Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb

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dc.contributor.advisorLinder, Peteren_ZA
dc.contributor.advisorStock, WDen_ZA
dc.contributor.authorVerboom, George Anthonyen_ZA
dc.date.accessioned2014-08-13T14:10:26Z
dc.date.available2014-08-13T14:10:26Z
dc.date.issued2000en_ZA
dc.descriptionIncludes bibliography.en_ZA
dc.description.abstractThis thesis uses phylogenetic and comparative data to test an hypothesis of adaptive radiation in the Cape grass genus Ehrharta Thunb. sensu stricto. Morphological data and sequence data from two noncoding regions of DNA (lTS1 and trnL-F) are used to produce a phylogenetic hypothesis for the tribe Ehrharteae. Combined analysis of these data sets resolves four principal clades that approximate the genera Ehrharta s. s., Micro/aena, Tetrarrhena and Zotovia and this result thus supports a four-genus classification. Poor resolution and a reduction in branch length at the base of a clade nested within Ehrharta s. s. suggests past radiation. Parsimony-based reconstruction of ancestral habitats and growth form attributes indicates that such radiation is associated with a historical transition to seasonallydrier but more fertile habitats, and the coincident or subsequent evolution of several growth form novelties (e.g. buried and swollen culm bases and annualness). These traits are interpreted to reflect divergent strategies for surviving seasonal drought (Le. via seed or storage). Much higher transpiration rates in summer-deciduous leaves than in perennating culms of two species suggest that the evolution of summer-deciduous foliage was important in the occupation of seasonally-arid habitats. Controlled growth experiments are used to test the hypothesis that divergence in persistence traits is associated with differences in seedling biomass allocation and relative growth rate (RGR). Ehrharta s. s. shows wide variation in seedling RGR and regressions based on phylogenetically independent contrasts suggest that differences are better explained by early biomass allocation than leaf area indices. Species with a high allocation to leaves grow faster and flower sooner, so these traits are typical of seeding species.en_ZA
dc.identifier.apacitationVerboom, G. A. (2000). <i>Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/6196en_ZA
dc.identifier.chicagocitationVerboom, George Anthony. <i>"Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2000. http://hdl.handle.net/11427/6196en_ZA
dc.identifier.citationVerboom, G. 2000. Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Verboom, George Anthony AB - This thesis uses phylogenetic and comparative data to test an hypothesis of adaptive radiation in the Cape grass genus Ehrharta Thunb. sensu stricto. Morphological data and sequence data from two noncoding regions of DNA (lTS1 and trnL-F) are used to produce a phylogenetic hypothesis for the tribe Ehrharteae. Combined analysis of these data sets resolves four principal clades that approximate the genera Ehrharta s. s., Micro/aena, Tetrarrhena and Zotovia and this result thus supports a four-genus classification. Poor resolution and a reduction in branch length at the base of a clade nested within Ehrharta s. s. suggests past radiation. Parsimony-based reconstruction of ancestral habitats and growth form attributes indicates that such radiation is associated with a historical transition to seasonallydrier but more fertile habitats, and the coincident or subsequent evolution of several growth form novelties (e.g. buried and swollen culm bases and annualness). These traits are interpreted to reflect divergent strategies for surviving seasonal drought (Le. via seed or storage). Much higher transpiration rates in summer-deciduous leaves than in perennating culms of two species suggest that the evolution of summer-deciduous foliage was important in the occupation of seasonally-arid habitats. Controlled growth experiments are used to test the hypothesis that divergence in persistence traits is associated with differences in seedling biomass allocation and relative growth rate (RGR). Ehrharta s. s. shows wide variation in seedling RGR and regressions based on phylogenetically independent contrasts suggest that differences are better explained by early biomass allocation than leaf area indices. Species with a high allocation to leaves grow faster and flower sooner, so these traits are typical of seeding species. DA - 2000 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2000 T1 - Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb TI - Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb UR - http://hdl.handle.net/11427/6196 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/6196
dc.identifier.vancouvercitationVerboom GA. Phylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunb. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2000 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/6196en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherBotanyen_ZA
dc.titlePhylogenetic and functional growth from diversification in the Cape grass genus Ehrharta Thunben_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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