Philosophiae Doctor - PhD (Biodiversity and Conservation Biology)

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How do teachers and learners navigate the terrain of ecology and what are the associated conceptual understandings?
(University of the Western Cape, 2011) Raitt, Rosemary Ruth; Holtman, L.B.
This thesis relates the teaching of ecology in schools to the requirements of the National Curriculum Statements, Grades R-9 and Grades 10-12, for Natural and Life Sciences. It examines the conceptual understanding of the learners to determine their level of bioliteracy. The effectiveness of various teaching strategies in enhancing bioliteracy is considered. The study was a case study involving classroom observations of Grades 4 to 7 at a primary school and Grades 8 to 11 at a high school in the Western Cape of South Africa, and the administration of a misconceptions questionnaire to learners in Grades 8 to 11. The Department of Education did not allow researchers into the Grade 12 classes. To counter this, the misconceptions questionnaire was also administered to first-year Life Science students and to students in one second-year course in the Department of Biodiversity and Conservation Biology. It was administered to a small sample of the Postgraduate Certificate in Education (PGCE) students (prospective teachers) at the University of the Western Cape, in order to determine whether misconceptions would be carried into their teaching. In-depth interviews which focussed on the particular student's misconceptions were used to verify the misconceptions which the first-year students held. The results of the misconceptions questionnaire for the PGCE students revealed that a high percentage of them had very little understanding of ecology and that they held several common misconceptions, despite having completed a degree which qualified them to teach Life Science or Natural Science in high school. This study demonstrated that more attention needs to be given to the proper training of Life Science teachers, and to instruction in practical work and fieldwork in the Life Sciences.
Salt tolerance and modification of wheat salt resistance by plant hormones
(University of the Western Cape, 2004) Adam, Muftah Ahmed; Raitt, Lincoln; Aalbers, Johannes
The history of salt tolerance and the factors effecting salt resistance of plants were literature surveyed, and it was concluded that ion concentration, salt accumulation, compatible solutes and the genetic traits play a major role in the salt tolerance of plants. Differences in salt resistance of wheat cultivars were investigated at the germination and early seedling stages. Considerable intervarietal differences in salt resistance between wheat cultivars were reported. The interaction between salinity and plant hormones was studied and showed that N6- benzyladinin treatments caused some changes in some parameters that were studies, GA3 treatments showed more effects on these parameters of salt stressed plants. This study showed that the treatment with some organic acids, citric acid and malic acid, did not cause significant changes in the parameters measured of the wheat plants. No effects on seed germination were due to the decreases in the pH value due to the GA3 treatment were found. The study concludes that treatment of salt stressed wheat cultivars with GA3 could alleviate some of harmful effects of high salt levels, and that it could be useful to treat plants grown in brackish soil or saline environment.
Snake community structure in a heterogeneous fynbos ecosystem
(University of the Western Cape, 2022) Cloete, Bryan Nathan; Maritz, Bryan
Snakes occur in most terrestrial ecosystems, forming an integral part of many ecological communities. A diverse community of snakes in an ecosystem can indicate a complex habitat structure capable of supporting a diverse assemblage of faunal species. I utilised multiple non-invasive and non-lethal trapping methods to quantify diversity metrics for the snake community occurring in a heterogeneous fynbos ecosystem within the Koeberg Private Nature Reserve (KPNR) over one-year period. Additionally, I sampled the species richness and abundance of snake predators and prey within the reserve and tested the hypothesis that the snake community was impacted by the abundance and diversity of snake predators and prey. I performed several statistical analyses to identify the factors that influence the snake community structure observed in KPNR.
Conservation and resource-use relations: Analysis for protected area expansion feasibility in the Western Cape
(University of the Western Cape, 2022) Dyssel, Michael; Knight, Richard
It is assumed that expanding the size and/or number of protected and conservation areas can contribute to more effective conservation, ecosystem services and environmental protection. Expansion is normally a response to continuous environmental threats and subsequent needs to enhance the protection and conservation of valuable biodiversity, geodiversity and heritage assets. Targets for global, regional and country-based protected area expansion are set and driven by conservation authorities across different geographical scales – from the global International Union for the Conservation of Nature (IUCN) to the local-level protected area.
Autecology of the rhombic egg-eater, Dasypeltis scabra
(University of the Western Cape, 2022) Barends, Jody Michael; Maritz, Bryan
Efforts to prevent global losses of biodiversity are hindered by incomplete knowledge of the functional importance of species. In part, this is due to a paucity of information on the basic biology of most species resulting in a poor understanding of their ecological roles. Snakes represent a speciose group of carnivorous predators that are likely important ecological components of a variety of environments given their roles in modulating the sizes of the populations of their prey. Unfortunately, the ecological importance of most species of snakes has yet to be empirically demonstrated, particularly in native systems.
How Do Teachers and Learners Navigate the Terrain of Ecology and What are the Associated Conceptual Understandings?
(University of the Western Cape, 2011) Raitt, Rosemary Ruth; Holtman, L.B.
This thesis relates the teaching of ecology in schools to the requirements of the National Curriculum Statements, Grades R-9 and Grades 10-12, for Natural and Life Sciences. It examines the conceptual understanding of the learners to determine their level of bioliteracy. The effectiveness of various teaching strategies in enhancing bioliteracy is considered. The study was a case study involving classroom observations of Grades 4 to 7 at a primary school and Grades 8 to 11 at a high school in the Western Cape of South Africa, and the administration of a misconceptions questionnaire to learners in Grades 8 to 11. The Department of Education did not allow researchers into the Grade 12 classes. To counter this, the misconceptions questionnaire was also administered to first-year Life Science students and to students in one second-year course in the Department of Biodiversity and Conservation Biology. It was administered to a small sample of the Postgraduate Certificate in Education (PGCE) students (prospective teachers) at the University of the Western Cape, in order to determine whether misconceptions would be carried into their teaching. In-depth interviews which focused on the particular student's misconceptions were used to verify the misconceptions which the first-year students held. The questionnaire revealed that learners lacked an understanding of photosynthesis and respiration, which forms the basis for an understanding of food chains and energy flow within an ecosystem. Learners were confused about ecology and did not understand basic concepts. The misconceptions held in high school carried over to university, as shown by the fact that the first-year Life Science students, tested before they had had any lectures, still held many of the misconceptions that were found among the high school learners. A few second-year students still held misconceptions, but their understanding of photosynthesis and respiration was better than that of first-year students. The questionnaire also revealed that learners lack language skills. Good language skills are necessary for the development of scientific literacy. Three of the seven teachers whose classes were observed admitted to finding it difficult to teach ecology. One of them suggested that the Department of Education provide special training to teachers in this area of teaching. Issues relevant to South African problems were not addressed in any of the classes observed. - Too-little time is allocated to the teaching of ecology to allow for any discussion of social issues relating to this subject. Time, resource constraints, and a lack of training in teaching ecology make it impossible for teachers to fulfil the requirements of the curriculum. Grade 10 learners were required to identify abiotic and biotic factors operating in a local ecosystem, and to describe the trophic relationships present. Grade 11 learners were required to study and report on one local example of human influence on the environment. These requirements were not met. While teachers were prepared to take learners out of the classroom to study ecology, some of them were not able to do so because of extremely large classes and associated problems. The results of the misconceptions questionnaire for the PGCE students revealed that a high percentage of them had very little understanding of ecology and that they held several common misconceptions, despite having completed a degree which qualified them to teach Life Science or Natural Science in high school. This study demonstrated that more attention needs to be given to the proper training of Life Science teachers, and to instruction in practical work and fieldwork in the Life Sciences.
Heteroscleromorph demosponge taxonomy and diversity of the Amathole region (Eastern Cape, South Africa)
(University of Western Cape, 2022) Payne, Robyn Pauline; Samaai, Toufiek
Sponges are functionally important and ubiquitous components of the global marine benthos. South Africa accounts for roughly 4% of the global marine sponge diversity, comprising 374 described species and seven varieties/forms, with elevated apparent endemism (59.3%). However, an estimated 900 sponge species are thought to be undescribed, and much work is needed to update and expand our knowledge of the South African sponge fauna. The Amathole region is situated offshore of the Amathole District, around the city of East London, on the south-east coast of South Africa.
The Shallow water bryozoans of the West Coast of South Africa
(University of the Western Cape, 2005) Florence, Wayne Kevin; Gibbons, Mark
The South African biota is characterised by high levels of diversity and endemism. While commercially viable taxa have been well-studied, cryptic organisms such as bryozoans, have been neglected in terms of study. Taxonomic research on the South African Bryozoa has a brief and fragmented history. As a consequence most of the previous studies have focused on the south and east coasts of South Africa, and at depths deeper than 100 m. It is suggested that previous studies of the Bryozoa in South Africa have failed to reveal more than a fraction of the potential faunal complexity for this region. Earlier studies of the South African bryozoan fauna have described -255 species, mainly from the south and east coasts. The current study, therefore, attempts to identify and describe the shallow water bryozoan fauna from the west coast of South Africa and to compare the South African fauna with that of other regions. Specimens collected from localities, ranging from False Bay to Port Nolloth, along the west coast of South Africa, yielded 63 species, representing three orders (Cyclostomata, Ctenostomata and Cheilostomata), 32 families and 46 genera. Five species are cyclostomes, three are ctenostomes and 55 are cheilostomes. The ratio between the orders is not surprising considering the relatively low diversity of Cyclostomes and Ctenostomes in marine habitats. Thirteen species are new to science (-21% of the total species described in this study), of which seven species are found in seven genera (Eurystrotos, Klugeflustra, Thalamoporella, Bitectipora, Schizosmittina, Fenestrulina and Celleporina) that are newly reported from South Africa and thirteen species are reported from the west coast for the first time, of which one, Hippomonavella formosa, is a new record for South Africa. Including the species described here, approximately 269 valid species, representing three orders (Cyclostomata, Ctenostomata and Cheilostomata), 73 families, and 130 genera have been reported from South Africa. An accurate species number is not yet possible from this area as there are still outstanding problems with synonymies.
Studies on the ecology and taxonomy of nematodes of Saldanha Bay, South Africa
(University of the Western Cape, 2013) Hendricks, Martin Gustav John; Gibbons, Mark.J
Few studies of shallow water marine nematodes have been conducted around South Africa, and none from the west coast. Here, I analyse the composition of nematode communities from six stations along a 3 km transect in Saldanha Bay during both summer and winter, in order to describe the communities present and to explore the effects of sediment composition and heavy and trace metal concentrations on community structure. In order to put the local data into a global context, these data are analysed together with some consolidated data from elsewhere and patterns of richness and composition (at the level of genus and species) examined The transect in Saldanha Bay extended from below a mussel raft at one end into the bay, and six cores (35.7mm diameter) were collected at each station. All nematodes were counted and 100 randomly identified from each core. A total of 136 nominal species, 117 genera and 36 families were identified from both summer and winter stations. Nematode abundance was highest at stations under the mussel raft, which were characterized by high mud content and high concentrations of trace and heavy metals: diversity was comparatively low and the assemblage was dominated by a few, non-selective deposit feeders (especially Sabatieria). Abundance decreased, but diversity increased, with an increase in distance from the mussel raft, which was coupled with an increase in the particle size of sediments and a significant reduction in metal concentrations. There were three dominant (Comesomatidae, Desmodoridae and Linhomoeidae, present in 96%, 85% and 83% of samples, respectively) and four subdominant families (Chromadoridae, Microlaimidae and Xyalidae, all in 79% of samples) that were largely responsible for determining the community structure across the bay. Multivariate analysis of the data using PRIMER indicated that copper was the single variable that best accounted for the structure of the communities (70.1%), and the best 2-variable combinations were copper and organic nitrogen (70.3%), followed by copper, organic nitrogen and mean grain size (69.7%). Abundance was higher at all stations in winter than summer, and the results of the PERMANOVA test on station and season indicated that the variation in between Station- Season accounted for 27% of the differences in community structure. Although these results should be treated with caution owing to limited temporal sampling, they are similar to those obtained elsewhere in the world and indicate that nematodes can be used to study anthropogenic impacts in a local context. Despite the fact that Saldanha Bay has been subjected to industrial activities for more than thirty years, estimates of species richness for Saldanha Bay were surprisingly high: S= 136; ICE = 150; CFE= 173. As too were estimates of generic richness (S= 117; ICE = 131; CFE= 149), which were the fourth most rich of those global sites compared from similar depths. Incorporation of these data into a global dataset revealed an absence of any clear latitudinal pattern in the distribution of richness (genera or families), and there was no obvious geographic structure to global communities, based on the available data. These results suggest that genera and families are poor proxies for species (at the evolutionary level, but not at the ecological level) and they support the idea that everything is everywhere. Comments on ways that nematode research can be advanced in South Africa are made.
How do teachers and learners navigate the terrain of ecology and what are the associated conceptual understanding?
(2011) Raitt, Rosemary Ruth; Holtman, L.B
This thesis relates the teaching of ecology in schools to the requirements of the National Curriculum Statements, Grades R-9 and Grades 10-12, for Natural and Life Sciences. It examines the conceptual understanding of the learners to determine their level of bioliteracy. The effectiveness of various teaching strategies in enhancing bioliteracy is considered. The study was a case study involving classroom observations of Grades 4 to 7 at a primary school and Grades 8 to 11 at a high school in the Western Cape of South Africa, and the administration of a misconceptions questionnaire to learners in Grades 8 to 11. The Department of Education did not allow researchers into the Grade 12 classes. To counter this, the misconceptions questionnaire was also administered to first-year Life Science students and to students in one second-year course in the Department of Biodiversity and Conservation Biology. It was administered to a small sample of the Postgraduate Certificate in Education (PGCE) students (prospective teachers) at the University of the Western Cape, in order to determine whether misconceptions would be carried into their teaching. In-depth interviews which focussed on the particular student's misconceptions were used to verify the misconceptions which the first-year students held. The questionnaire revealed that learners lacked an understanding of photosynthesis and respiration, which forms the basis for an understanding of food chains and energy flow within an ecosystem. Learners were confused about ecology and did not understand basic concepts. The misconceptions held in high school carried over to university, as shown by the fact that the first-year Life Science students, tested before they had had any lectures, still held many of the misconceptions that were found among the high school learners. A few second-year students still held misconceptions, but their understanding of photosynthesis and respiration was better than that of first-year students. The questionnaire also revealed that learners lack language skills. Good language skills are necessary for the development of scientific literacy.
A yeast 2-hybrid screen to identify and characterize interaction partners of the cancer associated protein Retinoblastoma binding protein 6
(University of the Western Cape, 2009) Chibi, Moredreck; Pugh, David JR
Retinoblastoma binding protein 6 (RBBP6) is a 250 kDa protein that is implicated in mRNA processing and ubiquitination functions and has been shown to be highly up-regulated in a number of cancers. In humans and mice, RBBP6 interacts with both tumour suppressors p53 and pRb, suggesting that it is involved in regulation of transcription, induction of apoptosis and cell cycle control. Knock-out of an RBBP6 homologue PACT resulted in p53 dependent cell cycle arrest and apoptosis. Although the biological functions of RBBP6 remain largely unclear, it is possible that its functions are mediated through interaction with other cellular proteins. Since it is possible to unveil novel functions of a target protein through identifying its interacting protein partners, this study aims to further characterize the functions of RBBP6 through identifying novel protein interacting partners using a yeast 2-hybrid screen. In order to identify interaction partners of RBBP6, two well characterized domains of RBBP6, the N-terminal ubiquitin-like DWNN domain and RING finger domain, were used as baits in a yeast 2-hybrid screen of a human testis cDNA library. Putative interactors were verified using in vitro and in vivo immunoprecipitation assays. The RING finger domain was shown to interact with transcriptional factors V-Box binding protein 1 (YB-1) and zinc finger and BTB containing protein 38 (zBTB38), resulting in their ubiquitination. In the case of YB-1 ubiquitination was correlated with a decrease in the intra-cellular levels of YB-1, suggesting that ubiquitination leads to degradation in the proteosome. The DWNN domain was shown to interact with a splicing associated small nuclear ribonucleoprotein polypeptide G (snRPG) and heat shock protein 70 (Hsp70). The results of this work suggest that, at least in the case of YB-1 and zBTB38, RBBP6 plays a role in the regulation of gene expression by ubiquitination of transcription factors, causing them to be degraded in the proteosome. The study provides further evidence of RBBP6's involvement in mRNA splicing through its interaction with snRPG. The interaction with Hsp70 suggests a possible role in protein quality control similar to that played by other E3 ligases such as Parkin and CHIP.
Characterisation, Isolation, Purification and Toxigenicity ofDiplodiatoxin produced by Stenocarpella maydis in Maize
(University of the Western Cape, 2002) Rao, Shailaja Kishan; Rees, D Jasper G
Mycotoxins attract worldwide attention because of the significant economic losses associated with their impact on human health, animal productivity, domestic and international trade. Over 300 mycotoxins have been discovered, of which a few are of serious concern (Smith and Moss 1985; Rheeder et al., 1994). Exposure to these mycotoxins can produce both acute and chronic effects ranging from death to effects upon the central nervous, cardiovascular, pulmonary systems and upon the alimentary tract. Mycotoxins may be carcinogenic, mutagenic, teratogenic and immunosuppressive (Ferrante et al., 2002). Mycotoxins are currently considered as a major problem in developing countries (Miller, 1994).
Chemical investigation of some species of Amaryllidaceae from the Greater Cape Region of South Africa as a source of bioactive compounds
(University of the Western Cape, 2020) Ibrakaw, Abobaker Saleh Mohamed; Boatwright, James Stephen; Mohammed, Ahmed
The family Amaryllidaceae is widely distributed in the southern hemisphere. Members of the family are well known for their content of pharmacologically active alkaloids and represent an important epicentre of Amaryllidaceae-alkaloid diversity. Other metabolites from Amaryllidaceae, such as phenolics including flavonoids, lignans, chromones, and acetophenones, in addition to terpenoids and ceramides have been reported. Boophone haemanthoides (BHE), Crossyne flava (CRO), Clivia miniata (CME) and Nerine humilis (NHE) are members of Amaryllidaceae that have shown biological activity. Parkinson’s disease (PD) is a neurodegenerative disease that progresses with increasing age and some of its major symptoms include tremors, postural and movement related difficulties. To date, the treatment of PD remains a challenge because available drugs only treat the symptoms of the disease or possess serious side effects. In light of this, new treatment options are needed, hence this study investigates the neuroprotective effects of BHE and CRO along with the isolated compounds of BHE and CRO.
Native legume species from the Northern Cape province of South Africa and their potential use as forage crops.
(University of Western Cape, 2021) Müller, Francuois L.; Boatwright, Stephen; Raitt, Lincoln M.; Samuels, M. Igshaan; Chimpango, Samson
The lack of bioclimatically suitable forage species for livestock production in the water-limited agro-ecological areas of South Africa has resulted in significant feed shortages within these areas during the ongoing drought experienced within the country. This, in turn, has resulted in significant livestock mortalities leading to financial difficulties for the farmers and farming communities within these areas. Thus, many of the water-limited agro-ecological areas in South Africa have been declared disaster areas. These cyclic long-term droughts, as well as more common short-term droughts are expected to increase in frequency, duration and intensity under the predicted future bioclimatic conditions. Although there has been significant investment into the development of improved, better-adapted forage crops for these bioclimatically marginal agro-ecosystems, these efforts, to date, have largely been unsuccessful. Therefore, in this study, we propose to identify and evaluate species that are native to the water-limited South African agro-ecosystems and that can potentially be implemented in alternative fodder flow programs within these water-limited agro-ecological areas.
Biomonitoring of heavy metals in the Eerste River catchment area
(University of the Western Cape, 2020) Elmayhob, Esam S. A.; Raitt, L. M.; Rajkaran, A.
The risk of increasing global pollution dictates the need to understand environmental processes and develop innovative ways to monitor pollution levels and address associated problems. In order to address this need, this study used a selection of plants leaves (Commelina benghalesis, Paspalum urvillei, Persicaria lapathifolia and Salix babylonica) as biomonitors to assess the state of the environment, more specifically the concentration of certain heavy metal pollutants (Cu, Zn, Fe, Ni, Pb and Cd) of river water and soils in the Eerste River catchment, Western Cape, South Africa.
Linking biology and sustainable livelihoods to the proposed establishment of community -based Eucheumoid farming in southern Kenya
(University of the Western Cape, 2005) Wakibia, Joseph .G; Keats, Derek; Raitt, Lincoln; Bolton, John
Growth rates of three commercial eucheumoids: brown Eucheuma denticulatum and green and brown Kappaphycus alvarezii were studied at three sites (Gazi Bay, Kibuyuni and Mkwiro) in southern Kenya. The study was conducted using the fixed off-bottom rope technique over a 15 month period from August 2001 to October 2002, in 4 plots (5 m x 1.5 m) set up at each site. The brown E. denticulatum had the highest mean growth rate over the entire period of 4.7% day-I compared to the green and brown K. alvarezii which were 4.3% day l and 4.2% dayl, respectively. Mean relative growth rates were highest at Gazi (5.6% dayl), and lowest in Kibuyuni (3.2% day-I) with intermediate values of 4.8% dail at Mkwiro. Increased water motion was observed to increase thallus nitrogen and hence the growth of eucheumoids. The 'ice-ice' syndrome affected both brown E. denticulatum and brown K. alvarezii but not green K. alvarezii. Mean growth was higher during the southeast monsoon (4.7% day+) than during the northeast monsoon (4.0% dayl).The carrageenan characteristics of the three morphotypes were measured for 12 months. The highest carrageenan yield was obtained for green K. alvarezii (59.1% dry wt), whereas the average carrageenan yield for brown K. alvarezii was 56.5% dry wt and 56.6% dry wt for brown E. denticulatum. The plants at Gazi (58.0% dry wt) had a slightly, though significantly, higher carrageenan yield than both those at Kibuyuni (57.1 % dry wt) and Mkwiro (57.3% dry wt). However, from a commercial point of view the differences in carrageenan yields were not meaningful. Highest gel strengths were obtained in carrageenans from green K. alvarezii (1042.1 g cm") and brown K. alvarezii (1053.7 g ern"), whereas low values of 100.8 g ern" were obtained for brown E. denticulatum. The brown E. denticulatum had carrageenan with higher viscosity (81.7 mPa.s) and sulphate content (29.1% dry wt) than both green and brown K. alvarezii. The gel viscosities of all the morphotypes were higher during the southeast monsoon (67.3 mPa.s) than during the northeast monsoon (46.3 mPa.s) and were positively correlated with gel strengths.A survey was conducted among households in the three villages, from April to September 2001 to assess their socio-economic characteristics. There were 182 household heads interviewed; about 20% were women. Fishing was the main source of livelihood for about 48% of the household members. In 2001, the average monthly income for the surveyed households was Kshs. 9904 (1 US$=75 Kshs.), with about 67% having less than Kshs. 10 000. The average prevalence of poverty among the households surveyed was 45.1% with 38.8%,54.8% and 46.7% of households in Gazi, Kibuyuni and Mkwiro villages, respectively, living below the poverty line of Kshs. 1239 per month per adult person. An economic feasibility study for growing brown E. denticulatum and brown K. alvarezii in pilot farms of 0.1 ha was conducted at Gazi and Kibuyuni. A higher yield of 793 kg dry wt was obtained for plants grown at Gazi than those at Kibuyuni (793 kg dry wt). The net income derived from E. denticulatum was estimated at Kshs. 7549 annually in a 0.1 ha seaweed farm. A higher annual income of Kshs. 49 126 was generated from K. alvarezii. The rate of return on investment in farming E. denticulatum ranged from 15 to 63%, while 122 to 380% for K. alvarezii. The pay back period was shorter for the latter (0.3 to 0.7 years) than the former (1.2 to 2.7 years).A cross-sectoral policy analysis regarding legislation and policy relevant to the introduction and development of eucheumoid cultivation in Kenya, with particular reference to Kenyan legislation was conducted. The analysis showed that there is no system of promoting or regulating mariculture, though there are fragmented regulations that are scattered among the policies, Acts and regulations of various institutions. Such regulations were not designed specifically for mariculture and as a result they do not fully address the needs of mariculture. The establishment of a national mariculture development programme in Kenya is proposed as a means to develop and manage the farming of marine resources, including seaweeds.
Revealing the factors that promote divergence in the Bladder Grasshopper Bullacris unicolor (Orthoptera; Pneumoroidea)
(University of the Western Cape, 2019) Sathyan, Rekha; Couldridge, Vanessa; Engelbrecht, Adriaan
Variation in sympatric and allopatric populations is believed to be a precursor to eventual speciation. The dispersion of genes from one gene pool into another is prevented by various processes, including the founder effect, sexual selection, ecological differences and random genetic divergence. Examining patterns of intraspecific variation in phenotypic and genotypic traits may thus provide valuable insights into the processes that govern species origination. Bladder grasshoppers (Orthoptera; Pneumoroidea) are an ideal model system to investigate patterns of geographic and ecological divergence due to their high host plant specificity, low dispersal and distinctive acoustic signals. This dissertation investigates intraspecific diversification in the bladder grasshopper Bullacris unicolor (Orthoptera: Pneumoroidea). Recent research on this species has shown significant intra- and inter-population variation in male advertisement calls and morphological characters. However, the exact cause of this variation has remained unclear. Furthermore, a previous study showed that the calls of B. unicolor from one particular population are highly differentiated from other populations, possibly due to the effects of anthropogenic noise. Here we aim to examine the drivers of diversity within Bullacris unicolor by embracing a multidisciplinary approach that encompasses the effects of environmental factors, genetics, anthropogenic noise and host plant associated divergence.
Species recognition and reproductive isolation in Malawi cichlid fishes, Metriaclima estherae and M. callainos (Teleostei: Cichlidae)
(University of the Western Cape, 2019) Nyalungu, Nonhlanhla Precotia; Couldridge, Vanessa; Engelbrecht, Adriaan
Cichlids are one of the most diverse groups of fishes in the world. The highest concentration of cichlids is found in Lake Malawi, where over 1500 species are recorded to occur, which are dominated by the haplochromine tribe. Several authors proposed that sexual selection has been a major contributor in the high rate of speciation of haplochromine cichlids. However, sexual selection alone may not be sufficient to fully explain high speciation rates among cichlids. Many closely related cichlids in Lake Malawi differ only in coloration, yet occur in sympatry. It is still not fully understood how they remain reproductively isolated. Previous studies suggest that visual cues are primarily used for reproductive isolation and species recognition. In the current study, visual, chemical and acoustic cues were investigated to observe how they may potentially influence species recognition and reproductive isolation between two closely related species, Metriaclima estherae and M. callainos, as well as between alternate colour morphs of M. estherae.
The genus Spongites (Corallinales, Rhodophyta) in South Africa
(University of the Western Cape, 2019) Puckree-Padua, Courtney Ann; Maneveldt, Gavin W.; Gabrielson, Paul W.
Coralline red algae (Corallinales, Hapalidiales, Sporolithales: Corallinophycidae, Rhodophyta) are widespread and common in all the world’s oceans (Adey & McIntyre 1973; Johansen 1981; Littler et al. 1985; Björk et al. 1995; Aguirre et al. 2007; Harvey & Woelkerling 2007; Littler & Littler 2013). They achieve their highest diversity in the tropics and subtropics (Björk et al. 1995; Littler & Littler 2013; Riosmena-Rodríguez et al. 2017), and within the photic zone of rocky shores (Lee 1967; Littler 1973; Adey 1978; Adey et al. 1982; Steneck 1986; Kendrick 1991; Kaehler & Williams 1996; Gattuso et al. 2006; van der Heijden & Kamenos 2015; Riosmena-Rodríguez et al. 2017) where they serve as important carbonate structures (Adey et al. 1982; Littler & Littler 1994, 1997; Vermeij et al. 2011) and habitats for a host of marine species (Foster 2001; Amado-Filho et al. 2010; Foster et al. 2013; Littler & Littler 2013; Riosmena-Rodríguez et al. 2017). Coralline algae are resilient, inhabiting extreme conditions that include: low temperatures (Adey 1970, 1973; Freiwald & Hendrich 1994; Barnes et al. 1996; Freiwald 1996; Aguirre et al. 2000; Roberts et al. 2002; Björk et al. 2005; Martone et al. 2010); limited light exposures (Adey 1970; Littler & Littler 1985; Littler et al. 1985; Liddell & Ohlhorst 1988; Dullo et al. 1990; Littler & Littler 1994; Iryu et al. 1995; Stellar and Foster 1995; Gattuso et al. 2006; Aguirre et al. 2007; Littler & Littler 2013); severe wave action (Steneck 1989; Littler & Littler 2013); intense grazing pressures (Steneck 1989; Steneck & Dethier 1994; Maneveldt & Keats 2008; Littler & Littler 2013), highly fluctuating salinities (Harlin et al. 1985; Barry & Woelkerling 1995; Barnes et al. 1996; Wilson et al. 2004); including occurring in freshwater (Žuljevic et al. 2016), and constant sand scouring (Littler & Littler 1984; D’Antonio 1986; Kendrick 1991; Chamberlain 1993; Dethier 1994).
Water regime requirements and possible climate change effects on Fynbos Biome Restionaceae
(University of the Western Cape, 2018) Ayuk, James; Raitt, Lincoln
The Cape Floristic Region (CFR) of southern Africa is one of the world’s most unique biodiversity hotspots. However, this biodiversity continues to be threatened by habitat loss due to rapid urbanisation, agriculture and alien vegetation encroachment, and now, by future groundwater extraction and climate change. Previous work had shown that soil moisture is important in structuring wetland plant communities at fine-scale. What is not fully known, however, is how the spatial distribution of species at a local scale is related to soil hydrology and what the response in the future of species distributions will be to perturbations arising from changes in climate or subsurface moisture in the future. The current research investigated the water regime of the Restionaceae which is a key family in the Fynbos biome and the implications of possible changes in soil hydrology caused by climate change in communities within this region. The Restionaceae were particularly appropriate because they are shallow rooted perennials with the ability to tolerate a wide range of water regimes which allows them to successfully co-habit within mixed plant communities as segregated clusters along fine-scale hydrologic gradients. Vegetation survey counts for the presence of these species along with measurements of soil water table depth and moisture content data generated from eight small-scale plots (50 x 50 m) were used to investigate the possible hydrological niches and to envision the potential impacts of a substantial reduction in rainfall and an increase in temperature as projected by Global Climate Models (GCMs) on the structure of Restionaceae communities in seasonal wetlands by 2100. A comparative analysis of the effects of two extreme Representative Concentration emission Pathways (RCP2.6 and RCP8.5) on significant hydrological variables to plant water regimes was carried out. The IPCC AR5 report describes the RCP8.5 emissions scenario as the likely ‘business as usual’ scenario where emissions continue to rise through the 21st century while the RCP2.6 scenario assumes that emissions peak between 2010 and 2020 and substantially subside thereafter.

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