What occurs when populations of organisms are separated and can no longer interbreed?

Reproductive isolation occurs when populations of organisms are separated in such a way that they can no longer interbreed. This separation can be due to various factors, including geographical barriers, behavioral differences, or temporal isolation, which refers to mating at different times. When populations can no longer exchange genetic material, they begin to evolve independently. This independence can lead to the development of distinct traits, characteristics, and potentially new species over time, a process known as speciation. This is a fundamental concept in evolutionary biology, illustrating how the inability to interbreed drives divergence between populations.