Background Selection From Unlinked Sites Causes Nonindependent Evolution of Deleterious Mutations

Joseph Matheson, Joanna Masel

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Background selection describes the reduction in neutral diversity caused by selection against deleterious alleles at other loci. It is typically assumed that the purging of deleterious alleles affects linked neutral variants, and indeed simulations typically only treat a genomic window. However, background selection at unlinked loci also depresses neutral diversity. In agreement with previous analytical approximations, in our simulations of a human-like genome with a realistically high genome-wide deleterious mutation rate, the effects of unlinked background selection exceed those of linked background selection. Background selection reduces neutral genetic diversity by a factor that is independent of census population size. Outside of genic regions, the strength of background selection increases with the mean selection coefficient, contradicting the linked theory but in agreement with the unlinked theory. Neutral diversity within genic regions is fairly independent of the strength of selection. Deleterious genetic load among haploid individuals is underdispersed, indicating nonindependent evolution of deleterious mutations. Empirical evidence for underdispersion was previously interpreted as evidence for global epistasis, but we recover it from a non-epistatic model.

Original languageEnglish (US)
Article numberevae050
JournalGenome biology and evolution
Volume16
Issue number3
DOIs
StatePublished - Mar 1 2024
Externally publishedYes

Keywords

  • effective population size
  • expected heterozygosity
  • forward-time simulation
  • linkage disequilibrium
  • nearly neutral theory
  • population genetics

ASJC Scopus subject areas

  • General Medicine

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