Island biogeography

Definition

Island biogeography is the study of the distribution and diversity of species on islands and the factors that influence these patterns. It focuses on how the size, isolation, and habitat diversity of an island affect species richness and the dynamics of extinction and colonization, linking it to concepts like genetic drift and gene flow in population genetics.

5 Must Know Facts For Your Next Test

1. Larger islands typically support more species because they provide a greater variety of habitats and resources, reducing the risk of extinction.
2. Isolation plays a critical role in island biogeography; more isolated islands have fewer species due to the challenges of colonization.
3. The balance between immigration (colonization) and extinction rates determines the overall species richness on an island.
4. Genetic drift can have a significant impact on small island populations, leading to reduced genetic diversity and increased vulnerability to extinction.
5. Habitat fragmentation can mimic island biogeography effects on mainland areas, impacting gene flow and population dynamics similarly.

Review Questions

• How does the concept of island biogeography relate to the idea of genetic drift in small populations?
  • Island biogeography highlights how isolated environments can lead to smaller populations, where genetic drift becomes a significant evolutionary force. In these small populations, random changes in allele frequencies can lead to loss of genetic diversity over generations. This is especially critical for island species, which may have limited genetic variability, making them more susceptible to extinction due to environmental changes or disease.
• In what ways does island biogeography illustrate the importance of gene flow in maintaining genetic diversity within species?
  • Island biogeography demonstrates that gene flow is essential for maintaining genetic diversity by allowing individuals from different populations to interbreed. In isolated island scenarios, limited gene flow can result in inbreeding and increased genetic drift, causing populations to diverge genetically. The connectivity between islands or between islands and mainland can enhance gene flow, thus preventing isolation-related issues such as inbreeding depression.
• Evaluate how the principles of island biogeography could inform conservation strategies for endangered species in fragmented habitats.
  • Applying the principles of island biogeography can greatly enhance conservation strategies for endangered species in fragmented habitats by emphasizing the need for larger protected areas that support diverse ecosystems. By recognizing that larger patches of habitat can support more species and reduce extinction risks, conservation efforts can focus on creating wildlife corridors that facilitate gene flow between isolated populations. This approach not only aims to preserve existing biodiversity but also mitigates the effects of genetic drift by promoting genetic exchange among populations that might otherwise remain isolated.

Related terms

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

Colonization: The process by which species disperse to and establish populations in new habitats, including islands.

Extinction Rate: The frequency at which species become extinct, which can be influenced by factors such as habitat size and isolation.