Nonadaptive radiation

Nonadaptive radiation is a pattern of evolutionary diversification in which a group of species multiplies without being driven by resource partitioning, so that the resulting species occupy very similar ecological niches and often look much alike, in contrast with adaptive radiation, where species evolve distinct traits to exploit different niches. It tends to proceed through nonecological speciation, most often allopatric speciation among geographically isolated populations that nonetheless remain in similar environments, though sexual selection and species recognition can also maintain separate species even where their ranges overlap. Examples include Albinaria land snails on Mediterranean islands, Batrachoseps salamanders in California, and certain Hawaiian damselflies and crickets.