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Georeferenced phylogenetic analysis of a global collection of wild and cultivated Citrullus species
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  • Enoch Gbenato Achigan-Dako,
  • Herve Degbey,
  • Iago Hale,
  • Frank Blattner
Enoch Gbenato Achigan-Dako
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Herve Degbey
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Iago Hale
University of New Hampshire, Durham, New Hampshire, USA
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Frank Blattner
Leibniz Institute of Plant Genetics and Crop Research (IPK)
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Abstract

The geographical origin of watermelon (Citrullus lanatus) remains debated. While a first hypothesis suggests the center of origin to be west Africa, where a sister endemic species C. mucosospermus thrives, a second hypothesis suggests north-eastern Africa where the white-fleshed Sudanese Kordophan melon is cultivated. In this study, we infer biogeographical and haplotype genealogy for C. lanatus, C. mucosospermus, C. amarus, and C. colocynthis using non-coding cpDNA sequences (trnT-trnL and ndhF-rpl32 regions) from a global collection of 135 accessions. In total, we identified 38 haplotypes in C. lanatus, C. mucosospermus, C. amarus, and C. colocynthis; of these, 21 were found in Africa and 17 appear endemic to the continent. The least diverse species was C. mucosospermus (5 haplotypes) and the most diverse was C. colocynthis (16 haplotypes). Some haplotypes of C. mucosospermus were nearly exclusive to West-Africa, and C. lanatus and C. mucosospermus shared haplotypes that were distinct from those of both C. amarus and C. colocynthis. The results support previous findings C. mucosospermus to be the closest relative to C. lanatus (including subsp. cordophanus). West Africa, as a center of endemism of C. mucosospermus, is an area of interest in the search of the origin of C. lanatus. This calls for further historical and phylogeographical investigations and wider collection of samples in West and North-East Africa.

Peer review status:ACCEPTED

15 Aug 2020Submitted to Ecology and Evolution
17 Aug 2020Assigned to Editor
17 Aug 2020Submission Checks Completed
29 Dec 2020Review(s) Completed, Editorial Evaluation Pending
29 Dec 2020Editorial Decision: Accept