The process in which one species diversifies into many species that occupy different ecological niches is called adaptive radiation.
Adaptive radiation usually begins when an ancestral population encounters ecological opportunity, such as a new island, an isolated lake, a key evolutionary innovation, or the disappearance of competitors. Descendant populations then specialize on different resources or habitats. Over time, natural selection and reproductive isolation can produce multiple distinct species.
Darwin’s finches in the Galápagos are the classic example. Descended from a common ancestor, they evolved different beak shapes and feeding strategies, including adaptations for seeds, insects, and other foods. The cichlid fishes of Africa’s Great Lakes provide another dramatic example, with hundreds or even thousands of species occupying diverse underwater niches.
Adaptive radiation is not the same as ordinary speciation. It specifically emphasizes rapid diversification, common ancestry, ecological differences, and corresponding adaptations. Allopatric speciation may help start a radiation, while convergent evolution describes unrelated organisms evolving similar traits.