Island biogeography

Science

Definition

A theory explaining the number of species found on islands based on two factors: immigration rate (influenced by distance from the mainland) and extinction rate (influenced by island size). Closer, larger islands support more species. The theory also applies to habitat islands like mountaintops or forest fragments.

Examples

  • The Galápagos Islands having fewer species than similar-sized mainland areas
  • Large national parks supporting more species than small nature reserves
  • Mountain peaks acting as sky islands with isolated populations
Key Fact

Species richness = balance between immigration rate and extinction rate

Related Terms

Biodiversity Speciation Community ecology Invasive species

Study This Concept

Practice island biogeography with free review games in these units:

AP Environmental Science Unit 2: The Living World: Biodiversity