Allopatric speciation

Allopatric speciation is the formation of a new species from populations that are geographically isolated from one another. Physical separation (different homelands) prevents gene flow, allowing evolutionary differences to accumulate until new species form.

• Think "geographic isolation" for allopatric speciation: mountains, rivers, islands, or other barriers split a population and stop them from interbreeding.
• Over time, isolated groups experience different mutations, natural selection pressures, and genetic drift. Given enough generations, these differences can lead to reproductive incompatibility with the original population.
• Terminology: "allo" = other, "patric" = homeland. Allopatric speciation is often contrasted with sympatric speciation (speciation without geographic separation).

• If an exam describes species formation after a physical barrier divides a population (e.g., a canyon forming or a flock blown to a new island), the answer revolves around allopatric speciation.
• Common examples: Darwin's finches on different islands, or squirrels on opposite rims of the Grand Canyon evolving into separate species, illustrate allopatric speciation.
• Be careful not to confuse "allopatric" with similar-sounding terms; a tip is to remember allopatric = apart (separated populations).