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ENV510 Landscape Ecology and GIS
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MacArthur
and Wilson (1967)
made their original observations in the Pacific archipelagoes. They noted that
large islands had more species than small islands and that islands near to the
mainland had more species than others further away.
They related
patterns of distribution to rates of colonisation and extinction. This means
that the number of species found on an island represents a balance between the
rate of colonisation and the rate of extinction.
Islands
near a mainland have greater colonisation rates than those further away. This
is because the mainland provides a species source. That is, a larger area from
which species can disperse.
Extinction
is higher on smaller islands because the population size is smaller.
This theory was important in ecology because it described patterns of species distributions on islands quite well (Forman, 1995).
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