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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.
1

Islands, Metapopulations, and Archipelagos: Genetic Equilibrium and Non-equilibrium Dynamics of Structured Populations in the Context of Conservation

Reynolds, Robert Graham 01 May 2011 (has links)
Understanding complex population dynamics is critical for both basic and applied ecology. Analysis of genetic data has been promoted as a way to reconstruct recent non-equilibrium processes that influence the apportioning of genetic diversity among populations of organisms. In a structured-deme context, where individual populations exist as geographically distinct units, island biogeography theory and metapopulation genetics predict that the demographic processes of extinction, colonization, and migration will affect the magnitude and rate of genetic divergence between demes. New methods have been developed to attempt to detect the influence of non-equilibrium dynamics in structured populations. I challenged two of these methods: decomposed pairwise regression and allele frequency analyses, using simulations of genetic data from structured demes. I found that these methods suffer from a high type II error rate, or failure to reject the null hypothesis of mutation-migration-drift equilibrium for demes experiencing historical demographic events. In addition, island biogeography and metapopulation ecology predict that at equilibrium, some species in a patch will be recent colonists, as equilibrium indicates a balance between colonization of the patch and extinction from the patch. Recent colonists are unlikely to have reached population mutation-migration-drift equilibrium; hence a paradox exists between population and community level equilibrium. I used nuclear and mitochondrial genetic data from populations of two species of reptiles from the Turks and Caicos Islands, British West Indies to test for patterns of equilibrium vs. non-equilibrium. I found unexpected shallow genetic divergence in the Turks Island boa (Epicrates chrysogaster), indicating that this species likely existed as a panmictic population prior to the inundation of the Turks and Caicos Banks during the last glaciation. As the initial methods I tested using simulations proved unreliable, I used methods from phylogeography, landscape genetics, and island biogeography to detect significant non-equilibrium dynamics in the Turks and Caicos curly-tailed lizard (Leiocephalus psammodromus), finding evidence for high levels of biased gene flow. I propose that studies of genetic diversity on island archipelagos use tools from all three of these methods to evaluate empirical data in the context of equilibrium and the null hypotheses offered by island biogeography and population genetics theory. I frame the results both in the context of conservation and an understanding of equilibrium and non-equilibrium dynamics.
2

The Epidemiology and Surveillance of Ciguatera Fish Poisoning in the Turks and Caicos Islands

Schneider, Evan 11 September 2012 (has links)
Innovative ways to conduct disease surveillance are required to address the complexity of Ciguatera Fish Poisoning (CFP). Mixed methods were employed to explore CFP epidemiology and interdisciplinary approaches to its surveillance in the Turks and Caicos Islands (TCI). Quantitative analyses of cross-sectional data collected by the TCI’s National Epidemiology and Research Unit in 2010 demonstrated that a low percentage of residents reported lifetime histories of illness following fish consumption (3.9%). Furthermore, gender, age, island, and home remedy use were significantly associated with reported clinic visitation by ill individuals. Next, a multisectoral CFP surveillance model was conceptualized. A qualitative exploration of the model’s hypothetical integration into TCI’s health system revealed that several systemic and contextual factors could influence the future uptake of interdisciplinary CFP surveillance. Targeted interventions are recommended to improve national CFP surveillance and to facilitate the growth of interdisciplinary networks between stakeholders from TCI’s health, fisheries and environment sectors. / Canadian Institutes of Health Research, Ontario Veterinary College, University of Guelph, Ministry of Health and Human Resources of the Turks and Caicos

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