Watermelon origin solved with molecular phylogenetics including Linnaean material: another example of museomics

Area of Science:

• * Botany
• * Evolutionary Biology
• * Genetics

Background:

• * Type specimens are crucial for fixing species names, a practice mandatory since 1935.
• * Previous studies on the *Citrullus* genus have yielded contradictory results, potentially due to species misidentification.

Purpose of the Study:

• * To reconstruct the evolutionary history of the *Citrullus* genus using DNA sequencing.
• * To clarify the correct nomenclature for *Citrullus* species, including the watermelon.
• * To determine the origin and domestication history of cultivated melons.

Main Methods:

• * DNA sequencing of type specimens and recent collections of wild and cultivated *Citrullus*.
• * Phylogenetic analysis of nuclear and plastid DNA data.

Main Results:

• * The type specimen of *Citrullus lanatus* is not the common watermelon but a related species.
• * The closest relative of the watermelon is a West African species, not a South African one.
• * The genus *Citrullus* comprises seven species, not four as previously assumed.
• * Sweet watermelon likely originates from West Africa, with independent domestication of the South African citron melon.

Conclusions:

• * The study redefines the species boundaries and evolutionary relationships within the *Citrullus* genus.
• * Findings necessitate a revision of previous research on melon origins and domestication.
• * Correct identification of *Citrullus* species is essential for accurate crop origin studies.