The balance between pleiotropic mutation and selection, when alleles have discrete effects

Area of Science:

• Evolutionary biology
• Population genetics
• Theoretical biology

Background:

• Pleiotropic mutation affects multiple traits simultaneously.
• Stabilizing selection acts on Omega phenotypic characters.
• Discrete-effect alleles influence genotypic effects.

Purpose of the Study:

• Investigate pleiotropic mutation and selection theory in large asexual populations.
• Examine discrete-effect alleles and their genotypic effects.
• Contrast findings with continuous-allele models.

Main Methods:

• Developed a theoretical model for pleiotropic mutation and selection.
• Analyzed discrete genotypic effects with parameter Delta (effect size).
• Considered stabilizing selection on Omega phenotypic characters.

Main Results:

• Discrete-effect models differ from continuous-effect models, lacking a singular equilibrium distribution.
• Equilibrium frequencies depend on Omega and Delta.
• For low Omega (1, 2), decreasing Delta increases polymorphism.
• For high Omega, decreasing Delta decreases polymorphism.

Conclusions:

• The relationship between mutation effect size and polymorphism is complex and depends on the number of selected traits.
• Discrete-effect models offer unique insights into evolutionary dynamics under pleiotropy.
• A connection to continuous trait models emerges as Delta approaches zero for large Omega.