Neutral genetic diversity during selective sweeps in nonrecombining populations

Area of Science:

• Population Genetics
• Evolutionary Biology
• Genomics

Background:

• Selective sweeps significantly influence genetic variation patterns.
• Existing research on selective sweeps is limited in low-recombination populations, particularly concerning dominance and inbreeding effects.

Purpose of the Study:

• To derive the full expression for the expected site frequency spectrum (SFS) at linked neutral sites during selective sweeps.
• To investigate the impact of dominance and inbreeding on SFS patterns.
• To characterize SFS changes under varying selection strengths and clonal interference.

Main Methods:

• Utilized diffusion theory to model the site frequency spectrum (SFS).
• Analyzed SFS patterns immediately post-sweep and during fixation of beneficial mutations.
• Investigated scenarios with single hard sweeps and pervasive clonal interference.

Main Results:

• Identified universal 1/x and 1/x^2 power laws for SFS in low and high derived allele frequencies, respectively, independent of dominance and inbreeding.
• Demonstrated that the shift frequency between power laws is inversely proportional to selection strength.
• Showed that pervasive clonal interference leads to a U-shaped SFS post-fixation.

Conclusions:

• The derived power laws provide a universal framework for understanding SFS dynamics during selective sweeps.
• Results are vital for developing statistical methods to infer selective sweep timing and strength in asexual and low-recombination populations.
• Findings have implications for studying tumor evolution and other clonal populations.