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the ability of an organism to adapt prior in time to some change in its interaction with the environment; also, the ability of an organ to adapt to some change in its functions before the change occurs. The process of acquiring preadaptive characteristics is also called preadaptation.
The concept of preadaptation was introduced in 1911 by the French scientist L. Cuénot and later developed by the American biologists G. Simpson (1944) and W. Bock (1959–65) and the German scientist G. Osche (1962). Unlike Cuénot, later scientists emphasized the role of natural selection in the development of new adaptations by means of preadaptation.
The preadaptive state is not spontaneously caused by chance mutations but results from the adaptive evolution of a former function of a given organ. The preadaptive state is a chance by-product of evolutionary changes controlled by natural selection, which ensure more effective performance of the functions previously carried out by the organ. For example, in the evolution of the oldest vertebrates, jaws developed from the anterior gill arch after it divided into movable parts because of intensified respiration. Thus, the improvement of the gill “pump” preadapted the development of the jaws. The theory of preadaptation makes it possible to understand the functional change that occurs during organic evolution.
A species’ assimilation of a qualitative new habitat is possible only after the organism has acquired characteristics in the former habitat as preadaptations that enable it to survive in these new conditions. Thus, preadaptation is a universal mechanism for redirecting an organ’s evolution. Postadaptation occurs after an organ has acquired a new function perfected in the course of natural selection.
REFERENCESSimpson, G. G. Tempy i formy evoliutsii. Moscow, 1948. (Translated from English.)
Iordanskii, N. N. “Teoriia preadaptatsii i ee znachenie dlia ponimaniia rasshireniia i smeny funktsii organov v evoliutsii.” In the collection Nekotorye problemy teorii evoliutsii. Moscow, 1973.
Georgievskii, A. B. Problema preadaptatsii: Istoriko-kriticheskoe issledovanie. Leningrad, 1974.
Bock, W. J. “Preadaptation and Multiple Evolutionary Pathways.” Evolution: International Journal of Organic Evolution. 1959, vol. 13, no. 2.
Osche, G. “Das Praeadaptationsphänomen und seine Bedeutung fur die Evolution.” Zoologischer Anzeiger, 1962, vol. 169, issues 1–2.
N. N. IORDANSKII