Why are islands important?
''Islands and their surrounding waters account for around a sixth of
the world’s total area, but for their size they are home to a
surprisingly high proportion of the world’s animals and plants.
Estimates suggest that 20 percent of all species of birds, reptiles and
plants are found on islands. In addition to this, what makes islands
special is that many of the animals and plants found there are endemic,
meaning they are found nowhere else on Earth. For example, over 90
percent of the species found in Hawaii are endemic, and Madagascar alone
has over 8,000 endemic species.
Some of these species are descended from mainland ancestors, after
the land they inhabited drifted away from the main continent as the
Earth’s tectonic plates moved, while others colonised newly formed land
which had emerged from the sea bed. Over time these isolated species
developed adaptations to suit their habitat, distinguishing them from
their mainland counterparts, and they ultimately evolved into separate
species.
Remote islands often provide important habitats for migratory species, some of which, such as the Chatham albatross,
may only breed on a single island. Island biodiversity isn’t just
restricted to the land either. Over half of the world’s marine
biodiversity is found in the waters surrounding islands, including some
of the world’s most spectacular coral reefs..''
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