Geographic isolation of different populations of a species can lead to differential adaptations to their environments.

Over time, allele frequencies among the populations diverge, leading to speciation: the evolution from an ancestral species.

The finches of the Galapagos Islands provide an example.

• Descendants of an ancestral finch from Ecuador occupied separate islands.

• Geographic isolation led to diversification of the descendants, which developed different beaks that specialize in eating different food sources.