Island biogeography

Definition

Island biogeography is the study of the distribution of species on islands and the factors that influence species diversity and abundance in these isolated ecosystems. It connects to broader concepts of how geographical isolation, habitat size, and distance from the mainland impact species survival and colonization. This field examines both the ecological and evolutionary processes that shape the unique flora and fauna found on islands compared to mainland areas.

5 Must Know Facts For Your Next Test

1. The theory of island biogeography was developed by Robert MacArthur and Edward O. Wilson in the 1960s, providing a framework for understanding how island size and distance from the mainland affect species richness.
2. Larger islands typically support more species because they offer a greater variety of habitats and resources compared to smaller islands.
3. Islands closer to the mainland have higher rates of immigration, resulting in more diverse species assemblages due to easier access for colonizing species.
4. Extinction rates are generally higher on smaller islands, as they can support fewer individuals and have limited resources, making populations more vulnerable.
5. Islands can serve as natural laboratories for studying evolutionary processes, as species on isolated islands may evolve differently than those on continents due to unique environmental pressures.

Review Questions

• How does the size of an island influence its biodiversity according to the theory of island biogeography?
  • According to the theory of island biogeography, larger islands tend to support higher biodiversity than smaller ones. This is because larger islands provide more habitats and resources, allowing for a greater number of species to coexist. Additionally, larger areas can sustain larger populations, which reduces extinction rates and promotes stability within the ecosystem. This relationship emphasizes how area impacts species richness in isolated environments.
• Evaluate the role of isolation in shaping the unique flora and fauna found on islands compared to mainland areas.
  • Isolation plays a crucial role in shaping the distinct flora and fauna found on islands. Species that evolve in isolation often develop unique adaptations to their specific environments due to limited competition and predation. This isolation can lead to high levels of endemism, where certain species are found nowhere else on Earth. The reduced gene flow between island populations and mainland populations fosters evolutionary divergence, resulting in diverse ecosystems that differ markedly from continental habitats.
• Assess how human activities contribute to changes in island biogeography and the implications for conservation efforts.
  • Human activities such as habitat destruction, introduction of invasive species, and climate change significantly alter island biogeography. These changes can lead to increased extinction rates as native species struggle against competition from invaders or lose their habitats due to development. Conservation efforts must take these factors into account by focusing on habitat preservation, controlling invasive species, and creating corridors for species movement. Understanding island biogeography is essential for developing effective strategies to protect these vulnerable ecosystems amid increasing anthropogenic pressures.

Related terms

SLOSS: An acronym for 'Single Large or Several Small', this concept discusses whether it is better for conservation to have one large protected area or multiple smaller ones to maximize biodiversity.

Endemism:

The condition where a species is native to and restricted to a specific geographical area, often found in island ecosystems due to their isolation.

Habitat Fragmentation: The process by which large, continuous habitats are divided into smaller, isolated patches, often affecting species diversity and ecosystem function.