What process occurs when a population becomes divided by a geographical barrier?

The process that occurs when a population becomes divided by a geographical barrier is known as allopatric speciation. In this scenario, a physical barrier, such as a mountain range or a body of water, separates a single population into two or more isolated groups. Over time, these isolated populations can experience different evolutionary pressures, such as variations in climate, food sources, or predators, which can lead to genetic divergence. As the populations adapt to their distinct environments, they may accumulate differences in traits and eventually become separate species.

Allopatric speciation is significant because it highlights how geographical isolation can drive the process of speciation through mechanisms like natural selection and genetic drift. As the populations evolve independently, reproductive barriers may develop, preventing them from interbreeding even if the geographical barrier is removed later on. This process contrasts with other forms of speciation, such as sympatric speciation, where new species arise within the same geographical area, often due to behavioral or ecological factors.