Plant Sciences Commons^™

Population Genetics Of Transposable Element Load: A Mechanistic Account Of Observed Overdispersion, Gregory Conradi Smith, Ron D. Smith, Joshua Puzey

Arts & Sciences Articles

In an empirical analysis of transposable element (TE) abundance within natural populations of Mimulus guttatus and Drosophila melanogaster, we found a surprisingly high variance of TE count (e.g., variance-to-mean ratio on the order of 10 to 300). To obtain insight regarding the evolutionary genetic mechanisms that underlie the overdispersed population distributions of TE abundance, we developed a mathematical model of TE population genetics that includes the dynamics of element proliferation and purifying selection on TE load. The modeling approach begins with a master equation for a birth-death process and extends the predictions of the classical theory of TE dynamics in …

Climate Change And Conservation Of Milkweed: Evidence Of Extensive Admixture Between Common Milkweed And Poke Milkweed, Elizabeth Davies

Undergraduate Honors Theses

Global climate change can drive many changes in species interactions. One primary way it affects species is by changing climates, causing species to expand their ranges and allowing them to interact with species from whom they were previously isolated. In plants, new species interactions can result in hybridization – the creation of hybrid offspring between two separate species. This hybridization can increase gene flow between the species and lead to introgression, the transfer of genetic material from one species to another through hybrid backcrossing with the parent species. My thesis investigates hybridization in the model system Asclepias (milkweed) by analyzing …

Using A Machine Learning Model To Predict Plant Inflorescences Based Upon Its Soil Microbiome, Luke Denoncourt

Undergraduate Honors Theses

The UN estimates that the global population could reach 9.7 billion by 2050 (United Nations). As a result, the amount of food required to feed humanity is thought to double by 2050 (Ray et al., 2012). Humanity must find a way to increase crop production without increasing fertilizer usage and eutrophication, which can be done using the soil microbiome. Using potted plants with soils inoculated with Pseudomonas alcaligenes, Pseudomonas denitrificans, Bacillus polymyxa, and Mycobacterium phlei, both the shoot and root growth of pea and cotton plants was significantly increased (Egamberdieva & Höflich, 2004). In this study, utilizing a random forest …

Three Centuries Of Vegetation Change In The William & Mary College Woods Reconstructed Using Phytoliths, Timothy Terlizzi

Undergraduate Honors Theses

The College Woods, west of William & Mary’s campus, consists of ~900 acres of protected southern mixed hardwood forest. The woods surround Lake Matoaka, a former millpond established in ~1700. Despite the rich history of the area, little is known about how the dominant vegetative landcover has shifted over the last 300 years. This study set out to quantify the modern vegetation within the College Woods via the phytolith assemblages within the soil and identify shifts in the assemblages since the creation of Lake Matoaka and whether these changes are distinct from the vegetation that existed in the area before …

Associated Dataset: Climate Change Impacts On Southern Ross Sea Phytoplankton Composition, Productivity And Export, Daniel E. Kaufman, Marjorie A.M. Friedrichs, Walker O. Smith Jr., Eileen E. Hofmann, Michael S. Dinniman, John C.P. Hemmings

Data

This dataset includes data used in the publication Kaufman et al., 2017, JGR-Oceans, which investigates how these climatic changes in the Ross Sea, Antarctica, may alter phytoplankton composition, primary productivity and export. A one-dimensional version of the Model of Ecosystem Dynamics, nutrient Utilisation, Sequestration and Acidification was adapted for use in the Ross Sea (MEDUSA-RS). Glider measurements were used to force MEDUSA-RS, which includes diatoms and both solitary and colonial forms of Phaeocystis antarctica. Model performance was evaluated with glider observations, and experiments were conducted using projections of physical drivers for mid- and late-21st century. Additional scenarios examined the …

The Influence Of Environmental Factors And Resource Availability On Zostera Marina Flowering Intensity, Andrew J. Johnson

Dissertations, Theses, and Masters Projects

Sexual reproduction and the production of seeds are important for the resilience of all angiosperm species. For clonal species, such as the seagrass Zostera marina, resource allocation is complicated because these species reproduce both asexually and sexually, and the factors contributing to allocation to these two processes remains unknown. The goal of this study was, therefore, to investigate the importance of critical light, nutrient, and rhizome resources on Z.

marina sexual reproduction and flowering intensity. To evaluate the importance of sediment nutrients on Z. marina flowering intensity two distinct field manipulative experiments and one field survey were initiated: 1. Sediments …

The Roles Of Dispersal And Predation In Determining The Seedling Recruitment Patterns Of A Zostera Marina System, Stephen R. Manley

Dissertations, Theses, and Masters Projects

Seed dispersal and seed predation are two important processes in the early life history of plants. The interaction between these two processes influences the population recruitment from a parent plant. These mechanisms have been studied extensively in terrestrial plants and have resulted in various models to describe plant recruitment (e.g. Janzen-Connell, Hubbell, McCanny). However, seed dispersal and predation may also influence the population recruitment of marine angiosperms, such as Zostera marina (eelgrass). The objectives of this study were to determine: 1.) the patterns of seed dispersal as a function of distance from the seed source, 2.) the predation pressure on …

The Effects Of Salinity Pulses Of Varying Duration And Intensity On Three Freshwater Submerged Aquatic Vegetation Species, Rebecca Wright

Dissertations, Theses, and Masters Projects

No abstract provided.

The Effects Of Seagrass Species And Trophic Interactions In Experimental Seagrass Communities, Althea F. P. Moore

Dissertations, Theses, and Masters Projects

No abstract provided.

Vegetation Dynamics Of A Tidal Freshwater Marsh: Long-Term And Inter-Annual Variability And Their Relationship To Salinity, Sarah B. Davies

Dissertations, Theses, and Masters Projects

No abstract provided.

Application Of The Genetic Algorithm To An Ecological Simulation, William J. Seufzer

Dissertations, Theses, and Masters Projects

A computational framework is built and demonstrated which is capable of testing plant growth strategies. The framework consists of Vgrass, a carbon based simulation model of a single Zostera marina plant, and the genetic algorithm (GA). Vgrass is based on published seagrass models, published photosynthetic data, and general plant physiology information. The model grows individual leaves whose initiation times are based on degree-day intervals. Leaf size is computed and combined with shoot density to compute population self shading. Leaf length is an emergent property since leaf growth is limited by light attenuation caused by self shading. The model is able …

An Introduction To Wetland Seed Banks, Douglas A. Deberry, James E. Perry, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

Increasing The Probability Of Success In Restored Forested Wetlands, Kirk J. Havens, Gene Silberhorn

Reports

This study investigated survival and growth of two distinct ecotypic populations, with varying tolerance to waterlogging, of four species, Taxodium distichum (L.) Richard, Carpinus caroliniana Walt., Quercus michauxii Nutt. and Quercus pagoda Raf. (Syn. Q.falcata var. pagodifolia Ell.).

Studies On Processes Controlling The Input Of Agricultural Chemicals In Groundwater To Surface Waters, Edward Laurence Libelo

Dissertations, Theses, and Masters Projects

This dissertation describes several studies of groundwater quality, the fate and transport of nutrients and atrazine in groundwater systems and physical processes at the sediment-water interface which impact on groundwater discharge. Groundwater monitoring wells were installed at the Goodwins Island and Catlett Island NERRS sites in Virginia and agricultural, suburban and forest land use sites in the York and James River Basins. Groundwater was analyzed for nutrients, pH, salinity and trace organics. Shoreline land use, associated nutrient loading and an estimate of total groundwater flux suggest that groundwater contributes up to 30% of the total nitrogen input to the Chesapeake …

Measurement Of In Situ Eelgrass Community Metabolism In Standing And Flowing Waters: Methods And Models, William James Seufzer

Dissertations, Theses, and Masters Projects

No abstract provided.

The Role Of Predation On Zostera Marina L (Eelgrass) Seed Abundance, James Fishman

Dissertations, Theses, and Masters Projects

No abstract provided.

Growth Response Of Eelgrass (Zostera Marina L) To Root-Rhizome And Whole Plant Exposure To Atrazine, Arthur C. Schwarzschild

Dissertations, Theses, and Masters Projects

No abstract provided.

Vegetation Ecology Of Tidal Freshwater Swamps Of The Lower Chesapeake Bay, United States Of America, Richard D. Rheinhardt

Dissertations, Theses, and Masters Projects

Woody and herbaceous vegetation were sampled in 23 tidal swamps along a tidal freshwater tributary of lower Chesapeake Bay. Four vegetative categories were ordinated with Detrended Correspondence Analysis (DECORANA). Species distribution patterns of each strata were compared with respect to edaphic factors, a wetness index, and mean water table depth. Woody species are restricted to hummocks (topographic highs). Hummocks drain as quickly as the tide drops and so are partially inundated for only short periods each day. Although low in canopy diversity, tidal swamps are floristically rich in herbaceous and woody understory species, ranking them among the most speciose in …

Sediment Inorganic Nitrogen Stocks And Root-Rhizome Ammonium Uptake By Eelgrass (Zostera Marina L) In The Lower Chesapeake Bay, Christopher P. Buzzelli

Dissertations, Theses, and Masters Projects

No abstract provided.

The Ultrastructure Of Cell Division In Male Reproductive Branches Of Polysiphonia Denudata, Cynthia Louise Bosco

Dissertations, Theses, and Masters Projects

No abstract provided.

Geomorphic Interpretation Of Vegetation On Fisherman Island, Virginia, Mark Eliot Boule

Dissertations, Theses, and Masters Projects

No abstract provided.