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Genome-wide footprints in the carob tree (Ceratonia siliqua) unveil a new domestication pattern of fruit trees in the Mediterranean
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  • Alex Baumel,
  • Gonzalo Nieto Feliner,
  • Frederic Medail,
  • Stefano La Malfa,
  • Mario Diguardo,
  • Magda Boudagher-Kharrat,
  • Fatma Mirleau,
  • Valentine Frelon,
  • Lahcen Ouahmane,
  • Katia Diadema,
  • Hervé Sanguin,
  • Juan Viruel
Alex Baumel
Aix Marseille University

Corresponding Author:[email protected]

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Gonzalo Nieto Feliner
2. Real Jardín Botánico
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Frederic Medail
Aix Marseille University
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Stefano La Malfa
Università degli Studi di Catania
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Mario Diguardo
Università degli Studi di Catania
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Magda Boudagher-Kharrat
Laboratoire Caractérisation Génétique des Plantes, Faculté des sciences, Université Saint-Joseph, B.P. 11-514 Riad El Solh, Beyrouth 1107 2050, Liban
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Fatma Mirleau
Aix Marseille Univ, Univ Avignon, CNRS, IRD, IMBE, Marseille, France
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Valentine Frelon
Aix Marseille University
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Lahcen Ouahmane
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Katia Diadema
Conservatoire Botanique National Méditerranéen de Porquerolles
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Hervé Sanguin
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Juan Viruel
Royal Botanic Gardens Kew
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Abstract

Intense research efforts on phylogeography over the last two decades uncovered major biogeographical trends and renewed our understandings of plant domestication in the Mediterranean. We aim to investigate the evolutionary history and the origin of domestication of the carob tree that has been cultivated for millennia for food and fodder. We used >1000 microsatellite genotypes to identify carob evolutionary units (CEUs) based on genetic diversity structure and geography. We investigated genome-wide diversity and evolutionary patterns of the CEUs with 3557 SNPs generated by restriction-site associated DNA sequencing (RADseq). The 56 populations sampled across the Mediterranean basin, classified as natural, semi-natural or cultivated, were examined. Although, RADseq data are consistent with previous studies identifying a strong West-to-East genetic structure and considerable admixture in some geographic parts, we reconstructed a new phylogeographic scenario with two migration routes occurring from a single refugium likely located in South-Western Morocco. Our results do not favour the regionally bound or single origin of domestication. Indeed, our findings support a cultivation model of locally selected wild genotypes, albeit punctuated by long-distance westward dispersals of domesticated varieties by humans, concomitant with major cultural waves by Romans and Arabs in the regions of dispersal. Ex-situ efforts to preserve carob genetic resources should prioritize accessions from both western and eastern populations, with emphasis on the most differentiated CEUs situated in South-Western Morocco, South Spain and Eastern Mediterranean. Our study underscores the relevance of natural and seminatural habitats of Mediterranean forests and their refugia in the conservation efforts of tree crops.
21 Sep 2021Submitted to Molecular Ecology
22 Sep 2021Submission Checks Completed
22 Sep 2021Assigned to Editor
05 Oct 2021Reviewer(s) Assigned
13 Nov 2021Review(s) Completed, Editorial Evaluation Pending
06 Dec 2021Editorial Decision: Revise Minor
29 Jan 2022Review(s) Completed, Editorial Evaluation Pending
29 Jan 20221st Revision Received
30 Jan 2022Reviewer(s) Assigned
09 May 2022Editorial Decision: Revise Minor
13 May 2022Review(s) Completed, Editorial Evaluation Pending
13 May 20222nd Revision Received
08 Jun 2022Editorial Decision: Accept
Aug 2022Published in Molecular Ecology volume 31 issue 15 on pages 4095-4111. 10.1111/mec.16563