Island biogeography theory main idea and its ecological implications?

• A. Biogeography studies the distribution of species across space and time.
• B. Migration always leads to increased richness.
• C. Island biogeography theory posits that island species richness is governed by immigration and extinction rates influenced by island size and isolation.
• D. Biogeography has no conservation implications.

Answer: (C)

At its heart, the island biogeography idea is that how many species you have on an island comes from a balance between new species arriving and existing species going extinct, and that balance is pushed around by how big the island is and how isolated it is from other landmasses. Bigger islands provide more habitats and resources, so extinction is less likely, and they can sustain larger populations. Islands that are closer to sources of colonists get more immigrants, raising richness. When the number of arrivals equals the number of extinctions, you reach a dynamic equilibrium. Because both arrival and extinction rates depend on size and distance, the equilibrium richness is higher on large, near islands and lower on small, far ones. This has big ecological implications: it helps explain why habitat fragmentation reduces biodiversity, why maintaining connectivity between patches helps conserve species, and why protecting larger reserves or creating stepping-stone corridors can boost persistence. Even at equilibrium, there is turnover as species colonize and go extinct over time, a reality for fragmented landscapes as conditions change.