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



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