Biology Commons^™

Brainless But Smart: Investigating Cognitive-Like Behaviors In The Acellular Slime Mold Physarum Polycephalum, Subash Kusum Ray

Dissertations

Evolutionary pressures to improve fitness, have enabled living systems to make adaptive decisions when faced with heterogeneous and changing environmental and physiological conditions. This dissertation investigated the mechanisms of how environmental and physiological factors affect the behaviors of non-neuronal organisms. The acellular slime mold Physarum polycephalum was used as the model organism, which is a macroscopic, unicellular organism, that self-organizes into a network of intersecting tubules. Without using neurons, P. polycephalum can solve labyrinth mazes, build efficient tubule networks, and make adaptive decisions when faced with complicated trade-offs, such as between food quality and risk, speed and accuracy, and exploration …

The Effects Of Prescribed Fire On Ant-Mediated Seed Dispersal In Missouri, Eva M. Colberg

Dissertations

Many aspects of animal-mediated seed dispersal are vulnerable to disturbance, including partner identity and dispersal quantity and quality. This dissertation explores ant-mediated seed dispersal of the herb Sanguinaria canadensis in Missouri Ozark oak forests, where prescribed fire is a common land management tool. In Chapter 1, I test the definition of a keystone seed disperser using absolute and relative contributions of different ant species to the quantity and distance of seed dispersal, based on field observations of S. canadensis seed dispersal. I demonstrate that the ant Aphaenogaster rudis is better described as a numerically dominant rather than keystone seed disperser, …

Ocean Quahog (Arctica Islandica) Population Dynamics: Sex-Based Demographics And Regional Comparisons In The Northwest Atlantic, Kathleen M. Hemeon

Dissertations

Arctica islandica (ocean quahog) is the longest-lived bivalve on Earth. Individuals on the deep continental shelf of the Mid-Atlantic (US) can survive for centuries, and when found in the colder, boreal waters of Iceland, ages over 500 years can be reached. The ocean quahog is important in the US, yet very little is known about the resiliency of the ocean quahog stock to fishing activity, and ocean quahog recruitment patterns over time. To quantify and constrain age-reader error prior to age analysis, a triple-method error protocol was developed for A. islandica that included age-reader bias, precision, and error frequency. The …

Cognitive Ecology Of Color Vision In Orchid Bees, Andreia Queiroz Santos A Figueiredo

Dissertations

Animals interact with their environment and acquire information from it. Information can be processed by their sensory systems and influence behavior, often mediated through mechanisms of decision-making and learning. Animal pollinators acquire information from flowers and use this information to make decisions about the flowers they visit. My research aimed to understand the role of color vision in a tropical pollinator, the orchid bee Euglossa dilemma. Chapter 1 is a review exploring pollination through the lens of prepared learning. Prepared learning proposes that animals learn some associations better than others due to an evolved match with the environment. I …

The Interplay Of The Physical Landscape And Social Dynamics In Shaping Movement Of African Savanna Elephants (Loxodonta Africana), Maggie Wisniewska

Dissertations

Free ranging African savanna elephants (Loxodonta africana) are increasingly impacted by human-induced habitat loss and poaching for ivory. Because elephants live in tightly knit groups, this combination of threats not only reduces the size of their populations but also degrades their social interactions. Long-term relationships with socially competent individuals, such as experienced seniors, benefit the ability of other group members to access limiting resources and avoid danger. Understanding how anthropogenic pressure may affect persistence of elephant populations is important, because elephants are an economically important keystone species. This doctoral thesis characterizes how individual elephants influence the movement of their social …

Genetic Population Structure And Microbiome Of German Cockroaches In Urban Environments, Xueyang Fan

Dissertations

Pests of human habitats may harbor and disperse pathogens that cause human disease. One such pest is the German cockroach (Blattella germanica), which is known to harbor numerous pathogens, including Klebsiella and Pseudomonas. The aim of this study is to reveal the importance of the German cockroach as a potential vector of human medically important diseases. To do so, this study investigates German cockroach population structure and their associated bacterial microbiome in urban residential environments. Ninety German cockroaches are collected from three residential apartment buildings in three New Jersey cities. Samples are caught by glue traps and stored at -20°C. …

Plant Evolution And Urbanization: Quantifying The Effects Of Natural Selection In Shaping Shepherd’S Purse (Capsella Bursa-Pastoris) Populations In New York City, Rebecca Panko

Dissertations

The aim of this study is to quantify the effects of natural selection in shaping Capsella bursa-pastoris populations along an urban-rural gradient in New York City.

A reciprocal transplant experiment with 168 lab-germinated C. bursa-pastoris seedlings from both urban and rural populations are grown in eight paired home and away sites distributed throughout the New York metropolitan area. Sites are visited approximately thirteen times to record plant fitness. There is evidence for local adaptation of urban populations: urban plants have longer reproductive durations and produce more seed pods in urban environments. These findings suggest that urban plants are better adapted …

Vines In The Neotropics: Phylogenomics, Biogeography And Systematics In Passion Flowers (Passiflora Subgenus Decaloba Section Decaloba), Serena Acha

Dissertations

With 600 species, Passiflora is a large, morphologically complex and broadly distributed genus in Passifloraceae that represents a major challenge to scientists interested in understanding the evolutionary history of tropical vines. Passiflora has been divided into subgenera, super sections and sections. One of the most enigmatic and species-rich (~120 spp.) groups in Passiflora is section Decaloba, which occurs in the Neotropics and is particularly diverse in Andean montane forests. In this study, we used phylogenomic and population genomic approaches to investigate the evolutionary history, biologeography, species boundaries, and taxonomy of Passiflora section Decaloba. We sampled herbarium specimens, extracted …

Effects Of Trophic Relationships On Oyster Reef Restoration Success In The Mississippi Sound, Virginia Robin Fleer

Dissertations

Natural and anthropogenic changes resulting from altered hydrology, hurricanes, variable precipitation, and the BP oil spill have all taken their toll on oyster reefs in Mississippi. In response, oyster reef restoration efforts are currently underway within the Northern Gulf of Mexico. In order to understand why these efforts succeed or fail, it is crucial to consider predator-prey relationships within the context of the trophic dynamics of oyster reefs. Thus, for this dissertation study I integrated a multidisciplinary approach to understanding key trophic interactions affecting oyster recruitment, growth and survival, comprising field sampling, manipulative lab experiments, and individual-based modeling. Spat settlement …

Ecological And Oceanographic Influences On Leatherback Turtle Behavior And Scyphozoan Jellyfish Distributions In The Gulf Of Mexico, Katrina Aleksa

Dissertations

Leatherback turtles (Dermochelys coriacea) are a wide-ranging, oceanic species that feed exclusively on gelatinous zooplankton. Leatherback have been spotted in the Gulf of Mexico (GoM) for several decades and consistently had a high level of interactions with longline fisheries. However, no quantitative studies have been performed to address the spatiotemporal distribution of these turtles in the GoM. This research determines 1) leatherback movements and high-use areas in the GoM, 2) their association with oceanographic features, 3) the distribution and density of two abundant medusae in the northern GoM and any association with biophysical parameters, and 4) the body …

Minority Middle And High School Students' Interest In Science: An Exploration Of Teachers' Perceptions, Caroline Makere

Dissertations

A high school teacher conducted a study about minority middle and high school students’ interest in science. The problem was to find out why African American and Hispanic students were showing very little interest in science. The researcher used four middle school science teachers and nine high school science teachers, all from inner city schools in a big city of the Midwest United States except for one middle school teacher from a nearby suburb. The participants answered a survey questionnaire followed with a face-to-face recorded interview. The findings of the study confirmed that students showed little interest in science due …

Examining The Combined Effects Of Dissolved Oxygen, Temperature, And Body Size On The Physiological Responses Of A Model Macrobenthic Polychaete Species, Capitella Teleta, Kelsey Burns Gillam

Dissertations

While the scientific community is in consensus that coastal systems are threatened by climate change, few climate change studies test the effects of more than one variable directly related to climate change. The dissolved oxygen (DO) levels of the ocean are currently subject to both global warming and eutrophication; 94% of all hypoxia zones are expected to experience >2°C increase by 2035. This dissertation aims to examine how a model organism responds to simultaneous thermal and DO stress involving four levels of DO (100%, 70%, 50%, and 20%) saturation and three temperatures (15°C, 20°C, and 25°C).

The polychaete, Capitella teleta …

A Microbiomic Approach To The Characterization Of The Impacts And Influences Of Viral, Bacterial, And Harmful Algal Bloom Toxins On The Bottlenose Dolphin, Corey David Russo

Dissertations

As apex predators that display high site fidelity Tursiops truncatus (bottlenose dolphin) are indicators of marine ecosystem health. Bottlenose dolphins, additionally, display pathogenesis and immune response similar to that of humans. Humans and coastal bottlenose dolphins, in particular, are constantly exposed to the same industrial, agricultural and domestic toxins and pathogens, contaminants and pollutants. Thus, studies on the bottlenose dolphin are also valuable in bridging the gap between ocean and human health. Bottlenose dolphins are susceptible to viral bacterial and toxin infection. Infection in the bottlenose dolphin manifests itself in the form of mass stranding events, unusual mortality events, chronic …

Environmental Impacts And Carry-Over Effects In Complex Life Cycles: The Role Of Different Life History Stages, Nnaemeka F. Ezeakacha

Dissertations

A challenge faced by organisms with complex life cycles is how environmental factors experienced at an earlier life stage affect the fitness at that stage or are carried over to subsequent life stages. I used container-inhabiting mosquitoes: Aedes albopictus, Aedes aegypti, Aedes triseriatus and Culex quinquefasciatus to study the interactions and performance of life history stages under specific environmental factors. I investigated the effects of egg-desiccation tolerance on egg viability and larval performance in the Aedes mosquitoes. I found increase in egg hatch rate with relative humidity and interaction between relative humidity and egg storage period. Larval performance …

Population Genetics And Microbial Communities Of The Gopher Tortoise (Gopherus Polyphemus), Daniel Lyle Gaillard

Dissertations

The gopher tortoise, Gopherus polyphemus, is an endangered species living in the southeastern United States. The recent and drastic decline in tortoise numbers has resulted in a multi-faceted approach to conserve this species. I used a population genetic approach to determine the population structure, genetic diversity and barriers to gene flow at a broad, regional and local scale. Tortoises are divided into five distinct genetic populations at the broad scale, the central populations have the highest levels of genetic diversity and the Tombigbee, Mobile, Apalachicola, Suwannee and St. John’s Rivers appear to be barriers to gene flow. At the regional …

The Delivery, Speciation, And Fate Of Trace Elements In St. Louis Bay, Mississippi, Gopal Bera

Dissertations

Estuaries are dynamic regions in which there can be significant modification of the riverine flux of trace elements to the open ocean due to various geochemical, physical, and biological processes. Additionally, estuaries are often subject to anthropogenic inputs of trace elements. The first portion of this study investigated the source, behavior, and sediment interaction of anthropogenic stable cesium (Cs) in St. Louis Bay (SLB), MS. A consistent increase in stable Cs concentration was noticed in sediment cores starting from a period when a titanium dioxide refinery on SLB started operations. Weak correlation between Cs and clay percentage and strong correlations …

Population Demographics And Genetics Of Spix's Disk-Winged Bat: Insights Regarding Survival, Mate Choice, Gene Flow And Effective Population Size, Michael Buchalski

Dissertations

Simultaneous study of the demographics and genetics of populations are relatively rare within the literature, despite insights their combined use offers regarding the life history, ecology, and evolution of species. Here I take a comprehensive approach, using capture-recapture data, polymorphic microsatellite markers, and various modeling techniques to examine the demographics and genetics of multiple local populations of Spix’s disk-winged bat (Thyroptera tricolor) in southwestern Costa Rica. T. tricolor is a highly gregarious, neotropical bat species known to form kin-based social groups with high retention of offspring of both sexes. The implications of this highly unusual social structure for …

Marine Fungi Of U.S. Gulf Of Mexico Barrier Island Beaches: Biodiversity And Sampling Strategy, Allison Kathleen Walker

Dissertations

Marine fungi are an important but often overlooked component of marine ecosystems. Primarily saprotrophic, they are vital to coastal nutrient cycling processes and food webs. However, basic marine fungal distribution data are lacking in many parts of the world, as is knowledge of the sampling intensity required to characterize the biodiversity of these communities. The roles of substrate, season and latitude in shaping intertidal ascomycete community structure were examined for the U.S. Gulf of Mexico, and the role of sampling frequency on species richness estimates was also addressed. Best sampling practices were developed and 750 collections of beach detritus, sand …

Genetic Variation In Potentially Virulent Vibrio Parahaemolyticus From The Northern Gulf Of Mexico, Nicholas Felix Noriea Iii

Dissertations

Vibrio parahaemolyticus (V_p) is a gram-negative bacterium found naturally in marine and estuarine environments. V_p is found in oysters including those which are later consumed by the public. Sub-populations of potentially virulent Vp contain specific virulence factors and are relevant human pathogens capable of causing gastroenteritis, wound infection, and death. The tdh and trh genes, both encoding hemolysins, have been correlated with the majority of clinical V_p isolates but have not been shown to be the definitive virulence factors.

A total of 146 V_p isolates from the northern Gulf of Mexico were collected and probed …

Movement Ecology Of An Intercontinental Migratory Bird During Spring Stopover, Emily Beth Cohen

Dissertations

Movement ecology is a component of nearly all aspects of animal behavior and an animal’s decision to move is likely influenced by a complex combination of exogenous and endogenous factors. Therefore, an examination of the causes and consequences of organismal movement provides a conceptual framework for understanding complex behavioral strategies. My dissertation research is focused on the movement ecology of an intercontinental migratory songbird during spring migration. I adopted experimental approaches to study the factors influencing how a songbird migrant, red-eyed vireos (Vireo olivaceus), makes decisions in unfamiliar landscapes from the initiation of spring stopover.

I simulated the …

Geological And Ichthyological Investigations Into Palaeodrainage Hypothesis For The Tennessee River, Andrea Karen Persons

Dissertations

The course of the ancestral Tennessee River has been debated in both the geological and biological literature for over 100 years. Several of the proposed courses for the ancestral Tennessee place its course across the state of Mississippi. Geochemical analysis of sedimentary rocks in the Pascagoula River basin supports these hypotheses suggesting that the rocks in the Pascagoula basin were derived from the Highland Rim of Tennessee and northern Alabama, while geochemical analysis of rocks from the Pearl River basin point to deposition from a mixture of sources including the ancestral Mississippi River and perhaps the ancestral Tennessee. To delve …

Conservation And Ecology Of The Yellow-Blotched Sawback (Graptemys Flavmaculata), William Winsyl Selman Ii

Dissertations

The role of species conservation is becoming increasingly important due to the mounting pressures from humans on habitats and populations of organisms. This is particularly evident in riverine ecosystems throughout the world where the human demand for freshwater resources is increasing, and consequently, the number of imperiled aquatic organisms is also growing. The seven chapters of this dissertation primarily focus on the Yellow-blotched Sawback, Graptemys flavimaculata, an endangered riverine turtle that is endemic to the Pascagoula River system of southeast Mississippi, USA. At the population level, we aimed to study the impacts of Hurricane Katrina on two study populations within …

Determining The Relationship Of Human Enteric Viruses In Clinical, Wastewater, And Environmental Samples Utilizing Molecular And Cell Culture Techniques, Jacquelina Susann Williams Woods

Dissertations

This study was the first to examine five significant enteric viruses in human fecal material, sewage, and oysters to show a genetic relationship between human enteric viruses and different sample matrices. Fecal samples were collected from an area hospital and examined for norovirus genotype I (NoV GI), norovirus genotype II (NoV Gil), hepatitis A virus (HA V), adenovirus (ADV), and enteroviruses. During this study, sewage samples were collected from a Waster Water Treatment Plant (WWTP) in Mobile, ALand oyster sentinels were placed at 0.1 nautical miles (nm) (station 1 ), 0.2nm (station 2}, 1.5nm (station 3), and 4nm (station 4) …

Oceanic-Atmospheric Modes Of Variability And Their Effect On River Flow And Blue Crab (Callinectes Sapidus) Abundance In The Northcentral Gulf Of Mexico, Guillermo Humberto Sanchez-Rubio

Dissertations

Oceanic-atmospheric modes of variability occur on interdecadal, multidecadal, decadal, and interannual timescales and their influence on climate around the world has been confirmed. The present study investigates Mississippi River and Pascagoula River flows in response to the influence of one or more of the four oceanic-atmospheric modes of variability: the Pacific Decadal Oscillation (PDO), the Atlantic Multidecadal Oscillation (AMO), the North Atlantic Oscillation (NAO), and the El Nino Southern Oscillation (ENSO). These modes of variability are present in phases: PDO warm (PDOw) and cold (PDOc), AMO warm (AMOw) and cold (AMOc), NAO positive (NAOp) and negative (NAOn), and ENSO warm …

Roosting Ecology Of Rafinesque's Big-Eared Bat, Corynorhinus Rafinesquii, In Southeastern Mississippi, Austin Webb Trousdale Iii

Dissertations

Rafinesque's big-eared bat, Corynorhinus rafinesquii, is considered rare and/or declining throughout its range. Concrete bridges are potentially important roosts for C. rafinesquii, especially in the Gulf Coastal Plain where the species' natural roosts (caves and large hollow trees) are inherently scarce. Successful efforts to monitor and conserve this species must account for its movements among multiple roosts and determine the duration of its roost use (including bridges) at different temporal scales. Therefore, I investigated roosting ecology of C. rafinesquii from 2000-2005 within a mixed hardwood-pine (Pinus spp.) system in southeastern Mississippi. I conducted surveys of concrete bridges to determine phenological …