Effect of beneficial sweeps and background selection on genetic diversity in changing environments

• Published in: Journal of theoretical biology 2023-04, Vol.562, p.111431-111431, Article 111431
• Main Author: Kaushik, Sachin
• Format: Article
• Language: English
• Subjects: Background selection; Conditional fixation time; Dominance; Genetic Variation; Genetics, Population; Heterozygosity; Heterozygote; Inbreeding; Models, Genetic; Population Density; Selection, Genetic; Selective sweeps; Site frequency spectrum
• ISSN: 0022-5193; 1095-8541
• DOI: 10.1016/j.jtbi.2023.111431

Neutral theory predicts that the genetic diversity within a population is proportional to the effective population size. In contrast, the observed genetic diversity for various species vary in a narrow range for several orders of magnitude change in the population sizes (Lewontin’s paradox). The selective sweeps and background selection, reduce the genetic variation at the linked neutral sites and have been studied considering the environment to be selectively constant. However, in a natural population, the selective environment varies with time. Here, we investigate the impact of selective sweeps and background selection on neutral genetic diversity when the selection coefficient changes periodically over time. The reduction in genetic variation due to selective sweeps is known to depend on the conditional fixation time. Here, we find that the effect of changing environment on conditional mean fixation time is most substantial for the randomly mating population than the inbreeding population with arbitrary inbreeding coefficient. We also study the effect of background selection on neutral sites when the selection coefficient of linked deleterious mutation change periodically in time. In the slowly changing environment, we find that neutral heterozygosity is significantly different, and the site frequency spectrum has a different shape than that in the static environment. •Natural environments are not static and change with time.•The reduction in genetic variation can be caused due to selective sweeps and background selection.•The beneficial sweeps results in changing environment are robust for the inbreeding population.•In a slowly changing environment, genetic diversity at linked neutral sites differs significantly from that in a static environment when the selected site contains deleterious mutations.