Ecology and Evolutionary Biology Commons^™

The Effects Of Ericoid Inoculum Source And Nutrient Addition On Growth And Reproduction In Highbush Blueberry, Ilana Williams

Graduate College Dissertations and Theses

Ericoid mycorrhizal fungi (EMF) form symbiotic relationships with ericaceous plants such as Vaccinium corymbosum, or highbush blueberry and assist in nutrient acquisition. EMF help plants thrive in stressful environments by increasing the area in which roots can uptake water and nutrients. In plant-mycorrhizal symbioses, nutrient uptake may depend on the identity of the fungal partner. Therefore, differently sourced mycorrhizal fungi could show differences in nutrient uptake ability. Here, I hypothesized that inoculation of V. corymbosum with EMF would enhance plant growth and investment in reproduction, and that effect would be more pronounced for plants in low nutrient conditions. I also …

Diversity And Distribution Of The Malaria Parasites (Genus Plasmodium) Of The Common Loon (Gavia Immer) And Of Vermont Mosquitoes, Alyssa Neuhaus

Graduate College Dissertations and Theses

The emergence of infectious diseases has become an urgent concern for human and wildlife populations alike. Malaria parasites (genus Plasmodium), which are transmitted by mosquitoes, are major pathogenic disease agents in human and wildlife populations with numerous non-exclusive factors, including climate change and range shifts, acting to increase their threat. The malaria parasites that infect the Common Loon (Gavia immer) serve as an ideal system for studying emerging infectious disease threats with warming temperatures as the Common Loon is a northerly distributed, immunologically and evolutionary naïve species and of conservation concern across parts of its breeding range. I investigated the …

Elements Of Biocontrol Strategies For Pheretimoid Earthworms, Maryam Nouri-Aiin

Graduate College Dissertations and Theses

Jumping worms (Megascolecidae) in the pheretimoid complex, have raisedconsiderable environmental concerns with conservationists, ecologists, policy makers, and the public. Their impacts on North American forests and high density is distinct from earthworms in other families. Most of the infested forests are near horticultural settings. Practicable options to manage their dispersal into forests do not exist. This dissertation examines the potential of an entomopathogenic fungus to control them in horticulture. It also investigates major barriers to managing their spread and studying their ecology including species identification, phenology, and genetic diversity. First, to discover the best time to apply biocontrol agents, I …

The Effect Of Amphibian Host Ecology And Evolution On The Pathogen Dynamics Of Ranavirus, Lauren V. Ash

Graduate College Dissertations and Theses

Emerging infectious diseases threaten amphibian species around the globe. Ranavirus (Family: Iridoviridae) is associated with the majority of amphibian deaths in North America, with some species exhibiting mass mortality events in short periods of time. In contrast, some amphibian species show the capacity to resist or tolerate infection. Resistant individuals exhibit reduced infection intensity, while tolerant individuals display reduced fitness effects given the infection intensity. My research focused on how amphibian host dynamics at community, population, and individual-level scales relate to the wide variation in Ranavirus prevalence and severity. Through my work, I documented the first reports of Ranavirus in …

Spiny Spiders And Spiny Trees: Molecular Phylogenetics And Biogeographic Reconstruction Reveal History Of Recurrent Overwater Dispersal Events, Single-Island Endemics, And New Species Of Caribbean Micrathena (Araneae: Araneidae), Lily Kay Shapiro

Graduate College Dissertations and Theses

Elucidating the processes responsible for the provenance of taxon biodiversity on islands can help us to understand macroevolutionary mechanics in addition to specific organismal histories. Current species distributions are a result of an admixture of both abiotic (i.e. geologic) and biotic (i.e. dispersal capability, speciation and extinction rates) factors. The heterogeneous tectonic histories and local ecological differentiation among islands within the Caribbean contribute to high levels of endemicity and diversity. Differential historical biogeographic processes, namely vicariance (physical separation of populations by barriers) or long-distance dispersal, represent hypotheses to explain current distributions of species on islands resulting from colonization followed by …

Investigating Routes Of Pollinator Exposure To Pesticides, Jessica Cole

Graduate College Dissertations and Theses

Pesticides are widely used in agriculture to minimize the negative impact of harmful pests. However, the use of pesticides also has non-target effects on beneficial insects such pollinators. In addition to the direct harm to pollinators foraging on crops during pesticide application, pesticides are also frequently utilized in non-agricultural settings, and can drift to non-target areas via the wind and water. Plants growing in such contaminated soils may absorb pesticides and express them in their flowers, specifically the pollen and nectar upon which pollinators rely. This is particularly important because encouraging wildflower growth alongside fields is a common strategy to …

No Farm Is An Island: Pollinators And Pollination In Agricultural Landscapes, Charles C. Nicholson

Graduate College Dissertations and Theses

Productive, resilient and sustainable agricultural systems are required to meet the immediate needs of a burgeoning human population, while avoiding ecosystem collapse. Agriculture provides food, fiber, fuels and other products for our current population of 7 billion and is still the major livelihood for 40% of people worldwide. By replacing natural habitat and employing chemical inputs, agriculture also negatively impacts biodiversity and impairs the provision of ecosystem services. This poses a challenge for agriculture as these impacted services are often those required for high yielding and high-quality crop production. Evidence is accumulating that agricultural management can safeguard biodiversity and ecosystem …

Uncovering The Variable Life History Traits And Strategies Of The Gregarine Parasite, Monocystis Perplexa, In Its Invasive Earthworm Host, Amynthas Agrestis, Erin L. Keller

Graduate College Dissertations and Theses

Parasite life histories influence many aspects of infection dynamics, from the parasite infrapopulation diversity to the fitness of the parasite (the number of successfully transmitted parasites). Studies of medically important parasites, such as the parasite responsible for malaria (Plasmodium spp.), demonstrate the usefulness of investigating the life histories of parasites to better understand infection characteristics such as parasite load and probability of transmission.

The gregarines are a diverse group of apicomplexan parasites that infect invertebrates, and are particularly common in insects and annelids. Given the great biodiversity and importance of their hosts, coupled with their close evolutionary relationship with important …

Sexual Conflict And Chemical Communication In Hybridizing Harvester Ants, Michael Philip Herrmann

Graduate College Dissertations and Theses

Sexual conflict occurs when the fitness interests of males and females do not align with one another. The resolution of sexual conflict often depends on the level of control each sex has on the behavior in conflict. In Pogonomyrmex harvester ants with a genetically determined caste system, two separate lineages interbreed with one another during summer mating swarms. Diploid offspring sired by a single lineage develop into reproductive queens, while offspring sired by opposite-lineage parents develop into sterile workers. This results in sexual conflict, as males which mate with opposite lineage queens will produce only workers, resulting in no fitness …

Impacts Of Forest Disturbance On Small Mammal Distribution, Allyson Lenora Degrassi

Graduate College Dissertations and Theses

Natural habitat in the eastern United States has diminished over the past century because of the effects of invasive species. Both plant and animal invaders can alter habitat structure and may decrease survival of native species. The degree to which an invasive species alters ecosystem function depends on the functional characteristics of affected species and the resulting cascading effects. The loss of important native species, such as foundation species, can potentially influence the structure and distribution of animal communities because of the foundation species' unique ecosystem roles. The foundation species concept is relatively new to the terrestrial ecology and the …

Fixed Versus Plastic Partial Migration Of The Aquatic Macroinvertebrate, Mysis Diluviana, In Lake Champlain, Peter Thomas Euclide

Graduate College Dissertations and Theses

Partial migration, whereby populations consist of residents and migrants, is common among migrating organisms. Partial migration of aquatic organisms, however, remains largely under-studied even though many aquatic animals exhibit horizontal and vertical migrations during their lifetime. Macroinvertebrates of the genus Mysis exhibit diel vertical migrations (DVM). Some species have recently been observed to exhibit partial diel migrations where some individuals reside on the bottom throughout the night while others migrate into the water column. To test the hypothesis that individuals are fixed as residents or migrants, we compared demographic information and C and N isotope compositions of M. diluviana caught …

Investigations Into Host-Specific Interactions And Local Adaptation In The Mycorrhizal Symbiosis, Jonathan Gonzalez

Graduate College Dissertations and Theses

Mycorrhizal fungi are soil-borne organisms that form symbiotic associations with the majority of land plants. These fungi gather and exchange mineral nutrients with plants for photosynthetically derived carbohydrates. Mycorrhizal fungi can also confer other benefits onto plants, e.g. defense against pathogens, improved water relations, tolerance to heavy metal toxicity and herbivory. The influence of mycorrhizal fungi on plant mineral nutrition and response to stress suggests that these organisms may have a role to play sustainable agriculture as well as in bioremediation and ecosystem restoration.

In contributing to this important research, I investigated host-specific interactions between mycorrhizal fungi and the sex …