Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv & Cons Biol)

Permanent URI for this collectionhttps://hdl.handle.net/10566/13183

Browse

Now showing 1 - 20 of 141

Monitoring of heavy metals in the Kuilsriver and potential use of macrophytes in heavy metal remediation
(University of the Western Cape, 2003) Qoko, Mathabo Malishoane Indira; Raitt, Lincoln; Aalbers, Johannes
Water and soil pollution is one of the major concerns all over the world due to various activities such industrialization and urbanization. This is a problem because water is a vital resource for human survival and economic development; as populations and economies grow, water shortages increase. Phytoremediation is one of the promising techniques that can help to remove heavy metals from polluted and contaminated water and soil by using plants to clean up.
Genetics, morphology, and resource availability of two morphologies of eelgrass, in the Kromme Estuary, South Africa.
(University of the Western Cape, 2026) Mokwa, Omphemetse Kelebogile
Seagrasses are crucial coastal ecosystem engineers, providing habitats and nursery grounds for various marine species worldwide. However, seagrasses are declining globally due to natural and anthropogenic threats. In South Africa, the endemic and endangered Zostera capensis is the dominant seagrass species, it supports a wide diversity of invertebrates and algae and forms the base of estuarine food webs. In many estuaries, meadows of Zostera capensis have been lost or are declining, with major threats being eutrophication and climate change. As environmental conditions are changing, seagrasses have strategies such as adaptation and acclimation that allow populations to persist under shifting environmental conditions. In the Kromme Estuary, a predominantly open estuary on the Eastern Cape coast of South Africa, two distinct morphological forms of Zostera, characterised by short and long leaves, were observed. However, the factors underlying this morphological variation and its ecological significance remains unclear. It is not known whether differences between the forms are associated with environmental conditions and genetic variation, or whether morphological differences is associated with differences in abundance and diversity of associated fauna. This study 1) determined the morphological traits, genetic identity, and population traits of the two morphotypes of Z. capensis in the lower reaches of the Kromme Estuary and 2) estimated the abundance and diversity of invertebrate animals associated with the different forms of Z.
Temporal changes in sea surface temperatures and extreme events along the southern Agulhas Current
(University of the Western Cape, 2025) Phillips, Jesse; Smit, A.J.; Schlegel, Robert; Bornman, Thomas
Over the past several decades, both mean sea surface temperatures and extreme thermal events in and around the Agulhas Current have undergone notable shifts. Bayesian ensemble modelling identified significant changepoints in the seasonality and trends of southern Agulhas Current temperatures. Quantile regression further demonstrated that at coastal sites within upwelling cells along the eastern and western margins of the Agulhas Bank, mean and lowerbound (10th percentile) temperatures have declined, in contrast to the general warming observed across the broader Agulhas Current. While marine heatwaves have increased in frequency and dominate extreme events throughout much of the Agulhas system, the 2007 changepoint revealed a reversal at four of the five coastal sites: marine cold spells became the prevailing extreme events, rising sharply in both frequency and intensity, in the same coastal regions where mass fish kills and shoreline wash-ups have been observed over the past five years. This study demonstrates that following a critical shift in the temperature regime, extreme thermal events have become both more frequent and more severe, with potentially profound consequences for marine ecology and ecosystems.
Aspects of the breeding cycle and fecundity of the female West Coast rock Lobster, Jasus Telendii.
(Univesity of the Western Cape, 1998) Van Rooy, Celeste; de Villiers, Charl
This study examined the breeding cycle and fecundity of female west coast rock lobster, Jasus lalandii. Seasonal fluctuations in the biochemistry and indices of ovary and hepatopancreas state were monitored to elucidate the partitioning of organic resources between growth and reproduction. Samples were collected monthly from Hout Bay, a fast growth area, and Olifantsbos, a slow growth area, between February 1994 and January 1995. Peak ovarian activity was between January and June and was characterized by the dominance of ripe and ripening ovaries. The increased ovarian production was accompanied by high gonadosomatic indices (GSI) and high ovarian lipid and protein contents. The berry (incubation) period was defined by a dominance of spent and recovering ovaries coupled with low GSI and low ovarian lipid and protein values. After October, the ovary recovered and consequently the GSI, ovarian lipid and protein contents increased. Smaller size classes of females exhibited a dominance of immature to active ovaries throughout the breeding cycle. Smaller females from Hout Bay (50-60 mm) size class showed no clear seasonal trend in GSI and ovarian lipid and protein contents. However, smaller females from Olifantsbos exhibited higher GSI and ovarian lipid and protein during the ovarian growth phase than similar size females from Hout Bay. This was reflected in the greater fecundity exhibited by smaller females from Olifantsbos. In all females, GSI, ovarian lipid and protein content increased with increasing ovarian maturity and declined sharply in spent ovaries.
Systematics of subtribe Anthosperminae and the generic affinities of Anthospermum L. and Nenax Gaertn. (Rubiaceae: Anthospermeae)
(University of the Western Cape, 2021) Nemando, Rangani
The last taxonomic treatment of the subtribe Anthosperminae Benth. (Rubiaceae, Rubioideae, Anthospermeae) was in 1986 by Puff., nevertheless, few attempts have been made to resolve the phylogeny and the inter- and infrageneric relationships within the subtribe. The genera Anthospermum L. (39 species) and Nenax Gaertn. (11 species) are considered the most difficult groups to distinguish. Anthospermum species are widely distributed in Sub-Saharan Africa and Madagascar with the highest concentration of taxa in southern Africa, while Nenax species are restricted to southern Africa, in the south-western Cape Floristic Region. The two genera share common morphological and anatomical characters such as the growth form, presence of hairs on the stem, leaf arrangement, presence of petioles, flowers formation, dehiscence and presence of carpophore in fruits. currently combination of characters, woody shrub, needle-like leaves, few-flowered inflorescence and dioecy are considered unique in Nenax. The most recent phylogenetic analysis based on molecular data indicated insights into generic relationships within the two genera and the subtribe Anthosperminae. The present study focussed on expanding the phylogenetic analysis of Anthospermum, Nenax and other genera within the subtribe, as well as assessing the value of selected morphological and anatomical characters for re-assesing generic circumscriptions. Phylogenetic relationships were analysed using Maximum Parsimony, Maximum Likelihood and Bayesian inference, and a Maximum Clade Credibility tree was ii produced. These analyses were based on both nuclear (ITS, ETS) and plastid (trnL-f, rps16, rpl32) datasets.
The impact of the 2022 KwaZulu-Natal floods on mangrove communities, and how they responded to the extreme event
(University of the Western Cape, 2025) Roach, Danielle Cassy
Mangroves provide a wealth of irreplaceable ecosystem services, are crucial to the livelihoods of coastal communities and the sustainable functioning of our planet. They are considered rare in South Africa as they cover less than 1 % of the total land area. These ecosystems are situated at the confluence of the land and the sea, and are thus predisposed to the harshest impacts of climate change. South Africa has one of the highest vulnerabilities to extreme events, and these are increasing in frequency and strength due to climate change. The extreme flooding event which took place between 8 to 12 April 2022 in the greater Durban and South coast region in KwaZulu-Natal (KZN) was no exception to this, with 300 mm of rain recorded in 24 hours, claiming the lives of 459 people, this was the most catastrophic event to have occurred in the history of the province. We are likely to see another event such as this, yet it is currently unknown how mangroves in South Africa would cope with this. Therefore this study aimed to determine the impact of the 2022 extreme flooding event on mangroves and its associated fauna at three estuaries (Beachwood, Durban Bay and Isipingo) in Durban, KwaZulu-Natal.
Mangrove population dynamics in relation to disturbance and recruitment within South African estuaries
(University of the Western Cape, 2025) Theron, Wilmari Francette
Mangroves uniquely regulate their changing environment; however, as they complete their life cycle in this dynamic ecosystem, continuous monitoring is essential to determine if they are selfsustaining, regenerating sufficiently, and managing threats. This study evaluated the status of four mangrove sites on the eastern coast of South Africa. Observational quantitative data was used for disturbances, disease indicators and the population structure and recruitment status of the forests and respective species. Disturbance was quantified by ranking it on a scale from 0 to 4 (four being the highest) for each site. The presence was noted for disturbances (per estuary), disease indicators (canker, fungi, and gummosis) and reproductive structures (flowers, propagules, and calyxes) for each individual within our sampling sites. To quantify and assess the population structure of each estuary, various indices were used to establish the importance of different species, while also looking at different regeneration classes (RC) to evaluate their stocking densities and recruitment. The disturbance levels in the Eastern Cape are moderate (17-25 out of a possible 48), with specific emphasis on resource use as the source of disturbances. Of the disease indicators, fungal growth was present on the majority of all trees (> 90%), while gummosis showed the least incidences. Of the three prevalent species in South Africa, Avicennia marina was the most affected by both gummosis and canker, while B. gymnorrhiza and R. mucronata displayed reduced incidences. The likelihood of canker also increased with the age (DBH) of trees. This study shows that A. marina has the lowest reproductively active population, while the less abundant R. mucronata has the highest.
Zooplankton in and around South African kelp forests: community structure in relation to upwelling cycle.
(University of the Western Cape, 2024) Landsberg, Carlin Verna
Coastal upwelling and kelp forest ecosystems are highly productive environments. In the Benguela Upwelling System (BUS), a vast body of literature is available quantifying the upwelling process and its effects on the ecology in the region. However, very few studies investigate the effects of kelp forests combined with upwelling effects in shaping nearshore communities – especially zooplankton. This study aims to quantify the zooplankton communities in this dynamic region by testing whether the proximity to kelp and the phase in the upwelling cycle affects the zooplankton community structure. This was done by collecting samples inside and outside a kelp forest at upwelling and downwelling conditions to compare the Total Suspended Solids (TSS) and zooplankton abundances while relating these observed patterns to corresponding environmental factors. TSS was significantly higher during downwelling, as hypothesised, due to the formation of phytoplankton blooms during downwelling conditions, but TSS showed no significant difference between samples taken inside and outside the kelp forest. Zooplankton abundance was significantly higher outside the kelp forest compared to inside, regardless of upwelling or downwelling conditions, and samples were dominated by Copepoda (nauplii and adults), barnacle (Cirripedia) larvae, and Polychaeta larvae.
The apoptotic effects of Artemisia afra phytotherapy and modulation of an immune biomarker in cells
(University of the Western Cape, 2024) Govender Liezel; Johnson Quinton
Aim: Artemisia afro phytotherapy was assessed for its apoptotic effects on HeLa, Caski and CHO22 cells especially, and to determine its immune modulating effects on whole blood cell s. Apoptosis methods: For its apoptotic evaluation, aqueous extracts of phytotherapy (4, 6. 8 and 10 mg/ml) were incubated with the various ce ll lines over time (24 hours). L ight microscopy and flow cytometric analysis were completed to assess the possible pro--apoptotic activity of the extracts. The following assays were used as detectors for speci tic apoptotic markers: The ApoPercentageTM Apoptosis assay is a colorimetric assay system that was used to detect and quantify apoptosis. The Annexin V assay was used Lo detect phosphaticly l serine. The Caspase-3 assay was used to detect cells undergoing apoptosis through activation of the caspase-3 pathway. An induction of mitochondrial depolari zation in ce lls undergoing apoptosis was detected using the TMRE assay. Apoptosis results: Ir was noted in the A nnexin V assay that an increase in apoptotic ce lls occurred, as measured by the increased amounts of Annex in V V-PF: and dye 7 amino actinomycin (7aacl) in all three cell lines. An increase in the presence of the dye in cells implied that the membrane integrity of the ce ll lines was breached. \vhich suggests that these cells have undergone the process of apoptosis. Furthermore. an increase in the dose of the phytotherapy. led to a decrease in membrane integrity of these ce ll lines.
Systematics of subtribe anthosperminae and the generic affinities of anthospermum l. and nenax gaertn. (Rubiaceae: Anthospermeae)
(University of the Western Cape, 2021) Nemando, Rangani; Boatwright, James Stephen
The last taxonomic treatment of the subtribe Anthosperminae Benth. (Rubiaceae, Rubioideae, Anthospermeae) was in 1986 by Puff., nevertheless, few attempts have been made to resolve the phylogeny and the inter- and infrageneric relationships within the subtribe. The genera Anthospermum L. (39 species) and Nenax Gaertn. (11 species) are considered the most difficult groups to distinguish. Anthospermum species are widely distributed in Sub-Saharan Africa and Madagascar with the highest concentration of taxa in southern Africa, while Nenax species are restricted to southern Africa, in the south-western Cape Floristic Region. The two genera share common morphological and anatomical characters such as the growth form, presence of hairs on the stem, leaf arrangement, presence of petioles, flowers formation, dehiscence and presence of carpophore in fruits. currently combination of characters, woody shrub, needle-like leaves, few-flowered inflorescence and dioecy are considered unique in Nenax.
A comparative study of degeneration of the posterior limbs and girdles of some scelotes species.
(University of the Western Cape, 1981) Wilson, Brain .A; Skinner, J.H; Leonard, C.J
The genus Scelotes was instituted by Fitzinger in 1826 and is represented by nineteen species and subspecies in Southern Africa (Fitzsimons, 1943) . Valuable contributions have been made to our knowledge of the Lacertilia by pioneers such as Gadow (1881) , Cope (1892) , El-Toubi (1938) , King (1964) and Tiedeman et al . (1975) who investigated the osteology and myology. Essex (1927) , Stokely (1947) , Lande (1978) and Leonard (1979) dealt with the evolution of limb loss and pelvic girdle degeneration in the lizards , and especially in the skinks. van der Klaauw (1948), Snyder (1952; 1954) and Gans (1962; 1966; 1973) studied the ecology and behaviour of limbless tetrapods, while De Witte and Laurent (1943) and Greer (1970) contributed to our knowledge on the systematics of the skinks. Partial or complete loss of limbs and degeneration in the pelvic arch have possibly evolved independently in a variety of tetrapods. The genus Scelotes exhibits a full range of degeneration - from fully pentadactyle tetrapodous forms to limbless species. The question arises : Can a general pattern of devolution be observed in this genus? Al though many of the Scelotes species have already been described, it will here for the first time be attempted to compare the different stages of degeneration as exhibited in this genus. A major objective of this work will , therefore be to analyze the pattern of degeneration in Scelotes. Firstly, the osteology of the pelvic girdle and hindlimbs of the Scelotes species will be described and, secondly, these structures will be compared. Thirdly, an attempt will be made to graphically reflect the major trends associated with limb regression by employing morphometric data obtained from the limited number of specimens available
The roles of intertidal marine gastropod shells as secondary substrate for macroalgae
(University of the Western Cape, 2014) Padua, Courtney Ann; Maneveldt, Gavin W.
Primary space within the marine benthos is by far the most limited resource for which all sessile organisms must compete. It only ever becomes available when the organisms occupying it dies or are forced to leave the area. It has long been established that herbivorous molluscs play an important role in freeing up space on rocky intertidal shores. However, their grazing activities, although freeing up space. often result in diminished species diversity because most intertidal algae and invertebrates are either consumed or displaced. The exploitation of microhabitats (secondary space) therefore becomes important under such scenarios and is known to increase the biodiversity of a particular area. Ironically, mollusc shells are knom1 to provide such microhabitats as they increase the available surface area for the settlement of a variety of epizoic organisms. While the international literature abounds with examples of the importance of mollusc shells as secondary substrata, virtually nothing is known of these associations within a South African context. Surveys were conducted on five more or less equidistant intertidal rocky shore communities (Kalk Bay. Rooiels, Sandbaai, Pearly Beach, Stinkbaai) within the South African western biogeographic transition zone. At all sites, invertebrate densities and biomass, and algal and lichen percent cover abundance were sampled along transect lines running more or less parallel to the shoreline from mean highwater spring (MHWS) tide mark to mean low water spring (MLWS) tide mark.
Reptile community responses to an avian ecosystem engineer
(University of the Western Cape, 2023) Buckley, Emma Elizabeth; Maritz, Bryan
In the Kalahari, sociable weavers (Philetairus socius) build huge, communal nests. Although Kalahari tree skinks (Trachylepis spilogaster) are known to preferentially use trees that host such colonies, the degree to which other reptile species use these trees is not well documented. Sociable weaver nests can provide benefits to different animals and can provide food and shelter for reptiles. I trapped reptiles at Tswalu Kalahari Reserve to assess the impact of sociable weaver colonies on selected reptile populations during weaver breeding and non-breeding seasons. I tested the hypothesis that the reptile community under trees with colonies would differ in diversity compared to those at nearby control trees without colonies, because the sociable weaver colonies provide more resources (food and shelter) to the reptiles than trees without colonies. I also tested whether the abundance of the Kalahari tree skink, Cape cobra (Naja nivea), and Cape thick-toed gecko (Pachydactylus capensis) under trees with colonies differed from those at nearby control trees without colonies, as these were the most abundant species found at the sociable weaver nests. Trapping for 11 days at 24 sites (12 colony trees, 12 control trees), on two occasions, once in March when weavers were breeding, and once in September before they were breeding, resulted in 665 total detections of 13 reptile species, including 148 total recaptures. Mean species richness was significantly higher at colony trees than at control trees during both surveys (2.5 times higher when the birds were breeding; 1.6 times higher when the birds were not breeding). Poisson N-mixture modelling revealed that Kalahari tree skink was significantly more abundant on colony trees during the breeding (3.2 times) and non-breeding seasons (3.7 times).
Temporal and spatial variability in copepod abundance, distribution and community structure off Walvis Bay in the northern Benguela Current, 1979-1981
(University of the Western Cape, 2005) Tsotsobe, Sakhile Vincent; Gibbons, M.J; Verheye, H.M
The zooplankton samples used for retrospective analysis in this study form part of the historical SWAPELS (South West African Pelagic Egg and Larva Survey) collection from January 1972 to December 1989, which covered the entire Namibian shelf. The SWAPELS Programme was initiated following the collapse of the Namibian sardine fishery during the late 1960s and early 1970s. This study investigates variability in the temporal and spatial distribution of total zooplankton (non-gelatinous) biomass, total copepod abundance, as well as copepod community structure off the coast of Walvis Bay along, primarily, transect 70 (23° S), and secondarily, transects 66 (22°67 S) and 74 (23°33 S), over the period 1979- 1981. Included in the data set are sea surface temperatures (SSTs) and surface salinities, allowing for spatio-temporal trends in the hydrology of this region to be examined. Despite extensive variability in SST (1 1.27- 18.15 °C), the most frequently occurring SSTs were in the 15-16 °C range. In 1979 salinities ranged mostly between 35.1 and 35.2, whereas in 1980 and 1981 modal salinities fell within the 35.0-35.1 and 35.2- 35.3 ranges, respectively. A clear seasonal pattern in the cross-shelf distribution of SST and salinity was observed in 1979-80, when, generally, warm , high-salinity water covered most of transect 70 (23° S) in summer to early autumn. In spring the cool inshore water extended seaward, to recede again into summer. The existence of cool inshore surface water from mid-winter to mid-spring, warming up into summer and extending offshore, was indicative of a typical upwelling cycle off Walvis Bay.
The reproductive physiology of The south african pilchard.
(UWC, 1995) Leaner, JJ
Epipelagic fish species form an integral component of the world's supply of protein. The most abundant of these fish belong to the order Clupeiformes (clupeoids) which include sardine, pilchard, sardinella, sprat, and herring. This multi-species group has been estimated to have contributed up to 20% of the world's marine catch in the 1980's (Armstrong and Thomas, 1989). The economic importance of the clupeoids was not only realized by the world's commercial pelagic fishing industry, but the energy was soon directed into experimental research on the multi-species group, both locally and internationally.
Applying a lagrangian trajectory model to investigate and describe the distribution of drifting ecklonia maxima within the benguela upwelling system
(University of the Western Cape, 2023) Coppin, Ross Mark; Smit, AJ
Macroalgal morphological variation is determined to a large extent by a combination of environmental factors, with wave exposure and temperature perhaps the main influences, as they are key environmental properties to which a species becomes locally adapted. Macroalgae have shown to exhibit different responses to different magnitudes of exposure to waves, such as reduction in overall size and strength increasing traits. In terms of temperature, warmer environments have been shown to reduce the overall size of resident and transplanted species. However, none of the past studies have identified specific wave and temperature metrics responsible for the morphological adaptation macroalgae exhibit. Past research has often used simple or two-dimensional models of wave exposure, which do not take into account important aspects of the nearshore environment such as wave breaking, refraction and diffraction. Furthermore, past studies have often used satellite-derived datasets as sources for temperature data; however, such data have been shown to have large bias when applied to the nearshore environment. This study used in situ temperature data and wave power metrics calculated from a 3D-numerical model to identify specific temperature and wave metrics responsible for morphological adaptation of the kelp, Ecklonia maxima and Laminaria pallida. Between temperature and wave exposure, the results identify wave exposure as the main influencer of morphological adaptation while identifying specific wave metrics. Furthermore, the results show differences in wave metrics between species, and between deep and shallow populations. The findings from this chapter were used in the next chapter to investigate the role of hydrodynamic and wind drag on floating kelp trajectory. Ocean currents act as an essential dispersal mechanism of natural and anthropogenic material on the ocean surface. Macroalgae are one of the essential natural dispersal vectors of marine organisms and are regarded as the ‘tumble-weed of the ocean.’ Despite many studies on the topic, the relative role of wind and surface currents in influencing the trajectory of macroalgal dispersal is still uncertain. Past studies focused on kelp-rafts, which can vary significantly in size, making it difficult to form a consensus on the relative role of wind versus surface currents. In addition, these studies have not considered surface area in relation to drag characteristics of the macroalgae, both of which have been shown to play a role in the trajectory and accumulation of flotsam. Advances in Lagrangian trajectory modelling have been rapid in recent years and allow the use of numerical experiments to investigate trajectories of flotsam in the ocean. This study aimed to shed light on the relative role of wind versus surface currents and the role of drag in macroalgal trajectory and accumulation. We focused on solitary kelp plants. This was achieved by comparing simulations of virtual kelp ‘particles’ which incorporate drag with that of purely Lagrangian particles (no drag).
Species delimitation and assessment of genetic variability in Carpobrotus (Aizoaceae): evidence from amplified fragment length polymorphisms
(University of the Western Cape, 2004) Khunou, Angeline; Reeves, Gail
During the course of this thesis, AFLP technique was successfully applied to the Aizoaceae taxa. This study involved a substantial component of laboratory work including generating and analysing AFLP data, the operation of an ABI377 automated DNA sequencer, and use of GeneScan and Genotyper software (Applied Biosystems). The initial motivation for this study was to reconstruct relationships between species of the genus Carpobrotus. However, it soon became clear that this would be impossible via the use of DNA sequence data. This was due to the inability to find DNA regions with sufficient variable characters for phylogenetic reconstruction. Therefore applying the AFLP fingerprinting technique to the question of species-level relationships in Carpobrotus resulted in individuals of the same species not forming distinct groups. This has subsequently led to the conclusion that gene flow is common across species boundaries in Carpobrotus as a result of hybridisation. An alternative ved may be that current species delimitations in this group are not well defined. These results also concord well with isozyme studies taxa in the Mediterranean Basin. Increased sampling of species other than C. acinaciformis and C. edulis would allow further investigation into the genetic delimitation and affinities of Carpobrotus, and shed light on the In the biotechnological age the use of molecular techniques has has the potential to greatly improve the bio-prospecting process. This has particular relevance to plants with medicinal properties, such as Carpobrotus, whereby targeted selection of genotypes with well-characterised medicinal properties may increase efficiency. Genetic and phylogenetic information can also help to identify closely related species and genera that may share similar metabolic pathways and properties. These issues are quickly coming to the forefront in the new South Africa, with the opening up of traditional knowledge systems, and subsequent integration and contact with the biotechnology community. 79
Genetic analysis of resistance to powdery mildew (podosphaeara leucotricha) in apple (Malus x dornestica Borkh.)
(University of the Western Cape, 2008) Simayi, Zolani Ellias; Rees, Jasper G.
Apple powdery mildew, caused by Podosphaera leucotricha, is one of the major diseases of the cultivated apple in the Western Cape, causing severe losses in yield and affecting fruit quality. This affects the deciduous fruit industry as costs are incurred on the management of this disease. The application of fungicides is one of the strategies mostly used to control the spread of the pathogen. Since consumers demand high quality fruit with no harmful chemical residues, alternative approaches that minimize the reliance on agri-chemicals for the control of this disease must be developed. Marker-assisted breeding for the development of new varieties that exhibit durable resistance to the fungus is the best and safest way to reduce damage caused by powdery mildew.
Studies of foraminifera associated with gelidium pristoides (turner) keutzing (gelidiales: rhodophyta)
(University of the Western Cape, 2002) Toefy, R; McMillan, K; Gibbons, M.J
Our understanding of the macrofauna of hard intertidal substrata around South Africa is fairly comprehensive, and we have a good understanding of the environmental factors responsible for structuring macrofaunal communities (McQuaid & Branch, 1985; Bustamante et al., 1996; Emanuel et al., 1992). The same cannot be said for meiofaunal communities of rocky shores, which despite their neglect are known to play an important role in the functioning of many intertidal systems (Gibbons & Griffiths, 1986). While macrofauna may dominate rocky shores in terms of biomass, meiofauna are generally more abundant, and because they have faster turnover rates they make an important contribution to secondary production (Gibbons & Griffiths, 1986).
Specias delimitation and assessment of genetic variability in Carpobrotus (Alzoaceae): evidence from amplified fragment length polymorphisms
(University of the Western Cape, 2004) Khunou, Angeline; Reeves, Gail; Weitz, Frans
Species of Carpobrotus (Aizoaceae: Ruschioideae) are widely spread throughout South Africa and are commonly used for their medicinal properties. The genus consists of 13 species of which seven occur in South Africa, five in Australia and one in Chile. A number of investigations on South African species have demonstrated that some taxa exhibit anti-microbial activity. Using AFLPs (amplified fragment length polymorphisms) this study was undertaken with the primary aim of resolving relationships between Carpobrotus species in South Africa, and determining species limits by assessing their genetic distinctness. In addition, levels of genetic variability among populations of two South African species, C. acinaciformis and C. edulis werc assessed in more detail. AFLPs were not able to resolve conflict surrounding species boundaries, perhaps due to extensive hybridization. However, major groupings within South African species were identified, although no geographical structuring of these populations was evident. From a bio-prospecting perspective caution needs to be taken when sampling Carpobrotus due to difficulty in identifying species possibly as a result of hybridization.

Browse

Recent Submissions