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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Infraspecific systematics of the yellow mongoose Cynictis penicillata.

Taylor, Peter John. January 1990 (has links)
Geographic variation was analysed in morphological (colour, morphometric) and genetic (electrophoretic, chromosomal) characters in the yellow mongoose cynictis penicillata, a diurnal, colonial, burrow-dwelling viverrid, endemic to and widespread throughout Southern Africa. The causal bases of observed geographic patterns were investigated, and a taxonomic revision of the species was undertaken. Three physical properties of pelage colour (hue, value and chroma) were measured independently using Munsell colour charts and a tristimulus colorimeter. Hue and chroma varied from yellowish (hue) and bleached (chroma) in the north to a brighter, (chroma) tawny-orange (hue) in the south. A zone of rapid colour change separated northern and southern groups. Specimens from the drier western areas were paler (in value) than specimens from more easterly localities. Colour patterns were interpreted in terms in the principle of metachromism. Environmental correlates of colour were analysed. Non-geographic (age, sex, individual) and geographic variation was analysed in 14 cranial and two external characters, using multivariate and univariate techniques. The species does not show secondary sexual dimorphism. Multivariate analyses resulted in the description of four parapatric subspecies, three of which were distinguished on the basis of skull size (which accounted for 93% of geographic variation). Subspecies were separated by continuous zones of craniometric differentiation (transition zones). Craniometric overlap (intergradation) occurred across transition zones. The geographic pattern of craniometric variation in C. penicillata could be explained by either an allopatric or a parapatric mode of speciation. A cladistic analysis of coded cranial characters was used to infer the historical pattern of range expansion in the species. The population genetical structure, based on electrophoretic analysis of 28 loci in eight populations of yellow mongooses, was characterised by the absence of genetic divergence between morphometrically-defined subspecies, a mean expected heterozygosity of 3.4%, low genetic distances between populations (0.000--0.105 for Nei's genetic distance), and a surprisingly high fixation index (FST) of 0.585. The basic karyotype of the yellow mongoose was invariant geographically (2n = 36, NF = 72), although a single, supernumerary microchromosome was detected in four out of the five populations sampled. G- and C-banded karyotypes are presented. Evolutionary relationships among eight Southern African viverrid species, including the yellow mongoose, were inferred from phenetic and cladistic analyses of allelic variation at 18 protein loci. These data suggested the separate evolution of social and solitary lineages of mongooses. / Thesis (Ph.D.)-University of Natal, 1990.
22

A revision of the genus Ancilla Lamarck, 1799 (Mollusca : Olividae : Ancillinae)

Kilburn, Richard Neil. January 1982 (has links)
The genus Ancilla Lamarck, 1799, contains 34 valid species and subspecies; 41 names previously applied to the group are reduced to 23, and 11 new species described (Kilburn, 1977, 1980, 1981). A provisional subgeneric classification is proposed. Subgenus Hesperancilla Kilburn, 1981, is established for the Brazilian A. matthewsi Burch & Burch, 1967, and Javancilla Kilburn, 1981, for the Eocene A. boettgeri Martin, 1914. Inadequate data on its type species prevents definition of subgenus. Ancilla s.s. at this stage, but Recent Indo-Pacific taxa are provisionally divided into (a) subgenus Sparellina P. Fischer, 1883, with an autapomorphic pectinate rachidian and (b) subgenera sparella Gray, 1857, and Chilotygma H. &. A. , Adams, 1853, with synplesiomorphic tricuspidate rachidians. The phylogeny and biogeography of the genus are discussed. The subfamily Ancillinae is reclassified, and a tentative cladogram proposed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1981.
23

The incidence of helminths in pigs, sheep, cattle, impala and blesbok in the Transvaal.

Horak, Ivan Gerard. 09 September 2014 (has links)
The seasonal fluctuations in the worm burdens of pigs, sheep, cattle, impala and blesbok exposed to infestation on improved or natural pastures in the Transvaal were determined. The prevalence of infestation in pigs slaughtered at the Pretoria Municipal Abattoir and in impala near Pafuri and blesbok at Badplaas was also established. Sheep, goats and cattle were successfully artificially infested with a number of nematodes of impala origin and sheep with those of blesbok origin. The various methods used to determine the seasonal incidence of helminth parasites are discussed and the wastage of valuable material criticised when complete recoveries of both internal and external parasites are not attempted at each necropsy. Host specificity and the distribution of parasites according to climate and the zoogeographical distribution of their hosts are discussed and the epizootiology of the major nematode genera parasitizing sheep, cattle, impala and blesbok in the Transvaal is determined. The phenomenon of arrested development in nematodes is compared with that of diapause in insects and measures to control helminth parasites 1n domestic stock and antelope in the Transvaal are suggested. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1980.
24

Reproduction and population ecology of the blue wildebeest Connochaetes taurinus taurinus in Zululand.

Attwell, Charles Anthony Mallory. January 1977 (has links)
A two-year study was made of the blue wildebeest Connochaetes taurinus taurinus in Zululand, Natal. Aspects investigated included age determination methods, growth and condition, reproductive physiology, habitat interactions, and population dynamics. Findings were related to suggested management of the species. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.
25

Physiological variation in insects : metabolic scaling and gas exchange patterns

Marais, Elrike 04 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Physiological diversity in insects was investigated in terms of gas exchange patterns and metabolic rate. Since the majority of hypotheses that propose to explain the occurrence of Discontinuous Gas Exchange Cycles (DGCs) are adaptive, the possibility of adaptation was explored in two ways. First, since repeatability is one of the three prerequisites for natural selection, and rarely tested in insects, the repeatability of gas exchange characteristics and metabolic rate were tested in a Perisphaeria sp. cockroach. Four major gas exchange patterns were recognized and these patterns were found to be extremely variable within this species. However, repeatability was still generally high for the majority of the gas exchange characteristics and metabolic rate. Moreover, between individual variability generally accounted for a large proportion of the variance, supporting the repeatability findings. Therefore, both metabolic rate and gas exchange patterns might indeed be adaptive traits in this Perisphaeria sp. cockroach. Second, the distribution of the three gas exchange patterns (DGCs, cyclic and continuous) across the insect phylogeny was investigated. Data were extracted from the literature and gas exchange patterns for eight insect orders, representing mainly the endopterygotes, were measured. Using standard respirometry techniques, data for a total of ten additional orders were added, which represented both apterygote orders, six exopterygote orders and two endopterygote orders that were previously uninvestigated. In addition, four of the five adaptive hypotheses were tested by investigating the occurrence of DGCs in winged or wingless insects, subterranean and non-subterranean insects, and insects from mesic and xeric environments. Results indicate that DGC has evolved at least five times in the insects and that the cyclic gas exchange pattern is likely to be basal. No support was found for the chthonic, hybrid and oxidative damage hypotheses, while DGCs were associated with xeric environments. This analysis provides some support for the hygric hypothesis. In addition the prediction of the fractal network model for metabolic scaling which states that both intra- and interspecific scaling coefficients should be identical and equal to 0.75, was tested. Three species of polymorphic worker ants were used to determine the intraspecific scaling coefficient. Data from the literature were added to provide metabolic rate information on 42 species of the Formicidae. The interspecific scaling coefficient was determined in several ways: the traditional method (Ordinary Least Squares regression models), with the two respirometry techniques analyzed separately or in combination (e.g. open and closed system), and using phylogenetic independent contrasts with the same sets of data. Intraspecific coefficients were significantly different from 0.75. The slope of the interspecific regression obtained using Ordinary Least Squares regression models was not significantly different from 0.75. However, when phylogenetic relatedness was accounted for the slope differed significantly from 0.75. Therefore, the fractal network model was not supported by these findings, since slope values are not equal and also not statistically equivalent to 0.75. Overall, variability of both metabolic rate and gas exchange patterns in insects is higher than generally suggested by the literature. These findings provide much scope for future work. / AFRIKAANSE OPSOMMING: Hier word die fisiologiese diversiteit van insekte ondersoek in terme van hul gaswisselings patrone asook hul metaboliese tempo. Die oorgrote meerderheid van die hipoteses wat voorgestel is om die onstaan en bestaan van Diskontinue Gaswisseling in insekte te verklaar, is op ‘n evolusionêre grondslag gebaseer. Vir hierdie rede word die moontlikheid van Diskontinue Gaswisseling as ‘n aanpassing op twee maniere ondersoek. Herhaalbaarheid is een van die voorvereistes van aanpassing (in terme van evolusie) en dit is tot dusver slegs ‘n paar keer in insekte getoets is. Daarom word die herhaalbaarheid van die gaswisselings komponente, asook die metaboliese tempo hier in ‘n Perisphaeria sp. kokkerot ondersoek. Vier hoof gaswisselings patrone is geidentifiseer en die bevinding was dat die patrone geweldig kan varieer binne hierdie spesie. Ten spyte hiervan was die herhaalbaarheid steeds hoog vir die oorgrote meerderheid van die gaswisselings komponente asook vir die metaboliese tempo. Verder het die variasie tussen individue tot ‘n groot proporsie van die totale variasie bygedra, wat die betekenisvolheid van die hoë herhaalbaarheid beklemtoon. Dus, beide metaboliese tempo sowel as gaswisselings komponente kan moontlik as ‘n aanpassing beskou word in hierdie kokkerot. Tweedens, die verspreiding van die drie gaswisselings patrone (Diskontinue Gaswisseling, siklies en kontinu) in die insekte is ondersoek. Gaswisselings patrone vir agt van die dertig insek ordes is vanuit die literatuur verkry, alhoewel dit meestal verteenwoordigend van die Endopterygota is. Data vir tien additionele ordes wat nog nooit voorheen ondersoek is nie is bygevoeg, insluitende beide die ordes van Apterygota en ses ordes van die Exopterygota, asook twee ordes van die Endopterygota. Verder is vier van die vyf hipoteses met betrekking tot aanpassing ondersoek deur die teenwoordigheid van Diskontinue Gaswisseling in gevleuelde en ongevleuelde insekte, ondergrondse en bogrondse insekte, asook insekte van gematigde en droeë omgewings te ondersoek. Resultate dui aan dat Diskontinue Gaswisseling ten minste vyf keer onafhanklik in insekte onstaan het en dat die sikliese patroon heel moontlik basaal is. Die resultate bied geen ondersteuning vir die hipoteses wat gegrond is op gaswisseling in ondergrondse omgewing of oksidasie beskerming nie. Daar is wel ondersteuning vir die hipotese aangaande die rol van water verlies in die onstaan en onderhoud van Diskontinue Gaswisseling. Additioneel is daar ondersoek ingestel na die verwagting wat deur die fraktale netwerk model vir metaboliese glyskale gestel word, wat lui dat beide die binne- sowel as tussen-spesies koëffisiënte identies aan mekaar en gelyk aan 0.75 sal wees. Drie polimorfiese mier spesies is gebruik om die binne-spesies koëffisiënt te bepaal. Data vanuit die literatuur is hier bygevoeg en sodoende was informasie vir 42 mier spesies van die Formicidae beskikbaar. Verskillende metodes is gebruik om die tussen-spesies koëffisiënt te bepaal: die tradisionele metode (sg. “OLS”-regressie), met die twee tegnieke om metaboliese tempo te bepaal (bv. oop en geslote sisteem metodes) apart asook saam, en deur gebruik te maak van filogeneties onafhanklike vergelykings vir dieselfde datastelle. Die binne-spesies koëffisiënte was almal betekenisvol verskillend van 0.75. Die tussen-spesies regressie waar gebruik gemaak is van ‘n “OLS”-regressie model was nie betekensivol verskillend van 0.75 nie. Met filogenetiese verwantskappe egter in ag geneem, het die koëffisiënt wel betekenisvol verskil van 0.75. Dus word die fraktale netwerk model nie ondersteun deur hierdie studie nie, aangesien die koëffisiënte nie indenties aan mekaar is nie, en ook statisties verskil van 0.75. In die algemeen is die variasie in metaboliese tempo sowel as gaswisselings patrone aansienlik hoër as wat afgelei kan word uit die literatuur. Hierdie bevindinge stel ‘n basis vir heelwat verdere werk in die toekoms.
26

The mammals of the Transvaal.

Rautenbach, Ignatius Lourens. 19 September 2014 (has links)
The primary object of this study is to provide a checklist of the mammals occurring within the Transvaal. A general biological account of each species forms the bulk of this treatise, - discussing, in order of sequence, firstly the taxonomic status of each species as based on a study of available museum specimens. Thereafter the distribution of each species is discussed, and illustrated with a map of known distribution. Remarks are presented on the various environmental factors that may influence individual species ranges. Habitat preferences, habits, and food preferences are then discussed. Available data on breeding seasonality, as based on the monthly ratio of reproductively active and inactive females, are given. External measurements and masses of males and females are tabulated. Records of occurrence based on the number of museum specimens from each locality, and the institution where these specimens are housed, are finally listed for each species. The text is supplemented by a gazetteer, giving the latitudinal and longitudinal coordinates of all the collecting localities. This study is based on some 12 000 museum specimens, the greatest majority housed in the Transvaal Museum collections. During the field work phase of this project, 57 localities were sampled. This yielded the majority of the specimens and the greater part of the data on which this book is based. Information gained from a study of earlier collected material supplements these data files. Additional information such as sight records, field observations, and the published accounts of other scientists, have also been incorporated into the central data files and have been discussed in relation to my own findings. The results of selected studies comprise the discussion. The basic behavioural trends and mean mass of all the carnivore species of the Transvaal are employed to speculate on how interspecific competition is avoided. The distribution of all southern African mammals is employed to statistically evaluate the validity of the biotic zones previously empirically recognized for this subcontinent. The distribution patterns of Transvaal mammals are statistically analysed to subdivide the biotic zones overlying the Transvaal into community types of zoogeographical significance. Other zoogeographical phenomena are discussed in relation to regional species diversity. Reprints of papers arising from this study, and particularly the discussion, are bound in as appendices to this report. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1978.
27

Plant molluscicides for snail control in the South African context.

Clark, Tanza Elizabeth. January 1994 (has links)
Despite more than half a century of international research on schistosomiasis control, this disease remains a public health concern in many Third World countries. Four to five percent of the world's population is estimated to be infected. In South Africa, bilharzia is prevalent in rural communities which lack piped water and adequate sanitation. Transport and treatment costs limit access to Western medication. In the last decade, plant molluscicides have received considerable attention in the ongoing search for cheaper alternatives to chemotherapy and synthetic molluscicides. Plant molluscicides may be locally harvested, extracted and applied for the control of the snail host. This approach is based on a philosophy of self-reliance and self-determination. However, such involvement presupposes recognition of the infection as a real problem. Before selecting and evaluating plants for molluscicidal activity, it was first necessary to establish the status of schistosomiasis in rural communities, and the willingness of community members to become involved in control efforts. Field surveys showed that rural South African communities do not share the indifference of the past health-care system towards schistosomiasis in this country. Concern for the disease was matched by a prevalence of 75.14% for S. haematobium in the study area. The potential of the South African flora to provide suitable molluscicidal candidates has never been systematically assessed . As random screening is costly and is historically of limited success, a need has existed for the development of an objective selection procedure . A simple scoring system was devised, based on the criteria for "good" plant molluscicides as defined by the World Health Organization (WHO). Three plant species were subsequently selected for further intensive evaluation: Warburgia salutaris, Gardenia thunbergia and Apodytes dimidiata. Initially, the activity of crude aqueous suspensions of all three candidates was investigated, since this application form is the most practical for use in a rural situation. Further, the stability of extracts under changing physical and chemical conditions was assessed, as were t he effects of molluscicides on a wide range of to the toxicity of aqueous suspensions, cultivation potential, medicinal value, stability, and toxicity to non-target organisms. Studies on the mode of action of the three plant extracts revealed that death occurred via distinct physiological pathways; this despite the similarities in clinical symptoms. Such is the complexity of snail physiology that until more intensive neurological investigations are undertaken, the mechanisms of molluscicidal action can only be inferred. Chemical compounds responsible for activity were identified from Apodytes dimidiata; genipin, a monoterpene, was one such active constituent. Although not previously recorded as molluscicidal, earlier workers have isolated genipin from Genipa americana and Gardenia jasminoides. Notably, this compound has not yet been isolated from Gardenia thunbergia. Further activity in A. dimidiata extracts appeared to be the result of a synergistic effect, potentially involving (S)(-) ethyllactate. Research on mammalian toxicity, and registration procedures for plant molluscicides in South Africa should be prioritized for further investigation, before pilot field trials are initiated. Almost thirty years have passed since the first reports on the activity of Phyto!acca dodecandra. Although more than 1000 plant species have since been tested world-wide, it appears that no plant molluscicide has ever been endorsed by the WHO. More concerted efforts are necessary to ensure that appropriate molluscicidal technologies are provided to infected communities. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.
28

The Anostraca (crustacea : Branchiopoda) of southern Africa.

Hamer, Michelle Luane. January 1994 (has links)
The Anostraca are a group of crustaceans belonging to the class Branchiopoda. They are predominantly restricted to temporary, inland waterbodies, which in southern Africa, include rockpools, animal wallows, and large "pans". The anostracan fauna of southern Africa was last examined in detail in 1929 by Barnard, and recent collecting in a number of areas indicated the need to update earlier work. A total of four genera, each belonging to a separate family, and forty-six species, some of which had not previously been described, are presented in this thesis. The monogeneric family Streptocephalidae is well represented in Africa, and the fauna of Africa south and north of the Zambezi and Kunene Rivers, as well as Madagascar is reviewed. The Streptocephalus species are characterised by having an S-shaped antennal process, terminating in a cheliform "hand" region. The species were divided into ten groups based on similarities in antennal process morphology. The descriptions of five new species have been published, and an update on distribution and specimen data for a number of species are presented. An additional, as yet unpublished new species from Zimbabwe is presented. The genus Artemia, although well researched in other parts of the world, has been largely ignored in southern Africa. Bisexual populations occur along the Cape coast, and a set of specimens from Namibia, which includes only females, may indicate that A. parthenogenetica is also present on the subcontinent. The frontal knob morphology of the Cape specimens is similar to that of A. tunisiana from northern Africa and the Mediterranean. The family Branchipodidae is characterised by the fusion of the basal joints of the male antennae to form a so-called "clypeus". This family is represented in southern Africa by a diverse fauna of the genus Branchipodopsis. Eleven previously described species, as well as five new species are presented. An attempt was made to divide the sixteen species into species groups, as was done for the streptocephalids, but this proved difficult. The taxonomically useful characters in this genus are largely restricted to the basal processes. An additional character, the presence of expansions of the posterior thoracic segments in the females of some species could be useful. Much intraspecific variation in clypeus morphology was evident, particularly in two of the widespread species. Branchipodopsis species commonly occur in small pools which fill a number of times during the wet season and this has probably led to the development of localised adaptations, and intraspecific variation, or even species endemic to very restricted areas. Three sets of specimens which belong to the family Branchipodidae, but to no known genus, were recently collected from north-eastern Natal, the eastern Cape and the Namib desert in Namibia. These specimens share a single, large process positioned medianly on the fused basal joints, as opposed to a pair of processes in this position. However, the morphology of the penes, and the position and form of other antennal processes could indicate that the specimens are not congeneric. Unfortunately, more material is necessary before the descriptions of two of these possible new genera can be published. Three species of the genus Branchinella, of the family Thamnocephalidae, occur in southern Africa. These species have a well developed frontal process, and fully retractible penes. Bran chin ella spinosa was recorded from the Makgadikgadi Pan in northern Botswana, and was probably introduced to this area from north Africa, or Europe, where it has a wide distribution. The other two southern African species have been collected from few localities, and in small numbers, and this may be connected to cyst hatching processes. The southern African anostracan fauna exhibits distinct distribution patterns and these . appear to be influenced by climate, with rainfall having the dominant influence in the western half of the subcontinent, and temperature influencing distribution in the eastern half. The high altitude Escarpment forms a barrier to the movement of species between the coastal margin and the central plateau region. The formation of the Escarpment could have resulted in vicariance speciation in some anostracans, but in most cases, allopatric speciation appears to have occurred. The type of habitat also influences species distribution in a number of ways. The great anostracan species richness in southern Africa is probably related to the climatic heterogeneity of the subcontinent, as well as the possible origin of two genera in Gondwanaland, and the absence of a Pleistocene glaciation in Africa. Large parts of southern Africa have not been sampled, and the exact status and distribution of many species is uncertain. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.
29

Ecology and behaviour of the Seychelles giant millipede.

Lawrence, James M. 20 December 2013 (has links)
On certain islands in the Seychelles archipelago a large and abundant animal is the Seychelles giant millipede, Seychelleptus seychellamm (Desjardins, 1834). This study quantifies the ecological role of this species in litter breakdown on Cousine Island, Seychelles. Observations on various ecological aspects and surface behaviour of this millipede were also made. The population of the Seychelles giant millipede on Cousine Island consists mostly of mature females, with few mature males and immatures. Apparent millipede density was higher at night (i.e. 4.44 ind.m⁻²) than during the day (i.e. 0.19 ind.m⁻²). Millipede biomass was 1.95 tons.ha¯¹. Millipedes were observed feeding on eight food types, with the most common food types being leaf litter and fallen fruit. Predation and scavenging on the Seychelles giant millipede was rarely seen, with only a total of 18 observations being made. The giant ghost crab was the only predator observed killing a millipede. The most common scavenger on dead millipedes was the Seychelles magpie robin. Mean litter ingested by the Seychelles giant millipede was 157 ± 28.1 mg.day¯¹ (n = 45) and mean faecal production was 111 ± 12.8 mg.day¯¹ (n = 45). On Cousine Island, the Seychelles giant millipede consumed daily, approximately 4.6 % of the total litter standing crop and approximately 17.2 % of the daily litter fall. Daily faecal production by the Seychelles giant millipede on Cousine Island was equivalent to approximately 2.9 % of the litter standing crop and to approximately 11.0 % of the daily litter fall. The implications of these results for nutrient dynamics and soil fertility on Cousine Island are discussed. Seven types of surface behaviour were observed being performed by the millipede. More behavioural types were observed at night than during the day, with burrowing and grooming being exclusively nocturnal behaviours. The most commonly observed behaviours were walking and feeding. Movement was more evident in the males and immatures, whilst feeding was more apparent in the females. Less behavioural types were observed in areas of low vegetational heterogeneity and complexity. Vegetation disturbance also had an inhibitory effect on millipede behaviour. Possible explanations for these differences in behaviour are discussed. The implications of these results for the conservation of the Seychelles giant millipede and Cousine Island are also discussed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1999.
30

Use of space and activity rhythms of spotted-necked otters in the Natal Drakensberg.

Carranza, Ilaria d'Inzillo. January 1995 (has links)
The study was carried out in Kamberg Nature Reserve (Natal Drakensberg) from June 1994 to August 1995. Seven spotted-necked otters were fitted with an intraperitoneal radio-implant; radio-tracking was performed by both temporally independent locations and 24h continuous tracking sessions. When active, otters were always found in aquatic habitats, mainly dams, the river or oxbow lakes. Dense vegetation cover, as trees, reeds, and tall grass were preferred while resting. Otters were active both during the day and during the night, with peaks of activity at twilight. The amount of time spent in consecutive activity varied seasonally together with the main prey items exploited. Average home range area was 11.3km², including a stretch of river with an average length of 14.8 km. No intersexual nor intrasexual territoriality was detected. Intraspecific relationships varied with the dispersion and availability of food resources. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

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