Island Biogeography is the effect of distance from the mainland and size of the island on the colonization and extinction rates of organism. Island Biogeography doesn't have to be a literal island located in the ocean. It can also refer to land bridge islands and virtual island (i.e oceanic vents, isolated caves).1 There are three main factors that influence the islands biodiversity; Immigration, emigration, and extinction.1

Robert H. MacArthur and E.O Wilson are two ecologists who revolutionized the thinking of Island Biogeography and an equilibrium theorem. Through research using New Guniea islands they came to the conclusion that organisms on islands are constantly fluctuating due to immigration from the mainland and extinction of already present individuals.3 And rates of immigration and extinction are impacted by distance and size. Small islands will have less capacity for density per unit area. Greater distance between the island and the main source effects the ability of organisms to colonize.3 Therefore, Distant islands should have fewer species and closer islands should have more species. Also, smaller islands should have fewer species and larger islands should have the capacity to carry more species. 2




1Friedl, Sarah. "Island Biogeography: Theory." N.p., n.d. Web. 30 Mar. 2015. <>.

2Macarthur, Robert H., and Edward O. Wilson. "An Equilibrium Theory of Insular Zoogeography." Evolution 17.4 (1963): 373. Web.

3Simberloff, D. S. "Equilibrium Theory of Island Biogeography and Ecology."Annual Review of Ecology and Systematics 5.1 (1974): 161-82. Web.

Image is from Simberloff

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