Charles Heiser Special Contributed Paper Session
Filipowicz, Natalia , Schaefer, Hanno , Renner, Susanne .
How many species of Luffa (Cucurbitaceae) are there? Relationships in a small genus of worldwide distribution.
Among the economic plants that interested Charles Heiser was Luffa, a pantropical group of annual trailing vines with a suspected 5-6 species (Heiser and Schilling 1988; Heiser et al. 1988). Luffa aegyptiaca (incl. L. cylindrica) and L. acutangula are widely cultivated crops in tropical Asia, and the fruit fibers of the first are used as sponge. As discussed by Heiser, species circumscriptions have been controversial, partly because of naturalized escapes from cultivation. We have studied species circumscriptions and relationships based on combined nuclear and plastid DNA sequences for 50 accessions representing the entire geographic range of loofahs. Study of morphological traits is ongoing. In agreement with Heiser's findings, L. quinquefida from Mexico to Nicaragua is distinct from South American L. operculata and L. sepium. The neotropical species form a clade derived from a paraphyletic Indian/African/Australian group. Sister to all other loofahs is L. acutangula, from India and Yemen; followed by L. aegyptiaca from India, Indochina, and tropical Australia; L. echinata from India to Egypt; and L. graveolens from northern India, Nepal, Bangladesh, and Burma. The Australian material hereto attributed to the latter species represents a new species. Luffa thus comprises eight species, and a family-wide phylogeny suggests that Trichosanthes, an Asian genus of 100 species, is the sister clade of Luffa. The low genetic variability among accessions from vastly distant geographic regions suggests a young age of the species, but the stem age of the genus may be 35 (41-31) million years old (Schaefer et al. 2009).
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1 - University of Munich (LMU), Department of Biology, Systematic Botany and Mycology, Menzinger Str. 67, Munich, 80638, Germany
2 - Harvard University, Department of Organismic and Evolutionary Biology, 22 Divinity Avenue, Cambridge, MA, 02138, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Lindell D/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 8:30 AM