Browsing by Author "Channing, Alan"

Now showing 1 - 9 of 9
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    Chytridiomycosis in amphibian populations in the Western Cape, South Africa
    (University of the Western Cape, 2002) Hopkins, Samantha; Channing, Alan
    There have been many cases reported of amphibian populations declining. These are often due to anthropogenic factors such as habitat destruction and pollution. However, some declines have not had an obvious cause and many of these have been investigated and found to be due to pathogenic disease. Batrachochytrium dendrobatidis is a recently described pathogen of frogs. The population declines that have been associated with chytridiomycosis have occurred in relatively undisturbed areas such as national parks. The declines tend to occur at higher altitudes or in colder climates. This is thought to be because of the frog immune system being slower at lower temperatures. Chyt1id fungus has been found in frog populations throughout the world. Little research has been carried out in Africa although, chytridiomycosis has already been seen in Kenya and South Africa. In this project frogs were sampled from selected transects in the Western Cape and three sites in the Northern Cape. The effect of altitude on the occurrence of infection was tested in the Western Cape. It was found that 18 frogs were infected in the Western Cape and the effect of altitude was not significant. Large numbers of dead and dying frogs were found in two of the Northern Cape sites and the incidence of chytridiomycosis was high in these populations. Chytrid was found in two Bufogariepensis from the Eastern Cape and in Xenopus petersii from Kasanka National Park, Zambia. More research is needed on chytridiomycosis in these populations. The frogs in the Western Cape seem to survive with chytrid fungus infection whereas, the frogs in the Northern Cape are dying. This suggests another factor acting on the Northern Cape frog populations.
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    The distribution of the desert rain frog ( Breviceps macrops) in South Africa
    (University of the Western Cape, 2009) Bell, Kirsty Jane; Channing, Alan
    The desert rain frog (Breviceps macrops) is an arid adapted anuran found on the west coast of southern Africa occurring within the Sandveld of the Succulent Karoo Biome. It is associated with white aeolian sand deposits, sparse desert vegetation and coastal fog. Little is known of its behaviour and life history strategy. Its distribution is recognised in the Atlas and Red Data Book of the Frogs of South Africa, Lesotho, and Swaziland as stretching from Koiingnaas in the South to Luderitz in the North and 10 km inland. This distribution has been called into question due to misidentification and ambiguous historical records. This study examines the distribution of B. macrops in order to clarify these discrepancies and found that its distribution does not stretch beyond 2 km south of the town of Kleinzee nor further than 6 km inland throughout its range in South Africa. The reasons for this are not clear, as there appears to be adequate habitat south of this point. Habitat suitability, food availability and competition, anthropogenic disturbance, and historical distribution patterns are discussed in terms of their impact on B. macrops distribution however no significant correlations are found. In addition, examination of the available habitat within South Africa reveals that the anthropogenic impact of strip mining for alluvial diamonds has greatly transformed much of the west coast of southern Africa including vast tracts of B. macrops habitat. Previous estimates of distribution as pertains to available habitat are found to be overly generous and this study estimates that only 2l.84Vo of the original area remains. Thus the conservation status of this species is dire and should be reviewed by the IUCN in light of current findings. It is the assertion of the author that the current status of Vulnerable (VU) be elevated to Endangered (EN).
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    The distribution of the desert rain frog (breviceps macrops) in South Africa
    (2009) Bell, Kirsty Jane; Channing, Alan
    The Distribution of the Desert Rain Frog (Breviceps macrops) in South Africa Kirsty Jane Bell M.Sc. Thesis, Department of Biodiversity and Conservation Biology, University of the Western Cape. The desert rain frog (Breviceps macrops) is an arid adapted anuran found on the west coast of southern Africa occurring within the Sandveld of the Succulent Karoo Biome. It is associated with white aeolian sand deposits, sparse desert vegetation and coastal fog. Little is known of its behaviour and life history strategy. Its distribution is recognised in the Atlas and Red Data Book of the Frogs of South Africa, Lesotho, and Swaziland as stretching from Koiingnaas in the South to Lüderitz in the North and 10 km inland. This distribution has been called into question due to misidentification and ambiguous historical records. This study examines the distribution of B. macrops in order to clarify these discrepancies, and found that its distribution does not stretch beyond 2 km south of the town of Kleinzee nor further than 6 km inland throughout its range in South Africa. The reasons for this are not clear, as there appears to be adequate habitat south of this point. Habitat suitability, food availability and competition, anthropogenic disturbance, and historical distribution patterns are discussed in terms of their impact on B. macrops distribution however no significant correlations are found. In addition, examination of the available habitat within South Africa reveals that the anthropogenic impact of strip mining for alluvial diamonds has greatly transformed much of the west coast of southern Africa including vast tracts of B. macrops habitat. Previous estimates of distribution as pertains to available habitat are found to be overly generous and this study estimates that only 21.84% of the original area remains. Thus the conservation status of this species is dire and should be reviewed by the IUCN in light of current findings. It is the assertion of the author that the current status of Vulnerable (VU) be elevated to Endangered (EN). January 2009
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    The ecology of tadpoles in a temporary pond in the Western Cape with comparisons to other habitats
    (University of the Western Cape, 2006) Hopkins, Samantha; Channing, Alan; Faculty of Science
    This work centered on the tadpoles in a temporaray pond in the middle of Kenilworth racecourse, Cape Town, South Africa. Trapping was carried out over two wet seasons and five species were found. The racecourse was selected to investigate the tadpole community occupying temporary winter pools. The main focus of this study was the community of tadpoles that occur in the ephemeral ponds in the centre of Kenilworth Racecourse. This study was a very broad insight into tadpole ecology in the Western Cape.
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    Genetic analysis of the Cape Sand Frog, Tomopterna delalandii (Tschudi 1838)
    (University of the Western Cape, 2015) Wilson, Lyle; Channing, Alan
    Tomopterna delalandii occurs throughout the west coast, Western Cape and south coast of South Africa. This range stretches across three distinct biogeographical assemblages. Based on historical records and the fact that Tomopterna is a genus of cryptic frogs, it is possible that there are unknown genetic variations within the species. To investigate whether population structure is present within T. delalandii a mitochondrial gene and nuclear gene, 16S and Tyrosinase, was sequenced from across the range. Haplotype networks and cladograms were constructed to look at the relationship between the genetic samples. This revealed definite population structuring between samples from the western edge of the range and samples from the eastern edge of the range. It also revealed that samples taken from the northern edge of the range, while matching general T. delalandii tadpole morphology, are genetically different. Further study needs to be made into the identity of this new form. This study shows that by using both mitochondrial and nuclear DNA patterns can be discovered about the genetic structure of a species as well as revealing a new one.
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    Genetic variation of rana fuscigula in Southern Africa
    (University of the Western Cape, 1994) Arieff, Zainunisha; Channing, Alan
    Naturalists have long been engaged in describing and explaining diversity in the biological world. The discovery of the molecular basis of inheritance has led to rapid increase in the use of biological macromolecules in these investigations. Scientists now routinely investigate the DNA of a range of organisms. The elationships between taxa and the phylogeny of groups is determined by examining the differences and similarities between them. These differences are then appropriately analyzed. lt is important to understand the natural variation within a group, before the differences between groups can be established. This study aims to determine the molecular differences between individuals at the extreme edges of the distribution of a species. This will serve as a molecular baseline, from which other studies can proceed. The experimental species is the trog Rana fuscigula, which has a range restricted to southern Namibia and South Africa. lt was thus possible to collect material from the edge of the distribution assuming that maximum genetic difference would be found between individuals at the edge of the range
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    The invasive guttural toad, Amietophrynus gutturalis
    (University of the Western Cape, 2015) Telford, Nicolas S.; Couldridge, Vanessa; Channing, Alan
    The guttural toad, Amietophrynus gutturalis, Power 1927, is a common toad with a broad geographic range through much of temperate, sub-tropical and tropical southern and central Africa. Introduced to the islands of Mauritius and Reunion in the 1960’s, and subsequently to Cape Town in the 1990’s, the species has become invasive in its extra-limital ranges. Determining the invasion history of a species provides valuable information for conservation biologists and managers and it is fundamentally important for improving our understanding of the underlying processes of biological invasions. This study aimed to determine the source populations of the extra-limital populations from Mauritius and Cape Town. Furthermore, studies investigating genetic diversity and demographics of African Bufonidae are largely absent from the literature. Understanding the evolutionary history of the species may also assist with determining their invasive ability and identifying similar features in other bufonids such as Amietophrynus regularis and A. xeros. Using mtDNA sequence data from the 16S and ND2 markers four geographically distinct clades were identified through Bayesian phylogenies and haplotype networks. However, a spatial analysis of molecular variance (SAMOVA) indicated a grouping structure of three clades. A total of 16 haplotypes were identified from 53 samples for the 16S marker and 22 haplotypes were identified from 43 samples for the ND2 marker. Both the Mauritius and Cape Town invasive populations were found to have originated from the eastern clade. However, they matched the common haplotype from this region which was found across a vast area that spans the KwaZulu-Natal province and into the Mpumulanga and Limpopo provinces. This did not allow for identifying a more precise region for the origin of the founder populations. The presence of haplotypes unique to the Cape Town invasive population, which group with the eastern clade, indicates that there has potentially been more than one introduction event. Demographic analysis revealed a recent population expansion in both the northern (Fs = -2.92) and the eastern clades (Fs = -5.03). Significant genetic variation was found among groups (93.92%), with low variation among populations and among populations within groups. Population pairwise differences were found to be significantly different between all clades except between the central and the southern clade. There was a negligible difference in the genetic diversity of the invasive populations when compared to the eastern clade. The eastern clades’ genetic diversity was low compared to the two other clades and demographic analysis revealed that this region has undergone the most recent population expansion. The negligible difference between the eastern clades’ genetic diversity and both invasive populations indicate that founder effects and genetic bottlenecking should have no impact on the invasive populations.
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    A modern description of Crambionella stuhlmanni (Scyphozoa: Rhizostomeae) from St. Lucia Estuary, South Africa
    (Cambridge University Press, 2011) Neethling, Simone; Channing, Alan; Gershwin, Lisa-Ann; Gibbons, Mark J.
    A new record of Crambionella stuhlmanni is reported from the east coast of South Africa. The material is described using quantitative morphological data, and mitochondrial (CO1) and nuclear (ITS-1) sequence data. The species can be diagnosed by a combination of morphological features including the presence of conical projections on velar lappets, the absence of orbicular appendages among mouthlets and the short length of the terminal club on the oral arm. Mitochondrial sequence data unambiguously delineate C. stuhlmanni as a separate species from C. orsini, and phylogenetic analyses support its placement within the monophyletic genus, Crambionella
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    Systematics of the non-geniculate coralline red algae from the South African south coast
    (University of the Western Cape, 2015) Van der Merwe, Elizabeth; Maneveldt, Gavin W.; Channing, Alan
    The aim of this study was to document the intertidal and shallow subtidal species of non-geniculate coralline red algae from the South Africa south coast. The main emphasis of the study are encompassed in four research chapters and one concluding chapter focusing on: 1) the documentation of the non-geniculate coralline red algae occurring along the South Africa south coast; 2) revisiting the Leptophytum-Phymatolithon complex in order to resolve the taxonomic status of species previously ascribed to the genus Leptophytum from South African; 3) starting to prepare modern monographic accounts of the higher taxa; and 4) the production of updated keys to all the currently recognised taxa of non-geniculate coralline algae for South Africa. Although nowhere near complete, here we present our findings and report on the current biodiversity status of the non-geniculate coralline red algae after a further four years of extensive sampling.