The world's islands represent a small fraction of the Earth's surface (about 5%), but are home to an extraordinary diversity of flora and fauna, with approximately 50,000 species of plants and 15% of all mammals and birds found on islands. In some cases they are rich reservoirs of biodiversity, in others relatively few but well-known species. Islands represent a microcosm of ecological and evolutionary processes and are therefore scientifically significant. Notable examples of this interest include the influence of the Galapagos Islands on Charles Darwin's understanding of evolution, studies of the genetics of the snail Partula in Polynesia, and the evolutionary history of strange fauna in the western Indian Ocean (eg turtles). , and dodos).