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Urban Nesting Biology, Population Viability And Ecology Of The Willow Flycatcher, Empidonax Traillii, Stephanie Alexandra Byrne Doorly

Dissertations and Theses

Reproductive success, in any species, relies both on the habitat utilized to reproduce and on the successful reproductive output of individual animals within a population. Populations in turn rely on the reproductive fitness of the individual. Whether populations remain stable, grow, or decline ultimately relies on the combined reproductive output of the individuals within that population.

We studied the Willow Flycatcher (Empidonax traillii; henceforth WIFL), a well-studied Neartic-Neotropical migrant passerine whose breeding range extends from the east to west coast of North America. Across much of their range, and in particular in the western regions, breeding population are …

System Design For The Quantification Of Microbial Motility In Extreme Environments, Megan Marie Dubay

Dissertations and Theses

Motility of microorganisms is understudied but provides useful insights into their behavior. Organisms' ability to move autonomously changes how they interact with their environment--finding nutrients, interacting with other organisms, and avoiding unfavorable conditions. Understanding motility features can also be used to identify specific species, such as the identification of Vibrio cholerae in human samples. Motility might also be used as evidence of life existing in even the most extreme environments on Earth, and possibly beyond. Specialized microscopy systems can be required to examine the motility of microorganisms due to the nature of the environments to which the instruments are exposed. …

Post-Fire Erosional And Hydrological Processes Promoting Debris Flow Initiation In A Douglas Fir And Western Hemlock Forest In The Riverside Burn Area, Oregon, Morena Nicole Hammer

Dissertations and Theses

Post-fire debris flows initiated by overland flow in the Pacific Northwest (PNW) are largely undocumented. Instead, debris flows are typically initiated by shallow landslides that result in a mud slurry of water and sediments traveling downhill under the force of gravity. However, because of the Fall 2020 fires in Oregon, the typical initiation style and erosional patterns in burned catchments may have changed because of unusually high burn severity. Due to the intensity of these fires, we set out to determine how hydrologic processes and erosion occurred, when they occurred, and what process was primarily responsible for the erosion that …

Orthotrichum Lyellii As An Active Moss Biomonitor: Examining The Interplay Between Ambient Pm10, Bulk Deposition And Heavy Metals In An Urban Environment, Scott Bradley Kiel

Dissertations and Theses

The importance of monitoring and preventing pollution in the environment is a globally recognized issue. Of the criteria pollutants outlined by the United States Environmental Protection Agency, particulate matter is among these least understood in relation to toxicity and most wide-spread. Many governments have employed continuous air quality monitoring networks to track ambient levels of particulate matter, but are often too widespread to capture the heterogeneity of the urban environment, especially for heavy metal deposition. In Portland, OR, the epiphytic moss Orthotrichum lyellii was successfully used as a low-cost passive biomonitor to increase the spatial resolution of pollution around the …

Climate And Intraspecific Geographic Variation Of Nests And Eggs In The Eastern Kingbird Tyrannus Tyrannus, Samantha Marie Gillette

Dissertations and Theses

The reproductive success of birds is ultimately driven by the traits of nests, eggs, and incubation behavior and the interactions among them. Avian reproduction varies on large geographic scales, most prominently between tropic- vs. temperate-breeding species, but also on finer scales, such as along latitudinal and elevational geographic gradients. However, despite the importance of eggs and nests, how their traits vary geographically in response to differences in regional climate remains understudied.

We studied Eastern Kingbirds (Tyrannus tyrannus), which have been previously demonstrated to alter incubation length in response to local climate conditions. Our study sites, Kansas (KS), New …

In Sickness And In Health: Parasites Of Stranded Pacific Harbor Seals (Phoca Vitulina Richardii) In Northern Oregon And Southern Washington, Cecily Douglas Bronson

Dissertations and Theses

Parasites have the capability to infect virtually every living organism on the planet and have adapted to infiltrate every trophic level. Many species have complex indirect life cycles and rely upon hosts at different levels of the food web for growth and reproduction. In the marine environment, having a high level of parasite diversity is thought to indicate a more stable ecosystem than an environment with low parasite diversity. As one of the top predators in their environment and because of their amphibious behaviors, pinnipeds (seals and sea lions) are exposed to a wide variety of parasites, making them ideal …

A Multi-Species Study On Several Types Of Visitor Effects On The Behavior And Physiology Of Animals At The Oregon Zoo, Laurel Berylline Fink

Dissertations and Theses

The visitor effect on zoo animals is one of the expanding research topics in zoo animal research. As visitors are a mandatory feature of zoological institutions, understanding their effects on zoo animals is imperative for maximizing zoo animal welfare. Zoo animals are subject to many anthropogenic influences: visual, olfactory, and audible, for example. This dissertation investigates several of the effects of visitor presence and its relative influence on six mammalian species: cheetahs (Acinonyx jubatus), African painted dogs (Lycaon pictus), Asian elephants (Elephas maximus indicus & Elephas maximus borneensis), giraffes (Giraffa camelopardalis reticulata & …

Effects Of Pore-Forming Peptides (Melittin And Magainin 2) On The Phospholipid Bilayer Interior, Elmukhtar Ehmed Alhatmi

Dissertations and Theses

Antimicrobial peptides (AMPs) are one of the most promising solutions to drug-resistant bacteria. Melittin and magainin 2 are two of the most representative and extensively studied AMPs. In this research, I investigated the interaction of these two AMPs with three models of cell membranes: 80% POPC 20% POPG, 40%POPC 40% POPE and 20% POPG, and 80%POPC 20%POPG plus 30% mole fraction of cholesterol. Time-resolved fluorescence emission and fluorescence anisotropy decays of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) were analyzed to determine the effects of AMPs on the bilayer headgroup packing and changes in the interior of the phospholipid bilayer during the …

Aerosolization Of Catalytic Rna For Prebiotic Transport And In Situ Reactivity, Brennan Roland Farrell

Dissertations and Theses

Recent theoretical and experimental work suggests that aqueous aerosols in the early Earth's atmosphere might have been an essential component to the development of life. These complex droplets would have served to compartmentalize emerging biomolecules, thereby concentrating them, increasing reactivity, and facilitating transport and exchange between ocean and atmosphere. This project tests an underexplored but potentially important environmental paradigm for the RNA world hypothesis of prebiotic evolution, probing the effects of aerosolization on catalytic RNA using a model ribozyme. Here we demonstrate the successful transport and in situ self-assembly of the Azoarcus ribozyme from multiple independent fragments via a laboratory-constructed …

A Tale Of Two-Hybrids: Investigating The Interactomes Of Cullin-Associated Proteins, Elyse Reitter

Dissertations and Theses

Cul3 is the major component of an E3 ligase in human cells. Cul3 was initially identified in the Singer lab as a protein that binds and degrades cyclin E, and subsequent studies have shown it to be part of a complex that is involved in a multitude of biological functions. The nature of this complex, its constituents, its regulation, and its dynamics is just beginning to be understood. The research presented here utilizes a series of two hybrid screens to identify families of interactomes with Cul3 at the center. This information will complement other work in the lab in which …

Helminths Of Thomomys Species (Rodentia: Geomyidae) Of Oregon, Malorri Rene Hughes

Dissertations and Theses

Although often viewed as inconsequential, parasites have significant ecological and evolutionary importance, and studying them can generate knowledge regarding their environments and their hosts. Helminths (intestinal parasites) infecting Western pocket gophers (Thomomys species) in Oregon had been documented based only on morphology prior to this study. Basing parasite identification solely on morphology is problematic because the characteristics used to identify species can be vague or similar, leading to misidentification or obscuring the true biodiversity present. Using molecular markers to verify species present not only is more reliable but also can be informative in terms of the host-parasite association. To …

Effects Of Green Crab (Carcinus Maenas) Across Variable Densities Of Eelgrass (Zostera Marina), Kimberly Alexis Brown

Dissertations and Theses

Eelgrass (Zostera marina) plays a critical role in estuarine ecosystem function by sustaining a variety of marine and freshwater species, but it's increasingly threatened by the aggressive non-native green crab (Carcinus maenas). The abundance of C. maenas is on the rise within the coastal environment of Oregon and it is imperative to know how these populations will affect the long-term health of Z. marina. C. maenas have been linked to declines in Z. marina coverage and shellfish abundance, but there has been no research on to what extent the density of Z. marina affects its …

The New Shiny Penny? Regenerative Agriculture Beliefs And Practices Among Portland's Urban Agriculturalists, Melia Ann Chase

Dissertations and Theses

Regenerative agriculture (RA) is a set of farming and land management practices intended to support or enhance soil health and carbon sequestration potential of soils while producing food, fiber, or other agricultural products. It has received broad acclaim from scholars, corporations, and governmental bodies as a potential means of sequestering carbon and mitigating climate change impacts. It has also received critique and pushback for its vague definition, shifting metrics, and lack of acknowledgement of the Indigenous practices underlying the modern suite of regenerative practices. The purpose of this research is to investigate the beliefs Portland, Oregon urban agricultural practitioners hold …