(from Greek klados, “branch,” and “genesis”), a form of evolution of a group of living organisms leading by means of divergence to an increase in the number of separate species, genera, and families. The term, introduced by the German biologist B. Rensch in 1947, is often used as a synonym for speciation in the narrow sense—not completely accurately, since cladogenesis includes any increase in evolutionary diversity. The concept of cladogenesis is closely related to adaptive radiation and idioadaptation.