Epistatic selection in a multi-locus Levene model and implications for linkage disequilibrium

Area of Science:

• Population genetics
• Evolutionary biology
• Genomics

Background:

• The Levene (1953) model is foundational for understanding population subdivision.
• Linkage disequilibrium (LD) is a key concept in population genetics, often used to infer selection.
• Epistasis, or gene-gene interaction, plays a crucial role in evolutionary processes.

Purpose of the Study:

• To analyze a multiple-locus extension of the Levene model.
• To investigate conditions for maintaining stable linkage disequilibrium with free recombination.
• To examine the dynamics of neutral loci influenced by selection on linked loci.

Main Methods:

• Mathematical modeling of population genetics.
• Analysis of a multiple-locus extension of the Levene model.
• Simulation of genetic locus dynamics under selection and recombination.

Main Results:

• Stable linkage disequilibrium can persist between two selected loci with free recombination if epistasis is strong.
• A third neutral locus's approach to linkage equilibrium is influenced by recombination rates and selection intensities.
• An embedding or hitchhiking effect prolongs disequilibrium for neutral loci linked to selected loci.

Conclusions:

• Strong selection on nearby loci, not necessarily the loci themselves, can cause significant linkage disequilibrium.
• Screening for linkage disequilibrium to identify functionally important genomic sites may be misleading.
• Epistatic interactions are critical for maintaining non-random associations between alleles at different loci.