Systematics Section / ASPT
Ghebretinsae, Amanuel , Barber, Janet C. .
Phylogenetic Relationships of Cucumis and Cucumella (Cucurbitaceae): Evidence from Nuclear and Chloroplast DNA Sequence Data.
Cucumis is a well-known member of the Cucurbitaceae tribe Melothrieae and comprises ca. 34 species including several of major economic importance (e.g. cucumbers, melons). Two subgenera are recognized, differing in geographical distribution and chromosome number. Subgenus Melo (30 spp., n = 12) is native to Africa whereas subgenus Cucumis (4 spp., n = 7) is indigenous to Asia. However, the recent discovery of an Asian species (C. hystrix) with basic chromosome number n = 12 has challenged the classification, suggesting a possible bridge between the subgenera. Furthermore, derivation of the subgenera is under debate. The taxonomic relationship of species of Cucumis and the closely related genus Cucumella is also poorly understood. Cucumella comprises 11 species with a distribution that mirrors that of Cucumis. Long considered synonymous, Cucumella was placed as a distinct genus in 1990. Morphologically, Cucumella is separated from Cucumis by a single morphological character: anther shape. A number of molecular studies at various taxonomic levels have included species of Cucumis, but none have addressed generic-wide phylogenetic relationships and none have included any species of Cucumella. In the current study, sequences of nuclear ribosomal DNA from the internal transcribed spacer (ITS) region will be used to extend upon previous studies. Appropriate chloroplast markers will be included to confidently determine the origin of Cucumis species, investigate the intra- and inter-generic relationships in Cucumis and Cucumella, and infer evolution of anther shape.
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1 - Saint Louis University, Department of Biology, 3507 Laclede Avenue, St Louis, Missouri, 63103-2010, USA
Presentation Type: Poster
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM