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Description: |
1 online resource (113 pages) : illustrations, maps |
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General Note: |
Title from title page of PDF (University of Missouri--St. Louis, viewed March 9, 2010). |
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Dissertation Note: |
M.S. University of Missouri--St. Louis 2006 |
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Bibliography Note: |
Includes bibliographical references. |
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Summary, Etc. Note: |
Abstract: Introduction of exotic species is a major factor contributing to biodiversity loss, particularly in extinction-prone island ecosystems (Vitousek et al. 1997). While the Galápagos archipelago has experienced negative impacts from invasive plants and animals (Snell et al. 2002), its bird community has remained remarkably intact with no recorded extinctions - in contrast to the fate of the avian fauna of other oceanic archipelagos (VanRiper et al. 1986, Savidge 1987, Holdaway 1989, Steadman 1995, Blackburn et al. 2004). The role of introduced pathogens in species loss is not well understood, but there is evidence that they have contributed to the decline and extinction of species in several island systems (see Wikelski et al. 2004). For island birds in particular, avian malaria and avian poxvirus have contributed to the extinction of several Hawaiian land birds (Warner 1968, Van Riper III et al. 1986, Atkinson et al. 1995). In addition to the other challenges facing island biotas (isolation, various effects of small population size), they may also be more susceptible to introduced pathogens due to immunological naivety (Atkinson et al. 1995). In recognition of the potential consequences of pathogen introduction to the Galápagos Islands, the Saint Louis Zoo and the University of Missouri-Saint Louis, in cooperation with the Galápagos National Park Service and the Charles Darwin Research Station, implemented an avian disease surveillance program in 2001, with the objective of identifying and monitoring for pathogens that pose risk for native bird populations (Miller et al. 2002, Parker et al. 2006). The purpose of this thesis is identify environmental factors that might influence the geographic distribution of avian pathogen infection, based on two data sets obtained as a result of these surveillance efforts: 1) seroprevalence data on 10 common poultry pathogens from farm sites within the agricultural zone of Santa Cruz (Chapter 1); and 2) prevalence and intensity values of microfilarial infections of endangered flightless cormorants and Galápagos penguins (Chapter 2). Putative correlative factors were obtained from various geographic information system (GIS) and remotes sensing data sets, containing information on temperature, precipitation, water vapor, soil moisture, vegetative density and topography. Results of these analyses provide indications of correlation between pathogen infection measures and various ecological factors which may affect disease transmission. These observations may provide the bases for the formulation of specific hypotheses for more rigorous statistical verification. An understanding of the environmental factors influencing poultry pathogen prevalence may be useful in predicting the consequences of pathogen transmission across the poultry / wildlife interface (Chapter 1). Insight into the geographic distribution of arthropod-vectored microfilarial infections may allow us to predict the spatial distribution of transmission risk should other arthropod-borne pathogens, such as avian malaria or West Nile Virus, be introduced to this ecosystem (Chapter 2). |
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Elect. Loc./Access: |
http://irl.umsl.edu/thesis/11 Freely available online |