APES 2.3 Island Biogeography

Island biogeography

Study of ecological relationships & community structure on islands.

Figurative habitat island

A natural habitat surrounded by human-developed land.

Larger islands

Support more total species.

Why larger islands support more species

Greater ecosystem diversity means more food and habitat resources, and more niches, or “roles” organisms can play in the ecosystem.

Niches

“roles” organisms can play in the ecosystem.

Island size and species richness

Positive correlation between island size & species richness.

Larger island populations

More genetically diverse and more resistant to environmental disturbance; species also have a lower extinction rate.

Closer to the mainland

Higher species richness because it is easier for more species to migrate to the island.

Continual migration

Brings more genetic diversity and larger population size.

Distance from mainland and species richness

Inverse relationship: the further away from the mainland, the fewer species.

Adaptive radiation

Single species rapidly evolving into several new species to use diff. resources & reduce competition.

Island conditions and evolution

Limited space & resources create unique conditions for evolution and more pressure to adapt to narrower niches (more specific food/habitat).

Galápagos finches

Different beaks quickly evolve to fit a variety of different food sources on an island.

One mainland colonizer

Quickly evolves into many slightly different species to adapt to new island conditions.

a species originating from a large, continuous landmass (the mainland) that travels to, arrives at, and successfully establishes a new population on an isolated island.