this problem
could be countered through protection of the 25 hotspots.
An aggregate expanse of 800,767 square kilometres, 38% of the
hotspots total, is already protected in parks and reserves. True, some
of these are little better than `paper parks', but they offer a modicum
of legal status. All are in urgent need of stronger safeguards,
including those ®ve hotspots where the protected expanse is as
large as the hotspot itself. The areas without any protection at all
articles
856 NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com
Table 3 Leading hotspots in terms of endemics
Hotspot Endemic plants
(% of global total, 300,000)
Endemic vertebrates
(% of global total, 27,298)
.............................................................................................................................................................................
Tropical Andes* 20,000 (6.7) 1,567 (5.7)
Sundaland* 15,000 (5.0) 701 (2.6)
Madagascar* 9,704 (3.2) 771 (2.8)
Brazil's Atlantic Forest* 8,000 (2.7) 567 (2.1)
Caribbean* 7,000 (2.3) 779 (2.9)
Sub-totals (% rounded) 59,704 (19.9) 4,385 (16.1)
.............................................................................................................................................................................
Mesoamerica 5,000 (1.7) 1,159 (4.2)
Mediterranean Basin 13,000 (4.3) 235 (0.9)
Indo-Burma 7,000 (2.3) 528 (1.9)
Philippines 5,832 (1.9) 519 (1.9)
Totals 90,536 (30.1)² 6,826 (25.0)
.............................................................................................................................................................................
* Hotspots with at least 2% of the world's endemic plants and vertebrates, and comprising only
0.4% of the Earth's land surface (all nine amount to 0.7% of the Earth's land surface).
² This would total 30.2% but for rounding of numbers in the individual hotspots.
Table 4 Species/area ratios per 100 km
2
of hotspots
Hotspot Endemic plants Endemic vertebrates
Tropical Andes 6.4 0.5
Mesoamerica 2.2 0.5
Caribbean 23.5 2.6
Brazil's Atlantic Forest 8.7 0.6
Choco/Darien/Western Ecuador 3.6 0.7
Brazil's Cerrado 1.2 0.03
Central Chile 1.8 0.06
California Floristic Province 2.7 0.09
Madagascar 16.4 1.3
Eastern Arc and Coastal Forests
of Tanzania/Kenya
75 6.1
Western African Forests 1.8 0.2
Cape Floristic Province 31.6 0.3
Succulent Karoo 6.5 0.15
Mediterranean Basin 11.8 0.2
Caucasus 3.2 0.1
Sundaland 12.0 0.6
Wallacea 2.9 1.0
Philippines 64.7 5.7
Indo-Burma 7.0 0.5
South-Central China 5.5 0.3
Western Ghats/Sri Lanka 17.5 2.9
SW Australia 13.0 0.3
New Caledonia 49.1 1.6
New Zealand 3.1 0.2
Polynesia/Micronesia 33.3 2.2
.............................................................................................................................................................................
© 2000 Macmillan Magazines Ltd

amount to 1.3 million square kilometres or 62% of the total area of
the hotspots. This expanse surely represents the greatest biodiversity
challenge of the foreseeable future, and should be safeguarded
through, for example, a `hotspots rescue fund'. In some areas,
outright protection is still the best option. In other areas, this is
not feasible because of human settlements and other activities long
in place. These areas could receive a measure of protection as
`conservation units' that allow some degree of multiple use provided
that species safeguards are always paramount.
This is not to say that protection of the hotspots would safeguard
all their species inde®nitely. According to the well-established
theory of island biogeography
33
, when an area loses a large propor-
tion of its original habitat and especially when the remaining habitat
is severely fragmented, it will eventually lose some of its species
through what are technically known as `ecological equilibriation' or
delayed fallout effects. There is much empirical evidence to support
this; for instance, the loss of birds in Brazil's Atlantic forest
34
, in
Southeast Asia's forests
35
, in tropical forests generally
36,37
and in the
United Kingdom
38
; of tree species in tropical forests
39
; of forest
plants in eastern North America
40
; of primates in Africa's forests
41
; of
large mammals in Tanzania
42
; and of species generally
43
.
Consider the consequences for the smallest hotspot, the Eastern
Arc. The remaining primary vegetation is only 6.7% of the original,
and its expanse of 2,000 km
2
is split into no fewer than 128 patches
ranging in size from over 100 to 10 or fewer square kilometres.
A bigger hotspot, Cape Floristic Province, with an expanse of
18,000 km
2
and 24.3% of its original primary vegetation, is spread
around several thousand patches ranging from over 100 to 0.1 km
2
.
Although most island-biogeography losses are not likely to ensue
for some time, it makes sense to take immediate steps to safeguard
the hotspots to avoid an exceptionally large extinction spasm
through outright loss of habitat on a scale to swamp island
biogeography impacts. As for past extinctions in the hotspots, all
too little is known with respect to taxa across the board including
invertebrates; however, if we use birds extinct since 1800 as a
surrogate we ®nd that nearly 80% of those that disappeared were
from hotspot areas.
These considerations apart, the prospect of a mass extinction can
be made far less daunting and much more manageable through the
hotspots strategy, with its tight targeting of conservation efforts.
The hotspots ®ndings accord well with several other priority-
setting analyses. There is a 68% overlap with Birdlife International's
Endemic Bird Areas
44
, 82% with IUCN/WWF International's Cen-
tres of Plant Diversity and Endemism
17
and 92% with the most
critical and endangered eco-regions of WWF/US's Global 200 List
45
.
The hotspots approach is more comprehensive than the ®rst two
because it combines ®ve categories of species, and it is more closely
focused than the third.
Other areas appear to feature exceptional plant endemism and
exceptional threat, but are not suf®ciently documented to meet the
hotspots criteria. They include the Ethiopian Highlands, the Angola
Escarpment, southeastern China, Taiwan, and the forests of the
Albertine Rift in eastern Democratic Republic of Congo (formerly
Zaire), southwestern Uganda and northern Rwanda. Much better
known and with a high species/area ratio but without suf®cient
endemic plant species to qualify as a hotspot is the so-called Wet
Tropics and adjacent tropical forest tracts along the Queensland
coast in Australia, containing around 1,200 endemic plants in less
than 11,000 km
2
. Adding these areas to the hotspots list would
increase the total of plants endemics by only a few per cent.
In addition, there are a few tropical forest expanses, known as
`major wilderness areas'
46
or `good news' areas
5,6
. They total some
6±7 million km
2
and feature concentrations of endemic species
while retaining at least 75% of their primary vegetation, and have
fewer than ®ve people per square kilometre. One is the island of New
Guinea, with around 15,000 endemic plants. Others include the
Guayana Shield of northeastern Amazonia, the lowlands of western
Amazonia and the Congolian Forest, with perhaps another 30,000
endemic plants. Were these regions to compose a supplementary
conservation strategy, they could increase the number of plants
endemics to almost 60% of all plant species in roughly 5% of the
Earth's land surface.
Funding
Since the original hotspots strategy
5,6
began to be implemented in
1989, some $400 million has been invested by the MacArthur
Foundation, the W. Alton Jones Foundation, Conservation Inter-
national, the World Wildlife Fund and other non-governmental
organizations. An annual average of $40 million over 10 years is only
a tiny fraction of the amount spent per year on biodiversity
articles
NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com 857
Table 5 Congruence between plants and vertebrates
Hotspot Endemic plants as
% of global total
(300,000)
Endemic vertebrates
as % of global total
(27,298)
Congruence
(%) (rounded)
Tropical Andes 6.7% 5.7% 85
Mesoamerica 1.7% 4.2% 41
Caribbean 2.3% 2.9% 79
Brazil's Atlantic Forest 2.7% 2.1% 78
Choco/Darien/Western Ecuador 0.8% 1.5% 53
Brazil's Cerrado 1.5% 0.4% 27
Central Chile 0.5% 0.2% 40
California Floristic Province 0.7% 0.3% 43
Madagascar 3.2% 2.8% 88
Eastern Arc and Coastal Forests
of Tanzania/Kenya
0.5% 0.4% 80
West African Forests 0.8% 1.0% 80
Cape Floristic Province 1.9% 0.2% 11
Succulent Karoo 0.6% 0.2% 33
Mediterranean Basin 4.3% 0.9% 21
Caucasus 0.5% 0.2% 40
Sundaland 5.0% 2.6% 52
Wallacea 0.5% 1.9% 26
Philippines 1.9% 1.9% 100
Indo-Burma 2.3% 1.9% 83
South-Central China 1.2% 0.7% 58
Western Ghats/Sri Lanka 0.7% 1.3% 54
SW Australia 1.4% 0.4% 29
New Caledonia 0.9% 0.3% 33
New Zealand 0.6% 0.5% 83
Polynesia/Micronesia 1.1% 0.8% 73
.............................................................................................................................................................................
Table 6 The eight hottest hotspots in terms of ®ve factors
Hotspot Endemic plants Endemic
vertebrates
Endemic plants/
area ratio (species
per 100 km
2
)
Endemic
vertebrates/area
ratio (species per
100 km
2
)
Remaining primary
vegetation as % of
original extent
Times
appearing in
top 10 for each
of ®ve factors
Madagascar 9,704 4 771 4 16.4 8 1.3 7 9.9 9 5
Philippines 5,832 8 518 9 64.7 2 5.7 2 3.0 1 5
Sundaland 15,000 2 701 5 12.0 10 0.6 10= 7.8 7 5
Brazil's Atlantic Forest 8,000 5 654 6 8.7 0.6 10= 7.5 6 4
Caribbean 7,000 6= 779 3 23.5 6 2.6 4 11.3 4
Indo-Burma 7,000 6= 528 8 7.0 0.5 4.9 3 3
Western Ghats/Sri Lanka 2,180 355 17.5 7 2.9 3 6.8 5 3
Eastern Arc and Coastal Forests
of Tanzania/Kenya
1,500 121 75.0 1 6.1 1 6.7 4 3
...................................................................................................................................................................................................................................................................................................................................................................
© 2000 Macmillan Magazines Ltd

conservation by governments and international agencies, these
funds being assigned mainly to across-the-board activities rather
than the concentrated efforts advocated here. The traditional
scattergun approach of much conservation activity, seeking to be
many things to many threatened species, needs to be complemented
by a `silver bullet' strategy in the form of hotspots with their
emphasis on cost-effective measures.
We could go far towards safeguarding the hotspots and thus a
large proportion of all species at risk for an average of $20 million
per hotspot per year over the next ®ve years, or $500 million
annually. Although this is 12.5 times the annual average of the
$400 million spent on hotspots over the past decade, it is still only
twice the cost of a single Path®nder mission to Mars, which has been
justi®ed largely on biodiversity grounds (the search for extraterres-
trial life). The $500 million annually is to be compared, moreover,
with a recent estimate
47
for a comprehensive conservation pro-
gramme to protect biodiversity world-wide costing $300 billion
annuallyÐa total that should, in turn, be compared with subsidies
of various sorts that degrade environments and economies alike,
amounting to $1.5 trillion annually world-wide
48
.
Finally, recall that the mass extinction of species, if allowed to
persist, would constitute a problem with far more enduring impact
than any other environmental problem. According to evidence from
mass extinctions in the prehistoric past, evolutionary processes
would not generate a replacement stock of species within less than
several million years. What we do (or do not do) within the next few
decades will determine the long-term future of a vital feature of the
biosphere, its abundance and diversity of species. This expanded
hotspots strategy offers a large step toward avoiding an impover-
ishment of the Earth lasting many times longer than Homo sapiens
has been a species.
Received 22 September; accepted 22 December 1999.
1. Ehrlich, P. R. Energy use and biodiversity loss. Phil. Trans. R. Soc. Lond. B 344, 99±104 (1994).
2. Myers, N. Two key challenges for biodiversity: discontinuities and synergisms. Biodiversity Cons. 5,
1025±1034 (1996).
3. Pimm, S. L., Russell, G. J., Gittleman, J. L. & Brooks, T. M. The future of biodiversity. Science 269, 347±
350 (1995).
4. Wilson, E. O. The Diversity of Life (Belknap, Cambridge, Massachusetts, 1992).
5. Myers, N. Threatened biotas: `hotspots' in tropical forests. Environmentalist 8, 187±208 (1988).
6. Myers, N. The biodiversity challenge: expanded hotspots analysis. Environmentalist 10, 243±256
(1990).
7. Pressey, R. L., Humphries, C. J., Margules, C. R., Vane-Wright, R. I. & Williams, P. H. Beyond
opportunism: key principles for systematic reserve selection. Trends Ecol. Evol. 8, 124±128 (1993).
8. Prendergast, J. R., Quinn, R. M. & Lawton, J. H. The gaps between theory and practice in selecting
nature reserves. Cons. Biol. 13, 484±492 (1999).
9. Ginsberg, J. Global conservation priorities. Cons. Biol. 13, 5 (1999).
10. Dobson, A. P., Rodriguez, J. P., Roberts, W. M. & Wilcove, D. S. Geographic distribution of endangered
species in the United States. Science 275, 550±553 (1997).
11. Reid, W. V. Biodiversity hotspots. Trends Ecol. Evol. 13, 275±280 (1998).
12. Prendergast, J. R., Quinn, R. M., Lawton, J. H., Eversham, B. C. & Gibbons, D. W. Rare species, the
coincidence of diversity hotspots and conservation strategies. Nature 365, 335±337 (1993).
13. Williams, P. et al. A comparison of richness hotspots, rarity hotspots, and complementary areas for
conserving diversity of British birds. Cons. Biol. 10, 155±174 (1996).
14. Vane-Wright, R. I., Humphries, C. J. & Williams, P. H. What to protect?Ðsystematics and the agony
of choice. Biol. Cons. 55, 235±254 (1991).
15. Williams, P. H., Humphries, C. J. & Vane-Wright, R. I. Measuring biodiversity: taxonomic relatedness
for conservation priorities. Aust. Syst. Bot. 4, 665±679 (1991).
16. Mittermeier, R. A., Myers, N., Gil, P. R. & Mittermeier, C. G. Hotspots: Earth's Biologically Richest and
Most Endangered Terrestrial Ecoregions (Cemex, Conservation International and Agrupacion Sierra
Madre, Monterrey, Mexico, 1999).
17. Davis, S., Heywood, V. H. & Hamilton, A. C. (eds) Centres of Plant Diversity (three vols) (World Wide
Fund for Nature and International Union for Conservation of Nature and Natural Resources, Gland,
Switzerland, 1994±1997).
18. Groombridge, B. (ed.) Global Biodiversity (Chapman and Hall, London, 1992).
19. Heywood, V. H. (ed.) Global Biodiversity Assessment (Cambridge Univ. Press, Cambridge, 1995).
20. Prance, G. T., Beent J. H., Drans®eld, J. & Johns, R. The Tropical Flora Remains Undercollected
(Missouri Botanical Garden Scienti®c Publications, St. Louis, Missouri, in the press).
21. Nowak, R. Walker's Mammals of the World (Johns Hopkins Univ. Press, Baltimore, Maryland, 1999).
22. Sibley, C. G. & Monroe, B. L. Distribution and Taxonomy of Birds of the World (Yale Univ. Press, New
Haven, Connecticut, 1990).
23. Uetz, P. & Etzold, T. The EMBL/EBI reptile database. Herpetol. Rev. 27, 175 (1996).
24. Glaw, F. & Kohler, J. Amphibian species diversity exceeds that of mammals. Herpetol. Rev. 29, 11±12
(1998).
25. Eschmeyer, W. M. Catalog of Fishes (California Academy of Sciences, San Francisco, 1998).
26. Janzen, D. H. How to be a ®g. Annu. Rev. Ecol. Systemat. 10, 13±51 (1979).
27. Farrell, B. D. `Inordinate Fondness' explained: why are there so many beetles? Science 281, 555±557
(1998).
28. Gaston, K. J. Regional numbers of insect and plant species. Funct. Ecol. 6, 243±247 (1991).
29. Strong, D. R., Lawton, J. H. & Southwood, T. R. E. Insects on Plants: Community Patterns and
Mechanisms (Blackwell, Oxford, 1984).
30. Price, P. W. Insect Ecology 3rd edition (Wiley, New York, 1997).
31. Balmford A. & Long, A. Across-country analyses of biodiversity congruence with current conservation
efforts in the tropics. Cons. Biol. 9, 1539±1547 (1996).
32. Williams, P. H., Gaston, K. & Humphries, C. J. Mapping biodiversity value worldwide: combining
higher-taxon richness from different groups. Proc. R. Soc. Lond. B 264, 141±148 (1997).
33. MacArthur, R. H. & Wilson, E. O. The Theory of Island Biogeography (Princeton Univ. Press,
Princeton, 1967).
34. Brooks, T. & Balmford, A. Atlantic forest extinctions. Nature 380, 115 (1996).
35. Brooks, T., Pimm, S. L. & Collar, N. J. Deforestation predicts the number of threatened birds in Insular
Southeast Asia. Cons. Biol. 11, 382±394 (1997).
36. Brooks, T. M., Pimm, S. L. & Oyugi, J. O. Time lag between deforestation and bird extinction in
tropical forest fragments. Cons. Biol. 13, 1140±1150 (1999).
37. Laurance, W. F. Introduction and synthesis. Biol. Cons. 91, 101±107 (1999).
38. Gaston, K. J. & Nicholls, A. O. Probable times to extinction of some rare breeding bird species in the
United Kingdom. Proc. R. Soc. Lond. B 259, 119±123 (1995).
39. Turner, I. M. Species loss in fragments of tropical rain forests: a review of the evidence. J. Appl. Ecol. 33,
200±209 (1996).
40. Pimm, S. L. & Askins, R. A. Forest losses predict bird extinctions in Eastern North America. Proc. Natl
Acad. Sci. USA 92, 9343±9347 (1995).
41. Cowlinshaw, G. Predicting the pattern of decline of African primate diversity: an extinction debt from
historical deforestation. Cons. Biol. 13, 1183±1193 (1999).
42. Newmark, W. D. Insularization of Tanzanian parks and the local extinction of large mammals. Cons.
Biol. 10, 1549±1556 (1996).
43. Tilman, D., May, R. M., Lehman, C. L. & Nowak, M. A. Habitat destruction and the extinction debt.
Nature 371, 65±66 (1994).
44. Statters®eld, A. J., Crosby, M. J., Long, A. J. & Wege, D. C. Endemic Bird Areas of the World: Priorities for
Biodiversity Conservation (Birdlife International, Cambridge, UK, 1998).
45. Dinerstein, E. et al. The Global 200: Key Ecoregions for Saving Life on Earth (World Wildlife Fund-US,
Washington DC, 1996).
46. Mittermeier, R. A., Myers, N., Thomsen, J. B., da Fonseca, G. A. B. & Olivieri, S. Biodiversity hotspots
and major tropical wilderness areas: approaches to setting conservation priorities. Cons. Biol. 12, 516±
520 (1998).
47. James, A. N., Gaston, K. J. & Balmford, A. Balancing the Earth's accounts. Nature 401, 323±324
(1999).
48. Myers, N. Lifting the veil on perverse subsidies. Nature 392, 327±328 (1999).
Supplementary Information is available from Nature's World-Wide Web site (http://
www.nature.com) or as paper copy from the London editorial of®ce of Nature. This and
further information is also available at http://www.conservation.org.
Acknowledgements
We thank P. Robles Gil of Agrupacion Sierra Madre and the scientists listed in
Supplementary Information for their help with information and analysis; P. Chambers,
S. Norris and M. Prescott for research help; and D. Duthie and J. McNeely for comments
on an early draft. We also thank the Mexican company CEMEX for its major ®nancial
support, and the MacArthur Foundation and S. Concannon for additional support.
Correspondence and requests for materials should be addressed to N.M.
(e-mail: myers1n@aol.com).
articles
858 NATURE | VOL 403 | 24 FEBRUARY 2000 | www.nature.com© 2000 Macmillan Magazines Ltd