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Filtering by: Creator Helfand, Stuart C. Remove constraint Creator: Helfand, Stuart C. Advisor Blaustein, Andrew R. Remove constraint Advisor: Blaustein, Andrew R. Degree Name Doctor of Philosophy (Ph.D.) Remove constraint Degree Name: Doctor of Philosophy (Ph.D.)

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  • Environmental influences on host-pathogen dynamics of the amphibian chytrid fungus

    Creator:
    Buck, Julia C.
    Abstract:
    The causes of the global biodiversity crisis are varied and complex. Anthropogenic threats may act in isolation, or interact additively or synergistically with each other or with natural stressors to affect sensitive taxa. The recent emergence of many infectious diseases in wildlife has brought attention to the role of disease...
    Resource Type:
    Dissertation
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    amphibian chytrid fungus AN ABSTRACT OF THE DISSERTATION OF Julia C. Buck for the degree of Doctor

  • Multiple stressors and amphibian population declines

    Creator:
    Hatch, Audrey C.
    Abstract:
    In the past decade, declines in amphibian populations have captured scientific and popular interest. The causes of the declines are likely to be complex and involve interactions between several environmental stressors. Using multifactorial experiments, I investigated the combined effects of several anthropogenic stressors on developing amphibians in Oregon, USA. In...
    Resource Type:
    Dissertation
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    AN ABSTRACT OF THE DISSERTATION OF Audrey C. Hatch for the

  • The effects of multiple pathogens on amphibians in the Pacific Northwest

    Creator:
    Romansic, John M.
    Abstract:
    The earth is undergoing a “biodiversity crisis” characterized by loss of populations, species, genetic diversity, and ecosystem services. Part of this crisis consists of population declines, extinctions, and increased incidence of deformities in amphibians. It is unknown whether deformities contribute to these declines. Many cases of population declines in amphibians...
    Resource Type:
    Dissertation
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    disappearing (Houlahan et al., 2000, Stuart et al., 2004). The same factors discussed above appear to be

  • The Effects of Host and Pathogen Variation on Infection Dynamics in the Amphibian-Chytrid System

    Creator:
    Dang, Trang D.
    Abstract:
    This dissertation uses manipulative experiments to explore amphibian-Bd infection dynamics. Although there has been almost two decades research since the discovery of Bd, many questions still remain regarding what conditions mediate chytridiomycosis virulence. My research shows how certain host and pathogen factors can influence disease virulence. Identifying how host and...
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    Dissertation
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    Violin plot (with boxplot overlay) of Bd infection intensity A) P. regilla, B) A. boreas, and C) R

  • Disentangling the Biotic and Abiotic Drivers of the Amphibian Disease Chytridiomycosis

    Creator:
    Bradley, Paul W.
    Abstract:
    The ongoing worldwide loss of biodiversity has been described as a "biodiversity crisis," "the Anthropocene defaunation," and alternatively "an extinction spasm." More recently, many scientists have come to the conclusion that we are witnesses to Earth's sixth major mass extinction event, which has the potential to fundamentally alter basic ecological...
    Resource Type:
    Dissertation
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    the amphibians (Alford & Richards 1999; Houlahan et al. 2000; Stuart et al. 2004; Hof et al. 2011

  • Effects of Diversity on Emerging Infectious Diseases of Amphibians

    Creator:
    Snyder, Paul W.
    Abstract:
    Species declines and extinctions have been recorded across taxa as evidence of an ongoing global biodiversity crisis. Amphibians are at the forefront of these declines with nearly one third of amphibian species estimated to be at risk of extinction. While many factors contribute to population declines and extinctions, the role...
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    Dissertation
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    1999, Davidson, C 2004, Stuart et al. 2004, Fisher and Garner 2020) birds (Sodhi et al. 2004, Monroe

  • Effects of pesticides on amphibians with special reference to the pyrethroidinsecticide, cypermethrin

    Creator:
    Biga, Lindsay M.
    Abstract:
    Pollution by pesticides is a ubiquitous concern for wildlife. The effects of pesticides are especially concerning in aquatic environments, which are particularly vulnerable as they have several exposure routes for the influx of chemicals. These effects are of particular concern as biodiversity loss reaches unprecedented rates. This includes recent declines...
    Resource Type:
    Dissertation
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    , with about 1910 of the 6,312 known amphibian species in danger of extinction (Stuart et al. 2005

  • Ultraviolet radiation as an environmental stressor of amphibians

    Creator:
    Bancroft, Betsy A.
    Abstract:
    My thesis explored the effects of and potential mediating mechanisms for an important environmental stressor, ultraviolet-B (UVB) radiation. UVB radiation has negative effects on organisms in both terrestrial and aquatic systems. I used meta-analysis to quantify the effects of UVB radiation on a diversity of aquatic organisms (Chapter 2). UVB...
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    Dissertation
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    C The effect of UVB radiation on growth (log response ratio [lnR]) ……... 173 D Amphibian

  • Emerging infectious disease in lentic environments : the ecology and biogeography of the amphibian chytrid fungus Batrachochytrium dendrobatidis, with perspectives on water quality, limnology, and chemical contaminants

    Creator:
    Chestnut, Tara
    Abstract:
    Biodiversity losses in terrestrial, freshwater, and marine systems are accelerating at a global scale and the most threatened vertebrate taxa are those associated with freshwater habitats. The causes of biodiversity losses are often complex and include synergistic effects of natural and human-induced stressors, such as habitat loss and fragmentation, urbanization,...
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    Dissertation
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    exposed to two temperature treatments, frozen and not frozen (4 C

  • Ontogenetic Shifts in Disease Response in Native and Invasive Anuran Species

    Creator:
    Urbina Gonzalez, Jenny Cecilia
    Abstract:
    This dissertation presents a different approach to understanding how amphibians are responding to disease through ontogeny. Although numerous efforts have been conducted to understand host responses to the fungus Batrachochytrium dendrobatidis (Bd), studies have been restricted to distinct developmental stages. This dissertation provides information on host response to Bd across...
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    Dissertation
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    as a group of serious conservation concern (Stuart et al. 2004, Wake & Vredenburg 2008, Kilpatrick