What process results in two genetically distinct populations arising from a common ancestor?

Divergent evolution is the process that leads to two genetically distinct populations arising from a common ancestor. This process occurs when two or more species evolve distinct traits and adaptations due to different environmental pressures or niches. Over time, as populations of a species become isolated from one another—geographically or ecologically—they may undergo changes at the genetic level, leading to the formation of new species that are distinct from their common ancestor.

The concept of divergent evolution illustrates how one ancestral species can give rise to a variety of forms suited to different environments, resulting in biodiversity. For example, the evolution of finches on the Galápagos Islands from a common ancestor showcases how adaptations to different feeding habits and habitats can lead to significant genetic and morphological differences among species.

In contrast, adaptive radiation refers to a specific type of divergent evolution where many species evolve rapidly from a single ancestral species to exploit different ecological niches, while adaptive evolution focuses on the changes within a single lineage that enhance fitness. Parallel evolution denotes the development of similar traits in unrelated species due to similar environmental pressures, rather than from a common ancestor. Thus, divergent evolution aptly captures the essence of the emergence of distinct populations from a shared lineage.