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- aggregation classification "C3".
- aggregation creator B75736.
- aggregation creator B75737.
- aggregation creator person.
- aggregation creator person.
- aggregation creator person.
- aggregation creator person.
- aggregation date "2011".
- aggregation format "application/pdf".
- aggregation hasFormat 3097167.bibtex.
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- aggregation hasFormat 3097167.doc.
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- aggregation hasFormat 3097167.txt.
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- aggregation hasFormat 3097167.yaml.
- aggregation language "eng".
- aggregation rights "I have transferred the copyright for this publication to the publisher".
- aggregation subject "Biology and Life Sciences".
- aggregation title "Radiations and paraphyly in Cyperus: challenging taxonomy of a giant genus".
- aggregation abstract "Calibrated family level phylogenies of Cyperaceae, revealed several origins of C4 photosynthesis as a response to changing climatic conditions during the late Eocene (estimates between 15 and 10 mja) and seems to coincide with the origin of the savanna biome in Eastern Africa. The ecological advantages of C4 photosynthesis lead to a major radiative burst in Cyperus, resulting in a subclade of approximately 800 species (including 9 specialised, segregate genera). Eastern Africa can be identified as the original center of diversification of Cyperus C4, from there several smaller radiations occurred within other tropical regions. Unfortunately the fast mutation rates during this radiation result in poorly resolved phylogenies even when using fast mutating chloroplast and nuclear markers and AFLP. In contrast Cyperus C3 lineages are well resolved and form a grade at the base of the Cyperus phylogeny. Among the segregate genera, only Kyllinga is well supported as monophyletic. Lipocarpha and Ascolepis tend to be sister taxa, however, with various levels of support. In Pycreus one large clade is well supported, however, as sister group to Cyperus laevigatus a species with dorsiventrally flattened dimerous pistils (Pycreus has laterally flattened pistils). The other sections are nested within the Cyperus C4 polytomy as are the other (mostly monotypic) segregates. The presence of such a major hard polytomy, containing many convergent morphologies, forms an obstruction in building a modern classification for Cyperus. Two opposed classification strategies are possible. Following a cladistics method all segregate lineages are to be sunken into Cyperus. Due to the high morphological diversity among its lineages, Cyperus would then only be circumscribed by cladistics arguments. The other strategy is to maintain well supported segregate lineages on the generic level and circumscribe Cyperus s.s. as a paraphyletic entity, which reflects the evolutionary processes of the group. In deciding which strategy is be the most convenient for application on Cyperus, morphological characters which have been used for generic delimitations need to be reevaluated. Shifts in seed dispersal units from nutlets to complete spikelets, in glume placements from distichous back to spiral and from trimerous to dorsiventrally flattened dimerous pistils, have been proven to have occurred several different times throughout both Cyperus C3 and C4 and seem less feasible for generic delimitations. Laterally compressed dimerous pistils had been considered to be more reliable characteristics. However, broad ontogenetic and floral vascularization studies show reorganizations of the pistil occur relatively easy throughout Cyperoideae. Even the origin of specialised inflorescences as pseudospikelets seems to be convergent for several different lineages as Lipocarpha, Ascolepis, Alinula, Volckiella and Kyllinga among others.".
- aggregation authorList BK192980.
- aggregation endPage "249".
- aggregation startPage "248".
- aggregation aggregates 3097176.
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