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Do the six types of Sri Lanka's Oryza comprise a domesticated-weed-wild complex?
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  • Asanka Tennakoon,
  • Salinda Sandamal,
  • Song Ge,
  • Arthur Melo,
  • Yao Zhao,
  • Buddhi Marambe,
  • Norman Ellstrand,
  • Beng-Kah Song,
  • Disna Ratnasekera
Asanka Tennakoon
Eastern University Sri Lanka
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Salinda Sandamal
Institute of Botany Chinese Academy of Sciences
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Song Ge
Institute of Botany Chinese Academy of Sciences
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Arthur Melo
University of New Hampshire
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Yao Zhao
Nanchang University School of Life Sciences
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Buddhi Marambe
University of Peradeniya Faculty of Agriculture
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Norman Ellstrand
University of California Riverside
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Beng-Kah Song
Monash Univ Malaysia
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Disna Ratnasekera
University of Ruhuna

Corresponding Author:[email protected]

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Genetic studies of Domesticated-Weed-Wild Complexes (DWWC) have typically focused on one-way introgression of crop alleles into wild or weedy populations, with little consideration of the entire natural ecosystem. In Sri Lanka, DWWC is diverse, comprising six evolutionarily discrete groups in the genus Oryza. Using 33 neutral simple sequence repeat (SSR) loci, we characterized six Oryza groups to understand the genetic background and evolution of DWWC components. Our analysis found that Oryza groups have large population sizes and high inter-group long-term gene flows. Asymmetric gene flows were found between wild and weedy rice groups, but the rare alleles shared among DWWC components provide additional evidence for extensive and enduring exchange, highlighting the dynamic nature of this complex genetic admixture among different Oryza lineages. We found high genetic diversity at the population and species levels due to mixed DWWC components over the generations. Weedy rice types exhibit genetic incorporation through admixture from both crop and wild species, highlighting the multi-way genetic transfer in the evolution of weedy rice types. Our findings support the idea that the DWWC is an integrated complex in the Sri Lankan rice ecosystem and that its weedy rice has multiple origins, including de-domestication via feralization of cultivated rice, inter-varietal hybridization among distinct cultivated rice types, adaptation, and invasion of rice cultivation areas by wild Oryza species, and hybridization events between crop and wild rice populations. Abandoned rice domesticates can also evolve into weedy forms with less intimate human relationships and contaminate the rice ecosystem.
26 Sep 2023Submitted to Ecology and Evolution
27 Sep 2023Assigned to Editor
27 Sep 2023Submission Checks Completed
28 Sep 2023Reviewer(s) Assigned
23 Oct 2023Review(s) Completed, Editorial Evaluation Pending
27 Oct 2023Editorial Decision: Revise Minor