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Genetic variation maintained in multilocus models of additive quantitative traits under stabilizing selection
1Institut für Mathematik, Universität Wien, A-1090 Vienna, Austria. reinhard.buerger@univie.ac.at
Genetics
|June 3, 1999
Summary
Stabilizing selection depletes genetic variation in quantitative traits. This study shows that as more loci control a trait, genetic variation is lost more rapidly, contrary to some models.
Area of Science:
- Evolutionary genetics
- Quantitative genetics
Background:
- Stabilizing selection is thought to reduce genetic variation in quantitative traits.
- Previous models yielded conflicting results on variation maintenance under stabilizing selection.
Purpose of the Study:
- To analyze the ability of quadratic stabilizing selection to maintain genetic variation in additive quantitative traits.
- To investigate this across models with up to five loci.
Main Methods:
- A generalized two-locus quadratic-optimum model was analyzed.
- Numerical simulations used 4000 random parameter sets (allelic effects, recombination, selection strength).
- Recursion equations tracked gamete frequencies to equilibrium from 20 initial conditions.
Main Results:
- Polymorphic fraction and genetic variance decreased rapidly as the number of loci increased from two to five.
- Loci with smaller effects were more likely to remain polymorphic.
- Results were weakly dependent on selection intensity and recombination rates.
Conclusions:
- Stabilizing selection significantly reduces genetic variation, especially with an increasing number of loci.
- The equilibrium genetic architecture differs from models without fitness constraints.
- Genetic variation maintenance under stabilizing selection is sensitive to the number of loci involved.