Caribbean Islands

The Caribbean Islands Hotspot consists mainly of three large groups of islands between North and South America: the Bahamas, the Greater Antilles, and the Lesser Antilles. In contrast to the previous definition under the name Caribbean Hotspot, we now exclude southern Florida and its islands on the North American Continental Shelf because that area has greater floristic affinity to the rest of the continent, has few endemics, and has had only a marginal role in the phytogeographic history of the Antilles (Graham 2003). The Caribbean Islands themselves vary in their floristic affinities, but have in common a history of limited contact with the diverse biotas of the continents. As a result, their biotas share an “oceanic” character marked by a relatively low representation of higher taxa, but also having extraordinary diversity within those higher phyletic groups that are present.

The Caribbean Islands Hotspot is commonly referred to as the West Indies in the English-language literature. Our definition differs only in a few minor details from a biotic region formally defined by James Bond in his Birds of the West Indies (1936). The islands of the West Indies have a terrestrial surface area of only 229 549 km². The four largest islands, Cuba (105 806 km²), Hispaniola (73 929 km²), Jamaica (11 190 km²), and Puerto Rico (9 100 km²) make up over 90% of the land area of the hotspot, but the myriad smaller islands harbor large numbers of endemic species far out of proportion to their size. Geologically, the West Indies are a mix of old regions of the Caribbean Tectonic Plate (Cuba, Jamaica, Hispaniola, Puerto Rico, the Virgin Islands, and their satellite islands), the tops of volcanoes (the active volcanic arc from Saba to Grenada), and slightly raised limestone platforms (the Caribees from Sombrero to Barbados, plus the Bahamas, the Cayman Islands, southern Dutch islands, and Aves Island). Elevations range from over 3 000 m (the formerly glaciated summit of Pico Duarte) to a desert depression 40 m below sea level, both on Hispaniola.

Politically, this is a very diverse hotspot, with thousands of islands governed by 18 nations. Twelve of these are independent island nations (Commonwealth of the Bahamas, Republic of Cuba, Jamaica, Republic of Haiti, Dominican Republic, Federation of St. Kitts and Nevis, Antigua and Barbuda, Commonwealth of Dominica, Barbados, St. Lucia, St. Vincent and the Grenadines, and Grenada). Fifteen polities are dependencies of, in free association with, or integral parts of: the United States of America (Puerto Rico, U.S. Virgin Islands, Navassa); the United Kingdom (Cayman Islands, Turks and Caicos Islands, British Virgin Islands, Anguilla, Montserrat); the Kingdom of the Netherlands (Aruba and the Netherlands Antilles including Curaçao, Bonaire, Saba, St. Eustatius, and St. Maartin); the Republic of France (Departments of Martinique and Guadeloupe, including its dependencies St. Martin and St. Barthelemy); the Republic of Honduras (Swan Islands), or the Bolivarian Republic of Venezuela (Aves Island west of Dominica, and oceanic islands from Blanquilla to Islas las Aves).

The vegetation of the Caribbean Islands is variable due to the influences of climate and Earth history. Lowlying islands tend to be semiarid, and most were originally dominated by dry evergreen bushland and dry evergreen thicket, with savanna occurring on parts of Barbuda, Jamaica, and Puerto Rico (where the average rainfall at low elevations is only 300–600 mm per year). On the other hand, wetter environments occur where trade winds encounter the higher Caribbean mountains, giving rise to a variety of moist tropical forest types including marsh forest, various types of seasonal forest, montane forest, and elfin woodland (Beard 1955). In moister areas, around lagoons and river mouths, permanent brackish and freshwater swamps give way to extensive mangrove forests. The previously extensive lowland rainforests have mostly been destroyed.

Plant diversity and endemism in the Caribbean Islands Hotspot are both very high, with a total of 13 000 species estimated to occur in the Caribbean region (Davis et al. 1997), including perhaps 6 550 single-island endemics. Cuba's flora is particularly rich, with an estimated 6 505 vascular plant species, of which 3 224 are endemic (Davis et al. 1997); this represents 54% of the endemic plants for the hotspot as a whole, and indeed would qualify Cuba as a hotspot in its own right. Plant endemism at the generic level is also high in these islands. Of an estimated 2 500 genera of seed plants in the Caribbean, 204 angiosperm genera and one gymnosperm genus (Microcycas) are endemic to the Greater Antilles. Of these, fully 118 are restricted to single islands. Important families with endemic genera include Asteraceae (32), Rubiaceae (30), Euphorbiaceae (14), and Leguminosae (13). There is one endemic plant family, the Goetziaceae (Davis et al. 1997). Even mosses, with notoriously broad distributions, have around 500 species in the Caribbean Islands, with about 10% endemism (Delgadillo et al. 1995).

Vertebrate diversity and endemism in this hotspot are noteworthy. Mammals are represented by 89 extant species, of which 41 are endemic, including two endemic families: the solenodons (Solenodon spp.), with two species of rare giant shrews, and a large radiation of rodents called hutias (family Capromyidae), which are related to guinea pigs. The region hosts 15 endemic genera, including the fruit-eating bat genus Brachyphylla, with two species.

Birds are represented by 607 species, of which 167 are endemic, with many of those restricted in total range to small areas within islands. A remarkable 35 genera are endemic, and there are also two endemic families: the palmchat (Dulus dominicus) of the family Dulidae, and the todies (Todidae). The bird list includes some important flagship species, such as the St. Vincent parrot (Amazona guildingii, VU) from the island of St. Vincent, the St. Lucia parrot (A. versicolor, VU) from the island of the same name, and the imperial parrot (A. imperialis, EN) from Dominica; the bee hummingbird (Mellisuga helenae) from Cuba, the world's smallest bird; and the ivory-billed woodpecker (Campephilus principalis, CR), last recorded with any certainty in Cuba in 1987.

The Caribbean Islands Hotspot is particularly rich in reptiles with 499 native species, of which 468 are endemic. There are several large evolutionary radiations of lizards, such as the anoles (Anolis; 154 species, 150 endemic) with their colorful dewlaps used in displays; dwarf geckos (Sphaerodactylus; 86 species, 82 endemic) that include the world's smallest lizards (e.g., S. ariasae, with a body length of 18 mm); and curly tails (Leiocephalus; 23 species, all endemic) that hold their tails in a coil as they run. There are 11 species of rock iguanas (Cyclura), including some measuring more than one meter in length, and one that is blue (C. lewisi); one of these species, the Jamaican iguana (C. collei, CR), is confined to the Hellshire Hills in Jamaica. A species considered to be an ancient relict in the lizard family Xantusiidae, Cricosaura typica, occurs only in a remote part of eastern Cuba. Major radiations of snakes include the large boas (Epicrates, nine species); a genus of boldly patterned snakes that change colors (Tropidophis; 26 species, all endemic); fastmoving racers (Alsophis; 13 species, all endemic); and some pencil-thin and smaller burrowing snakes (Typhlops and Leptotyphlops) that include the smallest snake in the world (L. bilineata; 108 mm). The Aruba Island rattlesnake (Crotalus unicolor, CR) is found only on Aruba.

All 165 native species of amphibians present in the hotspot are frogs, of which 164 (99%) are endemic to the region. All but a few are endemic to single islands. The frog fauna is dominated by those of the genus Eleutherodactylus (139 spp.), which are forest frogs that lay eggs on land and hatch into miniature adults with no tadpole stage. One Cuban species (E. iberia, CR) is the smallest tetrapod in the Northern Hemisphere, with a length of only 10 mm, while a golden-colored species in Puerto Rico, possibly Extinct, is one of only a few species of frogs in the world known to be live-bearing. One of the largest tree frogs (Hylidae) in the world, the Jamaican snoring frog (Osteopilus crucialis, EN), has a length of about 120 mm and occurs in Jamaica, where males of this declining species make a loud snoring call from within giant, hollow trees. The toads (Bufo; 11 species) have also radiated in the West Indies, and captive-breeding programs have been implemented for the Puerto Rican crested toad (B. lemur, CR). An edible species of frog endemic to Dominica and Montserrat, the “mountain chicken” (Leptodactylus fallax, CR), is one of the largest frogs in the Western Hemisphere, but has been rapidly declining in numbers due to human consumption, habitat loss, and an outbreak of chytridiomycosis on Dominica.

The hotspot's inland fishes include 161 species, of which 65 are endemic to one or a few islands. Nearly half of the endemics are restricted to very small ranges, often consisting of a single lake or springhead, and these sites constitute the sole opportunities for conservation of these species in nature. As in other hotspots that are composed of islands, the freshwater fish fauna consists of two distinctive elements. The smaller and younger islands have faunas dominated by species that are widespread in marine waters, but that enter fresh water to some degree, especially when obligate freshwater species are absent or few in number. This component accounts for the relatively high diversity at the family level. The larger and older islands of the Greater Antilles differ in having faunas dominated by several groups that are old enough to have occupied inland waters of the proto-islands and continental coasts prior to extensive plate tectonic movements. These groups (e.g., gars, killifishes, silversides, and cichlids) include significant local radiations, which account for the hotspot's moderate number of endemic species. The hotspot's five endemic fish genera all have distributions that overlap in western Cuba, apparently the oldest part of the hotspot that has remained continuously above sea level.

Humans first populated the islands about 4 000 years ago, and there is evidence that even the early inhabitants were involved in modifying the biota through direct use or, perhaps more far-reaching, through the introduction of species from the continents. Early species introductions include the agouti on Dominica, tortoises on many islands, and possibly even large animals such as white-tailed deer (Odocoileus virginianus) on Curaçao. Introductions of species were enormously accelerated after the arrival of Europeans, whose transportation technologies led to the import of species —both intentionally and accidentally— from all parts of the globe. The introduction of the Indian mongoose (Herpestes auropunctatus) from Asia in 1872 resulted in a series of extinctions as it was moved from island to island. Even small, uninhabitable islands such as Navassa and Sombrero now have floras dominated by continental weed species, and throughout the hotspot native amphibian, reptile, and bird faunas have been devastated by rats and domestic cats and dogs. In total, some 36 vertebrate species are considered to have gone extinct in the region since 1500, including species like the Cuban macaw (Ara tricolor), Jamaican giant galliwasp (Celestus occiduus), and four species of Nesophontes (relatives of the solenodons).

The islands have been subject to Western-style development including extensive monoculture for five hundred years, longer than any other part of the New World. For most of this period, the exploration and development of the islands' natural resources were carried out by colonial centers outside the Caribbean Basin. In many cases, Caribbean natural resources were simply liquidated (e.g., semiprecious hardwoods of Haiti and many other states). The widespread cultivation of sugarcane (Saccharum officinarum) was also conducted for the benefit of foreign economies and, similarly, resulted in broad transformation of island landscapes. Consequently, as a result of changes that have taken place since European arrival, only a small portion of the vegetation that once existed still remains in more or less pristine condition, and it is estimated that intact vegetation covers no more than 10% of the original extent of the land area. Interestingly, although less than 15% of Cuba's original forests remain intact, they still represent the largest forested areas remaining in the Antilles.

According to the World Database on Protected Areas, some 12.9% of the hotspot is officially protected in a variety of different conservation units, although only 7.1% is conserved in protected areas classified in IUCN categories I to IV. In the largest Caribbean country, Cuba, about 15% of the total land area falls within protected areas, including the 300-km² Zapata Swamp, home to the Cuban crocodile (Crocodylus rhombifer, EN), the Zapata rail (Cyanolimnas cerverai, EN), the Zapata wren (Ferminia cerverai, EN), and the dwarf hutia (Mesocapromys nanus, CR), all threatened species found nowhere else. The country of Dominica leads in percentage coverage, with 21.4% of its territory designated for protection, while other countries also report relatively high protection (for example, the Dominican Republic, with 15%). However, in many of these countries, the existing protected area network is ineffective and poorly managed, while in other nations in the Caribbean protected areas are almost nonexistent. Haiti and Grenada, for example, both have only 1.7% of their respective land areas under protection, while Barbados and Aruba Island each have less than 1%. Indeed, in a recent global gap analysis, the Caribbean Islands emerge as a region of high urgency for expansion of the protected areas network (Rodrigues et al. 2003).

Prospects for the protection of biodiversity have been greatly enhanced by the development of alliances between major industries, such as tourism, and the governmental and private organizations that carry out conservation on the ground. Protected area systems are now being designed for the dual goals of safeguarding biodiversity and contributing to island livelihoods. A significant advance occurred in 2000, when the Protocol for Specially Protected Areas and Wildlife (SPAW) came into force. Created at the initiative of the Caribbean countries themselves, this protocol provides region-wide standards and mechanisms for harmonizing conservation efforts across the hotspot's diverse cultures and political systems.

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