Island biogeography

Definition

Island biogeography is the study of the ecological relationships and species diversity on islands, focusing on how island size, distance from the mainland, and environmental factors influence the number of species that can inhabit a given island. This concept highlights the dynamic interactions between species and their environments, emphasizing the balance of immigration and extinction rates that affect biodiversity. It provides insights into how geographic isolation impacts evolutionary processes and community composition.

5 Must Know Facts For Your Next Test

1. The concept of island biogeography was developed by Robert MacArthur and Edward O. Wilson in the 1960s, providing a framework for understanding species diversity on islands.
2. Islands closer to the mainland tend to have higher rates of species immigration compared to those that are farther away, impacting overall biodiversity.
3. Smaller islands generally have higher extinction rates due to limited resources and habitat space, which can lead to lower species richness over time.
4. The principles of island biogeography can also apply to other isolated habitats like mountaintops or fragments of forests, highlighting its broader ecological relevance.
5. Fossil records show that past island ecosystems have undergone significant changes in species composition due to shifts in climate and sea levels, illustrating the dynamic nature of island biogeography.

Review Questions

• How do size and distance from the mainland affect species diversity on islands according to the principles of island biogeography?
  • Size and distance from the mainland significantly impact species diversity on islands. Larger islands generally support more species due to greater habitat availability and resource diversity. Additionally, islands that are closer to the mainland experience higher rates of immigration as new species can more easily reach these areas. In contrast, smaller or more isolated islands may have higher extinction rates due to limited resources, resulting in lower overall biodiversity.
• Discuss how the equilibrium theory of island biogeography explains the balance between immigration and extinction rates.
  • The equilibrium theory of island biogeography posits that the number of species on an island stabilizes at a point where immigration and extinction rates are balanced. As new species arrive on an island, they increase the species count, but as resources become limited or competition increases, some species may go extinct. This balance is influenced by factors such as island size and proximity to other landmasses, leading to a dynamic yet stable community structure over time.
• Evaluate how studying island biogeography can inform conservation strategies for endangered species in fragmented habitats.
  • Studying island biogeography offers valuable insights for conservation strategies aimed at protecting endangered species in fragmented habitats. By understanding how isolation affects species richness and extinction dynamics, conservationists can design protected areas that maximize habitat connectivity and minimize isolation effects. Strategies may include creating wildlife corridors to facilitate immigration between patches or managing habitat size to reduce extinction risks. This knowledge is crucial for maintaining biodiversity in increasingly fragmented landscapes due to human activities.

Related terms

Species-Area Relationship: A principle stating that larger islands tend to support more species due to increased habitat diversity and resources.

Equilibrium Theory: A theory proposed by Robert MacArthur and Edward O. Wilson that describes how the number of species on an island reaches an equilibrium based on immigration and extinction rates.

Endemism: The ecological state where a species is native to a specific geographic location, such as an island, and not found naturally elsewhere.