Neutral genetic diversity during selective sweeps in non-recombining populations

Area of Science:

• Evolutionary genetics
• Population genetics

Background:

• Selective sweeps significantly alter genetic variation patterns at linked neutral sites.
• Understanding these patterns is crucial, especially in populations with limited or no genetic recombination, where theory is less developed.

Purpose of the Study:

• To develop a mathematical framework using diffusion theory to analyze the site frequency spectrum (SFS) during and after selective sweeps in populations with low recombination.
• To characterize the genomic signatures of beneficial mutations' fixation on linked neutral sites.

Main Methods:

• Utilized diffusion theory to model the site frequency spectrum (SFS).
• Analyzed the SFS immediately post- and during the fixation of beneficial mutations.
• Investigated the impact of selection strength and clonal interference on the SFS.

Main Results:

• Identified universal 1/x and 1/x^2 power-law decays in the SFS for single hard sweeps, independent of dominance and inbreeding.
• Demonstrated that the shift in the power-law dependence is inversely proportional to selection strength.
• Observed a U-shaped SFS under pervasive clonal interference, resembling the equilibrium SFS of selected sites.

Conclusions:

• The derived power-law relationships provide a theoretical basis for understanding genetic variation during selective sweeps in non-recombining populations.
• These findings are essential for developing statistical methods to infer the timing and strength of recent selective sweeps.
• The framework is applicable to asexual populations, recombination-poor genomic regions, and clonally propagating tumor populations.