ABSTRACT Namibian ethno-medicinal plants have not yet been evaluated for their efficacy in inhibiting the activities of Human Immunodeficiency Virus (HIV) reverse transcriptase (RT) and their toxicological effects to mammalian cells have not yet been reported. Hence the aims of this study were: (1) to evaluate selected Namibian plants for their biological activities against RT; (2) to evaluate their toxicity to mammalian cells, and (3) to isolate and characterize the active compounds from se...
ABSTRACT Inappropriate slaughtering and retail operations can compromise food safety specifically in densely populated areas like informal markets. The bacteriological quality and prevalence of Salmonella spp. and Escherichia coli O157:H7 on beef samples from the three different outlets (supermarket, butchery and open market) were assessed to determine their safety for human consumption. A total of 138 of beef samples were collected at random from three different outlets. The bacteriological...
ABSTRACT The main purpose of this study was to investigate the challenges affecting Grade 12 learners’ academic performance in Namibia Senior Secondary Certificate Ordinary level (NSSCO) Biology in the //Kharas Region, Namibia. The study addressed three research questions. Two categories of sample, made up of 140 learners and 12 teachers respectively were selected using the simple random sampling method to participate in the study. Furthermore, after the preliminary analysis of the questio...
While leopards (Panthera pardus) currently occupy the most extensive geographic range of all large felids, they are also suffering the highest rate of current range loss amongst large terrestrial carnivores. This is primarily because most leopards still range outside of formally protected areas where they are exposed to the full suite of anthropogenic threats affecting carnivores including habitat loss, prey depletion, conflict with humans, and commercial harvest for body parts. The extensive...
In comparison to their ecophysiological and behavioral aspects, the skeletal system of African mole-rats (Bathyergidae) has been relatively understudied. Only a few studies have assessed their skeletal system, but these have mostly focused on their cranial and dental systems, with little attention on their postcranial skeleton. This PhD thesis provides a considerable amount of information about the functional anatomy, morphological diversity and postnatal bone morphogenesis of the appendicula...
Abstract Coccolithophores are a biogeochemically important phytoplankton group, fulfilling an important role in the global carbon cycle through primary production and the formation and export of calcium carbonate. Despite this biogeochemical importance, relatively little is known about their ecophysiology, for example their response to nutrient availability in terms of both macronutrient (nitrate, phosphate) and micronutrient (trace metal) or how this impacts on their competition with other p...
Abstract Climate change is a reality. One of the main ecological concerns regarding climate change is the predicted increase in atmospheric and sea temperatures. The latter is expected to rise by roughly 2.5O C by the end of 2050 with dramatic impacts on marine ecosystems predicted around the world. Seagrass ecosystems are a good example of vital ecosystems that are threatened by climate change and other anthropogenic factors. A decline in global seagrass cover of 29% has been estimated over ...
Abstract The Karoo-Namib is a species rich region in which many iconic and keystone species are found, such as Aloe pillansii. The recent population history of A.pillansii is poorly understood. However the suggested climatic shifts that occurred throughout the Holocene era may have affected its distribution, demographics and gene flow. The glacial/interglacial refugia hypothesis predicts that the southernmost population served as a refuge population and that the subsequent expansion of the po...
The genus, Leucadendron, of the Cape Proteaceae family, is made up of over 70 dioecious species that vary in their degree of sexual dimorphism. Males are generally more highly ramified (branched) with smaller leaves compared to corresponding females. It has been hypothesised that sexual dimorphism in Leucadendrons is linked to serotiny (a fire-adapted reproductive strategy), where highly serotinous females may incur extra resource costs in order to keep their transpiring cones alive betwe...
ABSTRACT Stator limbatus is a generalist seed-feeding beetle (Coleoptera: Bruchidae) whose natural range extends from the southern USA to Latin America. Individuals have recently been collected in the Western Cape province of South Africa in seeds of the invasive alien plant species Acacia mearnsii and A. cyclops. This study conducted a preliminary examination of its oviposition preference, and development on, a number of indigenous and invasive alien Acacia species and the invasive alien Par...
Abstract Widdringtonia cedarbergensis is a critically endangered conifer restricted entirely to the Cederberg Mountain range in the Western Cape of South Africa. This study aimed to assess whether contemporary climate change could be a driver in the recently documented tenfold decline of W. cedarbergensis in the last 40 years. By building distribution models using Maxent bioclimatic modelling for pre- and post- 1970’s point occurrence data, the distribution of the species pre- and post-1970...
ABSTRACT Ehrharta calycina J. E. Sm. (Poaceae) is a widespread and often abundant species whose core distribution lies within the Greater Cape Floristic Region (GCFR). Importantly, it shows a high degree of morphological and ploidy level variation. Based on observations of distinct forms co-occurring at multiple sites, the hypothesis that E. calycina comprises more than one species was tested. Morphological analysis of herbarium specimens using a multivariate approach found strong evidence fo...
Abstract This study investigates the diet of breeding Black Sparrowhawks (Accipiter melanoleucus) on the Cape Peninsula of South Africa. Macro-remains of prey were collected from below and around the vicinity of nests throughout the breeding seasons of 2012 and 2013. These prey items were then identified down to species where possible through the use of a museum reference collection. In both years 85.9% of the individual remains were those of Columbidae, which corresponds with the only other ...
Abstract Interest in commercial sea urchin aquaculture is growing worldwide. This is because sea urchins have good quality roe which is a delicacy in many countries. Since the quality of sea urchin roe is dependent on what the sea urchin eats, increased research is being carried out to understand sea urchin feeding preferences. Feeding preference is related to the attractiveness/palatability of the feed, which is thought to be based on its chemical composition. Since an unpalatable feed will ...
Abstract Malaria is a major health concern in Sub Saharan Africa and there are few effective treatment options. Namibia has diverse flora with potent antimalarial phytochemicals and high ethnomedicinal plants uses. This study investigated the phytochemical and in vitro antiplasmodial activity of ten ethnomedicinal plants namely: Baikea plurijuga, Cyphostemma spp, Guibourtia coleosperma, Mundulea sericea, Neptunia oleracea, Diospyros mespiliformis, Acrotome inflata, Oxygonum dregeanum, Ziziph...