Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region

 

Show simple item record

dc.contributor.author Mann, Deborah Mary en_ZA
dc.date.accessioned 2016-01-02T04:51:38Z
dc.date.available 2016-01-02T04:51:38Z
dc.date.issued 1996 en_ZA
dc.identifier.citation Mann, D. 1996. Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/16136
dc.description Bibliography: pages 85-92. en_ZA
dc.description.abstract Patterns of speciation and potential evolutionary pressures and constraints were investigated in the genus Thamnochortus. Phenetic methods were used to define boundaries of species prior to cladistic analyses. Comparative techniques were employed to investigate aspects of dispersal biology and fire survival habit. Methods of historical biogeography were used to evaluate vicariance and dispersal hypotheses. The broader understanding of species evolution gained in such a comparative study is important in conservation of species or areas, forming a basis for further ecological and genetic predictions. The majority of Thamnochortus species have well-defined species limits; however, those of T. comptonii, T. platypteris and T. scabridus are more diffuse. For this species complex a matrix of 94 specimens, nine quantitative and sixteen qualitative characters was investigated, using cluster and ordination analyses, to define species boundaries. Thirty-four species of Thamnochortus, with three species of Rhodocoma as the outgroup, were used in the cladistic analysis. There were forty-three qualitative characters and ten quantitative characters. The number of species, height, reproductive output and geographic area were compared between sister lineages of seeding and resprouting species. In species classified as resprouters individuals survive fire by resprouting from the rhizome. In a post-fire environment seeding species recruit from seed and not by resprouting. Resprouters were significantly taller than seeders and covered a significantly larger distribution area. There was no significant difference in the amount of seed produced by seeding and resprouting lineages or in the geographic area covered by winged and keeled lineages. Correlated evolution tests indicated that wings of seeds evolved independently of the seeding condition, although the probability of wings evolving randomly was low. The evolution of keels was significantly associated with a switch to resprouting. There are few distinct ecological differences between the seeding and resprouting habits in soil type or rainfall; however, the inference is that resprouters do occupy habitats in higher rainfall areas than the sister seeders. Biogeographic analysis of species distributions, using cluster methods with a Jacard similarity coefficient, defined four phytogeographic areas which were considered to be areas of endemism. A concentric ring method recognised narrow areas of endemism and illustrated the overlap of species distributions between areas. The defined areas of endemism and similarity were used in general area cladograms to determine area relationships. The primary differentiations on the general area cladogram of areas of similarity distinguished a summer rainfall region (south coast) from a winter rainfall region (south Western Cape extending up the west coast). Within the winter rainfall region there is separation into a mesic (Cape Peninsula and south western mountain range) and an arid region (Cedarberg and Koue Bokkeveld). This analysis of Thamnochortus gives the first indication that the primary differentiation was between summer and winter rainfall, followed by the differentiation of the winter rainfall region into mesic and arid areas. Comparison within clades of distribution and habitat profiles indicated that, where distributions of closely related species overlap, there is niche differentiation in flowering time and substrate texture. Fire survival habit does not appear to have influenced speciation in Thamnochortus. There is, however, an evolutionary relationship between fire survival habit and female outer tepal specialization. Evidence from the general area cladogram indicates that speciation patterns in Thamnochortus may have been influenced by changes in rainfall in the Miocene. Habitat profiles of sister species indicate that alterations in flowering time and substrate texture are key factors in ecological differentiation of species. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Botany en_ZA
dc.title Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region en_ZA
dc.type Masters Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Biological Sciences en_ZA
dc.type.qualificationlevel Masters
dc.type.qualificationname MSc en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Mann, D. M. (1996). <i>Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/16136 en_ZA
dc.identifier.chicagocitation Mann, Deborah Mary. <i>"Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1996. http://hdl.handle.net/11427/16136 en_ZA
dc.identifier.vancouvercitation Mann DM. Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1996 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/16136 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Mann, Deborah Mary AB - Patterns of speciation and potential evolutionary pressures and constraints were investigated in the genus Thamnochortus. Phenetic methods were used to define boundaries of species prior to cladistic analyses. Comparative techniques were employed to investigate aspects of dispersal biology and fire survival habit. Methods of historical biogeography were used to evaluate vicariance and dispersal hypotheses. The broader understanding of species evolution gained in such a comparative study is important in conservation of species or areas, forming a basis for further ecological and genetic predictions. The majority of Thamnochortus species have well-defined species limits; however, those of T. comptonii, T. platypteris and T. scabridus are more diffuse. For this species complex a matrix of 94 specimens, nine quantitative and sixteen qualitative characters was investigated, using cluster and ordination analyses, to define species boundaries. Thirty-four species of Thamnochortus, with three species of Rhodocoma as the outgroup, were used in the cladistic analysis. There were forty-three qualitative characters and ten quantitative characters. The number of species, height, reproductive output and geographic area were compared between sister lineages of seeding and resprouting species. In species classified as resprouters individuals survive fire by resprouting from the rhizome. In a post-fire environment seeding species recruit from seed and not by resprouting. Resprouters were significantly taller than seeders and covered a significantly larger distribution area. There was no significant difference in the amount of seed produced by seeding and resprouting lineages or in the geographic area covered by winged and keeled lineages. Correlated evolution tests indicated that wings of seeds evolved independently of the seeding condition, although the probability of wings evolving randomly was low. The evolution of keels was significantly associated with a switch to resprouting. There are few distinct ecological differences between the seeding and resprouting habits in soil type or rainfall; however, the inference is that resprouters do occupy habitats in higher rainfall areas than the sister seeders. Biogeographic analysis of species distributions, using cluster methods with a Jacard similarity coefficient, defined four phytogeographic areas which were considered to be areas of endemism. A concentric ring method recognised narrow areas of endemism and illustrated the overlap of species distributions between areas. The defined areas of endemism and similarity were used in general area cladograms to determine area relationships. The primary differentiations on the general area cladogram of areas of similarity distinguished a summer rainfall region (south coast) from a winter rainfall region (south Western Cape extending up the west coast). Within the winter rainfall region there is separation into a mesic (Cape Peninsula and south western mountain range) and an arid region (Cedarberg and Koue Bokkeveld). This analysis of Thamnochortus gives the first indication that the primary differentiation was between summer and winter rainfall, followed by the differentiation of the winter rainfall region into mesic and arid areas. Comparison within clades of distribution and habitat profiles indicated that, where distributions of closely related species overlap, there is niche differentiation in flowering time and substrate texture. Fire survival habit does not appear to have influenced speciation in Thamnochortus. There is, however, an evolutionary relationship between fire survival habit and female outer tepal specialization. Evidence from the general area cladogram indicates that speciation patterns in Thamnochortus may have been influenced by changes in rainfall in the Miocene. Habitat profiles of sister species indicate that alterations in flowering time and substrate texture are key factors in ecological differentiation of species. DA - 1996 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1996 T1 - Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region TI - Evolutionary patterns in Thamnochortus (Restionaceae) : a study of specification in the Cape floristic region UR - http://hdl.handle.net/11427/16136 ER - en_ZA


Files in this item

This item appears in the following Collection(s)

Show simple item record