Final answer:
The process in which one species evolves into a variety of species is called adaptive radiation or divergent evolution. It involves speciation through branching events and common ancestry.
Step-by-step explanation:
The process in which one species evolves into a variety of species is called adaptive radiation. It is a mechanism for speciation that occurs when a single species evolves into many new species to fill available niches. This process results in enormous variation in form and function, and is seen in various organisms including flowering plants and hominids.
Divergent evolution is another term used to describe when two species evolve in different directions from a common point. This can be observed in reproductive organs of flowering plants or in the evolution of different hominid species.
A crucial aspect of this process is the concept of common ancestry, which means that related species share a common ancestor. This principle is illustrated in Darwin's concept of branching evolution, where one species branches to form more than one new species over time.