Rapid evolutionary divergence and ecotypic diversification of germination behavior in weedy rice populations

Authors

  • Han-Bing Xia,

    1. Department of Ecology and Evolutionary Biology, Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Ministry of Education, Handan Road 220, Shanghai 200433, China
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    • These authors contributed equally to this work.

  • Hui Xia,

    1. Department of Ecology and Evolutionary Biology, Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Ministry of Education, Handan Road 220, Shanghai 200433, China
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    • These authors contributed equally to this work.

  • Norman C. Ellstrand,

    1. Department of Botany and Plant Sciences, Center for Conservation Biology, and Center for Invasive Species Research, University of California, Riverside, CA 92521-0124, USA
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  • Chao Yang,

    1. Department of Ecology and Evolutionary Biology, Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Ministry of Education, Handan Road 220, Shanghai 200433, China
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  • Bao-Rong Lu

    1. Department of Ecology and Evolutionary Biology, Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Ministry of Education, Handan Road 220, Shanghai 200433, China
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Author for correspondence:
Bao-Rong Lu
Tel: +86 21 65643668
Email: brlu@fudan.edu.cn

Summary

  • Feral plants have evolved from well-studied crops, providing good systems for elucidation of how weediness evolves. As yet, they have been largely neglected for this purpose. The evolution of weediness can occur by simple back mutations in domestication genes (domestication in reverse). Whether the evolutionary steps to weediness always occur in reverse remains largely unknown.
  • We examined seed germination behavior in recently evolved weedy rice (Oryza sativa f. spontanea) populations and their coexisting cultivars in eastern and north-eastern China to address whether ‘dedomestication’ is the simple reverse of domestication.
  • We found that these weedy populations did not diverge from their progenitors by reverting to the pre-domestication trait of seed dormancy. Instead, they have evolved a novel mechanism to avoid growing in inappropriate environments via changes in critical temperature cues for seed germination. Furthermore, we found evidence for subsequent ecotypic divergence of these populations such that the critical temperature for germination correlates with the local habitat temperature at latitudinal gradients.
  • The origins of problematic plant species, weeds and invasives, have already been studied in detail. These plants can thus be used as systems for studying rapid evolution. To determine whether and how that evolution is adaptive, experiments such as those described here can be performed.

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