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Tackling convergent evolution, radiation and paraphyly: towards a modern classification of the giant genus Cyperus

Book Contribution - Book Abstract Conference Contribution

Originally, Cyperaceae species with flattened spikelets and distichous glumes were placed in the genus Cyperus. However, we now know that this morphology has independently evolved in other Cyperaceae genera, while reversal to spiral glumes has occurred in multiple Cyperus lineages. There has been disagreement whether to recognize Cyperus as a single large genus (c. 950 species) or to segregate it into c. 14 genera. Segregate genera in Cyperus s.l. have been delimited based on a single or a combination of characters, but molecular phylogenetic data demonstrated convergent evolution in several key characters. Using molecular phylogenetic data, we reconstructed a phylogenetic hypothesis of Cyperus s.l. The ancestor of Cyperus is a perennial with C3 photosynthesis, and spikelets with distichous glumes shedding individual fruits. Three segregate genera, differing by having spiral glumes (Kyllingiella, Oxycaryum) or spikelets dispersing as a single unit (Courtoisina), are derived from the C3 Cyperus s.s. ancestral morphology and were recently merged into Cyperus. A large (c. 760 species) monophyletic clade rapidly radiated from an ancestor, with an anthelate inflorescence and distichous glumes, which switched to C4 photosynthesis in the last 10 mya. Diversification has been accompanied by reductions leading to spikelets bearing single flowers (Alinula, Ascolepis, Lipocarpha, Volkiella), multiple origins of lateral nutlet orientation (Kyllinga, Pycreus, Queenslandiella), and evolution of sterile lower flowers (Remirea, Sphaerocyperus). To resolve the paraphyly of Cyperus and provide a classification reflecting evolution, we are revising generic delimitation, to recognize a single large genus Cyperus and delimit infrageneric taxa for clades supported by morphology.
Book: AMPEE1 : 1st annual meeting on plant ecology and evolution : abstracts
Number of pages: 1
Publication year:2012