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Theses/Dissertations

Life Sciences

Dissertations and Theses

Symbiosis

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Microbes On The Mountain: Plant-Microbe Associations And Interactions On Mount St. Helens, Emily Rose Wolfe Aug 2021

Microbes On The Mountain: Plant-Microbe Associations And Interactions On Mount St. Helens, Emily Rose Wolfe

Dissertations and Theses

Plant-microbe associations and interactions provide critical context to studies in both community and ecosystem ecology, especially in systems that are relatively new and still undergoing early successional processes. Microbes can colonize the surfaces and interiors of all plant tissues, and these assemblages vary in composition both spatially and temporally, even within the same plant. Endophytes are bacteria or fungi that spend most of their lifecycles living within plant tissues asymptomatically--typically, "endophyte" refers specifically to aboveground tissues such as leaves and stems, and therefore may have direct influences on defenses against herbivory, pathogen or pest tolerance, and even afterlife effects on …


Next Generation Sequencing Identifies Population Structure And Signatures Of Local Adaptation In Red Alder (Alnus Rubra Bong.), Jacob Brent Loveless Jun 2021

Next Generation Sequencing Identifies Population Structure And Signatures Of Local Adaptation In Red Alder (Alnus Rubra Bong.), Jacob Brent Loveless

Dissertations and Theses

Red alder (Alnus rubra Bong.) is the dominant hardwood tree species in the Pacific Northwest. Red alders are only found in western North America, generally within 200 km of the coast and below 1000 m in elevation--although there are several disjunct populations in the northern Rocky Mountains in Idaho. Commonly a riparian species, the shade intolerant red alder generates most of the leaf litter in the streams and rivers it occupies which has been shown to greatly influence the decomposer communities. This, in turn, has a cascading effect throughout the entire riparian ecosystem greatly influencing multiple levels of the …


Do Fungal Symbionts Of Salt Marsh Plants Affect Interspecies Competition?, Vanessa Robertson-Rojas Sep 2020

Do Fungal Symbionts Of Salt Marsh Plants Affect Interspecies Competition?, Vanessa Robertson-Rojas

Dissertations and Theses

The effects of arbuscular mycorrhizal fungi (AMF) as salt marsh plant symbionts may have significant effects on landscape scale distribution patterns and plant-related ecosystem functions that are important to estuarine habitats. This work investigates the effects AMF have on Phalaris arundinacea, Deschampsia cespitosa, and Juncus balticus when grown in a common garden experiment. Plants were grown with and without AMF inoculation in both polyculture and monoculture communities and examined for a variety of response variables that represent different competition strategies. Factorial ANOVA analysis revealed a significant three-way interaction among fungal treatment type, community type, and species for …


Symbiosis With Nitrogen-Fixing Rhizobia Influences Plant Defense Strategy And Plant-Predator Interactions, Adrienne Louise Godschalx Jun 2017

Symbiosis With Nitrogen-Fixing Rhizobia Influences Plant Defense Strategy And Plant-Predator Interactions, Adrienne Louise Godschalx

Dissertations and Theses

As sessile organisms, plants evolved a plethora of defenses against their attackers. Given the role of plants as a primary food source for many organisms, plant defense has important implications for community ecology. Surprisingly, despite the potential to alter entire food webs and communities, the factors determining plant investment in defense are not well-understood, and are even less understood considering the numerous symbiotic interactions in the same plant. Legume-rhizobia symbioses engineer ecosystems by fixing nitrogen from the atmosphere in trade for plant photosynthates, yet connecting symbiotic resource exchange to food web interactions has yet to be established. Here I test …