- Title
- The invasion autecology of Iris pseudacorus L. (Iridaceae) in South Africa
- Creator
- Sandenbergh, Emma
- ThesisAdvisor
- Coetzee, Julie
- Subject
- Iris pseudacorus South Africa
- Subject
- Invasive plants South Africa
- Subject
- Aquatic weeds South Africa
- Subject
- Plant genetics South Africa
- Subject
- Freshwater ecology South Africa
- Subject
- Iris pseudacorus Geographical distribution
- Subject
- Phytogeography
- Date
- 2022-04-06
- Type
- Master's thesis
- Type
- text
- Identifier
- http://hdl.handle.net/10962/232272
- Identifier
- vital:49977
- Description
- Iris pseudacorus L. (Iridaceae) is an emergent aquatic macrophyte originating from Europe, north Africa, and western Asia, and is becoming an increasingly problematic invader in South Africa. By forming dense rhizomatic mats in the absence of natural enemies, I. pseudacorus outcompetes co-occurring indigenous biota, causing serious environmental and socioeconomic challenges. Iris pseudacorus is a declared invader in South Africa, Argentina, New Zealand, the United States of America, and Canada, but little information is known regarding the species’ invasive potential, particularly in the southern hemisphere, hindering the effectiveness of control efforts. This study addresses this knowledge gap in a South African context, providing valuable insight into the invasion autecology of I. pseudacorus in South Africa. For effective management and control of I. pseudacorus in South Africa and the global south, its distribution and invasive potential must be determined, and its population genetics understood. Hence, this study aimed to map the current confirmed distribution of I. pseudacorus populations in South Africa, investigating the relative abundance of I. pseudacorus individuals in each population, and comparing their sexual reproductive outputs. Moreover, this study assessed the competitive interactions between I. pseudacorus and co-occurring native species T. capensis, and examined the genetic diversity present between and within South African I. pseudacorus populations. Through field surveys, I. pseudacorus infestations were confirmed in eight of the country’s nine provinces, with the highest number of infestations recorded in the urban hubs, and greatest population abundances reported in the warmer, wetter regions of South Africa. These surveys indicated that South African I. pseudacorus populations have enhanced their sexual reproductive output relative to native range populations, and a germination rate of ~ 83 % was determined in the laboratory. The results of a common garden competition experiment indicated that T. capensis may be a superior competitor over I. pseudacorus, but this was not supported by field observations, and may be a result of the short duration of the experiment. Using inter-simple sequence repeats (ISSRs), high genetic diversity was observed within and between populations of I. pseudacorus, indicating the employment of sexual reproductive strategies, and providing evidence for gene-flow between and within populations. Moreover, a weak negative correlation was observed between geographic distance and genetic similarity, ii indicating a largely anthropogenic spread of I. pseudacorus, and suggesting the occurrence of fewer founding events than reported in the United States. This study provides useful insight into the invasion autecology of I. pseudacorus in South Africa, contributing to the ongoing research surrounding I. pseudacorus invasions worldwide, particularly in the southern hemisphere. These results contribute to the development of appropriate adaptive and integrated management strategies to control I. pseudacorus invasions in South Africa, and should be implemented before South African I. pseudacorus infestations reach the severity observed elsewhere.
- Description
- Thesis (MSc) -- Faculty of Science, Botany, 2022
- Format
- computer, online resource, application/pdf, 1 online resource (101 pages), pdf
- Publisher
- Rhodes University, Faculty of Science, Botany
- Language
- English
- Rights
- Sandenbergh, Emma
- Rights
- Use of this resource is governed by the terms and conditions of the Creative Commons "Attribution-NonCommercial-ShareAlike" License (http://creativecommons.org/licenses/by-nc-sa/2.0/)
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details | SOURCE1 | SANDENBERGH-MSC-TR22-29.pdf | 2 MB | Adobe Acrobat PDF | View Details |