What defines allopatric speciation?

Allopatric speciation is a process that arises when populations of a species become geographically isolated from one another. This geographical separation can be caused by various factors like physical barriers (mountains, rivers, etc.) or distance. Once isolated, the populations undergo different evolutionary pressures and drift, leading to genetic divergence over time. This can result in the development of reproductive barriers and eventually the emergence of new species.

Understanding this concept is crucial in evolutionary biology, as it highlights how physical separation can lead to the formation of distinct species that cannot interbreed. The focus on geographic isolation is what distinguishes allopatric speciation from other forms of speciation. For instance, sympatric speciation involves species diverging while still in the same geographic area, which is not applicable in this case.