Mar 4, 2016

Resolving the conflict between associative overdominance and background selection

BioRxiv : the Preprint Server for Biology
Lei Zhao, Brian Charlesworth


In small populations, genetic linkage between a polymorphic neutral locus and loci subject to selection, either against partially recessive mutations or in favor of heterozygotes, may result in an apparent selective advantage to heterozygotes at the neutral locus (associative overdominance), and a retardation of the rate of loss of variability by genetic drift at this locus. In large populations, selection against deleterious mutations has previously been shown to reduce variability at linked neutral loci (background selection). We describe analytical, numerical and simulation studies that shed light on the conditions under which retardation versus acceleration of loss of variability occurs at a neutral locus linked to a locus under selection. We consider a finite, randomly mating population initiated from an infinite population in equilibrium at a locus under selection, with no linkage disequilibrium. With mutation and selection, retardation only occurs when S, the product of twice the effective population size and the selection coefficient, is of order one. With S >> 1, background selection always causes an acceleration of loss of variability. Apparent heterozygote advantage at the neutral locus is, however, always observed w...Continue Reading

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Mentioned in this Paper

Genetic Drift
Biological Markers
Dysequilibrium Syndrome
Genetic Linkage
Genetic Loci
Mutation Abnormality
Population Group

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