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Articles 2341 - 2370 of 252109

Full-Text Articles in Life Sciences

Distribution Of Tick Species On Free-Ranging Ungulates In Northern New England, Karisa Graham Jan 2024

Distribution Of Tick Species On Free-Ranging Ungulates In Northern New England, Karisa Graham

Honors Theses and Capstones

In Northern New England, ungulates are often parasitized by ticks, which is one of the leading causes for the decline in population. Ungulates are a good host for ticks, specifically deer ticks and winter ticks, and these ticks cause many tick-borne diseases in humans as well. The purpose of this study was to assess passive sampling from harvested animals as a means of tick surveillance in Vermont and New Hampshire. Ticks were collected from deer and moose and mapped throughout the two states by ArcGIS to visualize the trends in distribution. Relative abundance was greater in southeastern Vermont, with no …

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Comparing Alternative Developmental Modes: Structure And Gene Expression In The Olfactory System Of Plethodontid Salamanders, Giuseppina S. Lanzilli Jan 2024

Comparing Alternative Developmental Modes: Structure And Gene Expression In The Olfactory System Of Plethodontid Salamanders, Giuseppina S. Lanzilli

Cal Poly Humboldt theses and projects

The olfactory system of extant amphibians changes as the animal transitions from a fully aquatic to a terrestrial lifestyle at metamorphosis. Cellular morphology of the nose and expression patterns of olfactory genes in the nasal cavity have been examined for a variety of frogs and salamanders, but among plethodontid salamanders, molecular data are available only for Plethodon shermani. Using standard histology and micro-CT reconstruction, I investigated the structure of the olfactory organs of larvae, juveniles, and adults of six plethodontid species, with terrestrial, streamside, semiaquatic, and aquatic adults. The overall structure of the olfactory cavity was generally similar across …

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Antibiotic Resistance In A Coastal River In Mississippi, Usa – Potential Drivers, Shuo Shen, Wei Wu, Eric A. Saillant, Darrell Jay Grimes Jan 2024

Antibiotic Resistance In A Coastal River In Mississippi, Usa – Potential Drivers, Shuo Shen, Wei Wu, Eric A. Saillant, Darrell Jay Grimes

Gulf and Caribbean Research

Wastewater treatment plants (WWTPs) are major sources of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in water bodies. Most studies on the impact of WWTPs on antibiotic resistance have focused on freshwater systems, with little information on coastal and estuarine waters with variable salinity. This study monitored seasonal levels of ARGs at the effluent and downstream of the Pascagoula— Moss Point WWTP in the lower Pascagoula River, a coastal river in southeastern Mississippi, USA. Surface water samples were collected seasonally at upstream, outflow, and 3 downstream sites from February to November 2016. Bacterial resistance to sulfamethazine, tetracycline, and …

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The Effects Of Native Perennial Cover On Physiological Indicators Of Habitat Quality For Sparrows In California Coastal Prairie Rangelands, Madeleine A. Ybarra Jan 2024

The Effects Of Native Perennial Cover On Physiological Indicators Of Habitat Quality For Sparrows In California Coastal Prairie Rangelands, Madeleine A. Ybarra

Cal Poly Humboldt theses and projects

Prescribed grazing management can have myriad effects on wildlife, with low to moderate grazing being associated with an increased abundance of some grassland birds. Specifically, Grasshopper Sparrow (Ammodramus savannarum) and Savannah Sparrow (Passerculus sandwichensis) abundance have been shown to be positively associated with both grazing and a higher percentage of native plant cover. However, measures of abundance provide an incomplete assessment of habitat quality for birds. Physiological and morphological measurements can help indicate environmental stress in individual birds, which reveals more information about habitat quality. We measured body condition and heterophil:lymphocyte ratios to gauge avian stress …

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Using Novel And Traditional Survey Techniques To Monitor Small Mammal Species In Northwestern California, Sydney Mccluskey Jan 2024

Using Novel And Traditional Survey Techniques To Monitor Small Mammal Species In Northwestern California, Sydney Mccluskey

Cal Poly Humboldt theses and projects

Small mammal species play a critical role in forest ecosystems contributing significantly to overall forest biodiversity and ecological dynamics. Forest-dwelling species are among the most vulnerable to habitat loss and fragmentation. It is essential to develop efficient techniques for monitoring small mammal populations in forested ecosystems to inform conservation efforts and management plans; yet, monitoring small mammals in these habitats can be particularly challenging due to their size, activity patterns, and frequently nocturnal nature. In this study, I aimed to address two primary research objectives: 1) compare the effectiveness of 3 distinct camera-trap survey techniques (i.e., ground, tree, and tube) …

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Evolutionary Origins Of Secondary Growth - The Periderm Perspective: Integrating Evidence From Fossils And Living Plants, Madison A.K. Lalica Jan 2024

Evolutionary Origins Of Secondary Growth - The Periderm Perspective: Integrating Evidence From Fossils And Living Plants, Madison A.K. Lalica

Cal Poly Humboldt theses and projects

Periderm is a structural feature with roles in protection of inner plant tissues and wound healing. Knowledge of periderm occurrences in the fossil record and living lineages outside the seed plants is limited and its evolutionary origins remain poorly explored. Here, I review the known taxonomic distribution of canonical periderm (typical ontogenetic stage) and wound periderm (self-repair mechanism). To this sparse body of data I add new observations and experiments on living plant lineages and new occurrences from the fossil record. One of the latter, documented in the new early euphyllophyte species Nebuloxyla mikmaqiana, joins the oldest known periderm …

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Scale And Habitat Effects On Measurement Of Streptomyces Biogeography And Biodiversity, Terilyn A. Stoflet Jan 2024

Scale And Habitat Effects On Measurement Of Streptomyces Biogeography And Biodiversity, Terilyn A. Stoflet

Cal Poly Humboldt theses and projects

Bacteria in the genus Streptomyces are detected in most soils around the world, as well as on and in seeds, plants, animals, insects and the wind. Currently, more than 700 valid species of Streptomyces have been identified worldwide. Streptomyces produce the majority of antibiotics, antivirals and antifungals, as well as important agricultural bioactive molecules due to their unique genetic capabilities. Their distinct genetic abilities allow them to produce an unlimited amount of biosynthetic gene clusters, or BGC’s. Although many compounds come from Streptomyces, scientists have not discovered the biogeographic patterns of this genus. The biogeography of Streptomyces is a …

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The Dynamic Stability Of The Sewing Needle’S Mechanical Vibrations Under The Impact Of A Time-Dependent Penetration Force In The Multilayered Sewn Fabrics, Wael A. Hashima, Ibrahim A. Elhawary Jan 2024

The Dynamic Stability Of The Sewing Needle’S Mechanical Vibrations Under The Impact Of A Time-Dependent Penetration Force In The Multilayered Sewn Fabrics, Wael A. Hashima, Ibrahim A. Elhawary

Mansoura Engineering Journal

In this work the dynamic stability of the mechanical vibrations of the sewing needle during sewing process under the impact of the time dependent penetration force (cyclic type) were studied. The many mathematical equations were written and explained for both of the sewing needle dynamics and penetration force mechanics. They were related to the regions of sewing needle stability regions either mathematically or graphically. Mate equation (difficult one) was refereed to help in investigation the sewing dynamic stability during sewing process.

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Laboratory Characteristics, Performance Evaluation, And Agency Cost Analysis Of Cold-Recycled Asphalt Mixtures, Marwa B. Elaskary, Ahmed M. Awed, Alaa R. Gabr, Sherif M. El-Badawy Jan 2024

Laboratory Characteristics, Performance Evaluation, And Agency Cost Analysis Of Cold-Recycled Asphalt Mixtures, Marwa B. Elaskary, Ahmed M. Awed, Alaa R. Gabr, Sherif M. El-Badawy

Mansoura Engineering Journal

This technical study offers a comprehensive investigation into the utilization of Cold Recycled Asphalt Mixtures (CRAMs) with varying proportions of Reclaimed Asphalt Pavement (RAP) in the context of pavement maintenance applications. The study encompasses a multi-faceted analysis, encompassing laboratory mix design requirements, mix performance evaluations, and a thorough assessment of economic benefits, with the overarching goal of promoting the sustainable adoption of CRAMs in pavement maintenance. To achieve the objectives of the research, five ratios of RAP to virgin aggregates (VA) of (0%:100%), (25%:75%), (50%:50%), (75%:25%), and (100%: 0%). The research encompasses a wide array of laboratory tests and investigations …

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Deep Learning Based Classification Of Focal Liver Lesions With 3 And 4 Phase Contrast-Enhanced Ct Protocols, Ahmed El-Emam, Hossam El-Din Moustafa, Mohamed Moawad, Mohamed Aouf Jan 2024

Deep Learning Based Classification Of Focal Liver Lesions With 3 And 4 Phase Contrast-Enhanced Ct Protocols, Ahmed El-Emam, Hossam El-Din Moustafa, Mohamed Moawad, Mohamed Aouf

Mansoura Engineering Journal

It had been noticed that 3-phase and 4-phase computed tomography protocols with contrast serve as standard examinations for diagnosing liver tumors. Additionally, many patients require periodic follow-up, which entails significant radiation exposure for them. Advancements in image processing facilitate automated liver lesion segmentation. However, the challenge remains in classifying these small lesions by doctors, especially when the liver has different types of lesions with very little intensity difference. Therefore, deep learning can be utilized for the classification of liver lesions. The present work introduces a CNN-based module for the classification of liver lesions. The module consists of four stages: data …

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The Mechanical Performance Of Sustainable High Performance Concrete Containing Hybrid Polypropylene Fibers And Exposed To Elevated Temperatures, Ahmed M. Tahwia, Marwa M. Ouda, Mohamed Abdellatief, Walid E. Elemam Jan 2024

The Mechanical Performance Of Sustainable High Performance Concrete Containing Hybrid Polypropylene Fibers And Exposed To Elevated Temperatures, Ahmed M. Tahwia, Marwa M. Ouda, Mohamed Abdellatief, Walid E. Elemam

Mansoura Engineering Journal

The purpose of this research is to investigate the impact of hybrid micro and macro polypropylene fibers (PPFs) on the mechanical characteristics and microstructure of high performance concrete (HPC). Seven concrete mixes with different contents of hybrid polypropylene fibers were tested. The tests included the slump test, compressive and flexural strength, resistance to elevated temperatures, and concrete microstructure. Compared to the control mixture, introducing macro and micro polypropylene hybrid fibers to HPC mixes dramatically enhanced the flexural and compressive strength of concrete while lowering workability. HPC compressive and flexural strengths decrease as temperature rises, nevertheless, the strength loss rate was …

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Study The Application Of Different Building Technology Systems Case Study: A Residential Villa In Al-Qassim Region, Ksa, Ahmed Abdelmonteleb M. Ali, Essam S. Almahmoud, Basem O. Elgendy, Azzam I. Aljutayli, Meshal A. Alhrabi, Khattab I. Alyahya Jan 2024

Study The Application Of Different Building Technology Systems Case Study: A Residential Villa In Al-Qassim Region, Ksa, Ahmed Abdelmonteleb M. Ali, Essam S. Almahmoud, Basem O. Elgendy, Azzam I. Aljutayli, Meshal A. Alhrabi, Khattab I. Alyahya

Mansoura Engineering Journal

Buildings are responsible for 39% of global energy-related carbon emissions; 11% come from materials and construction, and 28% come from operational emissions (the energy required to heat, cool, and power). Embodied carbon will contribute an increasing amount to the emissions from new buildings in the future as carbon emissions from building operations continue to decline. This study examined several construction methods and materials to evaluate alternatives for remodeling a residential villa. A villa in the Al-Qassim Region, Buraidah, served as a case study for this research. The methodology employed provided a meticulous appraisal of the building materials and techniques currently …

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Environmental Impact Assessment Of Water Desalinating Systems: Kuwait As A Case Study, Eissa S. Al-Mutairi, Ibrahim.G. Rashed, Mohamed.M. El-Halwany, Mohamed A. Mosaad Jan 2024

Environmental Impact Assessment Of Water Desalinating Systems: Kuwait As A Case Study, Eissa S. Al-Mutairi, Ibrahim.G. Rashed, Mohamed.M. El-Halwany, Mohamed A. Mosaad

Mansoura Engineering Journal

The challenge of managing water resources is intensifying due to rapid urbanization, population expansion, and the growth of industry and agriculture. Furthermore, the looming threat of climate change significantly impacts both water resources and crop yields. In Kuwait, the majority of its potable water supply is dependent on seawater desalination. Specifically, multistage flash (MSF) desalination accounts for nearly 90% of the country's total desalination capacity, while the remaining 10% is generated using multi-effect distillation (MED) technology. Nevertheless, the environmental repercussions of desalination on Kuwait's ecosystem remain a subject of profound concern. This study employs a comprehensive approach, utilizing peer-reviewed journal …

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Unleashing The Potential: The Impact Of Biophilic Office Design On Enhancing Employee Productivity, Asmaa Elantary Jan 2024

Unleashing The Potential: The Impact Of Biophilic Office Design On Enhancing Employee Productivity, Asmaa Elantary

Mansoura Engineering Journal

The observed landscape influences people in numerous ways, including aesthetic appreciation, health, and well-being. The evidence of health benefits associated with viewing those landscapes has proven exceptional value. A comprehensive review of papers on landscapes and sound effects on health was conducted. According to a growing body of evidence, exposure to visible landscapes positively affects one's health and fitness. The most pressing social and economic challenge now is increasing worker productivity, attracting, and retaining exceptionally talented employees, and improving overall employee performance. This will not happen unless companies provide a safe, comfortable, and stimulating work environment; this will not happen. …

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Power Generation And Water Conservation Potentials For Several Photovoltaic Configurations Installed Over A Fresh Water Surface, Rana A. Kewan, Mohamed S. Salem, Mohamed R. Elmarghany, Maher Bekheit, Gamal I. Sultan Jan 2024

Power Generation And Water Conservation Potentials For Several Photovoltaic Configurations Installed Over A Fresh Water Surface, Rana A. Kewan, Mohamed S. Salem, Mohamed R. Elmarghany, Maher Bekheit, Gamal I. Sultan

Mansoura Engineering Journal

One of the challenges that face photovoltaic systems is depleting performance if their average temperature increases due to solar radiation. Floating photovoltaic (FPV) and submerged photovoltaic (SPV) systems offer a potential solution to such problem. Another major benefit is the decrease of water evaporation by creating an artificial shadow over water. In this paper, an experimental study is presented that includes three different systems: an inclined PV by 30⸰ over water (IPV), an SPV, and an FPV systems and compares their performance with that of a conventional PV system under the same operating conditions. The FPV and SPV systems exhibited …

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The Effects Of Scour And Marginal Inundation On Trinity River Invertebrate Biomass And Density With Potential Implications For Juvenile Salmonid Food Resources, Benjamin King Jan 2024

The Effects Of Scour And Marginal Inundation On Trinity River Invertebrate Biomass And Density With Potential Implications For Juvenile Salmonid Food Resources, Benjamin King

Cal Poly Humboldt theses and projects

Regulated flow releases on the Trinity River in northern California have shifted the timing of high flows from winter to late spring and reduced their magnitude. The timing and extent of scour from high flow events and the timing and duration of marginal (bankside) habitat inundation has shifted as a result. Literature is sparse regarding the effects of these hydrologic alterations on Trinity River benthic macroinvertebrate (BMI) communities, an important food resource for juvenile salmonids. In the 2023 water year, a wet winter coupled with additional flow releases from Lewiston Dam provided the opportunity to analyze the impact of scour …

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Building Detailed And Accurate Whole-Plant Concepts: A Morphometrics-Informed Reconstruction Of A Zosterophyll From The Lower Devonian Of Wyoming, Samar R. El-Abdallah Jan 2024

Building Detailed And Accurate Whole-Plant Concepts: A Morphometrics-Informed Reconstruction Of A Zosterophyll From The Lower Devonian Of Wyoming, Samar R. El-Abdallah

Cal Poly Humboldt theses and projects

The fragmentary state of plant fossils and the modular organization of plants make whole-plant reconstructions of fossil species desirable and feasible. Such reconstructions are key for integrating fossil species in systematic studies. The ca. 410 Ma Beartooth Butte Formation of Wyoming (USA) hosts the only rich Early Devonian plant assemblages in western North America, which fills a major gap in the phytogeography of this interval. I construct a whole-plant concept for a new zosterophyll from the Beartooth Butte Formation based on a detailed morphometric study. More than 600 fragments of the new zosterophyll were observed and 200 of those were …

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Post-Fire Vegetation And Pyrodiversity Influence Breeding Abundances Of Lewis's Woodpeckers In The Eastern Cascades, Oregon, Brittany Welch Jan 2024

Post-Fire Vegetation And Pyrodiversity Influence Breeding Abundances Of Lewis's Woodpeckers In The Eastern Cascades, Oregon, Brittany Welch

Cal Poly Humboldt theses and projects

Lewis’s woodpeckers (Melanerpes lewis) are described as "burn specialists" due to their preference for breeding in recently burned pine forests in the western US. However, despite increasing fire activity, this species experienced a 48% range-wide decline between 1968 and 2019, which raises questions about their adaptability to altered fire regimes in the region. We partnered with the Oregon Department of Fish & Wildlife to investigate how Lewis’s woodpeckers in the eastern Cascades, Oregon were influenced by post-fire habitat characteristics such as snag size, snag density, and burn severity across five wildfires that varied in fire age, size, and …

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Neurocinematics And Empathy: How Cognitive Neuroscience Enhances Our Understanding Of Emotional Responses Of Film, Kira Trinity Jan 2024

Neurocinematics And Empathy: How Cognitive Neuroscience Enhances Our Understanding Of Emotional Responses Of Film, Kira Trinity

Cal Poly Humboldt theses and projects

Cinema is a medium that is beloved around the globe since its inception over a century ago. There have been speculations on how it is that cinema works, from editing to emotional processing of the story, but only recently have we begun to explore the inner workings of cinematic impact on the brain. In this paper we will review research on cinematic impact and define cinematic editing, discuss the birth of “neurocinematics”, highlight what we have observed with regards to neuroimaging and empathy when viewing films, and speculate on how our responses to cinema may be driven by the Mirror …

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The Nature And Extent Of Algal Symbiosis In Three North American Ranids, Zachary T. Vegso Jan 2024

The Nature And Extent Of Algal Symbiosis In Three North American Ranids, Zachary T. Vegso

Cal Poly Humboldt theses and projects

The symbiotic relationship between the chlamydomonad green alga Oophila amblystomatis and embryos of certain amphibian species is often presumed to be mutualistic. However, the existence of a mutualism has only been experimentally tested and established in two closely related ambystomatid salamanders. These experiments showed a positive correlation between intracapsular algal density and embryonic growth, survival, hatching synchrony, and hatchling body size. Oophila has been documented within egg capsules of a growing number of amphibian species, including several frogs in the family Ranidae. However, the nature and extent of this relationship remains unclear. Ranid eggs are better oxygenated than ambystomatid eggs, …

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Longevity Of Prescribed Fire Effectiveness In Mixed-Evergreen Forests Of The Klamath Mountains, Kaily M. Fineran Jan 2024

Longevity Of Prescribed Fire Effectiveness In Mixed-Evergreen Forests Of The Klamath Mountains, Kaily M. Fineran

Cal Poly Humboldt theses and projects

Prescribed fire is a common management tool used across the western United States to create wildfire-resilient ecosystems and communities. The Klamath Mountains of northern California, USA has experienced numerous, large wildfires in recent years. This is due in part to a combination of highly flammable fuels, uncharacteristic weather events, and high fuel accumulations as a result of fire exclusion and forest management practices. Within the last decade, local land management organizations and the Karuk Tribe have begun re-introducing prescribed fire in low elevation, mixed evergreen forests. While the long-term effects of fuel treatments are not well-known, these efforts provided a …

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Post-Fire Persistance Of Sequoia Semperviens In A Secondary Forest: Examining Drivers Of Basal Resprouting Response, Jackson T. Carrasco Jan 2024

Post-Fire Persistance Of Sequoia Semperviens In A Secondary Forest: Examining Drivers Of Basal Resprouting Response, Jackson T. Carrasco

Cal Poly Humboldt theses and projects

Historically frequent-fire forest ecosystems are now facing increased size, frequency, and severity of fires attributed to climate change, intensive forest management, and fire exclusion. Understanding post-fire resilience in forest ecosystems is critical amidst escalating challenges posed by recent increases in fire activity. This study examined the basal resprouting response of coast redwood (Sequoia sempervirens) in a secondary forest two years after the CZU Lightning Complex fire on the central coast of California. Robust allometric equations were developed to quantify redwood resprout biomass and leaf area, revealing strong explanatory power for biomass equations (R² > 0.85). Probability of …

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The Larval Preference Of An Invasive Bryozoan (Watersipora 'New Species') For Copper-Based Antifouling Paints, Alexander K. Strawhand Jan 2024

The Larval Preference Of An Invasive Bryozoan (Watersipora 'New Species') For Copper-Based Antifouling Paints, Alexander K. Strawhand

Cal Poly Humboldt theses and projects

The bryozoan Watersipora subtorquata and its cryptic congener Watersipora ‘new species’ are now globally invasive species. Previous studies have found this species complex to have a high tolerance to copper-based antifouling paints, which represent a large portion of the mitigation effort toward preventing hull fouling by invasive invertebrates. Tolerance alone, however, is unlikely to explain the full extent of Watersipora’s massive and rapid worldwide invasion success. The aim of this research was to move beyond tolerance, and test whether larvae of Watersipora ‘new species’ exhibit a preference for copper-coated settlement surfaces in both laboratory and field settings. For the laboratory …

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Characterizing New Plant Fossils With Woody Growth From The Battery Point Formation Of Quebec (Canada), Emma T. Casselman Jan 2024

Characterizing New Plant Fossils With Woody Growth From The Battery Point Formation Of Quebec (Canada), Emma T. Casselman

Cal Poly Humboldt theses and projects

The oldest woody growth has been recognized in several Early Devonian (ca. 410-395 Ma) euphyllophytes. Their taxonomic diversity is difficult to evaluate due to a lack of quantitative methods for comparing plants based on secondary xylem anatomy. In turn, this hinders understanding of their implications for the evolution of plant development. To develop metrics that quantify secondary xylem anatomy and allow for conclusive comparisons, I investigated extant taxa and Early Devonian fossil woody taxa. I developed multiple metrics for quantifying tracheid size as a function of position in the secondary xylem and tested them on a dataset of extant gymnosperms. …

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Characterizing The Habitat Use Of Pacific Coast Feeding Group Gray Whales (Eschrichtius Robustus) And The Spatial And Temporal Variability Of Their Benthic And Planktonic Invertebrate Prey In Northern California, Robyn E. Norman Jan 2024

Characterizing The Habitat Use Of Pacific Coast Feeding Group Gray Whales (Eschrichtius Robustus) And The Spatial And Temporal Variability Of Their Benthic And Planktonic Invertebrate Prey In Northern California, Robyn E. Norman

Cal Poly Humboldt theses and projects

As opportunistic foragers, the Eastern North Pacific population (~20,000) of gray whales (Eschrichtius robustus) feed on diverse benthic and planktonic invertebrates in northern Alaska foraging grounds before they undertake one of the largest yearly migrations of any mammal to breed in Baja California, Mexico. While most of the population travels to the summer foraging grounds in Alaska, a sub-group of whales (~230) called the Pacific Coast Feeding Group (PCFG) summer between British Columbia, Canada, and northern California. The diet of PCFG whales typically includes high-density and/or high-caloric prey items like mysids and diverse species of amphipods, yet a …

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A Case Of Incipient Budding Speciation In The California Floristic Province, Infraspecific Divergence In Abronia Villosa, Eli J. Allen Jan 2024

A Case Of Incipient Budding Speciation In The California Floristic Province, Infraspecific Divergence In Abronia Villosa, Eli J. Allen

Cal Poly Humboldt theses and projects

Physical barriers to gene flow are the traditional evidence for species divergence. Conversely, there has been increasing acknowledgment of speciation in the face of gene flow as an evolutionary process. Budding speciation involves peripheral populations adapting to local ecological conditions, thereby budding off from a widespread progenitor species. Budding speciation is distinguished by ecological divergence and is generally evidenced by asymmetrical range size and nested phylogenetic relationships of sister species. The narrow endemic Abronia villosa var. aurita is adapted to montane sandy washes adjacent to its widespread sister variety, the desert dwelling var. villosa. Here, I tested the hypothesis …

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Comparative Morphology And Ultrastructure Of Olfactory Epithelia In Plethodontid Salamanders: Effect Of Life History Variation, Emily Gremling Jan 2024

Comparative Morphology And Ultrastructure Of Olfactory Epithelia In Plethodontid Salamanders: Effect Of Life History Variation, Emily Gremling

Cal Poly Humboldt theses and projects

Many amphibian species rely on olfaction for locating prey and for social interactions during different life stages. Despite the importance of the olfactory system, research on its structure has been taxonomically limited. The most diverse family of salamanders, the Plethodontidae, has been largely excluded from research efforts to describe olfactory morphology. Although several histological studies have been conducted, no studies have yet looked at morphology at the level of ultrastructure using electron microscopy. The primary goal of my research was to examine olfactory morphology and ultrastructure in plethodontid species with a range of life history strategies, to better understand the …

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Microbes: Key Constituent Of Predator Risk Cues?, Jake R. Vargas Jan 2024

Microbes: Key Constituent Of Predator Risk Cues?, Jake R. Vargas

Cal Poly Humboldt theses and projects

Chemical cues emanating from predators can play a key role in aquatic predator-prey interactions and food webs. Understanding how prey respond to these risk cues is therefore critical for understanding the direct effects of predators on prey populations and their indirect effects on communities. To respond adaptively, prey must accurately assess the risk of predation associated with perceived chemical cues, an oft-documented phenomenon. However, little is known about how cues disperse, persist, and degrade, all of which could limit the adaptive responses of prey. Using laboratory-based observations of a well-studied predator cue-induced antipredator behavior by the marine gastropod Tegula funebralis …

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Evaluating The Utility Of Tracers To Characterize Environmental Dna Transport And Inform Detection Of Fishes In Small Streams, Gavin B. Bandy Jan 2024

Evaluating The Utility Of Tracers To Characterize Environmental Dna Transport And Inform Detection Of Fishes In Small Streams, Gavin B. Bandy

Cal Poly Humboldt theses and projects

This study was motivated by the need to develop a noninvasive and highly sensitive monitoring tool for determining local occupancy of an endangered aquatic species To make inference into the occupancy of fishes within small stream sites, we developed a method to determine whether environmental DNA (eDNA) concentrations from a target species were elevated relative to a tracer, formulated to mimic eDNA and introduced at a single location. We examined patterns in the observed distribution of the tracer to account for the effects of site-specific transport processes and sampling on distributions of naturally occurring eDNA at small spatial scales (400 …

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Assessing Relocation Habitats And Assisted Migration Of The Lassics Lupine, An Endangered California Serpentine-Endemic, Caitlyn M. Allchin Jan 2024

Assessing Relocation Habitats And Assisted Migration Of The Lassics Lupine, An Endangered California Serpentine-Endemic, Caitlyn M. Allchin

Cal Poly Humboldt theses and projects

The Lassics lupine, Lupinus constancei, is a serpentine species endemic to the Lassics Mountains of northern California, listed as critically imperiled and federally endangered. Increased encroachment from reduced fire intervals has led to elevated herbivory from small mammals. While deployment of exclosure cages has decreased negative impacts, diminishing snowpack from shifting climate continues to threaten the Lassics lupine. To locate possible refugia, I evaluated alternative sites for assisted migration. I built a habitat suitability model (HSM) using MaxEnt software and WorldClim variables to predict optimal habitat. I then evaluated aerial imagery, topography, and geology to identify areas for microhabitat …

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