Stability and response of polygenic traits to stabilizing selection and mutation

Area of Science:

• Evolutionary genetics
• Population genetics

Background:

• Polygenic traits under stabilizing selection allow multiple allele combinations for adaptation.
• Alleles with equal effects simplify analysis, but real-world variation complicates fitness landscapes.

Purpose of the Study:

• To investigate the impact of varying allele effects on genetic variance and adaptation under stabilizing selection.
• To analyze the interplay between mutation, selection, and allele frequency dynamics.

Main Methods:

• Theoretical modeling of allele frequency dynamics under stabilizing selection.
• Analysis of genetic variance based on allele effect sizes and frequencies.

Main Results:

• A threshold effect size determines whether alleles remain polymorphic or become fixed.
• Genetic load is reduced, and fitness equilibria are more similar compared to equal-effect alleles.
• Displaced optima lead to rapid sweeps of near-threshold alleles, with convergence sensitive to initial conditions.

Conclusions:

• Varying allele effects lead to efficient adaptation and reduced genetic load under stabilizing selection.
• The dynamics of allele frequency change and population convergence are complex and sensitive to initial states and environmental shifts.