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Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae )
The mechanisms behind the high level of plant diversity and endemism observed in the Cape Floral Region (CFR) of South Africa have been the focus of many studies. Recently developed methods that employ DNA sequence data are making major contributions in reconstructing evolutionary histories of CFR s...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2019
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| _version_ | 1867613303331618817 |
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| access_status_str | Open Access |
| author | Chase, Rachel Renee |
| author2 | Hedderson, Terry A |
| author_browse | Chase, Rachel Renee Hedderson, Terry A |
| author_facet | Hedderson, Terry A Chase, Rachel Renee |
| author_sort | Chase, Rachel Renee |
| collection | Thesis |
| description | The mechanisms behind the high level of plant diversity and endemism observed in the Cape Floral Region (CFR) of South Africa have been the focus of many studies. Recently developed methods that employ DNA sequence data are making major contributions in reconstructing evolutionary histories of CFR species. Concurrently, palaeoenvironmental evidence is used increasingly to explain the impact of past climates on species ranges. This paper combines these two approaches by analysing the distribution of genetic diversity of the Afro-montane liverwort Jamesoniella colorata and associating its inferred evolutionary history with major palaeoclimatic trends in South Africa. Liverworts are generally well-suited for phylogeographical studies because they often have low dispersal rates, broad geographical ranges and long evolutionary persistence. In addition, the high among-population diversity observed in J colorata is conducive to the interpretation of significant historical events. The GIS-based bioclimatic envelope shows a strong correlation between potential habitat and the known distribution of J colorata and indicates that sampling in this study was sufficient to make accurate phylogeographical inferences. A combination of phylogeographical data and population genetics evidence suggests that populations of J colorata in the Western Cape Province have experienced range contractions into upper-montane refugia and range expansions into lower altitudes in response to warming and cooling climatic trends, respectively. These range shifts have probably taken place throughout the Quaternary glacial-interglacials cycles, , which are thought to have been influential in shaping modem patterns of diversity. In lV an attempt to assign approximate dates to the two expansion events inferred for J. colorata, an average chloroplast mutation rate was applied to the trnL-F cpDNA mismatch distribution. The results roughly place the expansions within the last glacial period, demonstrating the general accordance of the phylogeographical and palaeoclimatic data. The molecular work in this study also brought into question the taxonomic status of several specimens that showed distinctly divergent DNA sequences. Preliminary morphological inspection of the specimens revealed subtle but clear differences in leaf and stem anatomy that were once associated with J. oenops, a species synonymised with J. colorata in 1971. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/30658 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:59.204Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2019 |
| publishDateRange | 2019 |
| publishDateSort | 2019 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/30658 Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) Chase, Rachel Renee Hedderson, Terry A phylogeograph trnL-F chloroplast DNA Jamesoniella colorata liverwort South Africa The mechanisms behind the high level of plant diversity and endemism observed in the Cape Floral Region (CFR) of South Africa have been the focus of many studies. Recently developed methods that employ DNA sequence data are making major contributions in reconstructing evolutionary histories of CFR species. Concurrently, palaeoenvironmental evidence is used increasingly to explain the impact of past climates on species ranges. This paper combines these two approaches by analysing the distribution of genetic diversity of the Afro-montane liverwort Jamesoniella colorata and associating its inferred evolutionary history with major palaeoclimatic trends in South Africa. Liverworts are generally well-suited for phylogeographical studies because they often have low dispersal rates, broad geographical ranges and long evolutionary persistence. In addition, the high among-population diversity observed in J colorata is conducive to the interpretation of significant historical events. The GIS-based bioclimatic envelope shows a strong correlation between potential habitat and the known distribution of J colorata and indicates that sampling in this study was sufficient to make accurate phylogeographical inferences. A combination of phylogeographical data and population genetics evidence suggests that populations of J colorata in the Western Cape Province have experienced range contractions into upper-montane refugia and range expansions into lower altitudes in response to warming and cooling climatic trends, respectively. These range shifts have probably taken place throughout the Quaternary glacial-interglacials cycles, , which are thought to have been influential in shaping modem patterns of diversity. In lV an attempt to assign approximate dates to the two expansion events inferred for J. colorata, an average chloroplast mutation rate was applied to the trnL-F cpDNA mismatch distribution. The results roughly place the expansions within the last glacial period, demonstrating the general accordance of the phylogeographical and palaeoclimatic data. The molecular work in this study also brought into question the taxonomic status of several specimens that showed distinctly divergent DNA sequences. Preliminary morphological inspection of the specimens revealed subtle but clear differences in leaf and stem anatomy that were once associated with J. oenops, a species synonymised with J. colorata in 1971. 2019-12-02T13:37:14Z 2019-12-02T13:37:14Z 2004 2019-12-02T13:25:14Z Master Thesis Masters http://hdl.handle.net/11427/30658 eng application/pdf Department of Biological Sciences Faculty of Science |
| spellingShingle | phylogeograph trnL-F chloroplast DNA Jamesoniella colorata liverwort South Africa Chase, Rachel Renee Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) |
| thesis_degree_str | Master's |
| title | Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) |
| title_full | Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) |
| title_fullStr | Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) |
| title_full_unstemmed | Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) |
| title_short | Palaeoclimatic impacts on the phylogeography of an Afro-montane liverwort: Jamesoniella colorata (Lophoziaceae ) |
| title_sort | palaeoclimatic impacts on the phylogeography of an afro montane liverwort jamesoniella colorata lophoziaceae |
| topic | phylogeograph trnL-F chloroplast DNA Jamesoniella colorata liverwort South Africa |
| url | http://hdl.handle.net/11427/30658 |
| work_keys_str_mv | AT chaserachelrenee palaeoclimaticimpactsonthephylogeographyofanafromontaneliverwortjamesoniellacoloratalophoziaceae |