C3 CYPERUS - EXPLORING GIANT GENERA & THEIR SATELLITES

February 2007 to June 2011, PhD thesis

The Cyperus clade (Cyperoideae, Cypereae) includes ca. 950 species of grass-like plants with complex inflorescences. Species of the Cyperus clade either use C3 photosynthesis (linked with eucyperoid anatomy) (C3 Cyperus), or C4 photosynthesis (linked with chlorocyperoid anatomy) (C4 Cyperus). This PhD project focuses on C3 Cyperus. The aim is to create a detailed molecular phylogenetic hypothesis of C3 Cyperus in order to establish (1) how C3 Cyperus relates to C4 Cyperus, and (2) how the different C3 Cyperus taxa relate to one another. In this study, both nuclear ribosomal (ETS1f) and plastid (rpl32-trnL and trnH-psbA) DNA markers are used to create a molecular phylogenetic hypothesis. Molecular phylogenetic data are combined with carbon isotope analysis (δ13C), morphology, embryography, floral and spikelet ontogeny, anatomy and biogeography. In our opinion, the Cyperus clade includes two genera Androtrichum and Cyperus (s.l.). C3 Cyperus forms a grade at the basis of Cyperus (C3 photosynthesis is the plesiomorphic state for the Cyperus clade), in which a well-supported monophyletic clade is nested encompassing the C4 Cyperus species. C3 Cyperus (ca. 190 spp.) is less species rich and less diverse than C4 Cyperus (ca. 760 spp.). The small genera Courtoisina and Oxycaryum are included in C3 Cyperus as new sections, which also contain Cyperus s.s. species with intermediate morphologies. The small genus Kyllingiella is included in the existing C3 Cyperus section Leucocephali. These taxa were previously recognised at generic level due to specific characteristics which differentiate them from Cyperus s.s. The currently recognised sections in C3 Cyperus are generally well-supported in the molecular phylogeny, however, ‘Cyperus section Glutinosi’ and ‘C. section Dichostylis’ sensu Kükenthal are heterogeneous as they include both C3 and C4 species. We aim to provide a revision and a preliminary new classification of C3 Cyperus with clearly characterised monophyletic groups.
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Relevant publications:
Larridon I, Reynders M, Huygh W, Bauters K, Vrijdaghs A, Leroux O, Muasya AM, Simpson DA, Goetghebeur P. (2011) Taxonomic changes in C3 Cyperus (Cyperaceae) supported by molecular phylogenetic data, morphology, embryology, ontogeny and anatomy. Plant Ecology and Evolution 144 (3): 327-356.
Larridon I, Reynders M, Huygh W, Bauters K, Van de Putte K, Muasya AM, Boeckx P, Simpson DA, Vrijdaghs A, Goetghebeur P. (2011) Affinities in C3 Cyperus lineages (Cyperaceae) revealed using molecular phylogenetic data and carbon isotope analysis. Botanical Journal of the Linnean Society 167: 19-46.
Larridon I, Reynders M, Huygh W, Muasya AM, Govaerts R, Simpson DA, Goetghebeur P. (2011) Nomenclature and typification of names of genera and subdivisions of genera in Cypereae (Cyperaceae): 2. Names of subdivisions of Cyperus. Taxon 60 (3): 868-884.
Gautier L, Nusbaumer L, Larridon I, Callmander MW. (2010) Distribution of Cyperus chamaecephalus Cherm., a forest undergrowth species with inconspicuous inflorescences. Candollea 65 (2): 364-367.
Larridon I, Reynders M, Goetghebeur P. (2008) Cyperus limiticola, a new name for a Madagascan Cyperus (Cyperaceae). Novon: 18 (2): 187-188.
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Researcher:
Prof. Dr. Isabel Larridon

Supervisors:
Prof. Dr. Paul Goetghebeur
Prof. Dr. Paul De Vos - Ghent University, Department of Biochemistry and Microbiology

Members of the doctoral examination committee:
Prof. Dr. Dominique Adriaens - Ghent University, Department of Biology, Research Group Evolutionary Morphology of Vertebrates
Prof. Dr. Mieke Verbeken - Ghent University, Department of Biology, Research Group Mycology
Prof. Dr. A. Muthama Muasya - University of Cape Town, South Africa
Prof. Dr. David A. Simpson - Royal Botanic Gardens, Kew, UK
Dr. Alexander Vrijdaghs - KULEUVEN, Belgium

Funding:
BOF (Special Research Fund) PhD research grant (n° BO7418)

Research Foundation Flanders international mobility grants

King Léopold III Foundation for the Exploration and Protection of Nature (international mobility - Kenya)

Ghent University
Department of Biology
Research Group Spermatophytes
Ghent University Botanical Garden