A simple expression for the strength of selection on recombination generated by interference among mutations

Area of Science:

• Evolutionary biology
• Population genetics
• Molecular genetics

Background:

• The evolutionary maintenance of genetic recombination is often explained by its role in increasing natural selection efficiency.
• Theoretical work suggests recombination reshuffles genotypes, reducing interference among selected loci.
• Quantifying the selective advantage of increased chromosomal map length has been challenging.

Purpose of the Study:

• To derive a quantitative expression for the strength of selection on genes that modify genetic map length.
• To investigate the role of indirect selection in maintaining recombination.
• To assess the factors influencing the selective advantage of increased recombination.

Main Methods:

• Developed a theoretical model to derive a simple expression for selection strength.
• Analyzed selection on a modifier gene affecting genome-wide or chromosome-specific map length.
• Incorporated recurrent mutation into the model.

Main Results:

• Derived an expression showing indirect selection for recombination is proportional to effective population size, deleterious mutation rate, and chromosome map length.
• Found indirect selection is largely insensitive to fitness effects of deleterious alleles, epistasis, or recombination rate variation.
• Demonstrated that indirect selection can offset recombination costs with tight linkage but is weak in large, highly recombining populations.

Conclusions:

• Indirect selection, driven by interference among mutations, provides a quantitative explanation for recombination maintenance.
• The strength of this indirect selection depends on population size, mutation rate, and map length.
• While significant in certain conditions, indirect selection's effect is limited in large populations with high recombination rates.