Digital Commons Network^™

The Role Of Machine Learning And Network Analyses In Understanding Microbial Composition In An Experimental Prairie, Ali Eastman Oku

Graduate Research Theses & Dissertations

Machine learning and network analyses are powerful modern tools can process and map out connections between large amount of ecological data from complex environmental communities. Random forests, an ensemble machine learning algorithm, are particularly powerful as they can capture complex patterns in data while remaining easily interpretable. These tools are specifically useful in experimental settings where different types of data are collected. The aim of this study was to demonstrate the utility of machine learning models and network analyses at analyzing diverse ecological data from dynamic plant-soil microbial communities in a prairie ecosystem. Our experimental system is an experimental prairie …

Seedy Business: Unveiling Fruit-Frugivore Interactions In Loango National Park, Gabon, Diandra Mary Lewis

Graduate Student Theses, Dissertations, & Professional Papers

Fruit-frugivore interactions within forest ecosystems are intricate and are critical determinants of community structure, function, and composition. Increasing anthropogenic impacts on biodiversity in general and forests in particular highlight the need to better understand these plant-animal relationships. This thesis focuses on connections between fruit-bearing plants and the animals that eat their fruits in a relatively undisturbed rainforest in Gabon. The work combines two studies: one scrutinising fruit trait clustering, and the other delving into the difference between using dispersers versus consumers in seed dispersal networks.

In chapter 1, we focused on fruit traits and how they group together in order …

Spatiotemporal Analyses Of Pelagic Sargassum : Biodiversity, Morphotypes And Arsenic Content, Kristie Alleyne

World Maritime University Ph.D. Dissertations

Pelagic sargassum blooming in the Tropical Atlantic has been linked to the mass shoreline inundations observed over the last decade in Caribbean and West African countries. Since the onset in 2011, affected countries have and continue to experience multiscale impacts across fisheries, tourism, nearshore coastal ecosystems, maritime transport and public health. Impacts associated with influx events have generated significant economic damage across the region. Moreover, clean-up efforts in response to mass shoreline strandings placed further strain on national economies and in some instances amplified the negative environmental effects caused by inundations.

Evidence suggests that influx events are likely to continue …

Salinization Impacts On Heterotrophic Respiration, Ecosystem Respiration, And Plant Productivity In Tidal Freshwater Marshes, Kelsie J. Moses

Theses and Dissertations

Tidal freshwater marshes have preserved substantial stocks of soil carbon, which represents carbon dioxide that is no longer in the atmosphere. There is conflicting evidence in the literature about how disturbances such as sea level rise and associated wetland salinization impact the accumulation and long-term stability of this stored carbon. The goal of this experiment was to quantify how salinization impacts total ecosystem respiration and its component parts, autotrophic and heterotrophic respiration. This was a microcosm experiment using a C4 plant (Spartina cynosuroides) grown in soil derived from C3 plant matter and exposed to different salinities (0 to …

Population Demography Of A Neotropical Migratory Songbird In The Face Of A Changing Climate, Adele Balmer

Theses and Dissertations

This dissertation investigates the population dynamics and demographic trends of the Prothonotary Warbler (Protonotaria citrea), a migratory songbird that breeds in North America during the spring and summer and overwinters in Central and northern South America. The primary objective of this dissertation is to examine the combined implications of variation in weather and individual traits on demographic traits and to project the effects of climate change on population trajectories of the Prothonotary Warbler.

The analyses conducted in this dissertation centered around female Prothonotary Warblers; however, visual identification of a nestling’s sex is impossible in most altricial bird species, …

Exploring Beaver-Facilitated Restoration In Grassland Channelized Streams, Jessica L. Sikora

Graduate Research Theses & Dissertations

Freshwater streams provide vital ecosystem services, but their ecological function is gravely impacted by agricultural practices especially in grassland ecosystems. Though there is evidence that the re-introduction of beavers can help restore the ecological function of streams, little is known about their restorative impacts in grasslands. At Nachusa Grasslands Preserve in Franklin Grove, IL, we investigated the presence and impact of beaver dams on their waterways. With increasing beaver dam volume, we found an increase in sediment retention and less sediment retention with increasing beaver dams upstream from a dam. Though we did not find evidence that beaver dam volume …

The Influence Of Cover Crops On Grassland Restoration, Josh C. Poland

Masters Theses

Grassland ecosystems comprise almost a fourth of all Earth’s land mass; however, due to ever-increasing rates of agricultural land conversion, these habitats are facing a large-scale biodiversity crisis. The degradation of grasslands extends beyond physical impacts, such as soil erosion, to include the loss of soil microbial communities as a serious risk to the health and productivity of these habitats. Cover cropping, commonly used in agriculture to revive agricultural soils, has rarely been applied to grassland restorations, and could combat or reverse the harmful effects of modern agriculture techniques. For the first chapter of my thesis, I used a greenhouse …

Intraspecific Potency Of Predation Risk Cues, Delbert Lee Smee, Benjamin Belgrad

Gulf and Caribbean Research

No abstract provided.

The Systems Measurement Of Mammalian Biotas, Part Two, Charles H. Smith, Patrick Georges, Ngoc Nguyen

Faculty/Staff Personal Papers

For a recent publication, the authors identified a seven-region model of mammal family distribution patterns, in which each unit contributes equally to the system’s overall statistical characteristics of diversity, despite its individual units having measurably different levels of diversity and endemism. This systemization presents a highly efficient descriptive model that can possibly be interpreted as a form of natural classification. An additional analysis of the same mode is described here, in which the seven-region model of the distribution of mammal families’ spatial affinities is shown to closely approach a most-probable-state arrangement, as assessed through combinatorics, raising some important questions about …

Genetic And Environmental Contributions To Wolbachia-Induced Cytoplasmic Incompatibility, Kelley Van Vaerenberghe

Graduate Student Theses, Dissertations, & Professional Papers

Maternally-transmitted Wolbachia infect the cells of most insect species, but their frequencies in host populations vary. While much of their success can be attributed to their ability to manipulate host reproduction, these manipulations are context-dependent, varying due to several biotic and abiotic factors. Wolbachia’s most common manipulation, cytoplasmic incompatibility (CI), is a conditional sterility phenotype where male-female host compatibility depends on their infection status. Specifically, CI occurs when infected males produce modified sperm that cause increased embryonic lethality unless the female carries a similar infection. Rescuing their eggs from CI increases the relative fitness of infected females, promoting Wolbachia spread …

Responses Of Elk To Mangement Actions And Hunter Access In The Northern Sapphire Mountains, Montana, Usa, Peter O. Mumford

Graduate Student Theses, Dissertations, & Professional Papers

Chapter 1

Regulation of rifle hunting of adult female elk is the main tool wildlife managers use to manage the abundance of elk (Cervus canadensis) in the western United States. However, elk are increasingly located in areas where hunting access is restricted during rifle-hunting season, decreasing the ability of managers to reduce elk abundance through hunter harvest. Management actions that restricted hunter access in a 26 km2 area and closed 62 kms of predominantly 2-wheel motorized routes occurred in the northern Sapphire Mountains, Montana, USA. We collected data on elk locations before and two years after the management actions and …

How Aquatic Insects Mitigate Temperature-Oxygen Challenges Via Behavioral, Morphological, And Physiological Plasticity, Jackson H. Birrell

Graduate Student Theses, Dissertations, & Professional Papers

How do organisms respond to environmental challenges and to environmental change? These questions occupy a central place in ecology and answering them will help us to understand why species live where they do, how organisms are affected by human activities, and, ultimately, how to choose among alternative conservation strategies. These questions are difficult, however, for two reasons. First, environmental challenges often involve multiple, interacting stressors. Second, individual responses can be modified by behavioral, morphological, and physiological plasticity. My dissertation investigates how interactions between temperature and oxygen influence the performance and survival of aquatic insects and how plasticity allows individuals to …

Effects Of Oyster Aquaculture On Elasmobranch Abundance And Habitat Use In Humboldt Bay, Ca, Rose Harman

Cal Poly Humboldt theses and projects

Habitat modification from aquaculture can have large effects on natural communities, with the habitat complexity provided by aquaculture structure positively influencing benthic invertebrates and small fish abundance. However, the effects of aquaculture on larger predatory fish like elasmobranchs (i.e., sharks and rays), which use nearshore habitat to forage and provide top-down control of these ecosystems, is largely unknown. Over two years, I deployed baited remote underwater video systems (BRUVS) to examine the effects of oyster aquaculture and environmental variables such as habitat (mudflat or eelgrass), salinity (ppt), turbidity (m), temperature (°C), pH (mV), dissolved oxygen (mg · L^-1), …

Airborne Sound And Substrate-Borne Vibration In Orthopteran Communication, Ciara E. Kernan

Dartmouth College Ph.D Dissertations

The challenge of attracting and locating potential mates has driven the evolution of diverse mate-finding signaling systems. These systems can be complex, with multiple signals or signal components spread across different sensory modalities. When multiple modalities are combined in one communication system, features of each can be important to individual fitness; over evolutionary time, these can shape investment in different parts of a signal repertoire. One group of animals that commonly uses multiple signal modalities is Orthoptera. Cricket and katydid species within this order often produce airborne sound calls to advertise to potential mates. Many also produce substrate-borne vibrational signals. …

The Effect Of Environmental Factors On Movement Patterns And Habitat Use Of Young-Of-The-Year Scalloped Hammerhead Sharks (Sphyrna Lewini) In The Tolomato River Nursery, Matthew Bernanke

UNF Graduate Theses and Dissertations

Various shark populations on the southeastern coast of the United States experienced declines in the late 20^th century, including the scalloped hammerhead shark (Sphyrna lewini). Improved management strategies, implemented in the late 1990s, have helped these populations to recover, but they are still under threat from fishing pressure and habitat loss. In continuing to strive towards population recovery and conservation, it is important to identify Essential Fish Habitat, or habitats that are necessary for the spawning, feeding, breeding, or growth of marine organisms. One such habitat is that of the shark nursery habitat. Nursery habitats are those …

Emerging Patterns In Population Structure And Trap Efficacy After Three Years Of A Survey Of Western Painted Turtles (Chrysemys Picta Bellii, Gray, 1830) In Marshall County, South Dakota, Heather L. Waye, Amy C. Dolan, Peter C. Dolan

Biology Publications

Turtles are long-lived and globally declining, but relatively little is known about the natural history of many turtle species. Even amongst relatively well-studied species, there is a paucity of information for some habitats and long-term population trends are lacking. Here we report the results from the first three years of an intended long-term population survey of Western Painted Turtles (Chrysemys picta bellii) in the prairie highlands of the Coteau des Prairies, South Dakota. Turtles were sampled using basking traps, hoop traps, and dip nets. Catch per unit effort varied between years, but not significantly so, and hoop traps …

Documenting Range Expansion Of Two Invasive Tick (Acari:Ixodidae) Species In Eastern South Dakota, Braden Wojahn

Dissertations and Theses

This project documents the expanded zoogeographic ranges of the blacklegged tick (Ixodes scapularis) and lone star tick (Amblyomma americanum) within eastern South Dakota. Ticks are important when considering a “One Health” approach, as many species are competent vectors of zoonotic pathogens causing human diseases and conditions such as Lyme disease, tularemia, rickettsia, and alpha gal syndrome. The research involved constitutes two steps. First, tick surveillance was conducted in eastern counties of South Dakota, spanning March 2021 through August 2022. Surveillance took place along edge habitat at recreation areas, state and public parks, wildlife management areas and refuges, and other natural …

Host-Microbe Interactions In Non-Native Estuarine Anemones: Biogeography And Temperature, Parker K. Lund

Cal Poly Humboldt theses and projects

Non-native species are increasing in prevalence around the world, resulting in negative economic and ecological impacts. However, the broad distributions of non-native species also offer a system for investigating the response of host-associated microbial communities to environmental factors across a range of ecological scales. At the broadest scale, I investigated the geography of microbial communities in the non-native estuarine anemone Diadumene lineata on the west coast of the United States of America. Across latitudes, microbial community composition was very similar and displayed a high percentage of Klebsiella spp. at all sites. However, the communities in California tended to exhibit higher …

Sympatric Carnivores And Vegetation Structure Influence The Distribution And Abundance Of Humboldt Martens In Northern California, Erika L. Anderson

Cal Poly Humboldt theses and projects

The Humboldt marten (Martes caurina humboldtensis) is a species facing conservation concern in Oregon and California. Historical populations were subjected to unregulated fur trapping and timber harvest throughout the late 19^th and early 20^th centuries leading to a 90% decline in their distribution. As such, the Humboldt marten is listed as a state endangered species in California, and the analogous ‘coastal marten’ is listed as federally threatened under the Endangered Species Act and classified as a Species of Greatest Conservation Need in Oregon and California. Contemporary populations are small, and isolated, and threatened by habitat loss …

Polymorphism Of Melanin-Based Pigments In Barn Owls In Winegrape Vineyards In Napa Valley, California, Laura Mariana Echávez Montenegro

Cal Poly Humboldt theses and projects

Many raptor species exhibit plumage polymorphism. Through the expression of a particular phenotype, polymorphism allows individuals to exploit alternative spatial or temporal environments and food resources most successfully. Barn Owls display within-species variation in their plumage, ranging from reddish to whitish and from heavily spotted to having no spots at all. In heterogeneous landscapes in Europe and the Middle East, reddish Common Barn Owls (Tyto alba) inhabit territories with proportionally more arable fields and consume proportionally more voles than mice in contrast to their whiter counterparts; a phenomenon known as habitat matching choice. This study sought to quantify …

Identifying Habitat Suitability And Connectivity For Roosevelt Elk (Cervus Canadensis Roosevelti) On The North Coast Of California, Ashley Ann Harper

Cal Poly Humboldt theses and projects

As human development continues to expand, wildlife managers are faced with problems arising from human-wildlife conflict. To address conflict, it is vital to identify how animals view the landscape and move across areas of differing land use. On the North Coast of California, Roosevelt elk (Cervus canadensis roosevelti) are widely considered to be a valuable resource but are viewed by some as a nuisance due to economic losses caused by property damage. The aim of this study was to identify suitable habitat and movement corridors for Roosevelt elk across Humboldt and Del Norte counties in northern California. Suitable …

Evolution Of The Diets Of Australian Possums (Marsupialia: Phalangeriformes) From The Etadunna Formation In The Lake Eyre Basin, South Australia, Theodore C. Wheat

EWU Masters Thesis Collection

The Lake Eyre Basin in South Australia holds Australia’s oldest known fossil marsupials representing both extant and extinct families in the Etadunna Formation, a formation that spans nearly two million years from 23.3 to 25 MA. During that two-million-year period, the terrestrial herbivorous marsupials present in the area underwent a dramatic transition both taxonomically and dentally, likely brought on by a changing environment caused by a warming climate. However, it is unknown whether a similar change occurred to the marsupials like possums that live up in the canopy. Understanding this could help determine how extensively this change in the environment …

Effects Of Ph, Eelgrass, And Settlement Substrate On The Growth Of Juvenile Magallana (Crassostrea) Gigas, A Commercially Important Oyster Species, Johnny S. Roche

Cal Poly Humboldt theses and projects

Worsening ocean acidification (OA), resulting from ongoing absorption of atmospheric carbon dioxide (CO₂) by the oceans, threatens marine life globally. Calcifying organisms, especially their early life stages, are particularly vulnerable; this includes the economically important Pacific oyster, Magallana (Crassostrea) gigas. Uptake of dissolved CO₂ through photosynthesis by seagrasses, like eelgrass (Zostera marina), may benefit calcifying organisms by increasing pH and carbonate availability. I conducted laboratory and field experiments to quantify carbonate chemistry modification by eelgrass and potential mitigation of OA impacts on growth in juvenile Pacific oysters. In the laboratory experiment, daytime …

Carnivore And Ungulate Occurrence In A Fire-Prone Region, Sara J. Moriarty-Graves

Cal Poly Humboldt theses and projects

Increasing fire size and severity in the western United States causes changes to ecosystems, species’ habitat use, and interspecific interactions. Wide-ranging carnivore and ungulate mammalian species and their interactions may be influenced by an increase in fire activity in northern California. Depending on the fire characteristics, ungulates may benefit from burned habitat due to an increase in forage availability, while carnivore species may be differentially impacted, but ultimately driven by bottom-up processes from a shift in prey availability. I used a three-step approach to estimate the single-species occupancy of four large mammal species: mountain lion (Puma concolor), coyote …

Plant Sentience? Between Romanticism And Denial: Science, Miguel Segundo-Ortin, Paco Calvo

Animal Sentience

A growing number of non-human animal species are being seriously considered as candidates for sentience, but plants are either forgotten or explicitly excluded from these debates. In our view, this is based on the belief that plant behavior is hardwired and inflexible and on an underestimation of the role of plant electrophysiology. We weigh such assumptions against the evidence to suggest that it is time to take seriously the hypothesis that plants, too, might be sentient. We hope this target article will serve as an invitation to investigate sentience in plants with the same rigor as in non-human animals.

Investigating Dormancy And Germination Characteristics To Promote Restoration Success In The Northern Great Plains, Gregory A. Cooper

Electronic Theses and Dissertations

Failures in seed-based restoration can be partially attributed to a lack of knowledge on seed dormancy. Dormancy is beneficial for plant establishment in unpredictable environmental conditions, but a lack of uniform germination can hinder restoration efforts. The purpose of this research was to gain a better understanding of dormancy displayed by select forbs of the northern Great Plains. The first data chapter attempted to identify and break dormancy class. Seeds were treated with scarification, smoke, and fertilizer pretreatments in an attempt to break seed dormancy. Seeds were also placed in spring and summer temperatures to identify how seasonal phenology influenced …

C3 And C4 Grass Dominated Plant Communities Differ In Response To Future Larger And Less Frequent Rainfall, Zigeng Chen

Electronic Theses and Dissertations

Climate change is leading to larger and less frequent rainfall in the Northern Great Plains (NGP). We ask if this change in rainfall would influence carbon (C) and nitrogen (N) cycling in the NGP. First, we collected soils from C3 and C4 grass dominated plant communities from western South Dakota and conducted an incubation experiment to explore the effects of soil water content (SWC) and temperature on soil respiration (Rs) and N mineralization rate (ΔIN). Second, we conducted a three-year rainfallmanipulation (RaMP) experiment with two distinct rainfall regimes (frequent/small and infrequent/large events with constant total monthly precipitation) and two grasses …

Ecological Impacts Of Anthropogenic Chemicals On Non-Target Species And The Role Of Plant Diversity In Ecosystem Restoration And Resilience, Shiva Torabian

Electronic Theses and Dissertations

Understanding ecosystem processes in rangelands is of paramount importance for ensuring global food security, given their pivotal role in sustaining forage and livestock production. Central to this understanding are fundamental processes such as nutrient cycling, decomposition, and plant biomass dynamics. However, the use of anthropogenic chemicals in agricultural practices has the potential to exert significant influence on these critical ecosystem functions. A pivotal factor in this context is the plant diversity inherent to these rangeland ecosystems. Plant diversity not only provides essential ecosystem functions but also enhances them with the capacity to withstand and recover from perturbations. Ecosystems characterized by …

Effects Of Agricultural Chemicals On Native Plants Of The Northern Great Plains, Gabrielle Bolwerk

Electronic Theses and Dissertations

Agricultural chemicals are ubiquitous on the Northern Great Plains landscape and have negative impacts on non-target plant communities, even at small doses. Northern Great Plains grassland plant communities may experience herbicide drift from agricultural fields or be subject to livestock pharmaceuticals in grazing lands. My research objective was to evaluate if and how native plants are affected by agricultural chemical presence at different concentrations. In Chapter 2, I studied the effect of different concentrations of three common agricultural herbicides (2,4-D, atrazine, and trifluralin) on the germination, emergence, and growth of native plant species of the Northern Great Plains. I performed …

Proposing An Rna Interference (Rnai)-Based Treatment For Human Immunodeficiency Virus (Hiv) By Analyzing The Post-Transcriptional Gene Targeting Of Sars-Cov-2, Hepatitis C Virus, And A549 Lung Cancer Cells, Arjun Jagdeesh

UROP Posters

Human Immunodeficiency Virus (HIV) is a retrovirus that infects CD4+ T cell lymphocytes in humans, leading to the development of Acquired Immunodeficiency Syndrome (AIDS) if left untreated. While current treatment methods, including antiretroviral combination treatments, effectively limit HIV replication, HIV can evade these treatments due to its high mutation rate. Long-term antiretroviral treatment can also be toxic to patients, meaning patients would benefit from a new mechanism of HIV treatment. RNA interference (RNAi) is an antiviral pathway found in mammals, plants, and insects that involves a small-interfering RNA that is incorporated into a protein complex called the RNA-induced Silencing Complex …