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speciation spe·ci·a·tion (spē'shē-ā'shən, -sē-)
The evolutionary formation of new biological species, usually by the division of a single species into two or more genetically distinct ones.
The formation of new biological species by the development or branching of one species into two or more genetically distinct ones. The divergence of species is thought to result primarily from the geographic isolation of a population, especially when confronted with environmental conditions that vary from those experienced by the rest of the species, and from the random change in the frequency of certain alleles (known as genetic drift). According to the theory of evolution, all life on Earth has resulted from the speciation of earlier organisms. See also adaptive radiation.