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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.
11

The Origins Of Lactase Persistence And Ongoing Convergent Evolution

Keller, Beth A 01 January 2011 (has links)
As a primary factor in human evolution, natural selection is an important component of genetic research. Studies of lactase persistence suggest that positive selection has played a powerful role in the adaptation to a lifelong consumption of fresh milk. Using multiple research studies of lactase persistence and suspected corresponding single nucleotide genetic polymorphisms, this study combines data sources to determine whether evidence exists for natural selection of a specific cytosine-to-thymine genetic mutation located 13,910 base pairs (T-13910) upstream from the lactase gene. This polymorphism has potential to be a causal element for lactase persistence, and data suggest that natural selection has played a role in the rising frequency and distribution of this allele, if only in some regions. European and neighboring regions appear to have the highest frequencies with little or no frequency in Asia, Africa and Indonesia; however the presence of lactase persistence in those areas suggests convergent evolution may be occurring on a phenotypic level. To examine this possibility several other identified polymorphisms in the same region as the T-13910 will be included in this study
12

Pastoralism and the transformation of the rangelands of the South Island of New Zealand 1841 to 1912 : Mt Peel Station, a case study

Peden, Robert L, n/a January 2007 (has links)
The transformation of the rangelands of the South Island of New Zealand during the pastoral era fits into the wider international context of European expansion into the 'new' world. European settlers displaced native peoples, introduced 'old' world animals and plants, and imposed a capitalist system that converted local resources into international commodities. In New Zealand the orthodox explanation of the pastoral impact on the rangelands claims that pastoralists introduced an unsustainable system of land use to the region. The pastoralists� indiscriminate burning practices and overstocking with sheep opened up the country to invasion by rabbits. Burning and overgrazing by sheep and rabbits stripped the natural fertility of the soils and left the country depleted, eroded, and overwhelmed by pests and weeds. This thesis sets out to test those claims. It explores burning, the stocking of the rangelands with sheep and the impact of rabbits in detail. It also examines other land management practices, as well as sheep breeding, to see what impact they had on the landscape. The timeframe is set between 1841, when formal British settlement was established in the South Island, and 1912, by which time most of the great estates and stations had been broken up into smaller runs and farms. The thesis uses station diaries, memoirs, contemporary newspapers and farming journals to assess what happened on the ground during the pastoral era. In particular, the thesis uses Mt Peel Station as a case study to examine the intensification in land use that took place between 1841 and 1912, in order to explain the transformation of the landscape and to answer the questions: what happened, how did it happened and why did it happened as it did? These sources illustrate that the pastoral era was characterised by innovation. Pastoralists had access to technical and scientific information from around the world. Some conducted their own experiments to improve the productivity of the land and their stock. There was also a learning process involved in adapting their methods to fit the local rangeland environments. They were not simply rapacious capitalists out to strip the wealth from the land for their own personal gain; indeed, many pastoralists set out to establish viable and sustainable enterprises. The thesis argues that the rangelands consisted of a variety of landscapes and climates. Differences in resource endowments had a considerable influence in shaping the environmental outcomes on different stations. Aridity and rabbits were two key factors in the depletion of the vegetation and the degradation of the landscape in the rangelands. Runs in semi-arid districts that were overwhelmed by rabbits suffered long-term damage. In districts where rainfall was more reliable stations that had been overrun by rabbits recovered remarkably quickly. Stations like Mt Peel, that were largely unaffected by the first rabbit plague, were able to maintain and even increase their productivity up to the time they were subdivided. The orthodox analysis of the transformation of the rangelands in the pastoral era does not account for these differences in outcomes.
13

Pastoralism and the transformation of the rangelands of the South Island of New Zealand 1841 to 1912 : Mt Peel Station, a case study

Peden, Robert L, n/a January 2007 (has links)
The transformation of the rangelands of the South Island of New Zealand during the pastoral era fits into the wider international context of European expansion into the 'new' world. European settlers displaced native peoples, introduced 'old' world animals and plants, and imposed a capitalist system that converted local resources into international commodities. In New Zealand the orthodox explanation of the pastoral impact on the rangelands claims that pastoralists introduced an unsustainable system of land use to the region. The pastoralists� indiscriminate burning practices and overstocking with sheep opened up the country to invasion by rabbits. Burning and overgrazing by sheep and rabbits stripped the natural fertility of the soils and left the country depleted, eroded, and overwhelmed by pests and weeds. This thesis sets out to test those claims. It explores burning, the stocking of the rangelands with sheep and the impact of rabbits in detail. It also examines other land management practices, as well as sheep breeding, to see what impact they had on the landscape. The timeframe is set between 1841, when formal British settlement was established in the South Island, and 1912, by which time most of the great estates and stations had been broken up into smaller runs and farms. The thesis uses station diaries, memoirs, contemporary newspapers and farming journals to assess what happened on the ground during the pastoral era. In particular, the thesis uses Mt Peel Station as a case study to examine the intensification in land use that took place between 1841 and 1912, in order to explain the transformation of the landscape and to answer the questions: what happened, how did it happened and why did it happened as it did? These sources illustrate that the pastoral era was characterised by innovation. Pastoralists had access to technical and scientific information from around the world. Some conducted their own experiments to improve the productivity of the land and their stock. There was also a learning process involved in adapting their methods to fit the local rangeland environments. They were not simply rapacious capitalists out to strip the wealth from the land for their own personal gain; indeed, many pastoralists set out to establish viable and sustainable enterprises. The thesis argues that the rangelands consisted of a variety of landscapes and climates. Differences in resource endowments had a considerable influence in shaping the environmental outcomes on different stations. Aridity and rabbits were two key factors in the depletion of the vegetation and the degradation of the landscape in the rangelands. Runs in semi-arid districts that were overwhelmed by rabbits suffered long-term damage. In districts where rainfall was more reliable stations that had been overrun by rabbits recovered remarkably quickly. Stations like Mt Peel, that were largely unaffected by the first rabbit plague, were able to maintain and even increase their productivity up to the time they were subdivided. The orthodox analysis of the transformation of the rangelands in the pastoral era does not account for these differences in outcomes.
14

Pastoralism in Sardinia : ethnoarchaeological research into the material and spatial features of pastoralism in a regional context

Mientjes, Antoon Cornelis January 2002 (has links)
No description available.
15

Communal production systems of goats raised by resource-poor farmers in the Eastern Cape Province of South Africa

Gwaze, Francisca Rumosa January 2008 (has links)
Goats significantly contribute towards the subsistence, economic and social livelihoods of many resource-poor farmers in developing countries, the majority of which own goats. There, however, is dearth of information on communal goat production potential and roles to the rural populace. The broad objective of the study was to evaluate production practices, constraints, production efficiency and to determine nutritional and health status of goats raised by resource-poor communal farmers in the Eastern Cape Province of South Africa. Roles and management systems of goats, goat flock dynamics and, prevalence and loads of gastrointestinal infections and the nutritional status of goats in the study areas were determined. The relationships among body weight, body condition score, faecal egg counts and, haematological and biochemical profiles were also determined. Mean goat flock sizes per household were similar between the two districts studied; Amatole (14.0 ± 0.31) and Alfred Nzo (14.1 ± 1.42). Seventy-nine percent of households in Amatole and 78% in Alfred Nzo kept goats for ceremonies, such as the initiation ceremonies. Goat houses in the two districts were poorly constructed. Thirty two percent of farmers in Alfred Nzo district and 27% in Amatole district reported low buck to doe ratios, suggesting that inbreeding might have been reducing productivity of their flocks. Kid mortality had two major peaks; in May (21%) and in September (21%). Goat production potential (GPP), the proportion of mature and growing goats to the total flock size, was affected by gender of owner of goats. Goats owned by female had a significantly lower GPP value of 0.63 ± 0.015 than goats owned by male farmers (0.70 ± 0.010). Month also significantly affected GPP with the highest (P < 0.05) GPP recorded in May, June and July and the lowest in March and April. Village affected GPP with values for Nkosana and Qawukeni being significantly higher than for Mankone. Goat production potential was also higher (P < 0.05) in small flocks (0.04 ± 0.008) than in large flocks (0.02 ± 0.008). Goat production efficiency (GPE) ranged from 0.11 ± 0.193 in April to 1.55 ± 0.193 in December. The most prevalent gastrointestinal eggs were the strongyle egg type (68.4 ± 8.49 in Qawukeni and 96.1 ± 12.01 in Nkosana) followed by coccidia (53.3 ± 8.76 in Qawukeni and 68.8 ± 8.00 in Mankone). The other identified nematodes were Strongyloides and Trichostrongylus egg types. The trematodes observed were Fasciola and Paramphistomum species. High loads of strongyle eggs were observed in the hot-wet season and the post-rainy season, whilst the other egg types showed a peak in the hot-wet season only. For most of the gastrointestinal parasite eggs, prevalence was higher (P < 0.05) in the sour rangeland compared to the sweet rangeland. Higher (P < 0.05) levels of total protein (TP), globulin, aspartate aminotransferase (AST) and creatinine kinase (CK) levels were recorded in the wet than in the dry season. Body condition scores were positively correlated (P < 0.05) to albumin, body weight and packed cell volume. However, body condition scores were negatively correlated to TP, glucose, alanine transaminase (ALT) and AST. Strongyle egg loads were positively correlated to FAMACHA scores, packed cell volume, body weight and body condition score. The observed high globulin levels suggested a chronic health challenge. Thus, it is fundamental to devise affordable interventions for the control of gastrointestinal parasites in communal goats leading to improved goat productivity and hence rural livelihood
16

The changing meaning of work, herding and social relations in Rural Mongolia

Ahearn-Ligham, Ariell January 2015 (has links)
By using ethnographic methods based on extensive participant observation, this thesis explores the role of pastoralism and rural work as a medium of social reproduction for families in rural Mongolia. This work is reported in four articles, which examine herder household management, decision making, and the spatial aspects of household social and economic production. As standalone pieces and as a united work, the articles make a case for understanding social change through the lens of spatialized performative relations. Pastoralism as a form of work and social system is one aspect of these relations. I contend that people consciously engage with herding as a form of work, which is an important reference point in political subjectivities and administrative practices that idealize the state. The policies and practices of government institutions, including non-state agencies, play powerful roles in the particular forms through which relations are spatialized. By taking this approach and prioritizing herder critical reflections on their own lives, I argue against the dual claim that herders exist outside the state and are bound to local environments. I show, in contrast, how herder efforts to access resources beyond local environments, such as formal schooling for children, spatially transform the labour, finance, and mobility systems of households. My work presents three key arguments with reference to these concepts. The first is that patron-client relations continue to play a strong role in family hierarchies and wider social alliances used to gain access to needed resources and services. Secondly, I argue that pastoralist work is an integral part of governance and the propagation of the moral authority of the state. Pastoralism as a form of work should be seen as a political enterprise as much as an economic or cultural one. Finally, attention to the spatial organisation of household economies, including household splitting and new types of mobility, reiterates the significance of place in human agency.
17

Reproductive performance of cows in sweet and sour veld types under communal production systems in the Eastern Cape Province of South Africa

Nqeno, Noluvuyo January 2008 (has links)
The objective of the study was to evaluate cow reproductive performance in the sweetveld and sourveld communal grazing areas of the Eastern Cape Province, South Africa. In the first experiment, farmer perceptions were obtained using participatory rural appraisals. Farmers ranked lack of fences, tick-borne diseases, poor animal condition during winter and poor breeding practices, respectively as major constraints limiting cattle production in the Eastern Cape. Cattle, sheep and goats, in that order, were ranked as the most important livestock species and were mainly kept for meat, cash and ceremonies, respectively. The non-descript cattle breed was the most common breed found in the smallholder areas. Most farmers preferred Nguni breed because of its adaptive attributes. In the second experiment, structured questionnaires were administered, between June and August 2006, to a total of 551 farmers from 10 communities of the Eastern Cape. There was a significant association (P<0.05) between the use of pregnancy diagnoses and community. About 87 and 77 % of the interviewed farmers did not respond on the extent of pregnancy and calving rates in their herds. A higher proportion of farmers from Hekele (51%) and from Upper Mnxe (45.3%) communities reported low number of bulls as a major constraint to cow reproductive performance. Body condition and ovarian activity were measured in the sweet and sour veld types. Body condition score of animals was measured from March iii 2007 until January 2008 and ovarian activity of cows was performed by a veterinarian through rectal palpation in June, August and October 2007 and January 2008. From March to July, there was a marked decline in body condition on both veld types. In the sweetveld, body condition improved from September until January, whereas in the sourveld the improvement in body condition started in October. The cows in both veld types conceived throughout the year. Most cows in the sweetveld were cycling in January and August (P<0.05) whereas in the sourveld there was no distinct period when the animals were cycling. Overall, there were no differences in the proportion of cows that were cycling between the sour and sweet veldts (P>0.05). There were more cows cycling in sourveld in October than in the sweetveld. Reproductive performance of cows in communal areas could, therefore, be determined by levels and quality of nutrition. Keywords: Participatory rural appraisals; Structured questionnaires; Farmer participation; Farmer perceptions; Body condition scoring; Ovarian activity; Pregnancy diagnoses.
18

Keeping cattle in a changing rural landscape : communal rangeland management in Okhombe, KwaZulu-Natal, South Africa.

Salomon, Monique Louise. January 2011 (has links)
A research journey involving people, cattle, and the landscape in rural Okhombe in the western part of the province of KwaZulu-Natal and lying at the foot of the uKhahlamba Drakensberg Mountain Range, South Africa, is the focus of this work. Using action research involving community members as co-researchers, it investigates why a rotational resting system for communal cattle grazing collapsed within six months of its launch. Despite having been designed in a participatory manner, the rotational resting system was not applied by cattle keepers. As a backdrop to the concern around the rotational resting system, it is necessary to understand how the current landscape of Okhombe was shaped. The history of the uKhahlamba Drakensberg Region over the past two hundred years was, therefore, explored. Four historical episodes were distinguished: economic expansion, nature conservation efforts, colonial and apartheid legislation, and encounters between people all left their imprint on the landscape. Digitized maps of aerial photographs of Okhombe, taken between 1945 and 2004, showed how Government intervention changed people’s multifunctional use of the landscape to concentrated settlements and cropping fields in the valley and cattle grazing on the mountain slopes. A survey in Enhlanokhombe, one of the sub-wards of Okhombe, further investigates how cattle keepers use the rangeland commons, and what determines these practices. People are keeping fewer cattle than in the past. A 24% decrease in cattle numbers was recorded between 2001 and 2008. Cattle keepers perceive stock theft as the most important threat. Yet, figures of stock losses showed that cattle disease resulting in death is an equally pressing problem. The decline in authority of traditional leaders and the view that herding is a family task have compounded the dominant management practice of continuous grazing by cattle. Rotational resting was found to be unsuited to the majority of cattle keepers who want to keep a close watch on their herds as they graze on the lower hill slopes. People in Okhombe disagreed about the condition of the range and what comprised appropriate grazing management. A community initiative has emerged to form cattle patrols to address stock theft. If successful, it may further enhance collective action. The concern with communal grazing management investigated in this research and in the Okhombe Landcare project, of which it was part, aimed to reverse land degradation and overgrazing. An analysis of digitized maps of Okhombe taken in the period between 1945 and 2004, however, showed that soil erosion did not increase rapidly as is commonly assumed by conventional rangeland scientists and extension staff. Rather, an increase in bare soil coincided with a period of drought. The focus of the Okhombe Landcare project on combatting soil erosion and rehabilitate degraded lands was underpinned by a particular interest in and need to conserve the uKhahlamba Drakensberg as a near-pristine wilderness landscape which provides marketable ecosystem goods and services. As such, cattle keeping in Okhombe can be described as being embedded in a social-ecological system comprising a series of nested, self-organizing subsystems which are interconnected. Sub-systems include the cattle production system, cattle grazing management practices, the wider ecosystem, and government policies and regulations. A spatial-temporal and systemic approach is proposed to make meaningful, policy-related decisions regarding communal rangeland management in the future. Such an approach would enable cattle keepers, other rangeland users, and outside stakeholders, such as extension workers and policy makers, to respond effectively to changes in the landscape by taking into consideration and balancing a complex set of biophysical, socio-political, and economic variables. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

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