What evolutionary process occurs when an ancestral species splits into two groups under selective pressures?

The correct response highlights the concept of divergent evolution, where an ancestral species separates and evolves into two or more distinct species due to different selective pressures in their respective environments. This process often results in the development of distinct adaptations that enhance survival and reproduction in the varying conditions faced by each group.

For example, when a population of a species is divided by geographical barriers, such as mountains or rivers, each segment may encounter different ecological challenges. Over time, these groups will accumulate genetic changes that are advantageous for their specific environments, leading to the emergence of new species that are adapted to their unique niches.

Conversely, convergent evolution refers to unrelated species developing similar traits due to similar environmental pressures, while transformational evolution involves gradual change within a single lineage, leading to a shift in the characteristics of a species. Co-evolution describes the simultaneous evolution of interacting species, influencing each other's adaptations, which is distinct from the process described in the question. Thus, divergent evolution is the appropriate concept for understanding the scenario presented in the question.