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Articles 1 - 20 of 20
Full-Text Articles in Life Sciences
Comparing Alternative Developmental Modes: Structure And Gene Expression In The Olfactory System Of Plethodontid Salamanders, Giuseppina S. Lanzilli
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 …
A Case Of Incipient Budding Speciation In The California Floristic Province, Infraspecific Divergence In Abronia Villosa, Eli J. Allen
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 …
Evaluating The Utility Of Tracers To Characterize Environmental Dna Transport And Inform Detection Of Fishes In Small Streams, Gavin B. Bandy
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 …
Genetic Evaluation Of The Current Distribution And Possible Diffrentations Between Lasiurus Borealis And Lasiurus Frantzii In Southwestern North America, Zeinab M. Haidar
Genetic Evaluation Of The Current Distribution And Possible Diffrentations Between Lasiurus Borealis And Lasiurus Frantzii In Southwestern North America, Zeinab M. Haidar
Cal Poly Humboldt theses and projects
Several recent accounts of overlap and historic misidentifications regarding two species of the genus Lasiurus, Western red bat (Lasiurus frantzii) and Eastern red bat (Lasiurus borealis), have cast doubt on our understanding of their distribution, assumed spatial allopatry, and interactions in the United States Southwest. With the use of morphometrics and genetic sequencing, utilizing tissue collected from specimens throughout California and adjoining states, we have reassessed the current distribution, best practices for field identification, and genetic differentiation between both species. Appropriate species classification by region was achieved utilizing mitochondrial DNA, targeting the cytochrome c oxidase …
Host-Microbe Interactions In Non-Native Estuarine Anemones: Biogeography And Temperature, Parker K. Lund
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
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 19th and early 20th 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 …
Use Of Foreign Edna Tracers To Resolve Site- And Time-Specific Edna Distributions In Natural Streams, Braden A. Herman
Use Of Foreign Edna Tracers To Resolve Site- And Time-Specific Edna Distributions In Natural Streams, Braden A. Herman
Cal Poly Humboldt theses and projects
Substantial uncertainty in how to interpret eDNA observations motivates a need for a technique to effectively and efficiently measure of system- and time-specific eDNA distributions. Using a technique to robustly calibrate eDNA dynamics in a given system would improve established eDNA methods such as presence and absence and has the potential to refine estimates of organism abundance using eDNA concentration that are less well understood. Particles of eDNA are present in a wide variety of size and type resulting in varying transport dynamics, persistence, decay, among others. This variation likely makes eDNA transport more complex than that of conservative tracers …
Effects Of Depth, Distance To Shore, And Water Velocity On Organismal And Extra-Organismal Environmental Dna Concentrations In A Large River, Dylan Keel
Cal Poly Humboldt theses and projects
Environmental DNA (eDNA) is a sensitive tool for detection of aquatic species and concentrations of eDNA in water samples have been useful for estimating abundance. This study evaluated the effects of depth, distance to shore, and water velocity on the concentration of organismal and extra-organismal eDNA concentrations in the Klamath River, California (basin area ≅ 40,000 km2). At each of six river cross sections 32 water samples were collected, including surface samples and depth samples evenly distributed across the cross section, and eDNA concentrations were determined for the parasite Ceratonova shasta and Chinook salmon, Oncorhynchus tshawytscha, using …
Phylogenetic And Geographic Relationships Of Cheilostome Bryozoans In The Eastern Pacific, Hannah E. Lee
Phylogenetic And Geographic Relationships Of Cheilostome Bryozoans In The Eastern Pacific, Hannah E. Lee
Cal Poly Humboldt theses and projects
The phylum Bryozoa is an incredibly diverse group of marine invertebrates with a widespread global distribution that is well suited for evolutionary studies but whose phylogenetic relationships are still poorly understood. Although recent studies on bryozoan taxonomies and phylogenies have increased, there is still a lack of assessment of species found at shallow water (<1 m) to intertidal depths. In this study, I aimed to expand the taxonomic sampling and assessment of the phylogenetic diversity of cheilostome bryozoans along the California coastline by utilizing mitochondrial DNA as well as inferring potential correlations between species presence and dispersal range both within and between rocky outer coast and sheltered harbor habitats. Illumina high-throughput sequencing was used to produce mitogenomes for cheilostome bryozoan samples collected off rocks from two rocky intertidal sites and off settlement panels from two harbor sites. Phylogenetic analyses generated evolutionary hypotheses of species relationships alongside geographic mapping of their distribution. This study identified 15 distinct species that represent 10 different families to form the first comprehensive phylogeny for multiple bryozoan families in California across a total range of approximately 973 km of coastline. Three genetically distinct species were found at multiple sites that are separated by a combination of rocky shores and sandy beaches, which indicates that the dispersal range of these species are not limited by geographic barriers along the coast of California. These results provide a future opportunity for further integration of this data with the phylogenies generated in this study to examine more robust evolutionary hypotheses for the phylogenetic and geographic relationships of Californian bryozoan species.
Investigating The Genetic Diversity Of Immune Genes In Non-Native Populations Of American Bullfrogs (Rana Catesbeiana), Luisa Nereyda Segovia
Investigating The Genetic Diversity Of Immune Genes In Non-Native Populations Of American Bullfrogs (Rana Catesbeiana), Luisa Nereyda Segovia
Cal Poly Humboldt theses and projects
The American Bullfrog (Rana catesbeiana) is a highly invasive species that has successfully colonized habitats around the world. The genetic variability of immune genes within invasive populations, like that of bullfrogs, may contribute to how resistant a population is to pathogens. The objective of this project was to characterize the genetic diversity of an immune gene in invasive bullfrog populations in California to better understand how persistent these populations might be over time. To characterize immune gene variability, I isolated exon 2 of the Major Histocompatibility Complex (MHC) Class II Beta chain gene and a neutral mitochondrial marker, …
Degradation And Nitrogen Cycling In The Context Of Biodiversity-Ecosystem Function Relationships In The Inquiline Bacterial Community Of Darlingtonia Californica, Megan Teigen
Cal Poly Humboldt theses and projects
Biodiversity-ecosystem function (BEF) research aims to explain how species and their environments interact with each other. Microbial communities engage in vital biogeochemical pathways in a variety of natural ecosystems, and yet there are large knowledge gaps about the specific metabolic pathways in which they are involved. Degradation specifically contributes to nitrogen cycling globally through the breakdown of large organic nitrogen compounds into small inorganic nitrogen that is necessary for the survival of many other organisms. In this study, I focused on the degradative function of the inquiline microbial communities found within the carnivorous pitcher plant, Darlingtonia californica. Darlingtonia grows in …
Estrogen Disruption Of Hypothalamic Neural Activity, Princess Dickson
Estrogen Disruption Of Hypothalamic Neural Activity, Princess Dickson
Cal Poly Humboldt theses and projects
The brain is highly dependent on the endocrine system for proper neurodevelopment, as it plays a key role in many biological processes. Bisphenol A is a chemical found in plastics that has the potential to mimic the effects of Estrogen in the body, at least weakly. People interact with plastic that contains BPA regularly, and people are at risk for exposure even before being born. The abundance of BPA, along with other exogenous estrogens, makes examining the relationship between early exposure and changes in brain activity imperative. The current study aims to establish a relationship between disrupted estrogen function and …
Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong
Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong
Cal Poly Humboldt theses and projects
Distinct populations of steelhead in the wild are in decline. The propagation of steelhead in hatcheries has been used to boost population numbers for recreational fisheries and for use in conservation. However, hatchery breeding practices of steelhead can result in changes in genetic structure. I investigated the genetic structure of winter-run steelhead (Oncorhynchus mykiss) returning to the Mad River, California, where a hatchery has been used enhance production for recreational fisheries since 1971. Genetic variability in Mad River steelhead was evaluated using 96 single nucleotide polymorphisms (SNPs) among 4203 individuals, including the Mad River and nearby locations, and …
Neurodegenerative Modeling: Tau Protein, Degradative Pathways, And Gene Expression Profiling Of Human Ipsc-Derived Neural Precursors And Differentiated 3-D Neural Sphere Versus 2-D Monolayer Cultures, Kyle H. Anthoney
Cal Poly Humboldt theses and projects
Human induced pluripotent stem cells offer a model for human brain development and disease by differentiation into brain organoids; however, current neural culture systems lack the microenvironment, neuronal circuits and connectivity, vascular circulation, and immune system that exist in vivo. After differentiation and development of neuronal and non-neuronal cell types within two formats of cell cultures, we can visualize and recapitulate in vivo protein accumulation, gene expression, and degradative processes such as autophagy. Using RNA extraction, purification methods and reverse transcription I compared traditional monolayer cultures and novel 3-D neural sphere cultures via gene expression analysis. This analysis indicated …
Knemidokoptes Mites And Their Effects On The Gripping Position Of Steller’S Jay Feet, Wade M. Burris
Knemidokoptes Mites And Their Effects On The Gripping Position Of Steller’S Jay Feet, Wade M. Burris
Cal Poly Humboldt theses and projects
Steller’s jays (Cyanocitta stelleri) with swollen legs and feet resembling the signs of scaly leg have been commonly seen around Arcata, California, USA. These signs are thought to be caused by knemidokoptic mites, a group of parasites specialized at exploiting a range of avian hosts. I compared the gripping position in the feet of jays with variable signs of this condition as an index of their ability to perch, confirmed the presence of mites and identified them to the nearest species using genetic analysis, and compared the relatedness of the cytochrome oxidase subunit I (COI) gene between mites …
Using Environmental Dna And Occupancy Modeling To Estimate Rangewide Metapopulation Dynamics Of The Endangered Tidewater Goby Eucyclogobius Spp., Chad M. Martel
Using Environmental Dna And Occupancy Modeling To Estimate Rangewide Metapopulation Dynamics Of The Endangered Tidewater Goby Eucyclogobius Spp., Chad M. Martel
Cal Poly Humboldt theses and projects
Conservation of species is most effective when metapopulation dynamics are well understood and incorporated into management plans, allowing managers to target conservation efforts where they will be most effective. The development of environmental DNA (eDNA) methods provides an efficient and highly sensitive approach to generate presence and absence data needed to elucidate metapopulation dynamics. Combining sample detection histories from eDNA surveys with occupancy models that account for non-detection can offer unbiased estimates of rangewide metapopulation dynamics. However, traditional occupancy models do not allow direct evaluation of the drivers of site occupancy, extinction, and colonization. Herein, I utilize a novel dynamic …
The Effects Of Forest Degradation On Dna Methylation In Central African Songbirds, Andrew K. Wiegardt
The Effects Of Forest Degradation On Dna Methylation In Central African Songbirds, Andrew K. Wiegardt
Cal Poly Humboldt theses and projects
Environmentally-induced stress can initiate a molecular response through DNA methylation, which can alter gene expression, thereby serving as a mechanism allowing individuals to acclimate to a changing environment within their lifetime. In addition to DNA methylation, the production and release of corticosterone is a physiological mechanism by which birds can cope with acute environmental stressors. To assess how environmental stress impacted DNA methylation and corticosterone, I collected blood and feather samples from three understory avian species (Alethe castanea, Bleda notatus and Pseudalethe poliocephala), along a disturbance gradient in the lowland Guinean rainforest adjacent to the village of …
The Effects Of Increased Camp Levels On Neuronal Differentiation In Murine Embryonic Stem Cells, And The Creation Of A Crispr-Induced C.1252c>T Point Mutation In The Adcy5 Gene, Elizabeth Zepeda
Cal Poly Humboldt theses and projects
ADCY5-related dyskinesia is a rare movement disorder with early onset in childhood and adolescence. Previous studies linked this disease to various point mutations in the ADCY5 gene. Recent studies show that two of the point mutations cause an increase in cyclic adenosine monophosphate (cAMP) levels. However, it remains unknown how increased levels of cAMP result in the phenotypes associated with this disease. My study examines the effects of increased cAMP levels on neuronal differentiation of mouse embryonic stem cells (mESCs). My experiments demonstrated successful differentiation of mESCs into the dopaminergic neuronal lineage, indicated by the presence of Tuj 1 (a …
Evidence For The Genetic Basis And Inheritance Of Ocean And River-Maturing Ecotypes Of Pacific Lamprey (Entosphenus Tridentatus) In The Klamath River, California, Keith A. Parker
Cal Poly Humboldt theses and projects
Surveys of genetic variation have improved our understanding of the relationship between fitness-related phenotypes and their underlying genetic basis. However, how this information can be used to inform conservation has been unclear in many cases. The objective of this study was to combine next-generation genetic sequencing with traditional ecological knowledge to evaluate imperiled anadromous Pacific lamprey (Entosphenus tridentatus) and apply the findings to conservation in the context of resolving Native American traditional food security issues. In the Klamath River of California, a previously identified Pacific lamprey ocean-maturing ecotype was distinguished by a relatively advanced maturity of female fish …
Genetic Structure And Connectivity Of The Endangered Giant Kangaroo Rat (Dipodomys Ingens) In A Heterogeneous Environment, Nathan Alexander
Genetic Structure And Connectivity Of The Endangered Giant Kangaroo Rat (Dipodomys Ingens) In A Heterogeneous Environment, Nathan Alexander
Cal Poly Humboldt theses and projects
Movement ecology and dispersal are important aspects of species’ life histories that can inform conservation and management. Dispersal is often cryptic and difficult to detect, but recent advances genetic technology and applications have provided new approaches to identifying and describing dispersal patterns. Giant kangaroo rats (Dipodomys ingens) are an endangered heteromyid that appear to persist in small subpopulations in a heterogeneous environment of their northern range, the Ciervo-Panoche Natural Area, California. Previous work suggested high levels of genetic diversity between populations with genetic distances not being correlated to geographic distances. Here, I identified landscape population structure through clustering …