University of Oulu

Mattila TM, Laenen B, Horvath R, Hämälä T, Savolainen O, Slotte T. Impact of demography on linked selection in two outcrossing Brassicaceae species. Ecol Evol. 2019;9:9532–9545.

Impact of demography on linked selection in two outcrossing Brassicaceae species

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Author: Mattila, Tiina M.1; Laenen, Benjamin2; Horvath, Robert2;
Organizations: 1Department of Ecology and Genetics, University of Oulu, Oulu, Finland
2Science for Life Laboratory, Department of Ecology, Environment, and Plant Sciences, Stockholm University, Stockholm, Sweden
3Biocenter Oulu, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: John Wiley & Sons, 2019
Publish Date: 2019-10-21


Genetic diversity is shaped by mutation, genetic drift, gene flow, recombination, and selection. The dynamics and interactions of these forces shape genetic diversity across different parts of the genome, between populations and species. Here, we have studied the effects of linked selection on nucleotide diversity in outcrossing populations of two Brassicaceae species, Arabidopsis lyrate and Capsella grandiflora, with contrasting demographic history. In agreement with previous estimates, we found evidence for a modest population size expansion thousands of generations ago, as well as efficient purifying selection in C. grandiflora. In contrast, the A. lyrate population exhibited evidence for very recent strong population size decline and weaker efficacy of purifying selection. Using multiple regression analyses with recombination rate and other genomic covariates as explanatory variables, we can explain 47% of the variance in neutral diversity in the C. grandiflora population, while in the A. lyrate population, only 11% of the variance was explained by the model. Recombination rate had a significant positive effect on neutral diversity in both species, suggesting that selection at linked sites has an effect on patterns of neutral variation. In line with this finding, we also found reduced neutral diversity in the vicinity of genes in the C. grandiflora population. However, in A. lyrate no such reduction in diversity was evident, a finding that is consistent with expectations of the impact of a recent bottleneck on patterns of neutral diversity near genes. This study thus empirically demonstrates how differences in demographic history modulate the impact of selection at linked sites in natural populations.

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Series: Ecology and evolution
ISSN: 2045-7758
ISSN-E: 2045-7758
ISSN-L: 2045-7758
Volume: 9
Issue: 17
Pages: 9532 - 9545
DOI: 10.1002/ece3.5463
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: This work has been supported by the Emil Aaltonen Foundation and the Finnish Population Genetics Doctoral Programme to TMM. The University of Oulu Graduate School (UniOGS) and Oulun Luonnonystäväin Yhdistys are acknowledged for travel grants to TMM. TS acknowledges funding from the Swedish Research Council. This work was supported by the Science for Life Laboratory, Swedish Biodiversity Program. The Swedish Biodiversity Program has been made available by support from the Knut and Alice Wallenberg Foundation. BL was funded by a SciLifeLab grant to TS.
Copyright information: © 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.