Biology Commons^™

Anatomical Identification Of Primary Auditory Cortex In The Developing Gerbil, Luis Pendola

Dissertations and Theses

Cortical development is an active field of study. The gerbil provides an excellent model for research because at the moment of birth its brain is rather immature, anatomically and functionally. Furthermore, the gerbil auditory cortex is particularly amenable to investigation in that the gerbil's onset of hearing occurs approximately after 14 days of postnatal life. Despite these advantages of the gerbil for auditory cortex development not much is known about the anatomy of the postnatal gerbil auditory cortex. For example, where is the gerbil auditory cortex? Prior to the onset of hearing, sounds cannot be used to localize auditory cortex. …

Healthy Choices; Preferential Foraging Of Insects Within Senescent, But Nutrient-Rich, Tropical Flowers., Amie Whigman

Dissertations and Theses

No abstract provided.

The Development Of Hearing In Rats; Reliability Of Wave 1 As A Determinant Of Auditory Maturation And Contributions Of Peripheral Structure Progression, Aminat Saliu

Dissertations and Theses

No abstract provided.

Biological Reserves Under Climate Change; A Case Study In Brazil's Atlantic Rainforest, Maria Amin

Dissertations and Theses

No abstract provided.

Biogeography Of The American Pika (Ochotona Princeps) In Oregon And Southern Washington: Illuminating Genetic Relationships Among Disjunct Populations, George Washington Batten Iii

Dissertations and Theses

The American pika (Ochotona princeps) finds moderately warm temperatures (>25°C) lethally stressful, and at the end of the last Ice Age 10,000 years ago was forced to disperse to cooler, "sky island" mountaintops where they are almost exclusively found today. Thirty six subspecies are recognized, all established using morphological characters, and it is uncertain whether these subspecies' designations are corroborated by genetic analyses. This study elucidates three hypotheses regarding populations in Oregon and southern Washington: 1) O. p. fumosa constitutes a subspecies distinct form O. p. brunnescens, 2) the Columbia River constitutes a barrier to gene …

Phylogeographic Patterns And Intervarietal Relationships Within Lupinus Lepidus: Morphological Differences, Genetic Similarities, Kevin Allen Weitemier

Dissertations and Theses

Lupinus lepidus (Fabaceae) contains many morphologically divergent varieties and was restricted in its range during the last period of glaciation. A combination of phylogenetic (with the trnDT and LEGCYC1A loci) and population genetics approaches (with microsatellites and LEGCYC1A are used here to characterize intervarietal relationships and examine hypotheses of recolonization of areas in the Pacific Northwest affected by glaciation. Sequenced loci are not found to form a clade exclusive to L. lepidus, nor are any of the varieties found to form clades. Population genetics analyses reveal only negligible genetic structure within L. lepidus, with the majority of variation …

Spatial Segregation Of The Sexes In A Salt Marsh Grass Distichlis Spicata (Poaceae), Charlene Ashley Mercer

Dissertations and Theses

Understanding the maintenance of sexual systems is of great interest to evolutionary and ecological biologists because plant systems are extremely varied. Plant sexual systems have evolved to include not only complete plants with both male and female reproduction occurring on one plant (i.e., monoecious and hermaphroditic) but also plants with male and female function on separate plants (dioecious). The dioecious reproductive system can be used to test theories on niche differentiation given that having separate plants potentially allows for the exploitation of a broader niche. This increase in the realized niche is due to the ability for separate sexes to …

Mitochondrial Inheritance And Natural Phenotypic Variation Among Caenorhabditis Briggsae Populations, Anna Luella Coleman-Hulbert

Dissertations and Theses

Mutations affecting the mitochondrial electron transport chain cause numerous neurodegenerative disorders in humans and affect longevity in other organisms. A natural model system to study the relationship between mitochondrial function and aging within an evolutionary or population genetic context has been lacking. Natural populations of Caenorhabditis briggsae nematodes were recently found to harbor mitochondrial genetic variation with likely functional consequences for aging. Specifically, C. briggsae isolates containing high frequencies of a deletion mutation affecting the mitochondrial NADH dehydrogenase 5 (ND5) gene were found to have reduced reproductive fitness and lifespan and elevated levels of mutagenic superoxide. Here, rates …

The Impact Of Microclimate On Branch Colonization By Neotropical Cerambycid Beetles, Christina Lee

Dissertations and Theses

"Vertical stratification contributes to the great diversity of insects found in tropical rainforests. Due to differences in both biotic and abiotic factors, different strata of the forest provide different habitats for insects. A previous study in French Guiana revealed that wood-boring cerambycid beetles preferentially colonized branches at ground level in the dry season, but shifted to canopy level in the rainy season. The current beetle-rearing study was conducted to confirm the occurrence of this seasonal shift, explore possible causes, and to determine if similar microclimate conditions occurred at ground level in the dry season and the canopy level in the …

The Effect Of The Study Region On Gis Models Of Species Geographic Distributions And Estimates Of Niche Evolution; Preliminary Tests With Montane Rodents (Genus Nephelomys) In Venezuela, Ali Raza

Dissertations and Theses

Various niche-based techniques exist to model a species' potential geographic distribution in a Geographic Information Systems (GIS) framework. These models compare the environmental conditions of localities of a species' occurrence versus those of the overall study region. In addition to uses in areas such as macroecology and conservation biology, this approach has been applied recently to studies of niche evolution and historical biogeography. Definition of the study region is critical for all of these applications but has not been addressed previously. Here, I examine the effect of changes in the extent of the study region on potential distribution models of …

Role Of Drosophila Rap/Fzr (Cdh1) In Retinal Axon Targeting And Its Interactions With Loco, Liprin-A And Ras, Marta Gronska

Dissertations and Theses

The development of the wild type Drosophila compound eye involves stereotypical targeting of photoreceptor axons to the specific layers of the optic ganglion, medulla and lamina, in the third instar larvae. To test the hypothesis that ubiquitin ligases play an important role during retinal axon targeting we have examined the patterns of axon targeting in the developing eye of the retina aberrant in pattern (rap/fzr) mutants. Rap/Fzr is a homolog of mammalian Cdh1, an activator of anaphase promoting complex (APC), an E3 ubiquitin ligase. Previous work has shown that Rap/Fzr is required in cell cycle regulation, glia differentiation and pattern …

Using Geographically Structured Evaluations To Assess Performance And Transferability Of Ecological Niche Models For Species With Many Occurrence Records: A Test Using The Caribbean Spiny Pocket Mouse, Heteromys Anomalus, Aleksandarc Radosavljevi

Dissertations and Theses

No abstract provided.

A Phylogenetic Study Of The Old World Asclepiadinae (Apocynaceae) Based On Chloroplast And Nuclear Dna Sequence Data, David Chuba

Dissertations and Theses

Relationships within the African Asclepias generic complex (Asclepiadinae, Apocynaceae) have for a long time been only a matter of intuitive speculation and generic delimitations have been diverse and rather contentious. Generic delimitation in this group has been based on morphological characters that are usually not exclusive to any particular clade or genus. The difficulty of identifying taxonomically useful morphological characters for inferring generic delimitations has led to differences in the emphasized characters by different taxonomists. This study is aimed at understanding phylogenetic relationships of species within the African Asclepias complex based upon the nuclear PgiC and three chloroplast DNA regions, …

Phylogeographic And Phylogenetic Exploration Of Plethodon (Plethodontidae, Caudata) Salamanders In The Pacific Northwest, Tara Anne Pelletier

Dissertations and Theses

Genetic studies of amphibians often reveal substantial population structure due to either historical demographics from changing climate and geographic features over varying timeframes. Eight species of terrestrial salamanders (Family: Plethodontidae, Genus: Plethodon) reside in forests of the Pacific Northwest (PNW). Plethodon vehiculum is the most widespread and abundant terrestrial salamander in the PNW yet evolutionary studies are lacking. Using mitochondrial DNA (mtDNA) sequence data (D-loop and cytb) questions regarding the phylogeography of P. vehiculum and phylogenetics of western Plethodons are explored. Two major clades were defined in P. vehiculum, a southern clade in the Klamath-Siskiyou region and a …

Analysis And Classification Of Sounds Produced By Asian Elephants (Elephas Maximus), Sharon Stuart Glaeser

Dissertations and Theses

Relatively little is known about the vocal repertoire of Asian elephants (Elephas maximus), and a categorization of basic call types and modifications of these call types by quantitative acoustic parameters is needed to examine acoustic variability within and among call types, to examine individuality, to determine communicative function of calls via playback, to compare species and populations, and to develop rigorous call recognition algorithms for monitoring populations.

This study defines an acoustic repertoire of Asian elephants based on acoustic parameters, compares repertoire usage among groups and individuals, and validates structural distinction among call types through comparison of manual and automated …

Preliminary Characterization Of Mitochondrial Atp-Sensitive Potassium Channel (Mitokatp) Activity In Mouse Heart Mitochondria, Venkat Raghav Aachi

Dissertations and Theses

Myocardial ischemia, infarction, heart failure and arrhythmias are the manifestations of coronary artery disease. Reduction of ischemic damage is a major concern of cardiovascular biology research. As per recent studies, the mitochondrial ATP-sensitive potassium channel (mitoK_ATP) opening is believed to play key role in the physiology of cardioprotection, protection against ischemia-reperfusion injury or apoptosis. However, the structural information of mitoK_ATP is not precisely known. Elucidating the structural integrity and functioning of the mitoK_ATP is therefore a major goal of cardiovascular biology research. The known structure and function of the cell ATP-sensitive potassium channel (cellK_ATP) …

Molecular Coevolution Of Pacific Northwest Hantaviruses And Their Host, The Deer Mouse, Peromyscus Maniculatus, Philip Darren Jones

Dissertations and Theses

Sin Nombre virus (SNV, family Bunyaviridae, genus Hantavirus), hosted by the deer mouse, Peromyscus maniculatus (family Cricetidae, Subfamily Neotominae), is the primary etiological agent of Hantavirus pulmonary syndrome (HPS) in the western United States. HPS, with known pathogenicity only to humans and for which there is no cure or prophylaxis, affects the epithelium of the lungs by making the capillaries leaky, thereby resulting in bilateral infiltrates, and eventually leading to respiratory failure and death by drowning in approximately 38% of hospitalized patients.

In the Americas, Peromyscus has been co-evolving with hantaviruses for approximately 12–20 million years, since the first …

Cardioprotective Signal Transduction To Mitochondria, Casey Lee Quinlan

Dissertations and Theses

Intracellular responses to external stimuli require reception of the message at the plasma membrane followed by encoding and transmission of the message to its effectors downstream. In this process, diverse cellular responses are mediated by many redundant molecular players. The apparent generality and redundancy of many kinases, such as the mitogen-activated protein kinases (MAPKs), suggests that signal transduction must gain specificity through tight regulation. Diffusion and random collisions of relevant signaling components seem insufficient to explain the multilayered complexity observed in cell signaling cascades. Emerging hypotheses suggest that signaling machinery may achieve enhanced specificity and control by exploiting the compartmentalization …

Zoonotic Disease Emergence : A Study Of Host-Pathogen-Ecosystem Dynamics, Laurie Jeanne Dizney

Dissertations and Theses

A growing body of work demonstrates that loss of biodiversity negatively impacts ecosystem functions. One function, or service, that biodiverse ecosystems provide is suppression of zoonotic diseases, which are defined as diseases carried by wildlife hosts that can spill over into human populations. Ebola, SARS, West Nile virus, Hantavirus, Avian Influenza and Lyme disease are just a few of the recently emerging zoonotic diseases. Disease suppression has been shown for Lyme disease by the dilution effect, whereby increasing species diversity decreases disease prevalence in the host populations. But does a dilution effect apply to other disease systems? To test this …

The Reproductive And Conservation Biology Of The Spotted Towhee In Urban Forest Fragments, Sarah Bartos Smith

Dissertations and Theses

I studied the demography, reproductive biology, and mating behavior of Spotted Towhees (Pipilo maculatus) in four urban parks in relation to park area, the presence of recreational trails, and the effects of habitat edges. Despite high towhee abundance in the parks, two of the four are population sinks with levels of yearly reproductive productivity that do not offset adult survival. The other two parks have sufficient reproduction to adequately result in stable or growing population sizes. Park area and the proportion of habitat edge had no influence on population growth rate, reproductive productivity, or survival. However, trail density …

The Role Of Mitochondria Atp-Sensitive Potassium Channel In Cardioprotection, Ksenia Andrukhiv Everton

Dissertations and Theses

Mitochondrial ATP-sensitive potassium channel (mitoK_ATP) has been suggested to be the mediator of cardiac preconditioning. All of the diverse pharmacological and physiological agents that open mitoK_ATP provide protection against ischemia-reperfusion injury. Some investigators have pointed out that some of these mitoK_ATP channel openers also inhibit succinate dehydrogenase (SDH), complex II of the electron transport chain. Based on this observation they suggest that it is the inhibition of SDH, and not the opening of mitoK_ATP channel, that mediates the observed cardioprotection. In this study, I examined four chemically distinct and unrelated pharmacological agents, diazoxide, 3-Nitropropionic Acid …

Microbial Colonization Of Deep-Sea Hydrothermal Vent Chimneys, Antoine Pagé

Dissertations and Theses

Deep-sea hydrothermal vent chimneys harbor some of the most extreme environments supporting life on Earth. In the absence of sunlight, the microbial communities that colonize these deposits are based on energy harvested by chemolithoautotrophs exploiting the chemical disequilibria created as hydrothermal fluids mix with seawater. Although controversial, several models consider deep-sea vent chimneys as likely habitats for primitive ecosystems that developed during the Archean.

The goal of this study was to describe spatial and temporal patterns of microbial colonization in deep-sea vent chimneys emitting high temperature (>300°C) fluids. Microbial community composition and structure were evaluated through analyses of 16S …

The Family Fuselloviridae : Diversity And Replication Of A Hyperthermic Virus Infecting The Archaeon Genus Sulfolobus, Adam Joseph Clore

Dissertations and Theses

The virus family Fuselloviridae infects the hyperthermophilic and acidophilic Crenarchaeon genus Sulfolobus and has been isolated from terrestrial hotsprings worldwide. Two previously uncharacterized Fuselloviruses, SSV-13 and SSV-L1, were isolated and sequenced and are compared to the five fully sequenced viruses presently in the public databases. Conserved promoters in all viruses and similar putative origins of replication suggest that these viruses use a transcriptional and genomic replication program similar to the relatively well-characterized SSV1. Pairwise comparisons of conserved genes in the seven virus genomes show that, like its host Sulfolobus, these viruses' genetic divergence correlates with geographic separation. Genome rearrangements, horizontal …

The Effects Of Western Dwarf Mistletoe (Arceuthobium Campylopodum) On Radial Growth Of Ponderosa Pine (Pinus Ponderosa) In Managed Stands In Eastern Oregon, Sharon Marie Stanton

Dissertations and Theses

Dwarf mistletoes (Arceuthobium spp.) are native flowering plants that parasitize a range of conifer species throughout western North America. Dwarf mistletoes are considered destructive forest pathogens, but recent research indicates that mistletoes play a key role in structuring plant communities by increasing structural diversity and providing wildlife habitat. The primary objective of my research is to quantify the structural and functional differences between infected and uninfected forest communities.

I investigated the effects of mistletoe (Arceuthobium campylopodum ) on host community dynamics and the interaction between mistletoe infection and fire in old-growth ponderosa pine (Pinus ponderosa) forests. …

Avian Affairs: A Study Of The Occurrence And Benefits Of Extra-Pair Breeding Behavior In Eastern Kingbirds (Tyrannus Tyrannus), Amy Catherine Dolan

Dissertations and Theses

Over three consecutive breeding seasons I examined the breeding system of Eastern Kingbirds in Malheur National Wildlife Refuge in SE, Oregon. To assess genetic paternity, I optimized seven microsatellite markers and determined that extra pair paternity was common. Extra-pair young were present in approximately 60% of nests, representing 47% of young. I examined implications of extra-pair paternity from three perspectives.

First, I examined the impact of extra-pair paternity on the opportunity for sexual selection within a socially monogamous system and identified correlates of male reproductive success. Some males were successful at the expense of others, and 24% of males did …

Woodland Amphibian Distribution In Parks And Greenspaces Of The Portland, Oregon Metropolitan Area: A Multiple Scale Investigation, Laura A. Roberts

Dissertations and Theses

Loss of biodiversity due to habitat fragmentation is worldwide problem. With growing human populations and increasing urbanization, it is a necessity to conduct studies on wildlife occurring in urban areas. Currently there is a deficit of research investigating woodland amphibians in urban environments. My objectives were to describe amphibian species richness and abundance in the Portland, Oregon, Metropolitan region, and relate patterns of variation to variables at three increasingly large spatial scales: 1) local microenvironmental (i.e. amphibian/substrate interaction), (2) macrohabitat/patch (i.e. park or greenspace), and 3) landscape (surrounding parks and greenspaces). Environmental variables occurring within the three spatial scales were …

Tolerance, Performance, And Aerobic Metabolism Of Redband Trout (Oncorhynchus Mykiss Ssp.) During Acute Exposure To Elevated Temperature, Karen Reed Lizars

Dissertations and Theses

The objective of this thesis was to determine whether the redband trout (Oncorhynchus mykiss ssp.) of Oregon's inland desert basins are negatively affected by the high peak temperatures (> 20 °C) often observed in their native streams. Small (40 - 140 g) redband trout from three streams (Bridge, Rock, and Twelve-mile creeks) were collected and tested on-site for aspects of thermal physiology, including: critical swimming velocity (Ucrit), maximum metabolic rate (MO₂), metabolic power, and total cost of transport (TCT) at 24 °C; routine MO₂ at 14 to 2: 28 °C: and critical thermal maximum (CTM). At …

Enrichments And Isolations Of Mesophilic And Thermophilic Iron-Reducing Microbes From Deep-Sea Hydrothermal Vents And The Deep Subsurface, Melissa Mary Kendall

Dissertations and Theses

Microbes inhabiting the deep subsurface play an important role in geochemical processes and may be of practical value in bioremediation and biotechnology. Hydrothermal vents and the deep gold mines of South Africa have be likened to "windows" into the subsurface biosphere. The aim of this research was to isolate and characterize microbes involved in iron-cycling from deep-sea hydrothermal vents and from the deep gold mines of the Witwatersrand Basin. Three mesophilic bacteria, strains BB4, W3, and A6 were isolated from sulfide chimneys at 13°N and a thermophilic bacterium, strain GB21 was isolated from Guaymas Basin on the East Pacific Rise. …

The Response Of Mice To Infection By The Parasitic Nematode Trichinella: A Comparison Of Trichinella Spiralis And Trichinella Pseudospiralis, Barry Clayton Anderson

Dissertations and Theses

The intracellular parasite Trichinella is a genus in phylum Nematoda that contains six named species including Trichinella spiralis and Trichinella pseudospiralis. These parasites infect a large variety of wild and domestic animals, human beings and a few species of birds. The parasitic strategies and the pathological effects on the host between trichinella spiralis and Trichinella pseudospiralis are quite different.

The purpose of this study is to gain an understanding of the physiological, immunological and pathological differences between these two species of Trichinella using infections in the mouse as a model. In the course of this research I have attempted to …

Avian And Mammalian Use Of Three Small Urban Wetlands Invaded By A Pest Species, Reed Canarygrass (Phalaris Arundinacea L.), Laurie Dizney

Dissertations and Theses

Small urban wetlands are being destroyed and degraded at an alarming rate. One result of degradation is invasion by pest species, such as reed canarygrass (Phalaris arundinacea L. ). Reed canarygrass forms virtual monocultures in a wide range of wetland types. Wetlands normally have high plant species richness and abundance, which is widely believed to lead to faunal diversity. The purpose of the present study was to determine to what extent birds and mammals use a wetland dominated by reed canarygrass. The research was conducted at Tualatin Hills Nature Park in Beaverton, Washington County, Oregon. I examined three sites …