Background Selection Does Not Mimic the Patterns of Genetic Diversity Produced by Selective Sweeps

Area of Science:

• Evolutionary genetics
• Population genetics
• Genomics

Background:

• Natural selection shapes genomic diversity through positive and negative selection.
• Positive selection causes hitchhiking, reducing diversity around beneficial alleles.
• Negative selection causes background selection (BGS), also reducing linked variation.

Purpose of the Study:

• To investigate the similarity between background selection (BGS) and hitchhiking models.
• To determine if BGS creates false positives in hitchhiking detection.
• To assess BGS's impact on detecting positive selection across the genome.

Main Methods:

• Forward simulations of BGS under realistic genomic scenarios.
• Modeling locations of protein-coding and conserved noncoding DNA.
• Simulations based on human and Drosophila genomes with varied demographic histories.

Main Results:

• BGS rarely mimics hitchhiking patterns in realistic genomic arrangements.
• BGS does not substantially increase false positives for hitchhiking detection compared to neutrality.
• BGS was found to increase the false-negative rate for hitchhiking detection.

Conclusions:

• Hitchhiking detection methods do not need to account for BGS-induced false positives.
• BGS can mask true signals of positive selection, leading to false negatives.
• Further research is needed to understand BGS's impact on false-negative rates in selection scans.