GEOGRAPHY 316: BIOGEOGRAPHY
B. Holzman, PhD
12/09/02

I. Problems/Issues
     Access
     Habitat Diversity
     Isolation
     Hazards

II. Theory of Island Biogeography
     MacArthur & Wilson : Theory
     Problems
     Uses w/ natural reserves
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Concepts/Issues
What to consider when looking at islands with a biogeographic perspective:

1. Nature of the island biota..
how does it differ from the source areas, what is the nature of the immigrants that allowed them to reach and colonize the island

2. Identify and quantify the factors that control
a) rate at which new species reach an island
b) the rate at which species become extinct on an island
c) number of species an island can support

3. process of evolutionary change by which an island becomes an integrated ecosystem -each organism adapted to physical and biological aspects of its life on the island...occupation of niches

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ISLANDS AND COLONIZATION

Factors:
Dispersal abilities of immigrants
Diversity of habitats
Isolation
Hazards
Ability to Adapt
gene pool
founder effect
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Theory of Island Biogeography

The number of species found on an island depend on a number of factors:
area and topography
diversity of habitat
accessibility to colonists
richness of source

I.B. adds...
the equilibrium between the rate of colonization by new species and the extinction of existing species

R. MacArthur and E. Wilson: The Theory of Island Biogeography

Problems with IB Theory

-Applicability to all organisms is in question
-Simply looking at physical characteristics are limited:
- Equilibrium can only be maintained in a constant environment

Applications of the theory
The theory of Island biogeography has been used in the creation of nature reserves, designing habitat and determining the number of species a habitat can viably carry. Although there are many shortcomings of the quantitative nature of the theory, some of this work has been helpful.

Dr. Larry Harris of Florida has developed "Conservation Corridors" to help animals move between habitat islands.