Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2005. / Includes bibliographical references (leaves 49-51).

TELLES, Margareth Maria. Características fermentativas e valor nutritivo de silagens de capim-elefante contendo subprodutos do urucum, caju e manga. 2006. 130 f. Tese (doutorado em Zootecnia)- Universidade Federal do Ceará, Fortaleza-CE, 2006. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-04-19T19:32:50Z No. of bitstreams: 1 2006_tese_mmtelles.pdf: 612422 bytes, checksum: c80d63681a855fb7d8cbe000e31df740 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-05-27T17:42:37Z (GMT) No. of bitstreams: 1 2006_tese_mmtelles.pdf: 612422 bytes, checksum: c80d63681a855fb7d8cbe000e31df740 (MD5) / Made available in DSpace on 2016-05-27T17:42:37Z (GMT). No. of bitstreams: 1 2006_tese_mmtelles.pdf: 612422 bytes, checksum: c80d63681a855fb7d8cbe000e31df740 (MD5) Previous issue date: 2006 / This research was carried out at the Forage Research Sector – NPF/DZ/CCA/UFC. The chemical and fermentative characteristics elephant grass silages with increasing levels of annatto by-product processing (ABP) addition at ensiling were evaluated. The following treatments were used: T1 – Elephant grass silage, T2 - Elephant grass silage with 4% of annatto seed by-product processing (ABP), T3 - Elephant grass silage with 8% of ABP, T4 - Elephant grass silage with 12% of ABP and T5 - Elephant grass silage with 16% of ABP, on a fresh matter basis. A randomized completely design with four replicates was adopted. As experimental silos, plastic drums of 210 L were used. The dry matter (DM), the organic matter (OM), the crude protein (CP), the neutral detergent fiber (NDF), the acid detergent fiber (ADF), the hemicelluloses, the ether extract (EE), the total carbohydrates (TC), the non-fibrous carbohydrates (NFC), the neutral detergent insoluble nitrogen (NDIN,% total N), the acid detergent insoluble nitrogen (ADIN, % total N), the pH values, the ammonia nitrogen (in percentage of the total nitrogen, N-NH3, % total N), the lactic acid, the acetic acid, the butyric acid and the propionic acid levels were determined. A linear increasing effect (P<0.01) of the ABP addition on the DM, OM, CP, EE, NFC, acid propionic levels and on the pH values was verified. There was no significant difference among the silages on the hemicellulose, NDIN (% total N), lactic acid,acetic acid and acid butyric levels. With regard to ADIN (% total N) and N-NH3 (% total N) there was a quadratic effect and to NDF, ADF and TC a decreasing linear effect of the ABP addition was observed. One concludes that ABP improves the chemical and fermentative characteristics of the silages, recommending 16% of addition, in a fresh matter basis, at the elephant grass ensilage. / Esta Pesquisa foi conduzida no Núcleo de Pesquisa em Forragicultura-NPF no Departamento de Zootecnia do Centro de Ciências Agrárias da Universidade Federal do Ceará (UFC), em Fortaleza, CE. Avaliaram-se as características bromatológicas e fermentativas das silagens de capim-elefante contendo níveis crescentes de adição do subproduto do processamento do urucum (SPU), à ensilagem. Foram testados os seguintes tratamentos: T1 – silagem de capim-elefante, T2 – silagem de capimelefante com 4% de SPU, T3 – silagem de capim-elefante com 8% de SPU, T4 – silagem de capim-elefante com 12% de SPU e T5 – silagem de capim-elefante com 16% de SPU, com base na matéria natural. Utilizou-se um delineamento inteiramente casualizado com quatro repetições. Como silos experimentais, foram utilizados tambores plásticos de 210 L. Determinaram-se os teores de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), hemicelulose, extrato etéreo (EE), carboidratos totais (CHOT), carboidratos não fibrosos (CNF), nitrogênio insolúvel em detergente neutro (NIDN, % do N total), nitrogênio insolúvel em detergente ácido (NIDA, % do N total), os valores de pH e teores nitrogênio amoniacal (N-NH3, % do N total), ácido lático, acético, propiônico e butírico. Verificou-se efeito linear crescente da adição de SPU sobre os teores de MS, MO, PB, EE, CNF, valor de pH e teor de ácido propiônico. Não foi verificada diferença significativa entre as silagens quanto aos teores hemicelulose, NIDN (% do N total), ácido lático, acético e butírico. Para NIDA (% do N total) e N-NH3 (% do N total) houve efeito quadrático e para FDN, FDA e CHOT observou efeito linear decrescente em função da adição do SPU. Conclui-se que o SPU melhora as características bromatológicas e fermentativas das silagens, recomendando-se a adição de 16%, na matéria natural, no momento da ensilagem do capim-elefante.

Made available in DSpace on 2014-06-12T16:00:28Z (GMT). No. of bitstreams: 2 arquivo6669_1.pdf: 1298139 bytes, checksum: 82c0aa9def52f663c245e3f57be952ef (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2007 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The Transmission Control Protocol (TCP) is responsible for supplying reliable data transport service on the TCP/IP stack and for carrying most than 90% of all Internet traffic. In addition, the stability and efficiency of the actual TCP congestion control mechanisms have been extensively studied and are indeed well known by the networking community. However, new Internet applications and functionalities continuously modify its traffic characteristics, demanding new research in order to adapt TCP to the new reality of the Internet. In particular, a traffic phenomenon known as "mice and elephants" has been motivating important researches around the TCP. The main point is that the standard TCP congestion control mechanisms were designed for elephants leading small flows to experience poor performance. This is caused by the exponential behavior of Slow Start which often causes multiple packet losses due their aggressive increase. This work examines minutely the problems caused by the standard TCP congestion control to mice flows as well as it studies the most important proposals to solve them. Thus, based on such research studies, a modified TCP startup mechanism was proposed. The Burst TCP (B-TCP) is an intuitive TCP modification that employs a responsive congestion window growth scheme based on the current window size, to improve performance for small flows. Moreover, B-TCP is easy to implement and requires TCP adjustment at the sender side only. Simulation experiments show that B-TCP can significantly reduce both transfer times and packet losses for small flows without causing damage to large flows

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Esta Pesquisa foi conduzida no NÃcleo de Pesquisa em Forragicultura-NPF no Departamento de Zootecnia do Centro de CiÃncias AgrÃrias da Universidade Federal do Cearà (UFC), em Fortaleza, CE. Avaliaram-se as caracterÃsticas bromatolÃgicas e fermentativas das silagens de capim-elefante contendo nÃveis crescentes de adiÃÃo do subproduto do processamento do urucum (SPU), à ensilagem. Foram testados os seguintes tratamentos: T1 â silagem de capim-elefante, T2 â silagem de capimelefante com 4% de SPU, T3 â silagem de capim-elefante com 8% de SPU, T4 â silagem de capim-elefante com 12% de SPU e T5 â silagem de capim-elefante com 16% de SPU, com base na matÃria natural. Utilizou-se um delineamento inteiramente casualizado com quatro repetiÃÃes. Como silos experimentais, foram utilizados tambores plÃsticos de 210 L. Determinaram-se os teores de matÃria seca (MS), matÃria orgÃnica (MO), proteÃna bruta (PB), fibra em detergente neutro (FDN), fibra em detergente Ãcido (FDA), hemicelulose, extrato etÃreo (EE), carboidratos totais (CHOT), carboidratos nÃo fibrosos (CNF), nitrogÃnio insolÃvel em detergente neutro (NIDN, % do N total), nitrogÃnio insolÃvel em detergente Ãcido (NIDA, % do N total), os valores de pH e teores nitrogÃnio amoniacal (N-NH3, % do N total), Ãcido lÃtico, acÃtico, propiÃnico e butÃrico. Verificou-se efeito linear crescente da adiÃÃo de SPU sobre os teores de MS, MO, PB, EE, CNF, valor de pH e teor de Ãcido propiÃnico. NÃo foi verificada diferenÃa significativa entre as silagens quanto aos teores hemicelulose, NIDN (% do N total), Ãcido lÃtico, acÃtico e butÃrico. Para NIDA (% do N total) e N-NH3 (% do N total) houve efeito quadrÃtico e para FDN, FDA e CHOT observou efeito linear decrescente em funÃÃo da adiÃÃo do SPU. Conclui-se que o SPU melhora as caracterÃsticas bromatolÃgicas e fermentativas das silagens, recomendando-se a adiÃÃo de 16%, na matÃria natural, no momento da ensilagem do capim-elefante / This research was carried out at the Forage Research Sector â NPF/DZ/CCA/UFC. The chemical and fermentative characteristics elephant grass silages with increasing levels of annatto by-product processing (ABP) addition at ensiling were evaluated. The following treatments were used: T1 â Elephant grass silage, T2 - Elephant grass silage with 4% of annatto seed by-product processing (ABP), T3 - Elephant grass silage with 8% of ABP, T4 - Elephant grass silage with 12% of ABP and T5 - Elephant grass silage with 16% of ABP, on a fresh matter basis. A randomized completely design with four replicates was adopted. As experimental silos, plastic drums of 210 L were used. The dry matter (DM), the organic matter (OM), the crude protein (CP), the neutral detergent fiber (NDF), the acid detergent fiber (ADF), the hemicelluloses, the ether extract (EE), the total carbohydrates (TC), the non-fibrous carbohydrates (NFC), the neutral detergent insoluble nitrogen (NDIN,% total N), the acid detergent insoluble nitrogen (ADIN, % total N), the pH values, the ammonia nitrogen (in percentage of the total nitrogen, N-NH3, % total N), the lactic acid, the acetic acid, the butyric acid and the propionic acid levels were determined. A linear increasing effect (P<0.01) of the ABP addition on the DM, OM, CP, EE, NFC, acid propionic levels and on the pH values was verified. There was no significant difference among the silages on the hemicellulose, NDIN (% total N), lactic acid,acetic acid and acid butyric levels. With regard to ADIN (% total N) and N-NH3 (% total N) there was a quadratic effect and to NDF, ADF and TC a decreasing linear effect of the ABP addition was observed. One concludes that ABP improves the chemical and fermentative characteristics of the silages, recommending 16% of addition, in a fresh matter basis, at the elephant grass ensilage

Most elephants in South Africa live in enclosed areas such as the Tembe Elephant Park in Maputaland. The Park also protects sand forest. This can create a conflict of interest as elephants may influence species typical of these forests. To assess the effects that elephants may have for vegetation, I compare variables of similar plant communities inside and outside the Park. I then compared the space and landscape utilization of elephants living in the Park with those of free-ranging elephants living in southern Mozambique. In the final analyses, I used meta-analytical methods to interpret my findings. Woody seedlings showed no measurable response to tree canopies that elephants have altered, but the response of grasses and woody saplings depended on the landscape type. In closed woodlands, elephants generated gaps in the canopy layer that increased structural heterogeneity. These gaps favoured the establishment of grasses, and along with herbivory, may have been responsible for reduced occurrence of woody saplings. In the open woodlands, elephants and frequent hot fires in the Park apparently homogenised this landscape. In this case, altered tree canopies reduced grass and woody sapling presence. The species compositions of sand forests, closed woodlands and open woodlands between inside and outside the Park differed. However, tree and shrub densities, their abundance-incidence and rank-abundance relationships were similar for a given landscape inside and outside the Park. Ecological events operating at larger scales, such as seed dispersal and droughts, mask the influence elephant have for these community variables. Elephants in the Park had smaller home ranges than free-ranging elephants living in southern Mozambique. The size of these home ranges were however, similar to that predicted by rainfall, as suggested by my analysis of data collected across southern Africa. The elephants that roamed freely in southern Mozambique prefer closed woodlands throughout the year. However, elephants confined to the Park avoided reed beds (with natural surface water) in the dry season and showed no landscape preference in the wet season. My meta-analysis on the effects of elephants on other taxa included 230 peer-reviewed studies. These were published over a 40-year period and included information from 74 sites. From only those studies used in the effect size calculations, when conducted over a period of less than 5 years show a negative impact while those conducted over longer periods show a neutral effect. Site-specific differences, such as rainfall, may also influence the effect elephants have for plants. Twenty of the 230 studies shared more than 50% of all citings. The majority (16 of the 20) claimed that elephants had a negative influence for plants. This is in contrast with the findings of all studies included in the analysis – half of these concluded a positive effect and the other half a negative effect. In short, elephants do not decrease the diversity of other species present in the system, despite their adverse effects for individual trees. Elephants affect ecosystems at small scales. Providing an opportunity for elephants presently living in Tembe Elephant Park to disperse across their former ranges may negate negative influences on sensitive vegetation in the Park. / Thesis (PhD (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

The aim of this study was to define the ovarian follicular reserve of wild African elephants in terms of its type of small follicles (SF), its establishment and distribution throughout the ovaries, and the change in numbers of SF in the embryo and fetus as well as throughout prepubertal and adult life. The large elephant population in Zimbabwe provided the opportunity to collect ovaries from elephants culled for management reasons and hunted professionally. In total, gross morphological and histological studies were done on the gonadal ridges from 5 embryos (76–96 days post conception) and ovaries from 11 fetuses (4.8–22.2 months), 29 prepubertal females (2 months–10 years), 24 adult females (11–55 years) and 7 aged females (56–70 years). Specimens were fixed in 4% buffered formalin before a series of 25 ìm thick sections were cut and examined using stereological protocols to count SF numbers in each section and thereby calculate the follicle reserve of the whole ovary. Prior to counting SF numbers, their distribution throughout the ovary was studied and the repeatability of counts was validated. Numbers of SF were highest in mid-term fetuses, lower in fetuses during the second half of gestation, even lower in calves younger than 4½ years, whereas the numbers in calves aged 4½–9 years were significantly higher than those in younger calves, and similar to what they were in late-term fetuses. The numbers of SF were substantially and highly significantly lower in elephant 10–15 years in age compared to calves aged 4½9 years, suggesting a reduction around puberty. Thereafter the ovarian reserve fell steadily until depletion around the age of 70 years. During adult life the ovarian reserve was composed of early-primary (EP) and true-primary (TP) follicles. By 45 years of age only TP follicles remained although these enabled oestrous cyclical activity for many more years; of 7 sets of ovaries recovered from females aged 57–70 years, 6 showed evidence of cyclical activity or pregnancy within the preceding 6 years. The study shows that EP and TP form the follicular reserve from before birth until 45 years, with TP forming the reserve thereafter, which depletes in some old elephants and persists to maximum life span in others. / Thesis (PhD)--University of Pretoria, 2012. / Production Animal Studies / unrestricted

This study, undertaken under the auspices of the Centre of Wildlife Management and the former Centre for Indigenous Knowledge (University of Pretoria) was conducted in Maputaland, with special reference to the Tembe Elephant Park, Sileza Nature Reserve and in the neighbouring traditional wards (izigodi) of Mbangweni, Bhekabantu, Kwandaba, Zama-zama, Tsokotho, Manqakulani (which includes the Tshanini Community Conservation Area), Lulwane, Mntikini, Ndlondlweni, Ndovu and Sibonisweni. The main objective of this study was to evaluate the range condition and grazing capacity of the natural veld. A management plan for the Tshanni Community Conservation Area is presented, which could potentially serve as template for similar areas. To accomplish these objectives a cattle as well as a vegetation survey were conducted. The cattle surveys were conducted among the local communities (mentioned above) to identify and to evaluate the role played by cattle in the everyday lives of the communual people and to identify the types of grazing regime (practices). The vegetation surveys were undertaken to evaluate the range condition, grazing capacity and grazing quality of the herbaceous vegetation. The study also included methods to determine the number, distribution and health status of cattle present in the study area. The results indicated that social and religious values that were associated with cattle in the older Zulu culture have clearly faded in the Tembe Traditional Area. The current values of local communal people regarding cattle were concentrated on utilization and investment for future uncertainties. Cattle were still seen as wealth and status symbols in the local communities and were highly prized possessions if they could be obtained. The official cattle numbers did not seem to reflect the actual cattle numbers in the study area at the time of study. It was also clear that cattle were distributed in areas where the water supply was sufficient. The main grazing areas were thus in the east of the study area in the hygrophilous vegetation to the east of Manqakulani and mainly in Ndlondlweni. No specific grazing management practices could be identified and the grazing system could be best described by a continuous grazing practice. Grazing was not restricted to any part or piece of land inside the specific isigodi as long as the cattle stayed out of other people’s cultivated land. Overstocking the grazing area was not occurring at the time of the study as the stocking density was well below the area’s capacity. The general perception of the majority of the cattle owners was that their cattle were in a good condition. An analysis of the results obtained from the vegetation survey indicated that the herbaceous biomass yield did not vary noticeably among the management units within a site as well as among the different sites. The small fuel loads in the Tshanini Community Conservation Area did not necessitate burning and were probably below fuel loads needed for fires to spread. However, it was frequently observed that fire could be maintained in areas where the herbaceous biomass yield was below 2 000 kg/ha. The results represented in this study also indicated that the management units of the Tshanini Community Conservation Area were generally in a good condition and that the range condition of the Tshanini Community Conservation Area compared relatively well with the other reserves in the study area. The modified Ecological Index Method was reliable and time saving, yet simplistic enough for assessing the range condition of the management units of the Tshanini Community Conservation Area and the entire Tembe Traditional Area. The stocking density must be adaptable and based on the quantity and quality of grazing available at any time. The model that was used to calculate the stocking density of the study area allows for several elements to be modified to suit the conditions on a particular wildlife reserve at a particular time. For example, in future it may become necessary to adjust the percentage composition of graze and browse in the diet of some animal types for the calculation of Grazer Units (GU) and Browser Units (BU), mainly because the diet of the same type of animal may vary regionally. Finally, changes in the choice of the types of wildlife can be accommodated depending on the preferences and objectives of the management and steering committee of the Tshanini Community Conservation Area. This model can be applied as a tool for active adaptive management because it allows more control over the quantity and quality of available food plant resources and hence the stocking density of animal resources. It is proposed that the results of the present study be combined and integrated into a Geographic Information System (G.I.S.) database that could form the ecological basis for future management planning of the Tembe Traditional Area as part of the Usuthu-Tembe-Futi Transfrontier Conservation Area. / Dissertation (MSc)--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

When elephants leave primary protected areas (PPAs), such as national parks and game reserves, they may come into conflict with people residing on the adjoining land. In this study, I attempted to determine why African savannah elephants leave the PPAs in which they were collared. To accomplish this, I used telemetry locations of collared elephants in PPAs throughout southern Africa and investigated whether a range of intrinsic and extrinsic variables could explain why elephants crossed the boundaries of the PPAs. Adjoining many of the PPAs were secondary protected areas (SPAs), which consisted of community conservancies, and collectively with the PPAs formed clusters of protected areas. Most (45 of 49) elephants roamed beyond the PPAs but they remained within the clusters of protected areas. The elephants utilised both the PPAs and the SPAs and appeared to not feel threatened when using the SPAs. The reasons for elephants leaving PPAs varied both seasonally and between the sexes. The females roamed beyond the PPAs more during the wet season than the dry season, whereas, for males there was no seasonal difference. During the wet season, female and male habitat selection was similar within and beyond the PPAs. During the dry season, more females and males beyond the PPAs selected for areas close to people, which could be indicative of water. The proportion of male and female home ranges beyond PPAs did not increase with increasing density of elephant populations within the PPAs, nor did the proportion of female home ranges beyond PPAs increase with increasing population growth rate of elephant populations within the PPAs. Therefore, high numbers of elephants within the PPAs did not drive elephants beyond the boundaries. Contrastingly, the proportion of male home ranges beyond the PPAs did increase with increasing population growth rate. However, the results were inconclusive due to small sample size. This study confirms that elephants are utilising the SPAs as well as the PPAs. Therefore, the importance of including the SPAs in conservation actions for elephants cannot be over-emphasized. / Dissertation (MSc)--University of Pretoria, 2013. / Zoology and Entomology / unrestricted

The GnRH vaccine may offer an alternative to the current immunocontraceptive method in elephant cows which uses native porcine zona pellucida proteins derived from abattoir slaughtered pigs as the immunogen, greatly limiting its availability. The pZP vaccine is stored at -20 °C and must be mixed with an adjuvant before use. The GnRH vaccine Improvac® is commercially available, already contains the adjuvant and can be stored at 4 °C. The aim of this study was to evaluate the efficacy of the gonadotrophin releasing hormone (GnRH) vaccine Improvac® (Pfizer Animal Health, Sandton, South Africa) in the induction of anoestrus in elephant cows. The Improvac® was administered to eight adult, female, healthy, free-ranging elephants, located in Entabeni Private Game Reserve in the Limpopo Province, South Africa. Another four cows were left untreated and served as controls. The monitoring of the experimental population was conducted over a twelve-month observation period via non-invasive faecal steroid analysis. Progesterone metabolites in extracted samples were measured by Enzyme Immunoassay (EIA) to determine luteal activity and thus the effect of the GnRH vaccine on the endocrine correlates. This study started with a three-month control period prior to vaccination when faeces were collected from each study animal, as soon as possible after defecation to ensure positive identification of the individual with its sample. The three-month period was followed by the immunization protocol. The elephants all received a primary, followed by a booster vaccination dose five weeks later. Each dose of 3 ml contained 600 ìg of RnRF-protein conjugate; both treatments were applied via remote delivery. Monitoring continued until the end of the twelve-month observation period. Observations of oestrous behaviour during the twelve-month period were also recorded. The results showed no statistical difference between treated and control females. There was, however, marked individual variation in response to GnRH immunization. This was possibly influenced by physiological and environmental factors such as age, where the youngest cows showed a better response in terms of reduced progestagen secretion; as well as season, where progestagen levels increased 1.3 times during the rainy season compared to the dry season. There was no association between average progestagen concentration and social hierarchy ranking. A high percentage (86.48%) of behaviours that could be related to oestrus coincided with the onset of the luteal phase and a subsequent rise in progestagen concentrations. All the females (treated and control) showed some evidence of ovarian cyclicity during the study, although 75% of the cycles did not fall within the normal 13-17 week oestrous cycle range reported, suggesting that abnormal cycles are a common reproduction irregularity inherent to non-pregnant wild African elephants. Further research to determine the optimal vaccination protocol is indicated in order to obtain consistent responses to the vaccine that will provide an efficient and safe contraceptive for use in female African elephants. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Production Animal Studies / unrestricted

The southern elephant seal (SES), Mirounga leonina, was intensively harvested during the 18th and 19th centuries, though never reduced to the levels seen for the northern species (Mirounga angustirostris). Although a number of putative populations occurring within the species’ circumpolar distribution in the Southern Ocean have been genetically assessed, no data was previously available for the Marion Island population. This study integrates Marion Island into the broader database by genetically profiling individuals with 9 microsatellite DNA loci (n = 73) and a single mitochondrial DNA (mtDNA, n = 68) locus corresponding to hypervariable region I (HVRI) of the non-coding displacement loop (D-loop). These data were then combined with existing haplotype datasets from five island populations, namely Heard Island, Peninsula Valdés, Macquarie Island, South Georgia, Elephant Island, and Sea Lion Island breeding colonies, and with comparable microsatellite typing data from four populations, namely Peninsula Valdés, South Georgia, Elephant Island and Sea Lion island, respectively, permitting inter-population level comparisons. Genetic variation of the Marion Island population was high for both microsatellite and mtDNA and consistent with levels previously reported for the other populations, with the exception of Peninsula Valdés (Argentina) where diversity levels are low. Forty polymorphic sites defined 44 mtDNA haplotypes from 68 Marion Island individuals. Of the 44 sequence haplotypes, three were shared with Sea Lion Island, one with Elephant Island, two with Heard Island and one with Macquarie Island. From the microsatellite data, it was found that Marion Island, like most other SES populations, had no private alleles. The one exceptional population is that at Sea Lion Island which has several private alleles at two loci. Marion Island was significantly differentiated from each of the other breeding colonies included in the study based on FST analyses for both microsatellite and mtDNA data. The magnitude of genetic differentiation between Marion Island and the South Georgia, Sea Lion and Elephant Islands was somewhat higher than that previously reported when the latter three islands were compared, but considerably less than the differentiation found between Marion Island and either Peninsula Valdés or Macquarie Island. Though the two markers showed similar trends with respect to population structuring, the pairwise differentiation at microsatellite loci was an order of magnitude lower than that of mtDNA, suggesting more frequent male-mediated gene flow between putative populations than female-mediated gene flow. Higher male dispersal was also confirmed by migration rate estimates from the microsatellite data compared to estimates from the mtDNA locus. These data are consistent with the earlier interpretation that most putative island populations show moderate levels of differentiation not directly related to geographic distance, while the mainland population in Argentina and the population at Macquarie Island stand out as being highly differentiated from the rest. / Dissertation (MSc)--University of Pretoria, 2008. / Zoology and Entomology / unrestricted