| theory of, Biology. a hypothesis holding that the evolution of species proceeds in a characteristic pattern of relative stability for long periods of time interspersed with much shorter periods during which many species become extinct and new species emerge. Also called punctuationalism. Compare gradualism (def. 3). |
| punc·tu·at·ed equilibrium (pŭngk'chōō-ā'tĭd) n. The theory that speciation occurs in spurts of major genetic alterations that punctuate long periods of little change. |
The theory that new species evolve suddenly over brief periods of time, followed by longer periods during which there is no genetic change. Punctuated equilibrium is a revision of Darwin's theory of evolution. (Compare gradualism and catastrophism.)
punctuated equilibrium  (pŭngk'ch -ā'tĭd) Pronunciation Key
The theory that new species evolve suddenly over relatively short periods of time (a few hundred to a thousand years), followed by longer periods in which little genetic change occurs. Punctuated equilibrium is a revision of Darwin's theory that evolution takes place at a slow, constant rate over millions of years. Compare gradualism. See Note at evolution. |