Island biogeography theory

Definition

Island biogeography theory is a concept that explains the diversity and distribution of species on islands based on their size and distance from the mainland. The theory suggests that larger islands tend to support more species due to greater habitat variety and resources, while islands that are closer to the mainland have higher rates of immigration for species, impacting the overall biodiversity. This framework helps in understanding how ecological dynamics affect species survival and distribution in fragmented habitats.

5 Must Know Facts For Your Next Test

1. Island biogeography theory was developed by Robert MacArthur and Edward O. Wilson in the 1960s, forming a foundational concept in ecology.
2. According to the theory, the immigration rate of species is higher on islands that are closer to a mainland, while extinction rates tend to be lower on larger islands.
3. The balance between immigration and extinction determines the number of species on an island, leading to an equilibrium point where these rates stabilize.
4. The theory is not limited to oceanic islands but can also apply to isolated habitats like mountaintops or forest fragments within a landscape.
5. Island biogeography theory has practical applications in conservation biology, helping guide the creation of nature reserves and understanding how to maintain biodiversity.

Review Questions

• How does island size influence species diversity according to island biogeography theory?
  • According to island biogeography theory, larger islands tend to support more species because they offer more diverse habitats and resources. This increased habitat variety allows for greater ecological niches, which can accommodate a wider range of organisms. Additionally, larger land areas can support larger populations, reducing the risk of extinction due to environmental changes or disasters.
• Discuss how the distance from the mainland affects the immigration rates of species to islands.
  • The distance from the mainland is crucial in determining immigration rates as per island biogeography theory. Islands that are closer to the mainland experience higher rates of species arrival because it's easier for organisms to travel such distances. In contrast, more distant islands face barriers that limit immigration, leading to fewer new species establishing themselves, ultimately affecting overall biodiversity.
• Evaluate the implications of island biogeography theory for conservation efforts in fragmented habitats.
  • Island biogeography theory provides important insights for conservation strategies in fragmented habitats by emphasizing the need for larger and well-connected protected areas. It highlights how habitat size and connectivity influence biodiversity, suggesting that maintaining corridors between patches can enhance species immigration and reduce extinction risks. This understanding helps conservationists prioritize areas for protection and develop management plans that promote biodiversity resilience in increasingly fragmented landscapes.

Related terms

Species richness: The number of different species represented in a given ecological community or area.

Habitat fragmentation: The process by which large, contiguous habitats are divided into smaller, isolated patches, impacting species' survival and distribution.

Equilibrium theory: A concept within island biogeography that posits that the number of species on an island reaches an equilibrium based on the rates of immigration and extinction.