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The mutational load of a multigene family with uniform members

Published online by Cambridge University Press:  14 April 2009

Tomoko Ohta
Tomoko Ohta
Affiliation:
National Institute of Genetics, Mishima 411, Japan
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The mutational load of a multigene family with uniform members was studied by computer simulations. Two models of selection, truncation and exponential fitness, were examined, by using a simple model of gene conversion. It was found that the load is much smaller than the Haldane–Muller prediction under the truncation selection, and that it becomes approximately equal to the value calculated by the formula, nv(1 − q)/(m − nq), where n is the copy number, v is the rate of detrimental mutation per gene copy, m is the truncation point in terms of the number of detrimental genes eliminated, and q is the equilibrium frequency of detrimental mutation. However the equilibrium frequency cannot be analytically obtained. For the exponential fitness model, the load is close to the Haldane–Muller value. When there is no gene conversion, the load becomes larger than the cases with conversion both for the truncation and the exponential fitness models. Thus, gene conversion or other mechanisms that are responsible for contraction–expansion of mutants on chromosomes helps eliminating deleterious mutations occurring in multigene families.

Type
Research Article
Information
Genetics Research , Volume 53 , Issue 2 , April 1989 , pp. 141 - 145
Copyright
Copyright © Cambridge University Press 1989

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