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Full-Text Articles in Biology

Changes In Prey Mortality: The Efects Of Multiple Predators And Temperature On California Mussels, Wesley Hull Jan 2020

Changes In Prey Mortality: The Efects Of Multiple Predators And Temperature On California Mussels, Wesley Hull

Cal Poly Humboldt theses and projects

Organisms serve as prey to a variety of predators within natural systems, detecting threats through physical and chemical means. While predator feeding behavior is also affected by the presence of other predators, it is unclear whether differing modes of detection have similar effects on predator feeding behavior. In rocky intertidal zones in northern California, the California mussel (Mytilus californianus) is a competitively dominant foundation species consumed by a variety of predators. I quantified the individual and combined effects of ochre star (Pisaster ochraceus) and rock crab (Romaleon antennarium) predation on mussels by implementing mussel …


Assessing Methods For Estimating Biological Sex From Subadult Skeletal Elements, Dorota Zabnicka Jan 2020

Assessing Methods For Estimating Biological Sex From Subadult Skeletal Elements, Dorota Zabnicka

Cal Poly Humboldt theses and projects

While methods for estimating the sex of adult skeletons are relatively accurate, these methods are often inconclusive when applied to subadults (non-adults), especially when many secondary sexual characteristics have not fully developed. Furthermore, existing methods for subadults are often tested on samples with relatively homogenous ancestries, calling into question their reliability in more diverse populations. This thesis reviewed techniques for estimating sex in subadult skeletal remains, and the most promising methods were retested on individuals of known sex between ages 3 and 17 years (n=39, 14 males, 25 females) from the Hamann-Todd Osteological Collection. Data collection included measurements of the …


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 Jan 2020

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 …


Micronutrient Supplementation In Relation To Hair Loss Syndrome In California Mule Deer, Max W. Marquez Jan 2020

Micronutrient Supplementation In Relation To Hair Loss Syndrome In California Mule Deer, Max W. Marquez

Cal Poly Humboldt theses and projects

The Jawbone deer herd has been monitored on their wintering grounds since the 1950s and recently began decreasing over the last several years. The decline prompted an investigation into the reasons why. Coinciding with the population decline is the appearance of hair loss syndrome and two species of exotic lice. In order to evaluate the effects of hair loss syndrome and the influence of exotic lice infestation, 38 wild does from the herd were used in a modified-before-after-control-impact study. Does were treated with micronutrients selenium and copper via boluses in winter (December 2013-January 2014). Selenium treatment, at a dose of …


Multivariate Habitat-Based Predictive Modeling Of Three Demersal Rockfish Species In Central California, Georgia R. Martel Jan 2020

Multivariate Habitat-Based Predictive Modeling Of Three Demersal Rockfish Species In Central California, Georgia R. Martel

Cal Poly Humboldt theses and projects

Accurate, spatially explicit models of rockfish abundance are critical in implementing ecosystem-based management strategies and designating essential fish habitats and marine protected areas. Multibeam bathymetry methods and visual, non-extractive submersible transect surveys were combined to collect environmental variables and fish abundance data at three distinct sites within the study region. Zero-adjusted models were developed using habitat classification analyses of high-resolution (5 m) digital elevation models. Model accuracies were assessed by using a reserved subset of the original datasets. To demonstrate that a model’s predictive power was linked to its spatial origins, Mean Absolute Error and coefficient of determination values were …


The Ability Of Fragmented Kelp Forests To Mitigate Ocean Acidification And The Effects Of Seasonal Upwelling On Kelp-Purple Sea Urchin Interactions, Kindall A. Murie Jan 2020

The Ability Of Fragmented Kelp Forests To Mitigate Ocean Acidification And The Effects Of Seasonal Upwelling On Kelp-Purple Sea Urchin Interactions, Kindall A. Murie

Cal Poly Humboldt theses and projects

Bull kelp (Nereocystis leutkeana) forests along the coast for northern California have decreased dramatically as a result of a ‘perfect storm’ of multiple environmental stressors. The disappearance of a predatory sea star and subsequent increase in purple sea urchins (Strongylocentrotus purpuratus) and the recurrence of marine heat waves have caused these once diverse ecosystems to be rapidly converted into relative species-depauperate urchin barrens. By examining the interactive effects of both a rapidly changing abiotic environment and the increase in urchin grazing pressure that is affecting this vital ecosystem, we can better understand its ultimate fate and …


Effects Of Gap Junction Blockage On Regenerating Body Segments Of Lumbriculus Variegatus, Monica K. Richmond Jan 2020

Effects Of Gap Junction Blockage On Regenerating Body Segments Of Lumbriculus Variegatus, Monica K. Richmond

Cal Poly Humboldt theses and projects

Lumbriculus variegatus is a freshwater annelid that is well known for its regenerative capacity. There are many different factors that affect regeneration in animals. Cell-to-cell communication is a key component of regeneration. Gap junctions are made up of proteins that create a channel that connects the cytoplasm of two cells. Many molecules and ions pass through the gap junctions that can affect regeneration. The purpose of this study was to determine if blocking gap junctions would have an impact on regenerating body segments of L. variegatus and what effects it would produce. L. variegatus was exposed to a known gap …


Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong Jan 2020

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 …


The Rattle Call: A Female-Specific Vocalization In Steller's Jays, Kachina L. Rowland Jan 2020

The Rattle Call: A Female-Specific Vocalization In Steller's Jays, Kachina L. Rowland

Cal Poly Humboldt theses and projects

While the elaborate songs of male passerines are well documented for their role in intrasexual resource competition and mate attraction, vocalizations used in female competition are poorly understood. Research has suggested that the female-specific rattle call of Steller’s jays (Cyanocitta stelleri) is used in competition for access to a territory and mate. I describe structural properties of the rattle call, and compare life history traits of individual females to rattle call occurrence. I used two rates to quantify rattle call occurrence from 20 females: rattles per observation period (RPO), and proportion of observations with a rattle call (POR) …


An Ecomorphological Analysis Of Locomotion In Larvae And Neotenes Of Two Salamander Species: Dicamptodon Tenebrosus (Stream-Type) And Ambystoma Gracile (Pond-Type), Ethan Hardister Snee Jan 2020

An Ecomorphological Analysis Of Locomotion In Larvae And Neotenes Of Two Salamander Species: Dicamptodon Tenebrosus (Stream-Type) And Ambystoma Gracile (Pond-Type), Ethan Hardister Snee

Cal Poly Humboldt theses and projects

Morphology is the physical expression of a species’ evolutionary history and adaptation to its environment and as such is tied to ecology. Salamander larvae have historically been separated into "pond-type" and "stream-type" groups based on their morphology, however no studies have been performed quantifying the relationship between morphology and ecology. In this study I utilized in-situ behavioral observations, morphological measurements, and in-lab performance tests of Dicamptodon tenebrosus (stream-type) and Ambystoma gracile (pond-type) to examine the relationship between salamander larval morphology and ecology. In the field, behavior was video recorded during nighttime surveys; afterwards animals were captured and limb measurements were …