a. The coastal forest of Ecuador has been almost entirely clear-cut since 1960 for banana plantations and oil exploration. Eight to ten thousand plant species (40%-60% of them endemic) had been identified in this area, and, assuming 10 to 30 animal species per plant species (including insects), there may have been 200,000 or more species in this region. Perhaps half of these species are now gone, this in only 40 years. There are a few reserves. One contains 1033 identified plant species, one-quarter of which are known only from this area. Of some of these species, only one known individual remains (Wilson, 1988).
b. In the Caribbean, dense human populations and intensive land use and degradation, the introduction of exotic species, habitat destruction, the waste of resources, and intensive hunting have had a severe impact on animal and plant populations. In Puerto Rico, the area of primary forest had been reduced by 99% by the mid-1980’s, although some secondary forest has grown up. This led to the extinction of seven species of birds (almost 12% of the native bird species). Many exotic species have been introduced as well. The removal of primary forest and the regrowth of secondary forest in some areas have also led to changes in forest structure. Those species characteristic of primary undisturbed forest are rare, while other species, those compatible with secondary forests, are pre-eminent because of human activity. Elsewhere in the Caribbean, only 10% of the original forest habitat remains in tiny patches on small islands. Forty-three of the 197 known larger endemic animals have become extinct during the past 500 years, an extinction rate one-thousand times the expected figure, and 84 more species are on the IUCN Red List – in danger of extinction (Brooks and Smith, 2001). Without massive conservation efforts, these creatures will soon become extinct, and more will disappear at later times.
c. More than 65% of the wildlife habitat in Africa has been lost within the past 30 years due to population growth, which has resulted in deforestation for timber, farmland, pasturage and housing. Furthermore, even protected forests and biologically rich areas are small and increasingly isolated within converted areas. Many are not large enough for species conservation. Poaching for subsistence and for cash is common, and few resources are available for protection of reserves. Many African forests are so-called “empty forests,” where large animals are virtually absent, since they have been hunted to near extinction.
d. Tropical Asia is very rich in species, many of which have been and are being heavily exploited. As with other tropical areas, habitat destruction, modification of waterways, and overexploitation are leading to serious declines in the populations of many animals and plants. Several of the eight crocodilian species (seven of them endemic) are in trouble. Gharials are at risk because they prefer fast-moving water, and most rivers are being dammed. The Philippine crocodile population stands at about 500, all living in a single area. The Siamese crocodile is considered “critically endangered.” The Chinese alligator (with a population of about 400) no longer has a home because its floodplain and marsh habitats have been converted to agriculture. The three species of Asian rhinoceri are also greatly reduced in number, the Japan rhinoceros numbering fewer than 100 – the most rare of the large mammals. Water pollution, deforestation, dams and overexploitation have led to severe declines in fish diversity. Many species are probably already extinct, but few estimates of population sizes exist.
e. Madagascar, with a fauna which has been separated from the African continent for 200 million years, is the only repository for many of the perhaps 40 species of lemurs, which are highly endangered because of hunting and human demands on its forests for firewood, charcoal and slash-and-burn agriculture. Because of this, Madagascar has the distinction of having 8% of the world’s endangered mammal species, although it itself has a relatively small land mass. Fourteen of its lemur species are seriously endangered. Madagascar has many other interesting and unique mammals, such as the porcupine-like tenrecs (29 of 30 known species). It has also many endemic reptiles (233 of its 245 reptile species are found nowhere else) and frogs (Mittermeier, 1988). The larger species (pygmy hippo, aardvark) have already been eliminated because of hunting and substantial loss of habitat.
Increasingly, humans are acting as the selective agents in evolution, rather than environmental conditions. We have the ability to determine the existence or absence of at least some species; how should we exercise this power? Should we be concerned about extinction and loss of biodiversity? There are those who suggest that, as extinction of species is a normal part of the evolutionary history of our planet, we should not worry about species loss. Further, some would argue that extinction of species which are not important or useful to man is of little consequence (the “utilitarian” point of view). Unless organisms have a “resource value” or are key to their ecosystems, let them go. Others feel that the usefulness of a species is not the only criterion for its existence, even should it be possible to evaluate all species in this way. They cite the human need for beauty, wilderness, and richness of environment. Arguments may also be made against the utilitarian point of view in that we have very little knowledge of the ecology of most ecosystems (particularly rainforests) and that we do not know the consequences of species losses. Moreover, narrowing our genetic pool is inherently dangerous. We do not know what species might have useful genetic potential. If disaster struck some of our food plants, we would lack the genetic potential to produce new varieties. When the potato blight struck Ireland, many people starved since they had no alternative staple food. How much worse if there were no alternative food staple anywhere in the world!
In addition, extinctions in the present day are catastrophic in scope, of magnitudes so much greater than “background” extinctions due to non-anthropogenic causes. These losses cannot help but be extremely destructive. The loss of rainforests and their species cause alterations in rainfall and climate, both locally, regionally and, probably, globally. This makes species loss a disaster, utilitarian and otherwise. (For an excellent discussion of these issues, see Chapin, et al., 1998, 2000.)