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BOX 6–1
Some Examples of Species Extinction
- In Madagascar, until about mid-century, there were 12,000 plant species and probably around 190,000 animal species, with at least 60 per cent of them endemic to the island's eastern strip of forest (that is, found nowhere else on Earth). At least 93 per cent of the original primary forest has been eliminated. Using these figures, scientists estimate that at least half the original species have already disappeared, or are on the point of doing so.
- Lake Malawi in Central Africa holds over 500 cichlid fish species, 99 per cent of them endemic. The lake is only one-eighth the size of North America's Great Lakes, which feature just 173 species, fewer than 10 per cent of which are endemic. Yet Lake Malawi is threatened through pollution from industrial installations and the proposed introduction of alien species.
- Western Ecuador is reputed to have once contained between 8,000 and 10,000 plant species, some 40 and 60 per cent of them endemic. Given that there are between 10 and 30 animal species for every one plant species in similar areas, western Ecuador must have contained about 200,000 species. Since 1960, almost all the forests of western Ecuador have been destroyed to make way for banana plantations, oil wells, and human settlements. The number of species thus eliminated is difficult to judge, but the total could well number 50,000 or more — all in just 25 years.
- The Pantanal area of Brazil contains 110,000 square kilometres of wetlands, probably the most extensive and richest in the world. They support the largest and most diversified populations of waterfowl in South America. The area has been classified by UNESCO as 'of international importance'. Yet it suffers increasingly from agricultural expansion, dam construction, and other forms of disruptive development.
Sources: W. Rauh, 'Problems of Biological Conservation in Madagascar', in D. Btamwell (ed.), Plants and Islands (London: Academic Press, 1979): D.C.N. Barel etal., 'Destruction of Fisheries in Africa's Lakes', Nature, Vol. 315, pp. 19-20, 1985; A.H. Gentry, 'Patterns of Neotropical Plant Species Diversity', Evolutionary Biology, Vol. 15, pp.l-84, 1982; D.A. Scott and M. Carbonell, 'A Directory of Neotropical Wetlands', IUCN, Gland, Switzerland, 1985.
far more important in terms of the role they play in a healthy and productive ecosystem. It would be grim irony indeed if just as new genetic engineering techniques begin to let us peer into life's diversity and use genes more effectively to better the human condition, we looked and found this treasure sadly depleted.
