Demography and mating system shape the genome-wide impact of purifying selection in Arabis alpina

Benjamin Laenen, Andrew Tedder, Michael D. Nowak, Per Toräng, Jörg Wunder, Stefan Wötzel, Kim A. Steige, Yiannis Kourmpetis, Thomas Odong, Andreas D. Drouzas, Marco C.A.M. Bink, Jon Ågren*, George Coupland, Tanja Slotte

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)

Abstract

Plant mating systems have profound effects on levels and structuring of genetic variation and can affect the impact of natural selection. Although theory predicts that intermediate outcrossing rates may allow plants to prevent accumulation of deleterious alleles, few studies have empirically tested this prediction using genomic data. Here, we study the effect of mating system on purifying selection by conducting population-genomic analyses on whole-genome resequencing data from 38 European individuals of the arctic-alpine crucifer Arabis alpina. We find that outcrossing and mixed-mating populations maintain genetic diversity at similar levels, whereas highly self-fertilizing Scandinavian A. alpina show a strong reduction in genetic diversity, most likely as a result of a postglacial colonization bottleneck. We further find evidence for accumulation of genetic load in highly self-fertilizing populations, whereas the genome-wide impact of purifying selection does not differ greatly between mixed-mating and outcrossing populations. Our results demonstrate that intermediate levels of outcrossing may allow efficient selection against harmful alleles, whereas demographic effects can be important for relaxed purifying selection in highly selfing populations. Thus, mating system and demography shape the impact of purifying selection on genomic variation in A. alpina. These results are important for an improved understanding of the evolutionary consequences of mating system variation and the maintenance of mixed-mating strategies.
Original languageEnglish
Pages (from-to)816-821
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number4
DOIs
Publication statusPublished - 23 Jan 2018

Keywords

  • Bottleneck
  • Demographic history
  • Fitness effects
  • Genetic load
  • Self-fertilization

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    Laenen, B., Tedder, A., Nowak, M. D., Toräng, P., Wunder, J., Wötzel, S., Steige, K. A., Kourmpetis, Y., Odong, T., Drouzas, A. D., Bink, M. C. A. M., Ågren, J., Coupland, G., & Slotte, T. (2018). Demography and mating system shape the genome-wide impact of purifying selection in Arabis alpina. Proceedings of the National Academy of Sciences of the United States of America, 115(4), 816-821. https://doi.org/10.1073/pnas.1707492115