|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.
|a grouping of tissues into a distinct structure, as a heart or kidney in animals or a leaf or stamen in plants, that performs a specialized task|
|the science dealing with the description, identification, naming, and classification of organisms|
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.)