Selection and gene flow shape genomic islands that control floral guides
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...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 43; pp. 11006 - 11011 |
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Main Authors | , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
23.10.2018
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Subjects | |
Online Access | Get full text |
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Summary: | 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 tightly-linked 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. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Edited by Nils Chr. Stenseth, University of Oslo, Oslo, Norway, and approved September 12, 2018 (received for review February 6, 2018) 1Present address: Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom. Author contributions: H.T., A.W., D.L.F., N.H.B., and E.C. designed research; H.T., A.W., D.L.F., D.B., M.C., L.C., J.E., and A.B.R. performed research; H.T., A.W., D.L.F., D.B., M.C., L.C., M.B., C.A., M.L., Q.L., Y.X., and N.H.B. contributed new reagents/analytic tools; H.T., A.W., D.L.F., M.C., M.L., N.H.B., and E.C. analyzed data; and H.T., A.W., N.H.B., and E.C. wrote the paper. |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1801832115 |