Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"density-independent"”.
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A test of the variable nature of density-dependent mortality in fish populations
… in power-plant cooling systems was questioned. Density-dependent dynamics were hypothesized as variable, not constant, making previous analyses based on constant density-dependent or density-independent mortality in error. This hypothesis was tested with a simulation model based on complex …
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Non-Linear Density Dependence in a Stochastic Wild Turkey Harvest Model
… gallopavo silvestris</I>) harvest models assume density-independent population dynamics despite indications that populations are subject to a form of density dependence. I suggest that both density-dependent and independent factors operate simultaneously on wild turkey populations, where the …
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Multi-Species Models of Time-Varying Catchability in the U.S. Gulf of Mexico
… and is usually assumed to be stationary and density-independent. However, recent research has shown that these assumptions are violated in most fisheries. Violation of these assumptions will cause underestimation of stock declines or recoveries, leading to inappropriate management policies. …
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A mastofauna do estado do Rio de Janeiro, com especial referência à ordem Polyprotodontia (Marsupiais)
… the foundations for future taxonomic work. The density-independent factors that might affect species' presence are reviewed, as is the history of mammal collecting and studies since the 16th century. A provisional species list for the state is also given. To exemplify the treatment to be given …
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Spatially-Explicit Agent-Based Modeling of Ecosystem Change and Epizootiological Impacts on Caribbean Spiny Lobster, <i>Panulirus argus</i>
… disease states, contact transmission, and two density-independent transmission mechanisms, to explore the effects of changes in host sociality on disease dynamics. I showed that when susceptible hosts avoid diseased conspecifics in a manner consistent with that demonstrated by <em>P. argus</em> …
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The ecological life history of the Cape Bulbul
… immigration which is apparently influenced by density-independent factors.
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Modeling Effects of Mortality on Indiana Bat (Myotis Sodalis) Populations at Wind Energy Facilities
… incorporating mortality and carrying capacities. Density-independent, density-dependent fecundity and density-dependent survival Leslie matrix models were developed and run. Results suggest that, depending on the model used, and the method by which mortality is incorporated, the effect of …
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<i>Staphylococcus aureus</i> virulence gene studies : a comparative microarray based approach
… in the non-mutant strain were found to be cell density independent, indicating that the expected quorum sensing mechanism was not functional.<br></br><br></br>Expression profiles of cells grown under biofilm simulating conditions were compared to their planktonic counterparts. Biofilm cells …
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Effects of abiotic and biotic factors on population dynamics of brook trout (<i>Salvelinus fontinalis</i>) within Shenandoah National Park, Virginia
Aquatic ecosystems are facing numerous threats that are products of anthropogenic activity, including habitat destruction and climate change. Monitoring aquatic ecosystems is important so that we can better understand and remedy the consequences of these threats. Native fish species found within …
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Microplastic pollution in the deep sea ecosystem: a study from the Rockall Trough, North East Atlantic Ocean
… from environmental samples, a validation of a density-independent oil based method for sediment samples was undertaken and a rapid and non-destructive enzymatic appropriate for biota was developed. The results of this thesis indicate the potential for the widespread presence of microplastics …
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The importance of density-dependent mechanisms in determining cohort survival in largemouth bass
… explore mechanisms of recruitment, because both density-dependent and independent processes have been identified as important in regulating populations. Timing of hatching can influence growth and survival of largemouth bass. Individuals hatched relatively early have a period of growth prior to …
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A mathematical analysis of evolutionary rescue and niche construction
… the rate of construction and thus lowering the density of habitats available to invaders. The lower habitat density leads to slower invasion, which in turn buys constructors more time to mutate. Finally, in Chapter 3, I consider the possibility that invaders directly interact with the resident …
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Spatial distribution of western corn rootworm (Diabrotica virgifera virgifera Leconte) trap counts and evaluation of a novel method for sampling soil pests of field corn
… the presence and type of spatial pattern was density-independent. Pests of germinating corn seeds comprise a guild of insects including seedcorn maggots, wireworms, and white grubs. No one method has yet been developed to sample all of the insects in the guild. A new method, the baited wire …
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Migratory Behavior and Survival of Adult Female Elk in a Partially Migratory Population
… both resident and migratory characteristics, and density-dependent switching such that at higher winter densities, elk switched from resident to migrant, whereas at lower densities, elk reversed direction. This evidence for flexibility in migration supports the idea of behavioral plasticity in …
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Migratory Behavior and Survival of Adult Female Elk in a Partially Migratory Population
… both resident and migratory characteristics, and density-dependent switching such that at higher winter densities, elk switched from resident to migrant, whereas at lower densities, elk reversed direction. This evidence for flexibility in migration supports the idea of behavioral plasticity in …
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Ecology of feral cats Felis catus and their prey in relation to shrubland fire regimes
… highest in long unburnt areas. Using giving up density experiments, I showed that rodents exhibited differential foraging behaviour in the two vegetation fire ages. The rodents foraged for longer in sheltered compared to open microhabitats, but this pattern only occurred in recently burnt, not …
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The population biology of Ligia oceanica (L.)(Crustacea: Oniscoidea)
… phenology, size and age structure, population density and size, female breeding size, fecundity regression and broodpouch mortality have been determined. From these data population natality, and schedules of survivorship, fecundity and reproductive value are calculated. Although the …
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Seed ecophysiology and plant population ecology of Cynoglossum officinale L. and Tragopogon spp.
… in 1990 and 1991 and their fates monitored. High density-independent seedling mortality was observed in both cohorts. None of the plants flowered in the first or second growing season in the 1990 cohort. These results indicate that T.pratensis is not a biennial species. Size of age-specific plants …
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Local and regional controls of brook trout (Salvelinus fontinalis) metapopulation dynamics within a complex Appalachian riverscape
… hypothesis. This hypothesis predicts stronger density-dependent regulation at the core of a species distribution, while density-independent factors become the limiting mechanism with distance from the core.;The second chapter of this dissertation also used the same data set as analyzed in …
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From data to mathematical analysis and simulation in models in epidemiology and ecology
… a fixed duration. If each host is subjected to density-dependent mortality in its larval stage, we obtain explicit conditions for coexistence of both hosts, as long as each 1 host-parasitoid system would tend to an equilibrium point. Otherwise, if mortality is density-independent, under the same …
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