THE SELECTION BARRIER BETWEEN POPULATIONS SUBJECT TO STABILIZING SELECTION

Area of Science:

• Population Genetics
• Evolutionary Biology
• Quantitative Genetics

Background:

• Gene flow between populations is a key evolutionary process.
• Understanding the factors influencing successful introgression is crucial for predicting evolutionary trajectories.

Purpose of the Study:

• To investigate the genetic factors that determine the success or failure of gene introgression from immigrant populations.
• To quantify the 'selection barrier' that impedes gene flow.

Main Methods:

• Modeling gene introgression with a focus on autosomal loci under weak selection.
• Considering additive allelic effects, dominance, and epistatic interactions.
• Quantifying the selection barrier using cumulative mean fitness ratios.

Main Results:

• Both monomorphic and polymorphic loci in the recipient population influence the selection barrier.
• For small genetic differences, monomorphic loci contribute positively to the barrier based on gene frequency differences.
• Polymorphic loci's contribution depends on linkage disequilibria and can either impede or facilitate introgression.

Conclusions:

• The genetic architecture of populations, including locus type and allele interactions, significantly impacts gene introgression.
• Polymorphic loci present a dynamic element, capable of either reinforcing or reducing the selection barrier.
• This study provides a framework for understanding the complex genetic forces governing gene flow.