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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

Stable Isotopes and the Ecology and Physiology of Reptiles

Durso, Andrew M. 01 May 2016 (has links)
Animals trade-off limited resources among competing demands. Trade-offs are difficult to quantify because it is challenging to measure investment into disparate physiological systems using a common scale. Additionally, biologists desire methods to more precisely measure energy status in wild animals. I used stable isotopes to help solve both of these problems. I examined natural spatial and temporal variation in stable isotope signatures of wild lizards and found significant variation. In the lab, I was able to demonstrate the utility of nitrogen stable isotope ratios of uric acid pellets for measuring nutritional stress. By tracing labeled amino acids through the bodies of gravid female lizards, I demonstrated that vitellogenesis and wound healing compete for amino acids and quantified the direction and magnitude of the trade-offs. I showed that reproductive-immune trade-offs vary based on reproductive stage and energy availability, have effects on metabolism and immune function, and are influenced by hormonal mechanisms. My findings shed light on the interconnectedness of stable isotope endpoints and key physiological systems in animals. I showed that isotopic signatures of physiological stress can be reflected at a large scale in natural populations, and I made novel measurements of the size and direction of trade-offs, which were formerly limited to physiological and performance outcomes.
12

Application of a land use planning decision support tool in a public participatory process for sustainable forest management

Cavill, Jacqueline 05 1900 (has links)
Persistent conflicts between stakeholders and complex trade offs among forest values have created a difficult decision environment for sustainable forest management. Tools developed for decision support in land use planning are essential for managing these challenges. This research study is an interactive assessment of a land use planning Decision Support Tool (DST) in the Invermere Timber Supply Area (TSA), located in the East Kootenay area of British Columbia. The aim of this study is to explore whether stakeholders' initial stated preferences change and whether trade-offs are made between various forest values upon observation of a long-term forecast of these values using a DST. Representatives from various stakeholder groups in the area were assembled for individual sessions to interact with the multi-criteria DST. Participants were required to state their preferences for six forest values using a weighting scheme. The DST developed an output for each forest value based on the participants' preferences. Upon review of the DST output, the participant had the opportunity to alter their initial preferences iteratively until a desirable output was found. The results indicate that participants' preferences changed after reviewing the DST outputs and that participants are willing to make trade-offs between various forest values using a DST to find a desirable solution. However, the preference order of the forest values changed only slightly from the participants' initial to preferred scenarios; instead participants made drastic changes to the weighting of each value to find a desirable output. Participants also stated their willingness to use DSTs for land use planning decision-making, although underlying assumptions built into the model must be improved before stakeholders can trust the tool as an aid for decision-making. Studies such as this can further the development of DSTs to help find desirable decisions for sustainable resource management and to help create a productive and engaging process.
13

Sustainable development in ecotourism : Tour operators managing the economic, social and environmental concerns of sustainable development in Costa Rica

Eriksson, Frida, Lidström, Matilda January 2013 (has links)
Sustainable development is concerned with acknowledging economic, social and environmental development aspects, catering for the current needs of society without damaging the well-being of future generations. Ecotourism is a niche market that emerged because of increased market demands for sustainable tourism practices. It serves to provide tourism products and services while accommodating for the economic, social and environmental aspects of society. However, earlier research suggests that it is difficult to handle the three dimensions of sustainable development, indicating that trade-offs may occur. Furthermore, as tour operators are able to affect local development prospects, it is of interest to examine how they handle sustainable development, and more specifically, contribute to trade-offs between the economic, social and environmental pillars of sustainable development. This thesis was aimed at answering the following research question; “How do ecotourism tour operators contribute to trade-offs between the economic, social and environmental dimensions of sustainable development?”, with the objective of examining how ecotourism tour operators handle the dimensions of sustainable development, and what trade-offs that may occur between economic, social and environmental concerns. This qualitative research was carried out in the context of ecotourism tour operators in Costa Rica through semi-structured interviews. Nine respondents participated in this research, representing seven local ecotourism tour operators. The data collected on the trade-offs of ecotourism and sustainable development has in turn been analysed with reference to a pre-established theoretical framework. This study has revealed that ecotourism tour operators are actively engaging in initiatives supporting the idea of sustainable development. The tour operators handle the economic, social and environmental concerns through different initiatives. One conclusion that can be derived from this research is that all pillars of sustainable development are important to acknowledge. However, this is difficult as the three dimensions are somewhat contradicting. Therefore, depending on how ecotourism tour operators prioritise different initiatives, trade-offs are inevitable as both inter- and intragenerational needs are difficult to align.
14

Application of a land use planning decision support tool in a public participatory process for sustainable forest management

Cavill, Jacqueline 05 1900 (has links)
Persistent conflicts between stakeholders and complex trade offs among forest values have created a difficult decision environment for sustainable forest management. Tools developed for decision support in land use planning are essential for managing these challenges. This research study is an interactive assessment of a land use planning Decision Support Tool (DST) in the Invermere Timber Supply Area (TSA), located in the East Kootenay area of British Columbia. The aim of this study is to explore whether stakeholders' initial stated preferences change and whether trade-offs are made between various forest values upon observation of a long-term forecast of these values using a DST. Representatives from various stakeholder groups in the area were assembled for individual sessions to interact with the multi-criteria DST. Participants were required to state their preferences for six forest values using a weighting scheme. The DST developed an output for each forest value based on the participants' preferences. Upon review of the DST output, the participant had the opportunity to alter their initial preferences iteratively until a desirable output was found. The results indicate that participants' preferences changed after reviewing the DST outputs and that participants are willing to make trade-offs between various forest values using a DST to find a desirable solution. However, the preference order of the forest values changed only slightly from the participants' initial to preferred scenarios; instead participants made drastic changes to the weighting of each value to find a desirable output. Participants also stated their willingness to use DSTs for land use planning decision-making, although underlying assumptions built into the model must be improved before stakeholders can trust the tool as an aid for decision-making. Studies such as this can further the development of DSTs to help find desirable decisions for sustainable resource management and to help create a productive and engaging process.
15

Invertebrate life-history trade-offs and dispersal across a pond-permanence gradient

Galatowitsch, Mark Louis January 2014 (has links)
Flexible life-history traits and dispersal may allow generalist populations to persist across a range of habitats despite experiencing contrasting selection pressures. Invertebrates exploiting temporary ponds must develop quickly and disperse as adults, or have wide environmental tolerances. Conversely, permanent-pond invertebrates must avoid a suite of predators (e.g., fish and dragonflies). This gradient of pond permanence can result in life-history trade-offs that influence fitness, population dynamics, and genetic structure. In addition, recruitment between habitats may balance juvenile life-history trade-offs and be crucial to sustain generalist invertebrate populations in ponds with unpredictable hydrology. Through a multi-year survey of three pond complexes in the Canterbury high-country and a series of mesocosm experiments using two generalist pond invertebrates, Xanthocnemis zealandica damselflies and Sigara arguta waterboatmen, I found these two species had alternative life-history strategies that influenced their distributions across the pond-permanence gradient. With longer juvenile development, X. zealandica benefited from flexible life-history traits: temporary-pond X. zealandica had accelerated development and short-term desiccation tolerance, but were excluded from ponds with long dry periods, whereas, permanent-pond X. zealandica had extended development and predator avoidance behaviours (e.g., reduced movement and refuge-use). In contrast, S. arguta had an opportunistic life-history strategy with a fixed, rapid development response that allowed them to inhabit more temporary ponds, but they were intolerant of drying and limited to permanent ponds that contained shallow refuges from fish. These results illustrate how alternative life-history strategies enabled two generalist species to achieve broad realised niches. Recruitment between habitats also appeared to be important for balancing trade-offs and maintaining meta-populations across the pond-permanence gradient. To evaluate the importance of X. zealandica dispersal among and within pond complexes I used microsatellite analyses. While there was unique genetic population structure between the North and South Islands, at lower spatial scales there was little variability in genetic diversity and limited genetic structure in populations, likely due to gene flow among different habitat types. Overall, this work shows how an interaction of juvenile strategies and adult dispersal could reduce life-history trade-offs, resulting in weak selection pressures across an unpredictable disturbance gradient. Whether increasingly unpredictable hydrological patterns under climate-warming favour generalist species will likely depend on how well generalist life-history traits and dispersal allow exploitation of a range of habitat types and resilience to variable selection pressures. Higher mean summer rainfall in New Zealand may allow both species to exploit more temporary ponds, whereas longer dry periods between extreme precipitation events could limit X. zealandica distributions. Thus, species with generalist strategies are likely to be favoured under warming, but their specific life-history strategies will likely promote or limit their ability to exploit more unpredictable habitats.
16

Life history trade-offs, immune function and the expression of sexual signals in two model groups of birds (Psittaciformes, Charadriiformes)

Edwards, Darryl Bryce 21 May 2014 (has links)
Ecological immunology is the study of the ecological and evolutionary factors that explain variation in the function of, and investment in, the immune system. Within this field, reproduction-based trade-offs are an important focus, where studies often address the immunological costs associated with the expression of secondary sexual traits used in mate choice. Specifically, the Immunocompetence Handicap Hypothesis (ICHH) links the expression of secondary sexual traits to immune function, stating that testosterone promotes the expression of these traits while suppressing the immune system. In doing so, testosterone may maintain the honest expression of such traits, but also ultimately cause sex differences in immunity because males tend to have high levels of testosterone. I explore aspects of these topics using two model systems: the Psittaciformes (Parrots: Chapter 2) and the Charadriiformes (shorebirds), in particular the sex-role reversed Red phalarope (Phalaropus fulicarius). In Chapter 2, I employed a phylogenetically informed approach to investigate the relationships among immune investment, plumage colouration and longevity in parrots. I found that immune investment was greater in more colourful species, as well as in those with a slower pace-of-life (i.e., longer incubation periods), but not specifically in those with longer lifespans. In Chapter 3, I investigated the role that reproductive behaviours play in determining sex differences in corticosterone levels. One explanation for sex differences in the stress response is that selection favours a reduced response in incubating birds to reduce nest abandonment. I generally found little support for sex differences in corticosterone being driven by behaviours related to incubation. Moreover, in phalaropes, sex differences in corticosterone were already present prior to incubation. In Chapter 4, I found that males have higher levels of testosterone than females, but that females were immunosuppressed compared to males. However, I found evidence that testosterone may regulate immune function in females, but not males. The observation of female-biased immunosuppression is consistent with Bateman’s Principle, and although there was some evidence of a testosterone-mediated handicap acting through immune function, these results attest to a fundamental lability in the relationship between testosterone and immunity. In Chapter 5, I demonstrated that plumage colouration in phalaropes is condition-dependent and so potentially conveys useful information to conspecifics. Yet, the relationship was negative in both sexes such that more colourful individuals had poorer immunocompetence, which was contrary to predictions. In Chapter 6, I demonstrated that phalaropes pair assortatively (positively) based on plumage colouration, but negatively based on aspects of size. I discuss the results of this dissertation in the light of life history theory, as well as in the context of mechanisms maintaining signal honesty.
17

Projeto Arquitetural Automatizado de Sistemas Self-Adaptive – Uma Abordagem Baseada em Busca

Andrade, Sandro Santos 19 December 2014 (has links)
Submitted by Kleber Silva (kleberbs@ufba.br) on 2017-05-31T20:12:19Z No. of bitstreams: 1 tese-sandroandrade-2014.pdf: 6962942 bytes, checksum: 6e55349061fd33f307cf9f2896c56436 (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2017-06-07T10:57:53Z (GMT) No. of bitstreams: 1 tese-sandroandrade-2014.pdf: 6962942 bytes, checksum: 6e55349061fd33f307cf9f2896c56436 (MD5) / Made available in DSpace on 2017-06-07T10:57:54Z (GMT). No. of bitstreams: 1 tese-sandroandrade-2014.pdf: 6962942 bytes, checksum: 6e55349061fd33f307cf9f2896c56436 (MD5) / Ao longo dos últimos anos, uma série de novas demandas contribuíram para aumentar ainda mais a complexidade essencial de sistemas de software. Como consequência, desenvolver sistemas computacionais que atendam satisfatoriamente a essas demandas requer um controle intelectual que rapidamente se aproxima dos limites humanos. Os Sistemas Self-Adaptive (SSA) representam uma solução promissora para este problema. Um SSA é caracterizado pela transferência, para run-time, de uma ou mais atividades do processo de desenvolvimento de software, suportadas por uma infraestrutura de adaptação que permite o raciocínio e execução automáticos de atividades antes realizadas off-line pelos desenvolvedores. Esta tese apresenta o projeto, implementação e avaliação de uma abordagem para projeto arquitetural automatizado de SSA, baseada na representação sistemática de conhecimento refinado de projeto e na aplicação de técnicas de otimização multiobjetivo. Para isso, uma nova linguagem (DuSE) para especificação de espaços de projeto e métricas de qualidade particulares a um determinado domínio de aplicação foi proposta, associada a uma plataforma de otimização de arquiteturas de software. A DuSE viabilizou a infraestrutura de metamodelagem necessária para a especificação do SA:DuSE -- espaço de projeto responsável pela captura sistemática das principais dimensões de projeto de SSA baseados em teoria de controle. A abordagem foi avaliada em relação à sua capacidade de manifestação de trade-offs, potencial de antecipação dos atributos de qualidade evidenciados e impacto na efetividade e complexidade dos projetos quando comparada a abordagens alternativas. Resultados indicam que a abordagem efetivamente captura o caráter multiobjetivo do projeto de SSA e que promove um melhor suporte à investigação de alternativas e tomada de decisão no projeto de aplicações deste domínio.
18

Inkubační strategie vybraných druhů kachen / Incubation strategies of selected duck species

Klvaňa, Petr January 2010 (has links)
- 9 - Incubation strategies of selected duck species Summary of the PhD. thesis Avian incubation is an energetically demanding process. It holds true especially for uniparental incubators in which all incubation efforts are restricted to one individual. All ducks species breeding in northern hemisphere are representatives of birds with uniparental care. High demands of clutch formation and incubation make from ducks perfect model for testing factors influencing parent investment decisions. On the other hand parental investment to actual breeding attempt depends on many factors including breeding season duration, food supply, female's age, risk of predation or resilt of previous nesting attempt. So investigation of this complex problematic is extremely difficult. This thesis is focused on the most important phase of breeding cycle - incubation of clutch. Clutch incubation is associated with high energy cost to maintenance optimal temperature conditions for developing embryos. Morover incubation process can has large effect on female's body mass because of reduction of feeding time. Incubation strategy of success female include many partial tactic reducing predation risk of clutch and incubating female or eggs cooling. The incubation strategies of three ducks species were investigated in this thesis - Mallard...
19

Application of a land use planning decision support tool in a public participatory process for sustainable forest management

Cavill, Jacqueline 05 1900 (has links)
Persistent conflicts between stakeholders and complex trade offs among forest values have created a difficult decision environment for sustainable forest management. Tools developed for decision support in land use planning are essential for managing these challenges. This research study is an interactive assessment of a land use planning Decision Support Tool (DST) in the Invermere Timber Supply Area (TSA), located in the East Kootenay area of British Columbia. The aim of this study is to explore whether stakeholders' initial stated preferences change and whether trade-offs are made between various forest values upon observation of a long-term forecast of these values using a DST. Representatives from various stakeholder groups in the area were assembled for individual sessions to interact with the multi-criteria DST. Participants were required to state their preferences for six forest values using a weighting scheme. The DST developed an output for each forest value based on the participants' preferences. Upon review of the DST output, the participant had the opportunity to alter their initial preferences iteratively until a desirable output was found. The results indicate that participants' preferences changed after reviewing the DST outputs and that participants are willing to make trade-offs between various forest values using a DST to find a desirable solution. However, the preference order of the forest values changed only slightly from the participants' initial to preferred scenarios; instead participants made drastic changes to the weighting of each value to find a desirable output. Participants also stated their willingness to use DSTs for land use planning decision-making, although underlying assumptions built into the model must be improved before stakeholders can trust the tool as an aid for decision-making. Studies such as this can further the development of DSTs to help find desirable decisions for sustainable resource management and to help create a productive and engaging process. / Forestry, Faculty of / Graduate
20

Thermal Physiology and Responses to Climate Change in a Montane, Desert Lizard Community

Clifton, Ian T. January 2021 (has links)
No description available.

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