Dynamics of genetic variability in two-locus models of stabilizing selection

Area of Science:

• Evolutionary genetics
• Quantitative genetics

Background:

• Phenotypic evolution is shaped by genetic variation, selection, and recombination.
• Understanding the interplay between these forces is crucial for predicting evolutionary trajectories.

Purpose of the Study:

• To investigate the dynamics of phenotypic evolution under stabilizing selection and recombination using a two-locus model.
• To analyze how linkage disequilibrium influences evolutionary constraints and equilibrium states.

Main Methods:

• A two-locus model with additive genetic contributions to the phenotype.
• Analysis of system dynamics on the genic variance (Vg) and linkage disequilibrium (CL) plane.
• Examination of the influence of selection strength, fitness function, and allelic effects.

Main Results:

• The interaction of selection and recombination imposes constraints on phenotypic evolution.
• System dynamics rapidly approach a line in the (Vg, CL) plane, followed by slow evolution along it.
• Linkage disequilibrium significantly affects dynamics when selection is not extremely weak relative to recombination.
• The model predicts stable polymorphic equilibria with positive linkage disequilibrium coexisting with monomorphic equilibria.

Conclusions:

• Stabilizing selection and recombination jointly dictate the pathways of phenotypic evolution.
• Linkage disequilibrium plays a critical role in shaping evolutionary dynamics and equilibrium outcomes.
• The findings are relevant to both natural and artificial selection experiments.