The effects of selfing on multi-step adaptation

Area of Science:

• Evolutionary Biology
• Population Genetics

Background:

• Macroevolutionary studies suggest self-compatible lineages face higher extinction rates than self-incompatible ones.
• A prevailing hypothesis links this to selfing hindering adaptation, particularly the fixation of beneficial mutations.

Purpose of the Study:

• To investigate the impact of selfing on multi-locus adaptation using population genetic models.
• To clarify how selfing affects the fixation probability of multiple adaptive alleles.

Main Methods:

• Population genetic modeling was employed.
• The study focused on adaptation requiring the fixation of two adaptive alleles.

Main Results:

• Intermediate selfing rates generally enhance adaptation by increasing the fixation probability of double-mutant haplotypes.
• In constant populations, selfing accelerates adaptation, even with dominant alleles.
• In declining populations, adaptation probability peaks at intermediate selfing rates, decreasing sharply as selfing approaches 1.0.

Conclusions:

• The findings contradict the hypothesis that selfing reduces adaptive potential, suggesting it can facilitate adaptation.
• These results may explain the prevalence of mixed-mating systems and the lack of detected selection relaxation in selfing species.