Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The invasion ecology of Acacia pycnantha : a genetic approach
Thesis (PhD)--Stellenbosch University, 2013.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2013
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613949703225344 |
|---|---|
| access_status_str | Open Access |
| author | Ndlovu, Joice |
| author2 | Richardson, D. M. |
| author_browse | Ndlovu, Joice Richardson, D. M. |
| author_facet | Richardson, D. M. Ndlovu, Joice |
| author_sort | Ndlovu, Joice |
| collection | Thesis |
| description | Thesis (PhD)--Stellenbosch University, 2013. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019/10640 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:16.501Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019/10640 The invasion ecology of Acacia pycnantha : a genetic approach Ndlovu, Joice Richardson, D. M. Le Roux, J. J. Wilson, J. R. U. Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. Acacia pycnantha Invasion phylogeography Botany and Zoology Thesis (PhD)--Stellenbosch University, 2013. Australian Acacia species are an important group of invaders and are known to form dense monospecific cultures in invaded habitats. Despite the ecological and economic importance of invasive acacias, little is known about their invasive biology both from an ecological and evolutionary perspective. Molecular genetic methods have increasingly become important in identifying source populations for invasive species and determining the population genetic structure of these populations. This thesis applied molecular tools to understand the invasion ecology of Acacia pycnantha and its rhizobial symbionts as a model system of Australian Acacia introductions. Specific objectives were to: reconstruct the molecular phylogeny of invasive and native populations of populations of Acacia pycnantha and identify the native provenance of A. pycnantha; identify microsatellite markers for Acacia pycnantha and other invasive Australian acacias based on transferring microsatellite markers developed for A. mangium, A. saligna, Paraserianthes lophantha and universal chloroplast microsatellites developed from tobacco; assess the introduction dynamics of Acacia pycnantha in South Africa and identify the source populations in the species’ native range; and determine which nitrogen fixing symbionts nodulate A. pycnantha and determine whether A. pycnantha brought its symbionts along from its native range or acquired them in the invasive range. Nuclear and chloroplast DNA sequence data were used to reconstruct phylogeographic relationships between native and invasive A. pycnantha populations. The chloroplast phylogeny showed that Australian populations of A. pycnantha are geographically structured into two previously informally recognized lineages (representing wetland and dry land forms). Habitat fragmentation is probably the result of cycles of aridity and abundant rainfall during the Pleistocene0. The invasive population in Portugal was found to be the wetland form while South African populations were found to be predominantly wetland form although some dryland forms were identified. Thirty microsatellites out of the forty nine tested microsatellites successfully amplified across all species tested (A. implexa, A. longifolia, A. melanoxylon, A. pycnantha and A. podalyriifolia). High Transfer rates varied between 85% for microsatellites developed for A. mangium to 50% for those developed in A. saligna. Although transfer rates were high only twelve microsatellites (24%) out of the fifty tested were polymorphic while the chloroplast microsatellites showed no polymorphism. The low level of polymorphic loci calls for development of more microsatellites in this genus especially for species that have high commodity value. Nuclear microsatellites revealed three genetic groupings with substantial admixture in the native range (1. wetland Victoria and South Australia populations; 2. dryland Victoria and Flinders Range population; and 3. New South Wales). Admixture in the native range may have occurred as a result of reforestation exercises. Acacia pycnantha has been widely used in real forestation projects in Australia because of its fast growth rate and ease of germination. Admixed populations were most - likely introduced to South Africa thus establishment of A. pycnantha may have been facilitated by already admixed propagules in the invasive range. Extensive admixture in the native range made it difficult to identify source populations of invasive A. pycnantha found in South Africa. The rhizobial symbionts of A. pycnantha were identified, showing that this species utilizes a wider suite of symbionts in its invasive range than its native range and there is support for both the co-introduction and host jumping hypotheses. This creates substantial opportunities for horizontal gene transfer between previously allopatric bacterial lineages, with as yet unknown consequences for plant and bacterial invasions. Doctoral 2013-06-26T10:11:45Z 2014-01-21T09:25:34Z 2014-06-13T03:00:04Z 2013-12 Thesis http://hdl.handle.net/10019.1/10640 en_ZA application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Acacia pycnantha Invasion phylogeography Botany and Zoology Ndlovu, Joice The invasion ecology of Acacia pycnantha : a genetic approach |
| title | The invasion ecology of Acacia pycnantha : a genetic approach |
| title_full | The invasion ecology of Acacia pycnantha : a genetic approach |
| title_fullStr | The invasion ecology of Acacia pycnantha : a genetic approach |
| title_full_unstemmed | The invasion ecology of Acacia pycnantha : a genetic approach |
| title_short | The invasion ecology of Acacia pycnantha : a genetic approach |
| title_sort | invasion ecology of acacia pycnantha a genetic approach |
| topic | Acacia pycnantha Invasion phylogeography Botany and Zoology |
| url | http://hdl.handle.net/10019.1/10640 |
| work_keys_str_mv | AT ndlovujoice theinvasionecologyofacaciapycnanthaageneticapproach AT ndlovujoice invasionecologyofacaciapycnanthaageneticapproach |