Island biogeography theory

Definition

Island biogeography theory is a scientific framework that explains the distribution of species on islands and the factors influencing species richness, primarily focusing on island size and distance from the mainland. It connects ecological processes with evolutionary dynamics, highlighting how isolation affects colonization, extinction rates, and the development of unique species.

5 Must Know Facts For Your Next Test

1. The theory was developed by Robert MacArthur and Edward O. Wilson in the 1960s and fundamentally changed how ecologists understand biodiversity on islands.
2. It posits that larger islands typically have higher species richness due to lower extinction rates and greater habitat diversity compared to smaller islands.
3. The distance from the mainland affects colonization rates; closer islands receive more immigrant species than those farther away, leading to different biodiversity levels.
4. Island biogeography theory explains patterns of extinction and endemism, especially in ecosystems that are highly isolated or fragmented.
5. Human activities such as habitat destruction and climate change can disrupt island ecosystems, leading to increased extinction rates and loss of biodiversity.

Review Questions

• How do island size and distance from the mainland influence species richness according to island biogeography theory?
  • Island size directly influences species richness because larger islands can support more diverse habitats and have lower extinction rates. In contrast, distance from the mainland affects the rate at which species can migrate to the island; closer islands are more likely to receive new colonizers. This combination leads to a higher diversity of species on large, near islands compared to small, distant ones.
• Evaluate the implications of island biogeography theory on conservation efforts for isolated ecosystems.
  • Island biogeography theory highlights the importance of maintaining large habitats and minimizing distances between them to promote biodiversity. Conservation strategies can focus on preserving larger areas of natural habitat and creating wildlife corridors to facilitate dispersal between isolated patches. Understanding these dynamics helps prioritize conservation actions that enhance species survival and ecological resilience in fragmented landscapes.
• Synthesize how climate change and urbanization challenge principles of island biogeography theory in modern contexts.
  • Climate change and urbanization pose significant threats to the principles of island biogeography by altering habitat availability and connectivity. Rising sea levels can submerge coastal islands while urban sprawl can fragment habitats, isolating populations. This results in increased extinction risks as species struggle to migrate or adapt. The challenges posed by these factors illustrate the need for innovative conservation strategies that consider dynamic ecological processes shaped by human impacts.

Related terms

Species-Area Relationship: The principle that larger areas tend to support more species due to a greater variety of habitats and resources.

Endemism:

A condition where species are native to and found nowhere else but a specific geographic area, often seen in isolated ecosystems like islands.

Dispersal:

The movement of organisms from one place to another, which is critical in determining how species colonize new areas, including islands.