The yule approximation for the site frequency spectrum after a selective sweep.

Area of Science:

• Evolutionary biology
• Population genetics
• Genomics

Background:

• Identifying genomic regions under natural selection is a central question in evolutionary theory.
• Genetic hitchhiking, the reduction in sequence diversity around a beneficial allele due to linkage, is a key concept for detecting selection.
• The site frequency spectrum (SFS) is crucial for genome scans, reflecting variant frequencies within a population.

Purpose of the Study:

• To develop an accurate analytical prediction for the site frequency spectrum during a selective sweep.
• To improve upon existing models for understanding the impact of beneficial alleles on genetic variation.
• To provide a tool for more precise identification of selection targets in natural populations.

Main Methods:

• Utilized a marked Yule process, building on previous genetic hitchhiking research.
• Derived an analytical formula for the site frequency spectrum in a panmictic population at fixation of a beneficial mutation.
• Combined neutral evolution models with the effects of selective sweeps.

Main Results:

• The new formula accurately predicts the entire site frequency spectrum, outperforming previous methods.
• It correctly captures the elevation of both low- and high-frequency variants expected under strong selection.
• Demonstrated significantly improved accuracy for intermediate frequency variants compared to prior models.

Conclusions:

• The developed analytical prediction offers a more precise tool for studying genetic hitchhiking and selective sweeps.
• This improved SFS prediction enhances the ability to detect targets of natural selection in genomic data.
• The findings contribute to a deeper understanding of evolutionary processes shaping genome diversity.