Stable equilibria at two loci in populations with large selfing rates

Area of Science:

• Population genetics
• Evolutionary biology
• Quantitative genetics

Background:

• Understanding genetic variation in populations is crucial for evolutionary studies.
• Selfing (inbreeding) significantly impacts genetic structure and diversity.
• Genetic disequilibrium (non-random association of alleles) is a key factor in population genetics.

Purpose of the Study:

• To analyze equilibrium structures in two-locus, two-allele models with high selfing rates.
• To investigate the conditions under which stable polymorphic equilibria exist.
• To evaluate the role of selection in generating observed disequilibria in selfing populations.

Main Methods:

• Employed perturbation techniques to analyze models.
• Focused on free recombination (r = 1/2) scenarios.
• Examined the influence of heterozygote fitness advantage and homozygote fitness differences.

Main Results:

• Stable equilibria with all alleles require specific fitness constraints if heterozygote advantage is below ~30%.
• Disequilibrium values (D) are limited by the outcrossing rate (t) under these conditions.
• High heterozygote advantage allows for stable equilibria with significant disequilibrium.

Conclusions:

• Selection alone is unlikely to explain the high levels of disequilibrium observed in selfing plant populations.
• The findings provide insights into the maintenance of genetic variation under selfing.
• Theoretical predictions are contrasted with empirical observations in natural populations.