Biology Commons^™

Seasonally Managed Connectivity Of An East Florida Mosquito Impoundment To Increase Emigration Of Juvenile Snook And Tarpon From The Nursery Habitat, Anthony Carl Cianciotto

Theses and Dissertations

Mangrove marshes are nursery habitats for juveniles of many fishes, including snook (Centropomus undecimalis) and tarpon (Megalops atlanticus), which are important recreational fisheries species in Florida. Thousands of acres of mangrove marshland in the Indian River Lagoon (IRL) have been impounded for mosquito control. Most of these impoundments are under Rotational Impoundment Management (RIM), in which culverts connecting to the IRL are closed in the summer to control mosquito reproduction, and opened Oct-May to allow water exchange. We conducted a quantitative assessment of the emigration of juvenile snook and tarpon from the Bee Gum Point Nature Preserve impoundment in Vero …

Identification Of Novel Nuclear Proteins Required For Meiotic Silencing By Unpaired Dna In Neurospora Crassa, Dilini Ralalage

Theses and Dissertations

A fundamental step that occurs during sexual reproduction is meiosis, which is a specialized type of cell division. During meiosis, pairs of chromosomes exchange genetic information via recombination. At this point, the genome is particularly susceptible to viruses and other foreign genetic invasions. Therefore, it is important to protect the genome to prevent the transmission of foreign genetic materials to the offspring. There are several mechanisms work together to protect host genome from foreign genetic materials. These are known as “genome defense mechanisms”.

The fungus Neurospora crassa is one of the best organisms for genome defense studies due to the …

Altered Na, K- Atpase Isoform Expression In Artemia Franciscana In Response To Hypersaline Environments, Jessica Drenth

Theses and Dissertations

The Na,K-ATPase (NKA) is an essential membrane pump that helps to establish cell ion gradients, and regulate intracellular salt in many organisms. One such species, Artemia franciscana (brine shrimp), extreme halophiles which live in hypersaline environments, expresses 2 distinct α-catalytic subunits of the NKA. One of these subunits, α2-(KK), has two key lysine substitutions located within the cation binding sites. Prior work has demonstrated this specific subunit may be directly involved in brine shrimp adaptation to their extreme environments. However, the precise molecular and physiological effects of α2-(KK) have not been entirely elucidated. I determined through immunohistochemistry that my initial …

Assessment Of Long-Term Effects Of Woody Plants Expansion In Humid, Tropical Grassland Of Venezuela, Soraya A. Delgado

Theses and Dissertations

The invasion of woody plants into grassland communities, or shrub encroachment, is a worldwide phenomenon usually attributed to anthropogenic interference. Most studies have focused on temperate and arctic biomes. Less is known about how shrub encroachment is affecting humid tropical grasslands, which have different climates, higher levels of biodiversity and different histories of human land use. This project quantifies the rate of woody vegetation change in a humid tropical grassland of Venezuela using remote sensing over the past quarter century and ground based measurements of selected individual species. Results of remote sensing indicate high rates of conversion of grasslands to …

Applications Of Side Scan And Parametric Echosounders For Mapping Shallow Seagrass Habitats And Their Associated Organic Carbon, Austin L. Greene

Theses and Dissertations

Despite a global valuation of $1.9 trillion seagrass habitats world-wide are in decline—directly impacting the large soil carbon stocks associated with seagrasses. Many methods exist to measure the health of seagrass habitats, yet few apply to shallow coastal ecosystems. Those that do lack spatial resolution (satellite surveys) or do not provide continuous data across large areas (point-based surveys). Furthermore, carbon content of these ecosystems is largely limited to destructive and time-consuming soil core sampling. Side scan and parametric acoustics represent a unique technological opportunity to study habitat coverage and carbon content of vegetated coastal habitats (< 3 m depth). This study presents proof of concept for applications of recreational side scan and parametric sub-bottom profiling sonars in mapping both habitat coverage and organic carbon distribution in shallow seagrass habitats, and explores how these methods might be improved in future applications.

Decomposition Of Black Mangrove (Avicennia Germinans ) Leaf Litter: Calibrating Estuarine Indicators Of Functional Recovery, Leticia Martinez Contreras

Theses and Dissertations

Decomposition of plant material produced by mangroves and other macrophytes in estuaries occurs in both sediments and the water column. Early and intense processing could be more common in the water. In a previous study, in situ decomposition rates of Black Mangrove (Avicennia germinans ) leaf litter suspended in the water column differed among three estuaries in south Texas with moderate differences in salinity, water temperature, available nitrogen (N), and tidal flow. A series of microcosm experiments were conducted to determine the influence, within observed ranges in the estuaries, of these water variables on mass loss of Black Mangrove …

Genetic Variation In Two Economically Important Arthropod Vectors Of Citrus Diseases, Alejandra Fuentes

Theses and Dissertations

Arthropod vectors are agriculturally and ecologically important because they transmit numerous plant pathogens. Commonly, control strategies for vector-borne plant pathogens focus on suppression of vector populations. Genetic variation studies in pest populations provide useful information for biological control, understanding pesticide resistance, and inferring global movement patterns. In chapter I, genetic variation of worldwide populations of Diaphorina citri, the vector of Citrus greening disease, was examined to assess potential sites of origin of invasive populations. The results showed population structure at regional levels, suggesting limited gene flow and revealing patterns of invasion. In chapter II, I explored the community of …

Increasing Marine Debris Awareness Through Public Education And Analyzing Fish For Microplastic And Pollutant Contamination, Stephanie R. Dubois

Theses and Dissertations

Marine debris is any persistent solid material that is manmade and then disposed of into the world’s oceans. Outreach and education was used in combination with biological research using an indicator fish species to raise awareness about the impacts of marine debris and encourage change in behavior to reduce marine debris. Pre and post surveys were administered during marine debris education tours for K-12 students at the Coastal Studies Lab on South Padre Island, Texas to determine change in knowledge and behavior regarding marine debris. Pinfish were collected from Laguna Madre and stomachs and livers removed for microplastics content and …

Timing And Consequences Of Pleistocene Megafaunal Population Collapse In South America, Marco Felipe Raczka

Theses and Dissertations

A key question for ecologists and paleontologists studying the extinction of the Pleistocene megafauna is: what caused the extinction of these animals? Was the extinction of megafauna caused solely by human-hunting pressure, or was it a consequence of climate change? Could these extinctions be caused by a combination of both factors? Was this wave of extinction temporally uniform across South America? Despite the recent surge of research on this subject, these questions remain largely unanswered. Spores of Sporormiella, a genus of obligate coprophilous fungi, are now widely used to detect mega-herbivore presence and even estimate their abundance in paleoecological reconstructions. …

The Vocal Babbling Behavior And Its Sibling Effects In A Wild Parrot, Tatiana Dolgushina

Theses and Dissertations

Vocal learning is a rare trait in the animal kingdom, defined as the sensorimotor imitation of sounds, and is only found in select groups of birds and mammals. Parrots are a behaviorally complex group of birds, famous for their ability to mimic social companions, but how they develop this ability in the wild has received little attention. The vocal learning period consists of a complex vocal babbling stage, a crucial developmental precursor for imitation of adult vocalizations in humans and songbirds, but has not been described in any of the 360+ parrot species. This project quantifies potential individual variation in …

Multifunctionality Of Cover Crops On Organic Vegetable Farms In South Texas, Savannah M. Rugg

Theses and Dissertations

Situated in deep South Texas, the Lower Rio Grande Valley (LRGV) is considered one the most productive agricultural regions in the southern US. With the highest concentration of organic farms in the state (Hidalgo county), finding management practices that comply with organic certification is increasingly pertinent. Cover cropping can serve multiple functions in an agroecosystem such as: suppressing weeds, increasing soil organic matter (SOM), increasing soil nitrates, and enhancing soil biodiversity. The four cover crops (lablab, sunn hemp, sudangrass, and pearl millet) were assessed to see their potential to increase soil nitrogen, to increase soil organic matter, and to suppress …

Thermal Response Of Behavior And Gene Expression Of Heat Shock Proteins In The Lined Seahorse, Hippocampus Erectus, Cara Johnson

Theses and Dissertations

The lined seahorse, Hippocampus erectus, is a dispersal-limited fish residing in the coastal and estuarine habitats of the Western Atlantic. With sea surface temperatures expected to rise +2°C in the next 85 years, these dispersal limited fish will experience varying degrees of short-term (acute) and long-term (chronic) heat stress events. Previous studies have indicated that these different durations of increased temperatures will elicit distinctive behavioral changes in seahorses, but the molecular mechanisms underlying these changes are yet unknown. Three-hundred captive-bred Hippocampus erectus were exposed to control, mild, severe, and lethal temperatures for different durations to assess how these animals respond …

The Impact Of Marine Protected Areas On Reef-Wide Population Structure And Fishing-Induced Phenotypes In Coral-Reef Fishes, Robert Young Fidler Iii

Theses and Dissertations

Overfishing and destructive fishing practices threaten the sustainability of fisheries worldwide. In addition to reducing population sizes, anthropogenic fishing effort is highly size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-selective mortality induces widespread phenotypic shifts toward the predominance of smaller and earlier-maturing individuals. Fish that reach sexual maturity at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of exploited populations. These directional phenotypic alterations, collectively known as “fisheries-induced evolution” (FIE) are among the primary causes of the loss of harvestable fish biomass. Marine protected areas (MPAs) are one …

Circadian Rhythms In The Retina Of The Atlantic Tarpon, Megalops Atlanticus, Kristin Leigh Kopperud

Theses and Dissertations

Light is a critically important environmental variable in the lives of marine organisms, affecting physiology and behavior acutely and dictating daily biological rhythms and seasonal reproduction in the long-term. In unpolluted natural environments, the daily light-dark cycle is a reliable environmental cue, but with today’s rapid coastal development, light pollution is an increasingly serious threat to living things, including marine fish. Alterations to the natural light-dark cycle may have profound implications for the health and longevity of organisms by interfering with the function of their internal timekeeping mechanisms. While extensive research exists on the harmful effects of inappropriate light on …

Reef-Building Threatened By Ecosystem Decline: A Case Study From Buck Island, U.S. Virgin Islands, Elizabeth M. Whitcher

Theses and Dissertations

Coral reefs are critical barriers to coastal erosion and flooding throughout tropical regions, but their role in coastal protection is threatened by declining coral populations and sea-level rise. Climate change is causing widespread losses of live-coral cover on Caribbean reefs, and is reducing the capacity of reef-building to keep pace with sea-level rise. Reefs that lag behind rising sea level will struggle to maintain their role as protective barriers, as rising water-levels over shallow reef-crests result in a reduction of the dissipation of wave energy. A clear understanding of reef-building processes in the Caribbean will be a critical component in …

Late Holocene Climate And Vegetation Change In Central Michigan, Rachel Kathleen Sales

Theses and Dissertations

Understanding the effects of drought and temperature change on eastern North America will be key in the context of future climate change. Perhaps the best method to understand how drought and temperature will impact this area is to study its paleoecological record. The records presented here, from Houghton Bog (44°23'4.50"N; 84°44'18.90"W) and Higgins Bog (44°28'58.90"N; 84°47'41.40"W) provide an opportunity to study the effects of drought and temperature on the interior of the Lower Peninsula of Michigan (hereafter central Michigan) during the Late Holocene (c. 4200 cal BP to present day). Pollen, charcoal, and testate amoebae records were analyzed to infer …

Lake Powell Food Web Structure: Predicting Effects Of Quagga Mussel, Joshua A. Verde

Theses and Dissertations

Food webs in aquatic ecosystems can be dramatically altered by invasive species. Quagga mussels are prevalent invaders that compete with existing species and disrupt nutrient cycling. In 2012, the Quagga Mussel (Dreissena rostriformus bugensis) was introduced into Lake Powell and is expected to move throughout the reservoir in the near future. Stable isotope analysis is a powerful tool for characterizing food webs and trophic interactions. To predict the long-term effects of Quagga Mussels, we used stable isotope analysis of primary producers, primary consumers, prey fish species, and predator fish species in Lake Powell to determine food web structure. …

Phylogenetics, Biogeography, And Patterns Of Diversification Of Geckosacross The Sunda Shelf With An Emphasis On The Genuscnemaspis (Strauch, 1887), Perry Lee Wood

Theses and Dissertations

In my dissertation I investigate two genera of geckos (Cyrtodactylus and Cnemaspis) that are distributed across Southeast Asia with an emphasis on Cnemaspis. In Chapter 1 I use a multilocus dataset, ancestral area analyses, and molecular clock dating to generate a species level time calibrated phylogeny to test the monophyly of Cyrtodactylus and to identify major biogeographical patterns. I identified that Cyrtodactylus is monophyletic only if the the Sri Lankan genus often recognized as Geckoella is included. The results of the Biogeographical analyses reveal a west to east pattern of diversification. Chapter 2 I use a traditional morphological dataset to …

Phylogenetic Relationships, Species Boundaries, And Studies Of Viviparity And Convergent Evolution In Liolaemus Lizards, Cesar Augusto Aguilar

Theses and Dissertations

In this thesis I have connected different evolutionary studies of Lioalemus lizards. In Chapter 1, I followed an integrative approach to delimit species in the Liolaemus walkeri complex. Using mitochondrial markers, morphological data, bioclimatic information and methods appropriate for each data type, we found that the name L. walkeri was covering three new lineages. Three new species were described and one of them (L. chavin) is now categorized as Near Threatened in the IUCN red list. In Chapter 2, I change the subject from species boundaries to the study of viviparity and placentation. In this paper we employed …

Assessing And Improving Student Understanding Of Tree-Thinking, Tyler A. Kummer

Theses and Dissertations

Evolution is the unifying theory of biology. The importance of understanding evolution by those who study the origins, diversification and diversity life cannot be overstated. Because of its importance, in addition to a scientific study of evolution, many researchers have spent time studying the acceptance and the teaching of evolution. Phylogenetic Systematics is the field of study developed to understand the evolutionary history of organisms, traits, and genes. Tree-thinking is the term by which we identify concepts related to the evolutionary history of organisms. It is vital that those who undertake a study of biology be able to understand and …

Effects Of Estrogens On Astrocytes Exposed To Stressors, Bridget N. Smith

Theses and Dissertations

Hormone replacement therapy (HRT), used by many women to alleviate menopausal symptoms such as hot flashes and mood swings, is often a combination of horomones such as estrogens, progesterone, and conjugated equine estrogens (CEE), extracted from the urine of pregnant mares. Previous studies have found positive correlations between estradiol and cellular protection, but recent research has concluded CEE provide less protective mechanisms as compared to endogenous hormones. This research sought to compare the effects of estrogen treatments (single and combined estrogen) on viability when astrocytes were induced with stressors (epinephrine, cortisol, and low oxygen concentration). Cultured human astrocytes were treated …

Mismatch Tolerance During Homologous Recombination In Mammalian Cells, Shen Li

Theses and Dissertations

Homologous recombination (HR) serves critical roles in DNA repair to maintain genome stability, and the malfunction of HR contributes to carcinogenesis and cancer development. Current research focuses on the regulation against deleterious recombination between imperfectly matching sequences, which has been documented in certain myeloid leukemias, hereditary nonpolyposis colorectal cancers and other genetic diseases. Homology dependency of recombination was examined in cultured thymidine kinase-deficient mouse fibroblasts. Cells have chromosomal integration of DNA constructs harboring a herpes tk gene (the “recipient”) and a closely linked truncated “donor” tk sequence. The recipient was rendered non-functional by insertion of the recognition site for endonuclease …

Characterizing The Role Of The E3 Ligase Itch In Gut Mucosal Homeostasis, Heather L. Mentrup

Theses and Dissertations

The mucosal barrier of the small intestine is highly dynamic, enabling the passage of nutrients that are necessary for the body’s function while simultaneously preventing a breach by harmful microorganisms that are damaging to the host. The effectiveness of the mucosal barrier is dependent on the cohesive relationship established between the luminal mucosal epithelium and the underlying immune compartment in the small intestine. The epithelium provides the first line of defense against pathogens by establishing a physical barrier separating the external environment from the body’s internal milieu, while the immune system secondarily responds to clear bacteria that have breached the …

The Role Of Lipocalin-2 In The Hepatic Microenvironment Of Colorectal Cancer Metastasis, Daniel Titus Hughes

Theses and Dissertations

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States. The major cause of death is metastasis and the frequent target organ is the liver. When diagnosed early at a localized stage, the five year survival rate after resection is 90%. However, after metastasis has occurred, this drops to less than 12%. Metastasis is often asymptomatic and diagnosed at the final stage when therapeutic options are limited. Because of this, the genetic and cellular mechanisms regulating metastasis are still poorly understood. Recent studies have shown that prior to the arrival of cancer cells at the …

Determining The Population Dynamics And Reproductive Life History Of Commercially Important Tunas In The Gulf Of Mexico, Katrina C. Hounchell

Theses and Dissertations

The Gulf of Mexico (GOM) is an important spawning ground for many commercially important fish species including yellowfin, skipjack, and blackfin tunas. In particular, it is an essential spawning habitat for Atlantic bluefin tuna, whose stock status is of great international concern. It is vital to the appropriate conservation management of these species to determine both the location of their spawning grounds and the genetic diversity found within them. Fish eggs are a fisheries-independent source of spawning information that can provide more accurate estimates of spawning sites compared to larvae. This study describes population diversity and reproductive life histories in …

Evolution Of Antagonistic Relationships In Proteins: A Case Study Of Radialis- And Diviricata-Like Genes, Ao Gao

Theses and Dissertations

The antagonistic relationship of proteins describes the opponent interactions that result in one protein suppressing the function of another. Developmental genetic studies of Antirrhinum majus demonstrated that two transcription factors from the MYB gene family, RAD and DIV, interact through antagonism to regulate floral dorsoventral asymmetry. Interestingly, similar antagonistic interactions were found among proteins of FSM1 (RAD-like), MYBI (DIV-like), and DRIF in Solanum lycopersicum, which is involved in fruit development. Here, we report on the homology of these antagonistic MYB proteins based on reconstruction of the phylogeny of I-box-like and R-R-type clades, where RAD- and DIV-like belong, …

The Status Of Snapping Turtles (Chelydra Serpentina) In Virginia: Population Viability, Demography, Regulatory Analysis, And Conservation, Benjamin C. Colteaux

Theses and Dissertations

Snapping turtles (Chelydra serpentina) are being harvested in unprecedented numbers in the United States (US) to meet the needs of international markets. Over three million live snapping turtles from farm and wild caught stock were exported from the US to Asia in 2012-14 alone. In the Commonwealth of Virginia, records indicate that 29,860 snapping turtles were commercially harvested between 2000 and 2015. Size limits are often used to regulate harvest pressure in snapping turtles and other game species. I analyzed the historic harvest of eleven US states to test the efficacy of minimum-size limit regulations at reducing commercial …

Molecular Evolution Of Major Epidermal Structure Genes And An Integrative Transcriptome Analysis Of Chicken Epidermal Embryogenesis, Weier Bao

Theses and Dissertations

Αlpha (α) and beta (β) keratins are the major structural proteins found in vertebrate epidermis and the β-keratins are only found in reptiles and birds. With the recent published 48 avian genomes, we searched and studied the molecular evolution of these gene families. We discovered that the expansion and contraction of different α- and β- keratins among the 48 phylogenetically diverse birds supports the importance of their role in the evolution of the feathers and the adaptation of birds to different ecological niches. Using a customized 44K microarray, we also performed transcriptome analysis on different epidermal regions (scutate scale, dorsal …

Expression Of Matrix Metalloproteinases In Naegleria Fowleri And Their Role In Degradation Of The Extracellular Matrix, Charlton Lam

Theses and Dissertations

Naegleria fowleri is a free-living amoeba found in freshwater lakes and ponds that is the causative agent of Primary Amoebic Meningoencephalitis (PAM). Matrix metalloproteinases (MMPs) have been described in protozoa, such as Plasmodium falciparum, Trypanosoma brucei, and Balamuthia mandrillaris, and have been linked to their increased motility and invasive capability by degrading components of the extracellular matrix (ECM). In addition, MMPs are often upregulated in tumorigenic cells and have been attributed as responsible for the metastasis of certain cancers. In the present study, in vitro experiments indicated that MMPs are linked functionally to the ECM degradation process. …

Moderate Severity Disturbance Has Similar Effects On The Production Of Three Forests Nested Within The Upper Great Lakes Landscape, Benjamin Tai Sagara

Theses and Dissertations

Moderate severity disturbances, which only kill a subset of canopy trees (e.g., via insects, pathogens, and windthrow), are increasingly widespread, and can alter forest structure and production. Whether moderate severity disturbance similarly affects the net primary production (NPP) of different forest stands within inherently heterogeneous landscapes, however, is unknown. We experimentally disturbed three, 2-ha stands varying in forest structure and primary production, reducing stand basal area 38 to 66 % by stem girdling all mature early successional aspen (Populus) and birch (Betula). For nearly a decade, we examined how the forest stands restructured and recovered, and linked post-recovery physical and …