Biological evolution is a process that is substantially governed by chance.Neither its result nor the actual course can be estimated in advance as unique random events are constantly occurring.Because of the lack of predictability of these events, e.g. collision of the Earth with cosmic bodies, the progress of evolution cannot be described by a deterministic model.However, a great many random processes occurring in the evolution of living systems can be successfully described by a stochastic model.For one of the best known and, according to a number of authors, the most important of these processes, genetic drift, this model permits prediction of the character of the evolutionary processes that will accompany its action.It has been found that, under certain circumstances, genetic drift can very substantially affect the progress of biological evolution in some systems to such a degree that it can reverse or at least substantially reduce the effect of such an important evolutionary factor as, for example, natural selection.Similar to practically all the important ideas of theoretical biological evolution, R.A. Fisher (Fisher 1958)outlined the basic principles of the action of genetic drift in his main work on evolution.However, the American S. Wright (Wright 1931) and the Japanese scientists M. Kimura (Kimura 1983b) and T. Ohta (Ohta 1993) were responsible for the greatest developments in this area.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more
Draft translation from: Evoluční biologie, 2. vydání (Evolutionary biology, 2nd edition), J. Flegr, Academia Prague 2009. The translation was not done by biologist, therefore any suggestion concerning proper scientific terminology and language usage are highly welcomed. You can send your comments to flegratcesnet [dot] cz. Thank you.