Selection and gene flow shape genomic islands that control floral guides Journal Article


Author(s): Tavares H; Whitley, A; Field, D. L.; Bradley D; Couchman M; Copsey L; Elleouet, J; Burrus, M; Andalo, C; Li M; Li Q; Xue Y; Rebocho, A B; Barton, Nicholas H; Coen E
Article Title: Selection and gene flow shape genomic islands that control floral guides
Affiliation IST Austria
Abstract: Genomes of closely-related species or populations often display localized regions of enhanced relative sequence divergence, termed genomic islands. It has been proposed that these islands arise through selective sweeps and/or barriers to gene flow. Here, we genetically dissect a genomic island that controls flower color pattern differences between two subspecies of Antirrhinum majus, A.m.striatum and A.m.pseudomajus, and relate it to clinal variation across a natural hybrid zone. We show that selective sweeps likely raised relative divergence at two tightly-linked MYB-like transcription factors, leading to distinct flower patterns in the two subspecies. The two patterns provide alternate floral guides and create a strong barrier to gene flow where populations come into contact. This barrier affects the selected flower color genes and tightlylinked loci, but does not extend outside of this domain, allowing gene flow to lower relative divergence for the rest of the chromosome. Thus, both selective sweeps and barriers to gene flow play a role in shaping genomic islands: sweeps cause elevation in relative divergence, while heterogeneous gene flow flattens the surrounding “sea,” making the island of divergence stand out. By showing how selective sweeps establish alternative adaptive phenotypes that lead to barriers to gene flow, our study sheds light on possible mechanisms leading to reproductive isolation and speciation.
Journal Title: PNAS
Volume: 115
Issue 43
ISSN: 1091-6490
Publisher: National Academy of Sciences  
Date Published: 2018-10-23
Start Page: 11006
End Page: 11011
Copyright Statement: CC BY NC ND 4.0
DOI: 10.1073/pnas.1801832115
Open access: yes (OA journal)
IST Austria Authors
  1. Nick Barton
    252 Barton
  2. David Field
    8 Field
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