Greenology: Island Biogeography Theory
January 29, 2008
This
info is paraphrased from Corridor Ecology
by Hilty, Lidicker, & Merenlender at Island Press 2006.
Island
biogeography theory was coined by MacArthur and Wilson in the 1960s. They developed a method to determine
species richness (the amount of species) on islands. They proposed that island size and distance from the
mainland were the two most important factors.
Islands
closer to the mainland will have more species richness, because in theory there
is a higher probability of successful migrations over shorter distances. Also, the larger islands will have more
species richness, because in theory large islands contain more resources,
habitats, and niches.
For
example, Madagascar,
a large island near the east African coast, has many more species than Mauritius,
a much smaller island further off the eastern coast of Africa.
The
theory is not limited to actual islands and is applicable to any suitable
habitat surrounded by unsuitable matrix space. Island-like habitats include mountaintops surrounded by
deserts, lakes surrounded by dry land, forest fragments surrounded by subdivisions,
and prairies surrounded by farmland.
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Figure 1 from http://ocw.tufts.edu/data/5/241030/72026_medium.jpg |
