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Systematics and bionomics of the scorpions of South West Africa (Arachnida, Scorpionida)Lamoral, Bruno H. 22 September 2014 (has links)
All the taxa of scorpions previously described from South West
Africa are revised and a monographic account presented with phylogenetic
and biogeographic discussions and conclusions derived in terms of
current concepts in systematic zoology which include cladistics and
historical biogeography. South West Africa is treated as a subregion
of the Afrotropical region and the limits of this subregion coincide
broadly with the political borders. All the characters used are defined
and illustrated. Many characters previously unstudied for the fauna
are investigated. These include comparative studies of trichobothria
distributions and detailed structures of the hemispermatophore. Disc
electrophoresis of the haemolymph of a few species was carried out and
the results discussed. Ecological factors are extensively described
and discussed. The nature of the substratum, taken in its broadest
possible definition, was found to be the most important single factor
determining species distribution. 70 subgeneric taxa were revised, 45
of which are retained as valid, while 11 new species are described
bringing the number of known species to 56. These are distributed among
seven genera as follows: Buthotus, two species; Karasbergia, one
species; Parabuthus, 14 species; Urop1ectes, 10 species; Hadogenes,
three species; Lisposoma, two species; Opisthophthalmus, 24 species.
Determination keys are provided for all levels of taxa occurring in
South West Africa. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1978.
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Thermoregulation in breeding crowned plovers (Vanellus coronatus)Brown, Mark. 18 December 2013 (has links)
Ground-nesting birds nesting in the open have to cope with an extreme thermal environment.
Their nests egos and chicks are often located within the boundary layer and are exposed to,
direct solar radiation. In preventing eggs and chicks from overheating, adult incubating birds
expose themselves to severe heat loads. This study looked at two aspects of this system.
Firstly, we examined the role of behaviour in the thermoregulation of breeding crowned
plovers (Vanellus coronatus). We then examined the development of independent
thermoregulation in hatchling crowned plovers.
This study assessed the role of shading behaviour in the thermoregulation of
incubating crowned plovers (Vanellus coronatus). Shading behaviour was shown to have no
direct benefit for eggs, at times even causing eggs to rise close to lethal levels. Instead,
shading behaviour played an important role in maintaining incubating bird temperatures at a
constant level. We therefore suggest changing the term "shading" to "standing" behaviour.
In addition, core body temperatures of free-ranging adult incubating birds and their
eggs were examined on both a daily and a seasonal scale. A range of core bird temperature of
8.8° C was measured during the course of the study. Both daily and seasonal differences in
core bird temperature occurred. Daily differences are a result of daily circadian rhythms while
seasonal differences are explained by changes in ambient temperature. Both daily and
seasonal differences in egg temperatures also occurred. The concept of optimum incubation
temperature for a species is therefore reconsidered. Differences between and within species
may not be as a result of phylogenetic differences as previously reported, but may be as a
result of relatively short-term changes in response to ambient temperature changes.
The validity of using taxidermic models in thermoregulatory studies was assessed by
comparing data collected using both real and model birds. No direct correlations were found between real and model eggs and birds. This suggests that the patterns seen in models may
not adequately reflect short term changes that occur in the real system, thus reducing the
ability to use such data to make broad generalizations about thermoregulation in general. The
models are, however, useful in providing insight into the heat load an animal carries under
different environmental conditions, and in estimating the overall, long-term effects of metabolic heat production in a real bird and egg.
Secondly, we looked at the development of thermoregulation in a ground- nesting
shorebird. An issue of general importance with regard to the ontogeny of precocial chicks is
the timing of the onset of independent thermoregulation. We wanted to determine the mass at
which crowned plover (Vanellus coronatus) chicks are able to thermoregulate independently
in both the laboratory and the field, and to compare this to predicted values previously
reported. Laboratory reared chicks attained independent thermoregulation at a mass of 65 g,
while chicks in the field did so at a mass of 55 g. This is 33 - 39% of adult body mass, or
approximately twice that predicted for a 167 g shorebird chick. Development of
homeothermy represents a trade-off between growth rate and development of
thermoregulation. Efficient use of behavioural thermoregulation, coupled with predation
risks, allows more energy to be channelled into growth early on in the development of
crowned plover chicks. Development of homeothermy in anyone taxonomic group may not,
therefore, always be described by a single function. Instead , differences reflect a balance
between growth rate, development of physiological thermoregulation, use of behavioural
thermoregulation, predation risk, and environmental factors. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.
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Warning vocalisations and predator information transfer in social birds.Seoraj-Pillai, Nimmi. January 2008 (has links)
Alarm or warning vocalizations are produced by many animals when they detect a potential predator. However little is known about the information contained in these vocalizations. This study investigated the warning vocalisations of three passerine species, viz. the Buff-streaked Chat Oenanthe bifasciata, the Stonechat Saxicola torquata and the Bronze Mannikin Spermestes cucullatus. The study investigated whether the alarm calls for terrestrial predators differ in their acoustic structure from alarm calls emitted for aerial predators. Birds were exposed to latex terrestrial snakes and mounted aerial raptors, while changes in six acoustic parameters of alarm calls were measured. Bronze Mannikins were investigated for differences in intra-specific alarm calls between familiar and unfamiliar group members by capturing wild groups of mannikins and randomly mixing these to form assorted groups. Bronze Mannikins emitting warning calls were able to discriminate differences in predator size, and increased their calling rate and decreased the end frequency of the alarm call in response to larger predators. This may be the caller’s response to increased threat or variation in frequency may obscure cues to the caller’s whereabouts. Assorted group members were less aggressive to predator models than original members and panicked more during confrontations. Hence the unfamiliarity of the caller may have disrupted group cohesion. The alarm call acoustics of the social Buff-streaked Chats and the solitary Stonechat were compared to examine the effect of group-living on alarm behaviour. Snakes elicited louder calls from both the chat species than raptors. Louder and collectively more vocal social groups might be more successful in discouraging attacks than an asocial species. Variation in amplitude and call frequencies by the Stonechat provided some evidence that they are equally adapted to identifying predator type. Although Buff-streaked Chats increased their call rate in response to nearby predator models, Stonechats produced shorter calls in response to terrestrial predation particularly when the predators were in close proximity. Knowledge gained through direct encounters with predators or the ease with which raptors and snakes can gain access to nests may have played a part in discrimination of predator threat. Overall this study indicated strong correlations between some alarm acoustic parameters and predator size as well as the degree of threat. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2008.
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Aspects of the biology of the caracal (Felis caracal Schreber, 1776) in the Cape Province, South Africa.Stuart, Christopher Trevor. January 1982 (has links)
Felis caracal, despite heavy hunting pressure, is common
and widespread throughout the Cape Province. Caracal
are considered to be the principal wild predator of
domestic livestock (goats and sheep) by most farmers and
hunt clubs.
Scat and stomach content analysis, as well as observations,
indicate that F. caracal prey primarily on small to
medium-sized mammals. The feeding habits of caracal-in
different areas varied, according to abundance and
occurrence of prey species. Captive animals required
an average of 586g of meat each day. Killing techniques
varied for different sized prey items.
Physical and behavioural ontogeny are described for
captive born animals. A technique for determining age
of F. caracal was developed from study of known-age
captive caracal.
Examination of females killed in the wild, captive births,
and births which were back-dated indicated that although
young were born throughout the year, there was a definite
birth peak between October and February with the lowest
point being in May/June. Caracal were distinctly
sexually dimorphic in size.
Six F. caracal (four females and two males) were trapped,
fitted with radio-transmitters, and released at the
capture sites. Animals were cumulatively tracked for
a total of 164 weeks. The mean range was 24,16km².
A young adult male covered approximately 138km before
settling in a 48km² area.
Recommendations are presented for reducing losses of
domestic stock by the caracal, based on the principal
of removing the problem individual rather than blanket
control. / Thesis (M.Sc.)- University of Natal, Pietermaritzburg, 1982.
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Diet, home range and movement patterns of serval on farmland in Natal.Bowland, Jane Mary. January 1990 (has links)
Servals (Felis serval) are rare cats occurring in the Natal
midlands farmland, Drakensberg mountains and in game reserves
in Zululand. They are thought to be extremely uncommon on
farmland, yet are sometimes caught and killed in predator
control programmes. The objectives of this study were to
determine home range, habitat requirements, population density
and diet of servals and thereby propose management
recommendations for their conservation on farmland in the
Natal midlands.
Radio-telemetry was used to determine home range and habitat
requirements, while diet was determined using scat analysis.
Prey availability and vegetation changes in the habitat were
monitored seasonally.
Servals range over areas of 15-30km², but concentrate their
activity in wetland areas where their preferred prey, Otomys
irroratus, are most abundant. Over 90% of serval prey
comprises small mammals, which occur at high density in the
wetlands, but low density elsewhere in the study area. The
results of this project have highlighted the importance of
wetlands to farmland ecosystems. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1990.
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Habitat use by ungulates in Thanda Private Game Reserve, KwaZulu-Natal.Canter, Kirsten. January 2008 (has links)
Knowledge of habitat use and selection is essential to managing ungulate populations. This study assesses habitat use by elephant (Loxodonta Africana), giraffe (Giraffa camelopardalis), kudu (Tragelaphus strepsiceros), nyala (Tragelaphus angasii) and impala (Aepyceros melampus) in Thanda Private Game Reserve, KwaZulu-Natal. Firstly, I examine the effects of body size dimorphism, sexual segregation and predation on habitat selection and resource partitioning by ungulates. The mechanisms driving resource partitioning strategies were studied at three environmental scales, namely broader habitat (using habitat preference ratios), local environment (using Multi-Dimensional Scaling (MDS) and Analysis of Similarity (ANOSIM)) and plant (feeding heights using Analysis of Variance (ANOVA) and Regression analyses). At the habitat level, ungulates show distinct habitat preferences, independent of body size, which did not overlap, thus promote resource partitioning. Habitat selection, at the local environment level, varied among species but not between sexes. Therefore, body size class may influence selection for particular environmental characteristics. At the plant level, resource partitioning was evident among the larger species (giraffe and elephant) versus the smaller species (nyala and impala), but there was no apparent segregation among the sexes within species. Therefore, resource partitioning was strongest at the habitat level, bit less noticeable at the intermediate and finer plant scale. Secondly, I assessed the antipredator behaviour of multi-species assemblage in an experimental context (before vs. after lion reintroduction). I examined herbivore responses in terms of aggregation (forming safer groups), predator avoidance (selecting areas that predators avoid), and habitat selection in terms of habitat structure (selecting areas where capture is less likely), in response to lion reintroduction. Ungulates shifted habitats to avoid lion presence, i.e. into habitats least preferred by lion, and dominant species (based on body size) forced subordinate species into suboptimal habitats. However, counter predictions, ungulates did not increase their group size after lion were released. With the development of small private game reserves, intensive management is essential to maintain ecological heterogeneity, in this case through trophic cascades which promote coexistence. Managing ungulates as ecologically different according to body size will accommodate differences among herbivore populations. Long-term studies of habitat use by ungulates and predators will provide management with information to manipulate factors affecting habitat selection and predation, and thus sustainability of ungulate populations. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.
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Physiological aspects of torpor in the fat mouse (Steatomys pratensis, Dendromurinae)Richardson, Eleanor Judith. January 1990 (has links)
Several aspects of the physiology of the fat mouse Steatomys pratensis natalensis were studied in the laboratory using standard techniques and custom-made data-logging equipment. The fat was studied both from a morphological and functional point of view. The measurement of metabolic rates showed that euthermic S.pratensis have very low basal metabolic rates of 36% of expected, with torpor saving up to 69% of expended energy. Body temperatures, oxygen consumption, and activity patterns monitored over 24 hour periods with a data-logging system showed that Sipratensis have very low body temperatures of 31.3 to 35.0°C which fluctuate on a circadian rhythm with activity and oxygen consumption, all being lower during the day and higher at night. Torpor started very early in the morning and lasted for 5.5 to 11.7 hours. Huddling with a mate could reduce energy expenditure by 18%. Torpid body temperatures lay just above ambient from 15 to 35°C, below which all animals tried to arouse. Forced arousal at 10 to 30°C was slow and depended on ambient temperature while no mouse could arouse at O°C. Thermal conductance was 97.4 % of expected but cooling rates of dead S.pratensis were slow due to the heavy fat layer. Non-shivering thermogensis (measured after noradrenaline injection) was normal at 369% of BMR but maximum metabolism was twice as much, indicating other means of thermogenesis used additively with NST. Dissection showed extremely heavy fat deposits in the normal mammalian positions and also three additional deposits. Histological studies revealed most deposits as white fat but there was brown fat in the interscapular region. Soxhlet analysis showed an extremely wide range of body fat content from normal mammalian levels to contents higher than in hibernating rodents. Deprivation of food and water, or food alone, was found to induce torpor and cause the mice to become non-reproductive. Deprivation of water but not food, and deprivation of a cage mate, triggered torpor in only 40 - 44% of the cases studied. The mice took 5 to 12 days to lose 30% of their mass, but theoretically could survive longer. Weekly measurements showed no annual mass fluctuations in the laboratory but the mice became reproductively active mid-summer to early winter while torpor was at a maximum around late winter. All animals showed torpor, young more than adults and females more than males. It is suggested that the low body temperature and metabolism of S.pratensis may have evolved to prevent overheating caused by their inability to lose heat through the heavy fat layer. The species could then disperse into areas where their low energetic demands would permit them to compete successfully with high metabolic rate rodents. / Thesis (M.Sc.)-University of Natal, Durban, 1990.
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A preliminary investigation into the status, distribution and some aspects of the foraging ecology of the southern ground hornbill (Bucorvus cafer) in Natal.Knight, Gary Malcolm. January 1990 (has links)
A study on the distribution, status and selected aspects of
the foraging ecology of B. cafer in Natal, was undertaken
from January 1989 to December 1990.
A census was initiated to assess the distribution of B.
cafer in Natal. 436 sightings were reported from 187 locations.
B. cafer occurs throughout Natal, except in the far
northwestern regions. A population estimation based on this
census suggest that between 300-350 B. cafer individuals exist
in Natal, excluding KwaZulu regions. The large area occupied
by KwaZulu and the protection of this species by Zulu
folk law, suggest that the population may be considerably
larger.
Selected aspects of the foraging ecology of the two study
groups in the Natal midlands were examined, focusing on the
role that individuals play in provisioning the nestling,
nest bound female and fledgling.
B. cafer are predominantly carnivorous. They are able to
utilise habitats used for a wide variety of agricultural
practices. The major criteria, in terms of habitat selection,
being a short (0.5 m) or sparse ground cover. Younger
birds were less successful than older individuals at digging
and probing for food. Foraging success rate of the juvenile
increased from 7.2% prior to nesting, to 51.2% during nesting.
The acquisition of foraging skills, particularly digging
and probing, takes time and experience.
Frogs were the major food item fed to the nestling and nest
bound female. The presence of helpers reduced the amount of
feeding by parent birds. Helpers in the stainbank group supp
plied 25% of food bundles to the nest. The juvenile did not
act as a helper. Subadults helped most during the periods
when the demand for food delivery to the nest was highest,
and at the end of the nesting period. Helpers reduced the
amount of time that the dominant female spent away from the
nest during incubation and early nestling phase. Once the
female left the nest, the male reduced his food delivery
rate. An abundance of frogs, close to the nest, enabled a
single pair to adequately provision a nestling. The parent
birds provisioned the fledgling until the following breeding
season. / Thesis (M.Sc.)-University of Natal, 1990.
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The breeding and reproductive biology of the vlei rat Otomys irroratus.Pillay, Neville. January 1990 (has links)
The breeding and reproductive biology of the vlei rat Otomys irroratus representing three allopatric populations (Committee's Drift, Hogsback and Karkloof) have been studied in the laboratory. The study attempted to establish whether the three populations differed in respect of selected reproductive parameters, and whether the populations are reproductively isolated from one another. The breeding biology of the Hogsback and Karkloof populations was similar while the Committee's Drift population differed from the other two in respect of its smaller litter size and increased interval between pairing and the production of the first litter. Pre-copulatory behaviour differed among populations, with a gradation of increasing intersexual aggression from Hogsback to Karkloof to Committee's Drift pairs. Postnatal growth and development patterns, as well as male reproductive morphology, were indistinguishable among the populations. Attempts at interpopulation breeding were successful. However, some hybrids died before weaning, while those that survived beyond weaning were sterile, particularly those resulting from cross-matings of Hogsback animals with individuals representing the other populations. Interpopulation pairs displayed higher levels of agonistic interaction than did the pure pairings. Growth and development and the reproductive morphology of male hybrids were indistinguishable from those of the parental populations. Interpopulation reproductive variation in o. irroratus appears to be due to a combination of environmental and phylogenetic constraints. 80th pre- and post-zygotic isolating mechanisms would impede gene flow between the populations should they meet in nature. All populations appear to be undergoing active speciation. / Thesis (M.Sc.)-University of Natal, Durban, 1990.
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The effect of different diets on the reproduction of two species of mosquitoes, Aedes aegypti and Culex pipiens.Spencer, Jennifer Ann. 11 November 2013 (has links)
Larvae of Culex quinquefasciatus and Aedes aegypti were raised on five
different diets and the effects thereof on various parameters was studied.
The diets used were: A = Pronutro and Tastee wheat, B = Epo 1 rat cubes,
C= Breeder's Dogmor puppy chunks, D = Vital Brewer's yeast powder and
E (the control) = Vital dessicated liver. The following results were obtained.
1. Fecundity appeared not to be affected by diet in both species. 2. Fertility did not appear to be affected by diet either. 3. Diets C and D significantly shortened the duration of the larval stage in C. quinquefasciatus when compared with the control Diet E. In A. aegypti diets B, C and D produced larval periods that were significantly shorter than the control. 4. The pupal stage in C. quinquefasciatus in diets C and D was also. Significantly shorter than that of the control diet E. In A. aegypti only diet B produced a pupal stage that was significantly shorter than the control. 5. Larval mortality was significantly higher than the control diet E in C. quinquefasciatus in diet group A. There was no significant differences between the experimental diet groups A to D and the control, in A. aegypti. 6. Pupa 1 mortality appeared to be unaffected by larval diet in both species. 7. Larval diet did not affect adult mortality either. 8. In C. quinquefasciatus the size of the ovaries was significantly smaller than the control in diet group B. Ovary size appeared to be unaffected by larval diet in A. aegypti. 9. Sex ratio appeared to be greatly affected by larval diet. There were significantly more males than females in diets D and E in Culex quinquefasciatus and in diets C and E in Aedes aegypti. 10. Oogenesis also appeared to be affected by larval diet. In C. quinquefasciatus oogenesis was found to be slower from 36 hours PBM in diet A. In A. aegypti oogenesis was slower in diets A and B from 60 hours PBM. The rate of oogenesis in C. quinquefasciatus was also found to be slower, than that in A. aegypti. / Thesis (M.Sc.)-University of Durban-Westville, 1987.
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