Science Collected Works - Theses
Permanent URI for this collection
Search Results
1 - 10 of 110
-
Item
-
ItemSilurian trilobites of central Victoria(University of Melbourne, 1996)
-
ItemTerritorial behaviour and mating success in male New Zealand fur seals, Arctocephalus Forsteri(University of Melbourne, 1997)Fur seals are polygynous marine mammals that breed in high densities in terrestrial colonies. Female fur seals deliver and nurse their pups within the breeding colony and male fur seals fight vigorously to acquire and defend territories in the areas of breeding colony that are used by females. The breeding season is extended over 6-8 weeks and some males retain a territory within the breeding colony throughout the season, during which time they fast. Male fur seals are thought to have highly variable reproductive success relative to that of females; some males mate up to 30 times within one season and may hold a territory for several seasons, while others never mate. In contrast, females may produce a maximum of approximately 20 offspring in their lifetime. The factors underlying the mating success of adult male New Zealand fur seals, Arctocephalus forsteri, were examined at Cape Gantheaume, Kangaroo Island, South Australia. Individually marked adult male fur seals were observed whilst ashore during three annual breeding seasons and during the intervening non-breeding seasons. The territorial behaviour and mating success of individually marked adult male fur seals were measured over three successive breeding seasons (1992-1994) and terrestrial behaviour was also measured during the intervening non-breeding seasons. Data on morphology and age were also collected for each male. Larger males gained territories during the breeding seasons and male mass correlated with the duration of territorial tenure, but mass was not correlated with mating frequency among males that mated within their territories. The maximum mass of adult males was 160 kg. The age range of adult male seals was 7 - 15 years. The males that held territories following the birth of the first pup were older than the males that did not, but age was only correlated with mating success in one of the three breeding seasons. The youngest of these males was eight years old. All of the marked males visited the colony outside the breeding season. Some males simply hauled-out in the haul-out areas of the colony while some visited the territories that they had held during the previous breeding season that were within the sections of the colony used by females and pups (breeding areas). The males that visited their territories spent more time in social behaviour than those that were in the haul-out areas and also tended to spend less time resting. The behaviour of these males was also compared to that in their territories during the breeding season: outside the breeding season they spent more time resting overall but were significantly more alert during the mornings than they were during the breeding season. Males were more reluctant to leave their territories when threatened than they were to leave the haul-out areas. The terrestrial behaviour of males outside the breeding season was associated with mating success because males that visited their territories in the non-breeding season were more likely to hold a territory the following season than those that did not.
-
Item
-
ItemThe importance of Tetrarrhena juncea R. Br. in the ecology of Eucalyptus regnans stands in Sherbrooke Forest Park(University of Melbourne, 1985)The native, climbing grass Tetrarrhena juncea (forest wiregrass) exhibits unusually prolific growth in Sherbrooke Forest Park. The distribution and abundance of this species within stands of Eucalyptus regnans and related forest types was investigated in relation to the range of vegetation in order to elucidate factors responsible for this prolific growth. Computer based techniques of pattern analysis were used to describe and compare the range of variation in vegetation floristics and structure, and in environmental features within the E. regnans and related forest types, for an area of approximately 290 ha located in the western section of the park. The major themes of variation in the vegetation parallel a suite of environmental changes. These are the maturity of the E. regnans over storey, an underlying topographical moisture gradient and the levels of light which are likely to penetrate to the forest floor. The fire history of the area is such that the majority of sites may be arranged along a multivariate environmental gradient. Mature forests, with dense small tree strata generally occur in the wetter sites, while younger (spar) forests with less dense small tree strata occur in drier areas. However, a small proportion of spar stands are associated with riparian environments. Changes in the abundance of T. juncea parallel the multivariate environmental gradient; this species is least abundant in moist sites dominated by mature E. regnans and most abundant in the drier sites where spar-aged stands predominate. Whilst the environmental pattern present is characterised by a suite of characters, the majority of the variation (91%) in the cover of T. juncea within the study area may be accounted for in terms of the level of light which penetrates the combined cover of the small tree stratum and the ground fern Polystichum proliferum. The activity of lyrebirds and wombats was investigated in relation to the cover of T. juncea. Dense cover of T. juncea excludes lyrebirds from feeding in certain areas, but provides an important food source for a small population of wombats. Field trials showed that grazing by wombats has potentially damaging effects upon the structure and regenerative capacity of dense swards, suggesting that recurrent grazing is likely to limit sward formation. However, the wombat population was shown to be small and the effects of their grazing to be localised. The development of the dense swards in Sherbrooke Forest Park is discussed in relation to the likely effects of grazing upon the post-wildfire development of vegetation in even-aged stands of E. regnans and the increasing pressures of urbanisation of the Dandenong Ranges during the post-war period.
-
ItemX-ray optics using capillary arrays(University of Melbourne, 1992)
-
ItemIdentification and characterization of a style specific glycoprotein from Nicotiana alata Link et Otto(University of Melbourne, 1988)Monoclonal antibodies were raised to an extract from Nicotiana alata Link et Otto (genotype S1S3) styles. The cell lines which produced antibodies that bound to N. alata style extracts but which did not recognize AGPs were partially characterized and one cell line was chosen for further study. This cell line (cell line 58 (766)) secreted an antibody which specifically bound to a major style glycoprotein (120 kD). The antibody was directed to the carbohydrate moiety of the glycoprotein; binding between the antibody and style extract was preferentially inhibited by ?-D- Galp-(l?6)-D-Gal. The N. alata style component that bound the monoclonal antibody 58 (766) is style specific, but does not segregate with self-incompatibility genotype. It is localized in the extracellular matrix of the style and is concentrated in the top section of the style. The concentration of the 120 kD component is developmentally regulated, increasing with maturation of the style. A polyclonal antiserum raised to a commercial preparation of Solanum tuberosum (potato) tuber, lectin also binds to the 120 kD component and the possibility that the 120 kD component is a lectin was investigated. Although style extracts contained no haemagglutinating activity and the 120 kD component did not bind to either fetuin or chitin oligomers, the strong cross-reactivity between the anti-potato lectin antibody and the 120 kD component indicates at least partial structural homology. Approaches were also made to purify the 120 kD component. This component can be substantially purified using a combination of (NH4)2SO4 precipitation, and hydroxylapatite and immunoaffinity chromatography. The final preparation does not contain contaminating proteins or AGPs. However, the yield using this procedure is low and hence, other purification techniques were also investigated. Preliminary amino acid data has been obtained from material which was electroeluted from a SDS-polyacrylamide gel. The 120 kD component has a relatively high concentration of glycine, alanine, 1/2-cysteine and methionine, and a low amount of hydroxyproline and the basic amino acids, lysine, arginine and histidine. Finally, an algal biliprotein from the cryptomonad, Proteomonas sulcata was isolated and partially characterized. The purified pigment has a single absorption peak at 549 nm with a slight shoulder at 555 nm and a single fluorescent emission peak at 583 nm. It has two subunits with the apparent molecular weights of 11 kD and 19 kD on SDS-PAGE. This pigment is potentially useful as a fluorescent marker in immunocytochemistry.
-
ItemThe value of zoos : a quantitative assessment of the prevailing paradigm(University of Melbourne, 1998)The roles of zoological gardens in modem society is controversial. Zoos or 'menageries' of the past were for human entertainment. Animals did not behave like those in the wild and thus portrayed distorted images of wildlife. Under increasing pressure from welfare organisations (hereafter referred to as animal liberationists) and conservationists, the role of zoos is evolving. The release of 'The World Zoo Conservation Strategy' (WZCS) (International Union for Directors of Zoological Gardens (lUDZG) / Captive Breeding Specialist Group of lUCN/SSC (CBSG), 1993) articulated the commitment of modem zoos to play a role in species and habitat conservation, education, research, and recreation. Education is an essential role of modem zoos (lUDZG/CBSG, 1993) and it relies on zoos displaying animals that represent those in the wild. This study aimed to examine the status of zoos in Australia and New Zealand, with an emphasis on the modem zoos' aim of education (lUDZG/CBSG, 1993; Appendix A). It assessed a range of captive environments. These included 'typical' metropolitan zoos and the more modem approach to animal management represented at Victoria's Open Range Zoo at Werribee (VORZ). Visitors to the latter view savanna animals in more 'natural' surroundings during a safari tour which takes them amongst the animals. The educational value of exhibits was assessed by measuring animal behaviour and school students' perceptions of the animals. This employed a model zoo species from a savanna habitat; the Plains or Burchell's Zebra Equus burchelli. More general visitor attitudes to zoos and conservation were also investigated. The low intensive management of animals at VORZ allowed a large degree of 'natural' behaviour to be displayed, evident through the social organisation and behaviour, group dynamics, time budgets, and night behaviour of the animals. Hence this population potentially provided a valuable educational resource. In contrast, the behaviour of zebras in most metropolitan settings was characterised by unnatural time budgets (particularly feeding times), high levels of aggression, unnatural mare / stallion relationships, and restricted behavioural repertoires of stallions. These settings provided the animals with little control over their behaviour, which was largely influenced by a number of exhibit and husbandry characteristics. This indicated little potential educational value of the metropolitan animals and poor animal welfare. The VORZ exhibit, while more successful than Royal Melbourne Zoo (RMZ) at representing the 'real' animal and simulating an African savanna for students, did little to promote positive attitudes towards wild animals and their conservation, and to provide accurate knowledge of wild animals. A number of factors potentially limiting the educational value of the VORZ exhibit were discussed, including students holding traditional preconceptions of captivity, and the age of students. Zoo exhibits, irrespective of how 'natural' they are, may have limited educational impact if not complemented by appropriate educational aids. The RMZ exhibit did little to enhance student knowledge. It played a more traditional role, with evidence of students perceiving the animals as the 'exhibit', and the animals and their surroundings as 'unnatural'. Hence the RMZ exhibit did not play an educational role. Visitors to VORZ and RMZ largely supported the roles of zoos in educating visitors, helping conserve threatened animals, and providing a modern approach to animal management. VORZ was more successful than RMZ at promoting positive attitudes towards conservation and the role of zoos in conservation. Additionally, VORZ was perceived as a more appropriate environment for practicing conservation, through education and breeding threatened animals. Traditional attitudes towards zoos were also evident by visitors to both zoos. The present study suggested that open-range zoos, such as VORZ, are a positive step towards meeting the standards set by both the world zoo community (lUDZG/CBSG, 1993) and animal liberationists (World society for the protection of animals (WSPA) / The Born Free Foundation (BFF), 1994). However appropriate educational aids, such as the tour guide commentary at VORZ, may be essential to the value of 'naturalistic' exhibits. The contribution that metropolitan zoos can make to conservation, through exhibiting non territorial equids such as Plains zebras, is negligible. Typical' metropolitan zoos of today may have little potential to be education facilities, and must accept their current role as primarily entertainment. Zoos committed to increasing their conservation roles need to do more than simply develop more 'natural' exhibits. This study supports the need for specialisation of exhibits (lUDZG/CBSG, 1993; Chapter 1), such as sanctuaries for threatened species, native wildlife parks and open-range zoos. Metropolitan zoos need to improve educational tools for visitors, and to re-assess the purpose of exhibited species with respect to education. They must present an environment that evokes learning in an entertaining way. Recommended animal management and educational aids for all zoos committed to playing a role in conservation education are detailed, with particular emphasis on enhancing the educational value of exhibiting non-territorial equids.
-
ItemSuperoxide production, hypersensitive response and phytoalexin accumulation during interactions between tobacco and phytophthora isolates(University of Melbourne, 1998)Plant and animal cells challenged by pathogens undergo an oxidative, rapidly release active oxygen species (AOS) at the cell surface. Active oxygen species, including the superoxide anion and hydrogen peroxide, are involved in a range of environmental responses in plants, although their precise role in disease resistance remains unclear (Low and Merida 1996; Sutherland 1991). The aim of this study is to examine the relationship between superoxide release and plant disease resistance responses, including hypersensitive cell death and accumulation of the sesquiterpenoid phytoalexin, capsidiol, in infected tobacco cell suspension cultures. Preliminary studies have shown that race-cultivar specificity in whole plants is retained in suspension cultures (Able et al 1998). Suspension cell cultures of the near isogenic N. tabacum cultivars Hicks (susceptible) and NC 2326 (resistant) of this cultivars maintained on MS liquid medium at 24�C, were inoculated with zoospores of the Black Shank pathogen Phytophthora parasitica var. nicotianae and the non-host pathogen Phytophthora palmivora. Inoculated suspension cells were examined at regular intervals from inoculation until pathogen sporulation in compatible interactions (approximately 30 hours). Superoxide release was monitored by staining with nitroblue tetrazolium (NET) for 15 minutes before each observation. Inhibition of staining by superoxide dismutase or Mn(III)-desferal, indicates stain specificity for the superoxide anion. Phytoalexin accumulation was monitored using gas chromatography, and cell viability was monitored using hypertonic red staining. Cell suspension cultures of N. tabacum respond to inoculation with incompatible strains of Phytophthora parasitica var. nicotianae or Phytophthora palmivora by rapidly releasing the superoxide anion in a zone surrounding the infection court. Superoxide release, indicated by SOD-inhibited NET reduction, is more intense in incompatible or non-host interactions than in compatible interactions. Later defence responses in cell suspension cultures, including cytoplasmic aggregation, nuclear migration, hypersensitive cell death, deposition of lignin and callose and phytoalexin accumulation, are also more rapid and intense in incompatible interactions. This hypothesis was tested by blocking superoxide release using the naturally- occurring enzyme, superoxide dismutase (SOD), or its analogue, Mn(III)-desferal. When present during attempted penetration and host colonisation, both suppress NET staining and capsidiol accumulation. SOD is less active than Mn(III)-desferal, possibly because its size excludes intimate contact with the plant cell membrane, the putative site of superoxide release. This work supports the hypothesis that superoxide release plays a role in the activation of defence responses, possibly through its ability to cause host cell membrane damage, leading to hypersensitive cell death and other responses. Superoxide release appears to be a key link in the signalling cascade leading to the elicitation of phytoalexins and other defence responses in this interaction. Further studies will examine the mechanism by which superoxide release elicits host defence responses.
-
ItemThe evolution of cryptomonads and chlorarachniophytes(University of Melbourne, 1998)Cryptomonads and chlorarachniophytes are unicellular algae whose plastids are associated with a miniature nucleus called the nucleomorph. Both groups have acquired the ability to photosynthesise by engulfing and retaining a eukaryotic endosymbiont with a plastid. The nucleomorph is the highly reduced nucleus of the photosynthetic endosymbiont. Evolution and phylogeny within cryptomonads has not been well studied using molecular techniques. An 18S ribosomal ENA phylogeny of cryptomonads is presented here (chapter 2) . Cryptomonas sp. ?, the model organism for studies of cryptomonad plastid evolution and cell biology, is also characterised and confusion regarding its identity resolved (chapter 3). Although cryptomonads and chlorarachniophytes habour a eukaryotic endosymbiont with a plastid, the nucleus of this endosymbiont (the nucleomorph) does not appear to contain a complete complement of genes for photosynthesis-related proteins. Instead these genes are thought to have relocated to the host nucleus. I demonstrate that cryptomonad and chlorarachniophyte light-harvesting complex proteins are encoded in the host cell nucleus and are apparently targeted to the plastid. The plastid targeting mechanism of cryptomonad and chlorarachniophyte light-harvesting complex proteins is investigated (chapter 4). The possibility that chlorarachniophytes have host-encoded endosymbiont tubulins is also examined (chapter 5)