Final answer:
Speciation is the process whereby taxonomic groups diversify into new species to fill different ecological niches.
Step-by-step explanation:
The process by which taxonomic groups diversify to fill different ecological niches, forming new species, is known as speciation. This evolutionary process can occur in several ways, including allopatric speciation, wherein a physical barrier divides a population, leading to the evolution of different species. Adaptive radiation is a type of speciation that happens when a single ancestral species evolves into an array of species adapted to different habitats and niches, typically following environmental changes or the availability of new habitats.