Adaptive gene flow is a consequential phenomenon across all kingdoms. Although recognition is increasing, there is no study showing that bidirectional gene flow mediates adaptation at loci that manage core processes. We previously discovered concerted molecular changes among interacting members of the meiotic machinery controlling crossover number upon adaptation to whole-genome duplication (WGD) in Arabidopsis arenosa. Here we conduct a population genomic study to test the hypothesis that adaptation to WGD has been mediated by adaptive gene flow between A. arenosa and A. lyrata. We find that A. lyrata underwent WGD more recently than A. arenosa, suggesting that pre-adapted alleles have rescued nascent A. lyrata, but we also detect gene flow in the opposite direction at functionally interacting loci under the most extreme levels of selection. These data indicate that bidirectional gene flow allowed for survival after WGD, and that the merger of these species is greater than the sum of their parts.
Bibliographical noteFunding Information:
This work was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme [grant number ERC-StG 679056 HOTSPOT], via a grant to L.Y.; and the Biotechnology and Biological Sciences Research Council [grant number BB/P013511/1], via a grant to the John Innes Centre (L.Y.). JDH was funded via BBSRC New Investigator grant BB/M01973X/1. Additional support was provided by the Charles University Grant Agency (GAUK 228716 to M.B.). Computational resources were partly provided by the CESNET LM2015042 and the CERIT Scientific Cloud LM2015085, under the programme Projects of Large Research, Development, and Innovations Infrastructures. The authors thank Jeff Doyle for critical reading of the manuscript.
© 2019, The Author(s).