Biological Science Research Papers/Topics

Lack of polymorphism suggests a recent bottleneck of Aloidendron pillansii

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...

Sexual dimorphism in the genus Leucadendron: Morphology and plant hydraulics

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...

Friend or foe? The arrival of Stator limbatus (Bruchidae) in South Africa

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...

Exploration of a climate mediated decline in a critically endangered southern hemisphere conifer over the last 40 years

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...

Polyploid speciation in the Greater Cape Floristic Region: Species limits within Ehrharta calycina

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...

Exploring the breeding diet of the Black Sparrowhawk (Accipiter Melanoleucus) on the Cape Peninsula

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 ...

Attractant properties of chemical constituents of the green macroalga Ulva and their response effects on the commercially important sea urchin Tripneustes gratilla.

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 ...

In Vitro Antiplasmodial Activity And Phytochemicals Screening Of Ethnomedicinal Plants Used To Treat Malaria Associated Symptoms

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...

The Effect Of Bush Encroachment On The Family Diversity And Composition Of Ground-Dwelling Invertebrates In Selected Sites In Omaheke Region, Namibia.

ABSTRACT Bush encroachment, characterized by increase in woody plants in ecosystems, is one of the manifestations of environmental degradation that is prevalent in many parts of Namibia. The present study was conducted in Ben Hur area in the Omaheke Region, about 60 km South-East of Gobabis with the objectives of comparing family diversity, abundance and composition of ground dwelling invertebrates in habitats that are at different levels of bush encroachment and determining their seasonal v...

Analysis Of The Mycochemicals Components Of The Indigenous Namibian Ganoderma Mushrooms

Abstract Ganoderma lucidum (Fr.) Karst. (Ganodermataceae) is a natural scarce basidiomycetous polypore fungus that has a variety of uses such as providing nutrition and as a medical remedy. It has been used in the Asian countries for many years to treat a wide range of ailments with polysaccharides, triterpenes, sterols, lectins and proteins as major active constituents. However, in Namibia, the traditional usage of the Ganoderma mushrooms have been used to relieve stress, calm nerves, heal ...

Assessment Of Carbon Stock And Selected Soil Fertility Indicators In A Bush Encroached Savanna At Erichsfelde Farm, Namibia

Abstract Bush encroachment is a form of land degradation common predominantly in semi-arid areas of the world. The resulting habitat degradation and loss of resource productivity make bush encroachment a serious environmental and economic problem in Namibia. Despite these negative effects, bush encroachment offers potential woody carbon stock storage, which can render Namibia a net carbon sink. This study was, therefore, aimed at quantifying potential woody carbon stock storage from differen...

Genetic and Root Growth Studies in Cassava (Manihot esculenta Crantz): Implications for Breeding

Cassava (Manihot esculenta Crantz) is a perennial tropical crop grown for its starchcontaining tuberous roots. It is cultivated mainly by small-scale farmers and consumed daily by an estimated 500 million people. Cassava mosaic disease (CMD) has long been recognized as a major limiting factor to cassava production in Africa and severe epidemics hit Uganda in the late 1920’s and late 1980’s. In spite of its importance as a major food crop it is the least researched major crop and many ques...

Investigating Conditions That Modulate Pyrazinamide Susceptibility in Mycobacterium Tuberculosis

ABSTRACT Tuberculosis (TB) remains one of the major life-threatening infectious diseases of public health concern globally. Its treatment is long and complex, requiring a cocktail of four drugs administered for six months. Pyrazinamide (PZA) is a cornerstone drug in the treatment regimen for tuberculosis that has contributed to reducing the treatment time from nine to six months. PZA is a pro-drug that is converted to its active form, pyrazines acid (POA) by the bacterial enzyme nicotinamida...

A Study Of The Reproductive Biology Of The Catfish, Chrysichthys Nigrodigitatus (Lacepede) In Nigeria

ABSTRACT The Catfish, Chrysichthys Nigrodigitatus (Lacepede) is widely distributed in Nigeria.

N Vitro Investigation Of The Relationship Between Schistosomiasis And Prostate Cancer

ABSTRACT Schistosomiasis is a neglected tropical disease that affects 200 million people and accounts for 100, 000 deaths annually. In endemic geographical areas, schistosomiasis has been implicated as an etiological agent in the pathogenesis of bladder, colorectal and renal carcinoma largely due to chronic infection of tissues with Schistosoma eggs. Several studies have also reported cases of association between Schistosoma infection and prostate cancer, one of the most common cancers in men...


181 - 195 Of 214 Results