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The extent to which gene conversion can change allele frequencies in populations

Published online by Cambridge University Press:  14 April 2009

B. C. Lamb  and
S. Helmi
B. C. Lamb
Affiliation:
Department of Botany, Imperial College, London, SW7 2BB
S. Helmi
Affiliation:
Department of Botany, Imperial College, London, SW7 2BB
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Summary

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The gene conversion parameters which affect allele frequencies in populations are defined, and their ranges and typical values are given for several genera of fungi, where meiotic octads and tetrads provide the best information on conversion. Both gene conversion and disparity in direction of conversion are common. Data from Ascobolus immersus show that conversion properties are largely stable with time, but can be changed environmentally and by genetic conversion control factors. Equations are given for the interactions of selection, mutation and gene conversion in determining equilibrium frequencies. Numerical examples, using typical values of conversion parameters from the fungal data, show that for alleles which are selectively neutral or have very low selection coefficients, conversion will often have very large effects on their equilibrium frequencies and may lead to fixation. Where selection coefficients are higher, conversion has major effects on the frequencies of deleterious recessive alleles, but lesser effects on deleterious dominant alleles: a critical comparison is that of s with 2y. The available estimates for conversion parameters (at least in fungi) are of a magnitude to make gene conversion an important factor in evolution.

Type
Research Article
Information
Genetics Research , Volume 39 , Issue 2 , April 1982 , pp. 199 - 217
Copyright
Copyright © Cambridge University Press 1982

References

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