ISLAND BIODIVERSITY

The islands of the world comprise a small proportion of the earth's surface (some 5%) but support a remarkable range of exceptional animals and plants with some 50,000 plant species and 15% of all mammals and birds being found on islands. In some cases they are rich reservoirs of biodiversity, in other there are relatively few, but still notable, species. Islands represent microcosms of ecological and evolutionary processes and so are scientifically important. Famous examples of this importance include the influence of the Galapagos islands on Charles Darwin's understanding of evolution, the study of genetics in the Partula snails of Polynesia and the evolutionary history of the strange faunas of the Western Indian Ocean (e.g. lemurs, giant tortoises and the dodo).

Islands are also important in human terms; waves of human colonisations have swept over some archipelagoes, while others have been left untouched until very recently. Islands are vulnerable to disturbance, due in part to their isolation making recolonisation difficult, in addition island species are inherently vulnerable to extinction due to their small ranges. Some 20% of amphibians, 25% of mammals and 33% of birds considered to be threatened with extinction are restricted to islands. 88% of recent (i.e. since AD1500) bird extinctions have been on islands, 86% of reptile extinctions and 54% of amphibian extinctions. Consequently islands have been highlighted in several prioritization programmes such as the Global 200 ecoregions (25% of which are islands), Endemic Bird Areas (48% insular), biodiversity hotspots (29% exclusively made up of islands), Alliance for Zero Extinction sites (39%), 70% of coral reef hotspots. Island species may be at particular risk due to unusual evolutionary processes, such as a tendency towards flightlessness in many areas, which may contribute to the loss of 40% of the birds on New Zealand in 1,000 years of human history. A large number of alien species has been introduced to islands, and low diversity island ecosystems appear to be particularly vulnerable to the invasion of aliens, these have led to dramatic extinctions.
With increasing development pressures and climate change islands are now more threatened than ever before.

This website focuses on different aspects of island evolution and conservation. At present the following aspects are covered:

 

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