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Connecting the sun to flowering in sunflower adaptation

Authors

  • BENJAMIN K. BLACKMAN,

    1. Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
    2. Department of Biology, Duke University, Box 90338, Durham, NC 27701, USA
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  • SCOTT D. MICHAELS,

    1. Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
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  • LOREN H. RIESEBERG

    1. Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
    2. Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4
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Benjamin K. Blackman, Fax: (919) 660 7293; E-mail: bkb7@duke.edu

Abstract

Species living in seasonal environments often adaptively time their reproduction in response to photoperiod cues. We characterized the expression of genes in the flowering-time regulatory network across wild populations of the common sunflower, Helianthus annuus, that we found to be adaptively differentiated for photoperiod response. The observed clinal variation was associated with changes at multiple hierarchical levels in multiple pathways. Paralogue-specific changes in FT homologue expression and tissue-specific changes in SOC1 homologue expression were associated with loss and reversal of plasticity, respectively, suggesting that redundancy and modularity are gene network characteristics easily exploited by natural selection to produce evolutionary innovation. Distinct genetic mechanisms contribute to convergent evolution of photoperiod responses within sunflower, suggesting regulatory network architecture does not impose strong constraints on the evolution of phenotypic plasticity.

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