Life Sciences Commons^™

Is Diversity Dammed? Analysis Of Fish Diversity In Dammed And Undammed Estuary Streams Within The Virginia Peninsula Using Environmental Dna (Edna), Melinda Ann Spence

Dissertations, Theses, and Masters Projects

Anthropogenic activities are the leading cause to biodiversity decline worldwide. It has been well documented that large dams disrupt dispersal and alter local habitat often leading to less diverse aquatic systems. Yet, it is not well known how much more numerous smaller dams impact fish communities in estuary systems where dispersal is a critical part of the ecosystem, or how dams affect variation in species composition across sites (beta diversity). Coastal waterways of Virginia are impounded by hundreds of small dams. Here we used eDNA (environmental DNA) to assess the alpha, beta, and gamma diversity of fish species within the …

The Characterization Of The Type I Dna Methyltransferase Hsdm1 (Hp0463) In Helicobacter Pylori, Elise Zimmerman

Undergraduate Honors Theses

Helicobacter pylori is a gram-negative spiral-shaped bacterium that colonizes the gastric epithelium and is the leading cause of gastric adenocarcinoma globally. For both H. pylori and many other bacterial species, there is an increasing body of evidence that methylation by restriction-modification systems regulates gene expression in addition to its traditional role in genome protection. The study aimed to further elucidate the mechanisms through which H. pylori achieves methylome plasticity. We demonstrated that the Type I DNA methyltransferase hsdM1 (HP0463) is regulated by the main acid sensing mechanism of H. pylori, the two-component system (TCS) ArsRS. ArsRS induces hsdM1 …

Investigating The Effect Of Longhorned Milkweed Beetle Larval Root Feeding On Resprouting In Common Milkweed, Margaret Donnan

Undergraduate Honors Theses

Clonal reproduction is an important form of reproduction for many plants, and plants can grow clonally through a variety of methods, such as belowground stems, specialized organs, or adventitious buds on their roots (Herben and Klimešová 2020). In plants that reproduce via buds on their roots, researchers have shown that damage to roots can stimulate bud production and sprouting (Bartušková and Klimešová 2010). Common milkweed (Asclepias syriaca) is a root- sprouting perennial plant that receives yearly damage to its roots via the feeding of the larvae of the specialist longhorned milkweed beetle (Tetraopes tetrophthalmus) (Erwin et al. 2013). In this …

Carrying Capacity Of Cultured Bivalves In Cherrystone Inlet, Va, And The Implications Of Spatial Distribution And Environmental Change, Sophia Chirico

Undergraduate Honors Theses

Aquaculture is a growing industry internationally. In the United States, aquaculture of bivalves occurs throughout the Chesapeake Bay. Cherrystone Inlet, a tidal inlet on the Virginia Eastern Shore, is the location of intensive hard clam culture, and recently oyster aquaculture has become common there as well. Given the intensive culture in Cherrystone and similar systems in the Chesapeake, it is important to understand the carrying capacity of the respective bivalves and how they can be grown together. Carrying capacity is defined here as the largest population of individuals that can be supported that allows individuals to reach a harvestable size …

Relating Occupancy Patterns To Multi-Life-History Scales For Pond-Breeding Anurans In Eastern Virginia, Patrick A. Hardner

Undergraduate Honors Theses

Amphibians are experiencing population declines worldwide due to a multitude of factors, including habitat loss. Therefore, assessments of breeding habitat occupancy are important to determine which environmental characteristics are crucial for conservation of amphibians. While most research assesses habitat conditions at the breeding site (i.e., pond or wetland), for many species this misrepresents annual habitat use as many migrate to terrestrial habitats once breeding is completed. To provide a comprehensive assessment of annual habitat use, we evaluated how anuran (i.e., frog and toad) breeding site occupancy related to three life-history scales: breeding, migration and dispersal. Basically, the three scales define …

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 …

Honey As A Biomonitor For Air Pollutant Deposition In The Eastern United States Using Ion Chromatography And Scanning Electron Microscopy, Cole Cochran

Undergraduate Honors Theses

Anthropogenic activities generate metal, acid, and particulate air pollutants which negatively impact human and ecological health. In the United States, power plant, industrial, and vehicle emissions are leading causes of air pollution, however, the measurement of air pollution at high-resolution spatial regimes remains a challenge. Honey has emerged as a powerful biomonitoring tool to effectively quantify contaminants without the need for a large array of monitoring instruments. I hypothesized that honey could be used to effectively measure and map modern air pollutant spatiotemporal relationships over the Eastern U.S. Using ion chromatography with sulfate as an indicator for air pollution and …

Ecosystem Enriching And Efficient Solar Energy: Exploring The Effects Of Pollinator-Friendly Solar Facilities On Ecosystem Function And Solar Panel Efficiency, Jordan Martin

Dissertations, Theses, and Masters Projects

As the solar energy industry grows, many hundreds of thousands of acres of land will be transformed into solar panel facilities. With this large change in land use, there is the opportunity to promote biodiversity and support pollinators by using pollinator-friendly management practices at the solar facilities. This paper explores the ecological and economic effects of a pollinator-friendly solar facility compared to a turfgrass solar facility.

I hypothesized that a pollinator-friendly solar facility would be functionally equivalent in pollinator support and overall insect diversity to a pollinator-friendly non-solar field and that both sites would have far greater pollinator support and …

Characterizing The Microbiome Of Floral Nectar Of Asclepias Syriaca And Other Asclepias Species, Heather Natterer

Undergraduate Honors Theses

In recent decades, Danaus plexippus (the monarch butterfly) has experienced a drastic decrease in population size due to urbanization, climate change, and habitat loss. The primary habitat and food source of D. plexippus is plant species that are within the genus Asclepias (milkweed). The preservation and propagation of Asclepias spp. is necessary to combat D. plexippus’s population declines. A plant’s reproductive success is dependent upon its ability to attract pollinators, which is linked to the plant’s nectar qualities. We propose that, in turn, these nectar qualities may be influenced by the nectar microbiome. This study aims to better understand the …

Mysteries And Uncertainties In Tracing Cryptic Viral Infections, Melaina Jacoby

Undergraduate Honors Theses

Viruses are the most abundant biological entities on Earth. Viral impacts are evident from the level of individual cells and population all the way up to ecosystems and global elemental cycles. Since bacteriophages (viruses that infect bacteria) were first identified in the early twentieth century, the study of these fascinating entities has shown how viral dynamics within ecosystems can influence microbially-mediated processes at a large scale. Viral infections can impact hosts and host-mediated processes in in multiple ways, one of which is through cryptic infections. This state, in which a bacterium may harbor a cryptic phage infection, is known as …

Bird-Window Collisions And Reflection As A Daytime Risk Factor, Lauren Celeste Emerson

Dissertations, Theses, and Masters Projects

Bird-window collisions account for millions of bird deaths annually in the United States. Despite many correlative studies citing the potential influence of reflective glass on daytime collision risk, few studies have explicitly tested this hypothesis. We aimed to determine whether reflection from a window influences daytime collision risk by manipulating the lighting conditions on exterior and interior window surfaces. We conducted this research within a flight tunnel in which domesticated zebra finches (Taeniopygia guttata) flew towards a window structure with two windows situated behind a mist-net. We assessed collision risk and flight velocity through 3D videography. We predicted that risk …

Search For Selection: Genomic, Transcriptomic, And Phenotypic Investigations Of Spotted Seatrout (Cynoscion Nebulosus), Jingwei Song

Dissertations, Theses, and Masters Projects

Climate change has resulted in both increased mean water temperature and higher frequencies of extreme water temperatures in coastal areas. These new thermal regimes exert strong selective pressure on the thermal physiology of coastal aquatic species. Phenotypic plasticity (the ability of one genotype to display multiple phenotypes) and local adaptation (increased fitness to local environment due to natural selection) dictate both short-term (from hours to days to weeks) and long-term (from years to decades) resilience of a species. To better predict how a species will respond to the negative impacts of climate change, one first needs to know the current …

The K. Marxianus Small Protein Modifier Sumo Enhances Stress Tolerance In The Mesophilic Yeast S. Cerevisiae, Yasaman Setayeshpour

Dissertations, Theses, and Masters Projects

SUMO, a small ubiquitin-like modifier protein, becomes attached to specific eukaryotic proteins to modulate their function and activity. The importance of SUMO modification in cell cycle progression, transcriptional regulation, and DNA damage-related processes has been firmly established. In contrast, a SUMO-dependent Stress Response (SSR) exists, but this process remains ill-defined. When cells are exposed to proteotoxic and genotoxic stressors, the SSR involves a rapid and dramatic increase in SUMO-modified proteins. The SSR is believed to play a cytoprotective role for normal cells, but it may also enhance the robustness of cancerous cells and eukaryotic pathogens. To test our hypothesis that …

Population Structure Of The Hard Clam, Mercenaria Mercenaria, Along The East Coast Of North America, Ann Janette Ropp

Dissertations, Theses, and Masters Projects

Virginia leads the nation in production of aquacultured hard clams, Mercenaria mercenaria (Linnaeus, 1758), with an estimated farm gate value of $38.8 million in 2018. Despite the high economic value, there are few genomic resources available to support the hard clam aquaculture industry.To develop effective genetic tools for industry, it is important to first understand population structure. Hard clams have a pelagic larval phase that allows for dispersal, but the level of genetic connectivity among populations is not well understood. This study used genotyping-by-sequencing to delineate the genetic stock structure of wild clams sampled along the East Coast of North …

The Epibiont-Host Interaction Between Zoothamnium Intermedium And Estuarine Copepods, Lucia S.L. Safi

Dissertations, Theses, and Masters Projects

Ciliates are basal eukaryotes from Phylum Ciliophora that were first described 400 years ago, but their origins date back 800 million years. Such early origins have allowed contemporary ciliates to be remarkably diverse in both their species numbers and ecological adaptations. Peritrichia, a subclass of ciliates, represents an ideal model to study ciliate diversity, as its members display complex phylogenetic relationships and can be epibionts colonizing the body surface of other organisms. Epibiotic relationships are ecologically and evolutionarily important due to the extensive adaptations in epibiont biology to the life cycles of hosts. These relationships are also important for host …

Semester-Long Instruction In Drawing For Biology Changes Study Habits, Motivation To Draw, And Approaches To Problem-Solving, Jessica Rose Burns

Dissertations, Theses, and Masters Projects

Model building can use drawing or sketching as a mechanism to help the drawer learn information (study), solve problems (model-based reasoning), and communicate. Unfortunately, many students fail to master drawing or sketching skills due to the effort and instruction required. Additionally, few longitudinal, real-world classroom studies have been conducted on the teaching of drawing to students. We applied guided practice of drawing or sketching to an undergraduate first-semester Introductory Biology majors course, aiming to assess (1) the patterns of growth and decline in the use of sketching and other active study methods over subsequent semesters, (2) the relationship between usage …

Invasive Species Research In Compensatory Wetland Mitigation: Investigating Plant Community Composition And Environmental Correlates With Three Invasive Plants, Dakota Hunter

Dissertations, Theses, and Masters Projects

Invasive plant species can alter natural communities and degrade ecosystem function, yet the factors influencing species invasion are poorly understood. Understanding how environmental factors affect plant invasion on compensatory wetland mitigation sites would allow wetland managers to approach invasive species management using a proactive approach (prior to invasion), thus minimizing the likelihood of invasive plants colonizing the system and degrading ecosystem function. In Chapter 1, I introduce the concepts and relevant literature used repeatedly in my project. In Chapter 2, I examine which key environmental factors are associated with altered plant community structure and invasive species prevalence on compensatory wetland …

Ecology And Evolution Of Common Milkweed, Angela Ricono

Dissertations, Theses, and Masters Projects

All organisms must interact with and adapt to their surrounding environment. There are myriad ways in which species accomplish this; ultimately resulting in the vast diversity of life on earth today. Changes in the environment can have profound impacts on an organisms' ability to compete and utilize their surroundings. Plants are particularly impacted by local environmental differences because of the fact that they are immobile. This environmental variation exists at both large and small spatial scales. For example, on larger scales, forces such as fire and grazers can remove dominant plant competitors. on smaller scales, variation in resource availability (e.g. …

The Effects Of Dietary Mercury Exposure On Male Fertility In The Zebra Finch, Ananda Menon

Dissertations, Theses, and Masters Projects

Sperm traits, including morphology, number and function, have been linked to fertilization ability and offspring quality in several species. However, many of these traits are artificially influenced by anthropogenic pollutants. Mercury, a globally distributed heavy metal pollutant, has been linked to altered testicular morphology and reduced fertility in many vertebrates. in this study, we exposed domestic male zebra finches (Taenopygia guttata) to dietary mercury at concentrations found in prey species in a highly polluted watershed region. We then compared sperm traits from these males to those of controls, and found a significant effect of mercury on sperm length and variability. …

Immune Changes In The Anterior Kidney Of Spawning Sockeye Salmon, Meaghan K. Smith

Dissertations, Theses, and Masters Projects

During the return journey to their spawning grounds, sockeye salmon are exposed to various pathogens and undergo major endocrine changes. Little is known about how these changes affect their immune system. The immune system of salmon is similar to mammals; myeloid lineage cells provide the first response to infection and B lineage cells protect against specific pathogens. After activation by pathogen, B cells may differentiate into long-lived plasma cells (LLPCs) in the anterior kidney, where they can survive for years, continuously secreting protective antibody. This research focused on salmon from two rivers, the Kenai and the Copper River, and characterized …

Range-Wide Variation In Common Milkweed Traits And Its Effect On Larvae Of The Monarch Butterfly, David De La Mater

Dissertations, Theses, and Masters Projects

Plants play an important role in structuring ecological communities from the bottom up through interactions with herbivores, and environmental variation can affect these interactions. We use the interaction between common milkweed (Asclepias syriaca) and the monarch butterfly (Danaus plexippus) to examine 1) the role of environmental variation in dictating plants traits, and 2) how those variations affect herbivores. We quantified intraspecific trait variation in 53 natural common milkweed populations, then remeasured these traits when population representatives were regrown in a common garden to control for environmental variation. We then measured growth, performance, and survival of monarch larvae feeding on these …

Subcellular Localization Dynamics Of Thyroid Hormone Receptor And Mediator Complex Subunit 1, Matthew Robert Femia

Dissertations, Theses, and Masters Projects

Intracellular trafficking of transcription factors is an essential cellular function that has implications in regulating gene expression. For thyroid hormone receptor (TR), nuclear localization is fundamental to its function of mediating gene expression in response to thyroid hormone (T3). Yet, we’ve previously shown that TR contains both nuclear localization signals and nuclear export signals, and shuttles rapidly between the nucleus and cytosol. Mislocalization of TR, and loss of transcriptional control, may lead to negative consequences for growth, development, and metabolism. Here, we explore factors that enhance nuclear retention of TR. Emerging studies suggest that Mediator complex subunit 1 (MED1 or …

Superoxide Dismutase In Songbirds: Effects Of Mercury, Exercise, And Sex On An Enzymatic Antioxidant, Juan Mateo Botero

Dissertations, Theses, and Masters Projects

Anthropogenic activities such as burning of fossil fuels, mining, and industrial processes continue to increase the levels of mercury circulating in the environment. Once methylated, mercury can be incorporated into animal tissues, causing it to biomagnify up the food web. Deleterious fitness impacts are commonly associated with increased mercury content in birds. The mechanistic pathway to those effects on fitness needs further research in order to develop appropriate remediation efforts and predict future harm on bird populations. Oxidative stress is proposed as one of the primary ways though which mercury causes accumulation of cellular damage. Well-documented cases of mercury induced …

Age, Growth And Reproduction Of Western North Atlantic Butterfly Rays (Myliobatiformes: Gymnuridae), With The Description Of Two New Species, Kristene Teal Parsons

Dissertations, Theses, and Masters Projects

Batoid fishes are among the most threatened and least understood chondrichthyan species worldwide due to their large body size, conservative life-history characteristics, and predominantly coastal distributions where fishing and habitat degradation threaten the stability of populations. A lack of empirical life history data is widespread across batoid taxa — nearly half of all species are considered data deficient, thus hindering species assessments and the development of effective management strategies. Furthermore, many batoid taxa are in need of taxonomic re-examination. Increasing our understanding of life history traits that determine population productivity, such as age and size at maturity, growth rate, and …

Integration Of Undulatory Swimming Kinematics And Ram Suspension Feeding In A Model American Paddlefish, Grant Emerson Haines

Dissertations, Theses, and Masters Projects

Ram suspension-feeding fishes are a taxonomically diverse group that is both economically and ecologically important. However, many questions remain pertaining to how they feed, including the types of prey they are capable of capturing, the metabolic costs associated with feeding, and the process of manipulating and transporting food around the oral cavity. Recent research has shown that the American paddlefish (Polyodon spathula) employs vortical cross-step filtration, which includes crossflow filtration processes that are organized into a spatial structure across the gill rakers by the formation of vortices behind the branchial arches. Potential temporal organization of filtration mechanisms in ram suspension-feeding …

The Effects Of Timing Of Mercury-Induced Developmental Stress On Songbird Reproductive Success, Ohad Jonathan Paris

Dissertations, Theses, and Masters Projects

This thesis explored two questions – Does developmental exposure to methyl-mercury affect the later reproductive success of songbirds? Does the timing of such developmental exposure affect the severity of any effects on reproductive success? The second question was formulated to test the Developmental Stress Hypothesis (DSH), which states that early developmental conditions incur later-life fitness consequences. Methyl-mercury (MeHg), a potent environmental toxicant, may induce stress in developing organisms, and have far-reaching negative effects on adult fitness. I tested the DSH by investigating whether the timing of MeHg-induced stress, early vs. late in development, affected later-life reproductive success (a strong measure …

Functional Analysis Of Chinmo, A Presumed Transcriptional Regulator Of Cell Fate And Behavior In Drosophila., Leanna Rinehart

Dissertations, Theses, and Masters Projects

Sex determination, the assignment of sex along a male or female fate, is essential for a species to retain sexual dimorphism and the ability to reproduce sexually. In many organisms, sex-specific transcriptional programs must also be maintained throughout an organism’s lifetime. For instance, if sex of stem cells is not continually reinforced, then entire organs could undergo a sex transformation (Zarkower, 2014). Chronologically inappropriate morphogenesis (Chinmo) is a putative transcription factor found in Drosophila that regulates cell fate and behavior. Specifically, it is essential for maintenance of male stem cell sex in the adult testis (Ma et al., 2014). Goals …

Discovery And Characterization Of Novel Sperm Development Patterns In The Nematode Rhabditis Sp. Sb347, Caitlin M. Mccaig

Dissertations, Theses, and Masters Projects

Studies of gamete production in Caenorhabditis elegans self-fertile hermaphrodites have informed textbook descriptions of nematode reproduction and have significantly contributed to our understanding of fundamental cellular and developmental mechanisms. However, C. elegans is one species within a large phylum of mostly dioecious (male/female) species. Whether the C. elegans pattern of self-fertile hermaphroditism and gamete development is representative of other nematodes remains largely unexplored. In Chapter 1, we describe an alternative pattern of sperm production in the trioecious (male/female/hermaphrodite) nematode Rhabditis sp. SB347 that differs from C. elegans in two striking ways. First, instead of making a one-time switch from sperm …

Impacts Of Invasive Phragmites Australis On Diamondback Terrapin Nesting, Cassandra Cook

Dissertations, Theses, and Masters Projects

The diamondback terrapin (Malaclemys terrapin) is a species of turtle found exclusively in brackish water habitats. Terrapins are currently facing population threats including by-catch mortality in crab pots, predation, and habitat loss. The expansion of the exotic, invasive reed Phragmites australis is causing widespread structural and functional changes to coastal ecosystems throughout North America, which could negatively impact the nesting success of female terrapins by invading preferred nesting habitats. I examined the extent to which Phragmites affects nesting of a breeding population of diamondback terrapins at Fisherman Island National Wildlife Refuge on the eastern shore of Virginia, where Phragmites has …

A Test For Heritable Variation In A Wild Population In Response To Endocrine Disrupting Events, Emily Van Den Blink

Dissertations, Theses, and Masters Projects

Endocrine disrupting chemicals (EDCs) are a pervasive threat to the health of both human and wildlife populations. EDCs bind to hormone receptors and mimic or block their action, causing disrupted growth, metabolism and reproduction. Fertility affected by EDCs might be compensated if some individuals are genetically resistant. Genetic resistance in a variable population might cause hormonal feedback pathways to be more resilient to disruption. The effects of EDCs on fertility will be studied using a naturally variable population. A wild population of neonatal male mice, Peromyscus leucopus, was treated with testosterone propionate during a critical developmental period. Genetic variation was …