Loci under balancing selection facilitate the emergence of pseudo-overdominance and recombination suppression

Balancing-selection loci in individual-based simulations ease the establishment of pseudo-overdominance, especially in low-recombination, high–partially recessive deleterious load regions flanking the locus.

• Why it matters: Recombination suppression commonly flanks balancing-selection loci, but the evolutionary mechanism linking balancing selection to suppressed recombination is unclear.
• What they did: Simulations show that overdominant loci maintain partially recessive deleterious mutations and linkage disequilibrium in flanking regions, enabling complementary haplotypes that are selected against in homozygous and recombinant offspring.
• The result: Pseudo-overdominance can then favor recombination suppression around permanently heterozygous loci, and selfing generally hinders establishment but can facilitate it around a permanently heterozygous locus.