Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach

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dc.contributor.advisorVerboom, George Anthonyen_ZA
dc.contributor.advisorCramer, Michael Den_ZA
dc.contributor.authorMoore, Timothy Een_ZA
dc.date.accessioned2017-11-16T07:10:00Z
dc.date.available2017-11-16T07:10:00Z
dc.date.issued2007en_ZA
dc.date.updated2017-02-02T13:42:08Z
dc.description.abstractThe adaptive significance of variety in leaf forms remains a mystery for many plant groups. This study aimed, using a combined experimental and comparative approach, to investigate the functional significance of leaf size and shape variation, as well as the patterns of leaf form variation in the genus Jamesbrittenia within the context of phylogenetic history. Leaf sizes 63-measured Jamesbrittenia varied between 0.006cm² (in J. microphylla) and 6.52cm² (in J. megaphylla). Correlations between leaf form and the environment suggest leaf size and shape are primarily adapted to water availability, with only leaf dimension being significantly associated with temperature, while, soil fertility shows no relationship with leaf size. Life history is important, however, as broader leaved annuals and species with shorter-lived leaves are associated with more arid habitats. Results of the experimental trials suggest that the primary function leaf size and shape reduction is to reduce water loss, and not to increase heat shedding. While larger leaves transpire more on a leaf-by-leaf basis, transpiration may be higher in broader leaved species at the whole-plant due to higher total plant transpiration. Thus, it is suggested a reduction in leaf size and dimension in Jamesbrittenia is an adaptation to more arid environments. Alternatively, a change in life history may enable a plant to escape harsh periods and capitalise on favourable times. A small- to intermediate-leaved, perennial ancestor is inferred for Jamesbrittenia, which was associated with arid regions in either the summer or winter rainfall regions of southern Africa. Shifts to an annual life history in Jamesbrittenia are associated with a shift to drier habitats, particularly in the arid winter rainfall region of South Africa.en_ZA
dc.identifier.apacitationMoore, T. E. (2007). <i>Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/26300en_ZA
dc.identifier.chicagocitationMoore, Timothy E. <i>"Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2007. http://hdl.handle.net/11427/26300en_ZA
dc.identifier.citationMoore, T. 2007. Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Moore, Timothy E AB - The adaptive significance of variety in leaf forms remains a mystery for many plant groups. This study aimed, using a combined experimental and comparative approach, to investigate the functional significance of leaf size and shape variation, as well as the patterns of leaf form variation in the genus Jamesbrittenia within the context of phylogenetic history. Leaf sizes 63-measured Jamesbrittenia varied between 0.006cm² (in J. microphylla) and 6.52cm² (in J. megaphylla). Correlations between leaf form and the environment suggest leaf size and shape are primarily adapted to water availability, with only leaf dimension being significantly associated with temperature, while, soil fertility shows no relationship with leaf size. Life history is important, however, as broader leaved annuals and species with shorter-lived leaves are associated with more arid habitats. Results of the experimental trials suggest that the primary function leaf size and shape reduction is to reduce water loss, and not to increase heat shedding. While larger leaves transpire more on a leaf-by-leaf basis, transpiration may be higher in broader leaved species at the whole-plant due to higher total plant transpiration. Thus, it is suggested a reduction in leaf size and dimension in Jamesbrittenia is an adaptation to more arid environments. Alternatively, a change in life history may enable a plant to escape harsh periods and capitalise on favourable times. A small- to intermediate-leaved, perennial ancestor is inferred for Jamesbrittenia, which was associated with arid regions in either the summer or winter rainfall regions of southern Africa. Shifts to an annual life history in Jamesbrittenia are associated with a shift to drier habitats, particularly in the arid winter rainfall region of South Africa. DA - 2007 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2007 T1 - Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach TI - Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach UR - http://hdl.handle.net/11427/26300 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/26300
dc.identifier.vancouvercitationMoore TE. Investigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approach. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2007 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/26300en_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.titleInvestigating the functional and adaptive significance of leaf size and shape variation in Jamesbrittenia (Scrophulariaceae (s.s). tribe Manulae) : an experimental and comparative approachen_ZA
dc.typeBachelor Thesis
dc.type.qualificationlevelHonours
dc.type.qualificationnameBSc (Hons)en_ZA
uct.type.filetype
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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