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Maintenance of genetic variability under strong stabilizing selection: a two-locus model
1Division of Environmental Studies, University of California, Davis 95616.
Genetics
|May 1, 1993
Summary
Genetic variability can be maintained under stabilizing selection when recombination is present. This study shows that even strong selection may not eliminate variation, aligning with experimental findings.
Area of Science:
- Population Genetics
- Quantitative Genetics
Background:
- Stabilizing selection often reduces genetic variation.
- The interplay between selection and recombination in maintaining variability is complex.
Purpose of the Study:
- To investigate how stabilizing selection and recombination interact to affect genetic variability in a two-locus model.
- To determine conditions under which genetic variation is maintained despite stabilizing selection.
Main Methods:
- Utilized a two-locus model with additive genetic contributions to the phenotype.
- Analyzed a symmetric stabilizing selection fitness function, focusing on a quadratic fitness function.
- Examined the stability of polymorphic equilibria and their dependence on selection strength, recombination rate, and allelic effects.
Main Results:
- Genetic variability can be maintained if the double heterozygote has the optimum phenotype and loci contributions differ, provided selection is strong relative to linkage.
- Polymorphic equilibria are stable even when selection is not extremely strong relative to recombination.
- Negative linkage disequilibrium can mask additive genetic variance at stable equilibria, which may not match the optimum phenotype.
Conclusions:
- Stabilizing selection does not invariably lead to a loss of genetic variability.
- The findings are consistent with experimental observations of maintained genetic variation under strong stabilizing selection.