macromutation

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Related to Macromutations: punctuated equilibrium, macroevolution

macromutation

[‚mak·rə·myü′tā·shən]
(genetics)
Any genetic change that leads to a pronounced phenotypic alteration.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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Long jumps, forced macromutations might prove very effective on rugged landscapes, where many fitness peaks exist, though they become a weak strategy as the complexity (diversity and numbers) increases.
Many mechanisms have been proposed to explain these shifts, most prominently Wright's (1977) shifting balance; others have included Fisher's (1958) idea that individual fitnesses change frequently and Goldschmidt's (1940) macromutations. Here I suggest a modification of Wright's idea that applies when adaptive landscapes are defined with respect to phenotypes - that changes in the phenotypic variance resulting from drift allow transition to occur.