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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.
511

Nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers in relation to nest predation

Fisher, Ryan Jeffrey 28 April 2005
I studied nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers (<i>Colaptes auratus</i>, hereafter flickers) in central interior British Columbia with respect to nest predation. My research focused on three questions: (1) Are there nest characteristics associated with the risk of nest predation and nest loss to European Starlings (<i>Sturnus vulgaris</i>)? (2) Does nest predation influence breeding dispersal? (3) Do parental attributes influence nest defence behaviour? <p> An examination of flicker nest-site characteristics at five spatial scales revealed that nests were safer from mammalian predators (N=81) when they were higher, concealed by vegetation, farther from continuous coniferous forest blocks, and contained fewer conifers within the nesting clump. Proximity to conifers increased predation risk, but nests safe from competitors (N=18) were closer to coniferous forest blocks and contained a higher percentage of conifers in the nesting clump. Flickers face a trade-off between being safe from predators and safe from competitors. <p> Nesting success did not influence between-year breeding dispersal by 159 male or 76 female flickers. Because nests and forest clumps were not predictably safe from predators, benefits of dispersing likely outweigh costs. Other factors such as mate-switching, nest ectoparasites, and a fluctuating food source may play larger roles in dispersal than nest predation. Within years, 73% of pairs switched nest sites after their first attempt failed due to predation (N=37); however, there was no reproductive advantage for these pairs compared to pairs that remained at their original nest. Stressful encounters with predators involving nest defence may trigger dispersal, although it seems to offer no greater nest success. Of 24 flicker pairs presented with a control model before egg-laying, 3 pairs abandoned their nest, whereas 4 out of 24 pairs presented with a squirrel model abandoned their nest. This suggests that a one-time encounter with a nest predator is not a sufficient deterrent against continued nesting. Rather, costs of finding and excavating or renovating a new cavity may cause individuals to tolerate some risk in nesting at a location with an active predator. <p> In experimental trials (N=94), intensity of nest defence behaviour against a model predator was not related to the sex, age, body size, and body condition of the defending adult(s). The sexes may have behaved similarly because they are similar in size and have similar survival patterns. Costs and benefits of nest defence for flickers of different ages may also be equal because flickers are relatively short-lived and their survival rate is not linked with age. Brood size of the defending adult was also unrelated to the intensity of nest defence. If flickers have adjusted their clutch size in relation to the number of young for which they can optimally provide care, then no effects of brood size on nest defence behaviour should be recorded, as was the case here.</p>
512

The Evolution of Caenorhabditis elegans Sperm Traits Involved in Reproductive Success by Self-fertilizing Hermaphrodites and in Male-male Post-mating Contests

Murray, Rosalind Louise 15 February 2010 (has links)
Sperm play a pivotal role in determining the reproductive success of individuals whose sperm must compete directly with that of others. I used sperm precedence assays and experimental evolution to examine the role of sperm traits in the reproductive success of hermaphrodites and males in the androdioecious nematode Caenorhabditis elegans. First, sperm size and the rate of reproduction were analyzed, in the context of male-male sperm competition, for evidence of natural heritable variation. Sperm size proved to be a strong indicator of second-male sperm precedence in the genotypes examined. Second, I tested the theoretically predicted effect of larval development time on the number of self-sperm produced by hermaphrodites. I demonstrated that a short larval development period favored the evolution of fewer sperm, inline with theoretical predictions. These results provide important insights into C. elegans reproductive biology and more generally to our understanding of the evolution of reproductive systems.
513

Unlocking the Competitiveness of the Fee: Is Canadian Mobile Service Providers Charging a Fee to Remove the Software Lock after the Contract Expires Anti-competitive?

Marrello, Byron 22 November 2012 (has links)
Most mobile phones in Canada contain software that prevents the consumer from using the phone on multiple networks. This is known as a ‘software lock’, and is installed prior to the point of sale by the mobile service providers. As of 2011, all three large Canadian service providers have adopted a similar practice to charge a fee to remove the software lock from phones. This fee applies even after the consumer’s service contract with the provider ends. This thesis examines whether the practice of charging consumer a fee for removing the software lock after the contract expires is anti-competitive in Canada. Through examining economic theory and undergoing legal analysis, this thesis will argue that while the practice is clearly anti-competitive, it does not substantially lessen competition enough to be prevented under competition law. This thesis suggests that this industry practice should be prohibited through the passing of consumer protection legislation.
514

Unlocking the Competitiveness of the Fee: Is Canadian Mobile Service Providers Charging a Fee to Remove the Software Lock after the Contract Expires Anti-competitive?

Marrello, Byron 22 November 2012 (has links)
Most mobile phones in Canada contain software that prevents the consumer from using the phone on multiple networks. This is known as a ‘software lock’, and is installed prior to the point of sale by the mobile service providers. As of 2011, all three large Canadian service providers have adopted a similar practice to charge a fee to remove the software lock from phones. This fee applies even after the consumer’s service contract with the provider ends. This thesis examines whether the practice of charging consumer a fee for removing the software lock after the contract expires is anti-competitive in Canada. Through examining economic theory and undergoing legal analysis, this thesis will argue that while the practice is clearly anti-competitive, it does not substantially lessen competition enough to be prevented under competition law. This thesis suggests that this industry practice should be prohibited through the passing of consumer protection legislation.
515

The Evolution of Caenorhabditis elegans Sperm Traits Involved in Reproductive Success by Self-fertilizing Hermaphrodites and in Male-male Post-mating Contests

Murray, Rosalind Louise 15 February 2010 (has links)
Sperm play a pivotal role in determining the reproductive success of individuals whose sperm must compete directly with that of others. I used sperm precedence assays and experimental evolution to examine the role of sperm traits in the reproductive success of hermaphrodites and males in the androdioecious nematode Caenorhabditis elegans. First, sperm size and the rate of reproduction were analyzed, in the context of male-male sperm competition, for evidence of natural heritable variation. Sperm size proved to be a strong indicator of second-male sperm precedence in the genotypes examined. Second, I tested the theoretically predicted effect of larval development time on the number of self-sperm produced by hermaphrodites. I demonstrated that a short larval development period favored the evolution of fewer sperm, inline with theoretical predictions. These results provide important insights into C. elegans reproductive biology and more generally to our understanding of the evolution of reproductive systems.
516

Factors and mechanisms that influence intraorganisational collaboration and competition

Chambers, Morgan 08 1900 (has links)
Recently, some authors point to value creation from the structure and behaviours associated with competition and collaboration inside the organisation (Helfat and Eisenhardt, 2004; Birkinshaw and Lingblad, 2005). While both competition and collaboration have been studied extensively between organisations, less attention has been focused on them and their interaction between units inside the organisation, particularly within complex and heterogeneous multinational corporations. The question is how to achieve the coordination and collaboration that is necessary for a multinational organisation to reap the benefits that international expansion has to offer and yet balance the propensity for competition that exists as business units struggle for scarce resources or new opportunities. In order to answer this question, the aim of this review is to first of all know what the factors and mechanisms are that influence competition and collaboration between organisational units within multinational organisations. Methodology: This study has been conducted using a systematic review methodology with the aim of producing a search of extant literature which can be trusted by others as being thorough, transparent, replicable and clear. Both quantitative and qualitative techniques have been used to achieve this. Findings: This review finds that the there is minimal extant literature that addresses competition and collaboration between business units within the multinational corporation and that it also fails to provide a comprehensive understanding of the factors and mechanisms that influence the co-existence of intraorganisational competition and collaboration. They are typically viewed as mutually exclusive or at opposite ends of a continuum. While there has been some recent research attention given to intraorganisational collaboration and competition, each in their own right, there has not been an extensive review of the factors and mechanisms when looking at their coexistence within the multinational corporate environment. By bringing the two literatures into view and investigating the paradoxical nature of the influences on andthe interactions between competition and collaboration, insights into an optimal mix based on the corporations strategy and value creation logic can be gained for both academics and business unit leaders.
517

The Technological Landscape: Competition and Opportunity

Aharonson, Barak Simcha 20 January 2009 (has links)
Technological position is a dimension along which organizations can either differentiate from or mimic the behavior of other organizations in the technological landscape. This paper is aimed at providing empirical evidence of the specific ways in which an organization’s technological position choice is impacted by the tension that arises from technological co-location; the information available to the focal firm; and the focal firm’s usage of such information. In this dissertation I examine the factors influencing technological agglomerations in technological positions in the technological landscape. I further examine how the organization’s experience impacts its strategic positioning choice while facing the tradeoff between the expected derivatives of co-location - opportunities and competition. I argue and find that an organization strategically positions itself in the technological landscape based not only on the information it has gathered on its technological environment but also using its own experience and information. Further, my findings show that the organization’s technological positioning choice reflects the tension between opportunity and competition, which questions the notion of isomorphism.
518

School Choice, Competition, and Public School Performance

Chan, Ping Ching Winnie 23 September 2009 (has links)
Reforms that expand school choice have been the focus of considerable policy interest, not least as a possible means of improving public school performance. According to the standard argument, increased choice will intensify competition, forcing public schools to improve quality in order to retain enrolment. Yet in principle, increased choice need not always raise performance, pointing to the need for careful empirical analysis. A key challenge in measuring the effects of greater choice on school performance is that convincing variation in choice is often hard to come by, especially in cross-sectional studies. And while school choice policy experiments have the advantage that choice increases in a clear way, few large-scale school choice policies have been implemented in North America. An important exception is the 2002 Ontario tuition tax credit, which eased access to private schools throughout Canada's most populous province. Analyzing the effects of the tax credit reform provides the focus of this thesis. The thesis begins by presenting the literature and gaps in existing research. The next chapter presents a model to clarify the link between increases in competition and school performance, and to motivate the empirical identification strategy. To set the stage for the main empirical analysis, I also provide some relevant institutional background relating to the Ontario education policy environment and the Ontario tuition tax credit as well as a descriptive analysis on the Ontario private school market. I then present an initial examination of the possible performance effects of the Ontario tuition tax credit using a difference-in-differences setup, before turning to the main empirical analysis, which exploits the differential competitive effects for public schools in districts with relative to those without a significant private school presence. The empirical results indicate that public school performance improved for schools facing the greatest competitive pressures following the introduction of the policy, controlling for a host of other relevant factors. To assess whether the effect is due primarily to increases in productivity, the analysis controls carefully for a series of alternative mechanisms. Overall, the Ontario findings are consistent with increased choice giving rise to productivity improvements in public schools.
519

DETERMINANTS OF THE BIODIVERSITY AND COMPOSITION OF STREAM INSECT COMMUNITIES

Sircom, Julie 19 March 2009 (has links)
The North Mountain of the Annapolis Valley, NS, in eastern Canada, is a ~200 km basalt ridge drained by many small first or second order streams in independent catchments. The area is fairly uniform geologically, presenting an opportunity to compare streams of similar chemistry, slope and aspect, that vary in other respects, such as invertebrate community structure. In this thesis, I examine two macroinvertebrate functional groups to determine key factors influencing their abundance, composition and diversity across catchments. Chapters 2 and 3 are concerned with the predatory invertebrate guild in eight of the streams, in two groups separated by ~65 km. In Chapter 2, I assessed factors influencing composition of the predator guild using similarity matrices. Similarity in predator composition declined with distance, and streams that were more similar in disturbance (spates) were more similar in predator composition. Similarity within one family, Rhyacophilidae, was related to similarity in fish population. Chapter 3 reports the results of laboratory experiments involving two widespread species. Field data suggested an asymmetric interaction between Sweltsa onkos (Plecoptera: Chloroperlidae) and Rhyacophila vibox (Trichoptera: Rhyacophilidae); behavioural observations in artificial streams supported this. In the presence of R. vibox, S. onkos had higher mortality and injury rates, and grew less. The results of these chapters suggest that, although disturbance is important in shaping community structure, the results of interspecific interactions can be detected at large scales. S. onkos can only attain high numbers in streams where fish predation reduces the abundance of R. vibox. Chapter 4 examines biodiversity patterns in the macroinvertebrate detritivore guild in 25 streams encompassing ~80 km of the ridge. Using density and richness of the detritivore community, detrital resource quantity, and top predator abundance, I looked for evidence in support of several mechanisms that can lead to positive species-energy relationships. Patterns conformed to expectations of the More Individuals Hypothesis. It appears that taxonomic richness of the detritivore guild increases with detrital resource availability because more taxa can attain their minimum viable population size where more resources are available.
520

Climate, grazing and plant interactions : Does climate and grazing shape plant interactions in alpine environments?

Marberg, Mikael January 2013 (has links)
Increased knowledge of plant interactions is important for our understanding of how ecosystems will respond to climate changes. Using four common low-herb and three tall- herb species as phytometers I measured the net outcome of plant interactions in an alpine environment by a neighbour removal experiment. Grazing and climate were tested as explanatory factors for differences in the outcome of plant interactions, with two altitudes representing different climates. The most important finding in this experiment is that competition is the dominating interaction among plants in this habitat, regardless of plant size, climate and grazing. Climatic exposure and grazing only influenced tall-herb species while low-herbs were mainly limited by competition, presumably for light. These results are important since facilitative interactions and net facilitation in plant communities are often reported to become more common in severe climates.

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