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A Model of a Genetic System which Leads to Closer Linkage by Natural Selection
Vol. 10, No. 3 (Sep., 1956), pp. 278-287
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2406012
Page Count: 10
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As has been pointed out by various authors, frequency of recombination within a chromosome is subject to selective adjustment. In this sense, the history of the control of recombination may be regarded as a part of the history of the evolution of genetic system. In 1930 Fisher said that with two pairs of linked loci such that A1 is favored in the presence of B1 while A2 is favored with B2 selection will act in such a way as to decrease the amount of recombination between the two loci. He did not, however, specify how a stable polymorphism of this type might be maintained. In this paper a model suggested by Sheppard is examined. It is shown that, if the first locus is maintained in balanced polymorphism by heterozygote superiority in fitness, the second locus will remain polymorphic if linkage is sufficiently close. Under this condition an inversion (or other crossover reducing mechanism) will be favored by selection and, other things being equal, will eventually be established in the population.
Evolution © 1956 Society for the Study of Evolution