Life Sciences Commons^™

Anatomical Analysis Of Somatic Mutation Accumulation In Mimulus Guttatus, Amanda Burrell

University Honors Theses

Plants are seemingly immortal in their abilities to survive long periods of dormancy in different life stages, live for thousands of years, and even grow into whole forests from one clone, all through a series of mitotic and meiotic events, but how many mutations do plants acquire in their lifetime? And just how many of these mutations are heritable? To answer these questions, first we must answer: how many cell divisions are there in the length of a stem? The purpose of this study is to answer just that by establishing a protocol for estimating the number of germ cell …

Recurrent Formation, Low Levels Of Ecological Differentiation, And Secondary Dispersal Facilitate The Establishment And Persistence Of Autopolyploids In Eriophyllum Lanatum, Nicolas Alexander Diaz

Dissertations and Theses

The high rates of polyploidization events in angiosperms is a well-documented driver of diversification and speciation. The consequences of polyploidy--from gene expression up to ecology--and the processes facilitating the persistence of polyploidy in its early establishment in populations are poorly understood. In this thesis, I examined the role of recurrent formation, ecological differentiation, and secondary dispersal via biotic vectors in the maintenance and persistence of an intervarietal polyploid contact zone of Eriophyllum lanatum in Southern Oregon. Sampling 35 total populations, I used a whole chloroplast capture and flow cytometry to determine the diversity and distribution of chloroplast haplotypes and estimate …

Genetic Diversity Correlates With Morphological Diversity Among Populations Of Achyrachaena Mollis, Rachel S. Bice

University Honors Theses

Biodiversity is important for ecosystem health and sustainability, especially in the current, rapidly changing climate. Understanding the underlying causes behind morphological variation will allow for more accurate predictions about how a population will respond to climate change, and potentially yield better natural resource management strategies. Achyrachaena mollis is an annual, self-fertilizing, range-limited, endemic species found in Northern California and Southern Oregon. This species depends primarily on wind seed dispersal for gene flow, making it a good study species in seed dispersal experiments. Additionally, A. mollis is more readily influenced by changes in its environment than a perennial due to its …

Impact Of The Urban Heat Mosaic On The Leaf Senescence In Two Acer Species, Jeffrey D. Smith

University Honors Theses

Due to the heterogeneity of the urban heat island, we can think of the variable influence of urbanization on air temperature as more of an urban heat mosaic. Climate change has caused a resurgence of interest in the way temperature affects how organisms, such as street trees, undergo cyclic changes in their life cycle. Such changes include budburst or, less commonly, timing of senescence. Little is known about how the urban heat mosaic could be affecting the phenology of different urban trees. Because street trees are one of the more prominent ecosystem engineers of the urban landscape, variable influences of …

Is Protection Against Florivory Consistent With The Optimal Defense Hypothesis?, Adrienne L. Godschalx, Lauren Stady, Benjamin Watzig, Daniel J. Ballhorn

Biology Faculty Publications and Presentations

Background: Plant defense traits require resources and energy that plants may otherwise use for growth and reproduction. In order to most efficiently protect plant tissues from herbivory, one widely accepted assumption of the optimal defense hypothesis states that plants protect tissues most relevant to fitness. Reproductive organs directly determining plant fitness, including flowers and immature fruit, as well as young, productive leaf tissue thus should be particularly well-defended. To test this hypothesis, we quantified the cyanogenic potential (HCNp)—a direct, chemical defense—systemically expressed in vegetative and reproductive organs in lima bean (Phaseolus lunatus), and we tested susceptibility of these …

Small Unmanned Aerial Vehicles (Micro-Uavs, Drones) In Plant Ecology, Mitchell B. Cruzan, Ben G. Weinstein, Monica R. Grasty, Brendan F. Kohrn, Elizabeth C. Hendrickson, Tina M. Arredondo, Pamela G. Thompson

Biology Faculty Publications and Presentations

Premise of the study: Low-elevation surveys with small aerial drones (micro–unmanned aerial vehicles [UAVs]) may be used for a wide variety of applications in plant ecology, including mapping vegetation over small- to medium-sized regions. We provide an overview of methods and procedures for conducting surveys and illustrate some of these applications.

Methods: Aerial images were obtained by flying a small drone along transects over the area of interest. Images were used to create a composite image (orthomosaic) and a digital surface model (DSM). Vegetation classification was conducted manually and using an automated routine. Coverage of an individual species …

Assessment Of Arbuscular Mycorrhizal Symbiosis On Invasion Success In Brachypodium Sylvaticum, Caitlin Elyse Lee

Dissertations and Theses

The effects that mutualistic soil biota have on invasive species success is a growing topic of inquiry. Studies of the interactions between invasive plants and arbuscular mycorrhizal fungi (AMF) have shown changes in AMF community composition, reductions in AMF associations in invasive plants, and changes in native species fitness and competitive outcomes in invasive-shifted AMF communities. These findings support the degraded mutualist hypothesis, where invasive species alter the mutualist community composition, resulting in detrimental associations with the new mutualist community for native species. Here I present two studies that examine various aspects of the arbuscular mycorrhizal fungal (AMF) mutualism in …

Testing The Ecological And Physiological Factors Influencing Reproductive Success In Mosses, Erin Elizabeth Shortlidge

Dissertations and Theses

As non-vascular, early land plants with an aquatic ancestry, mosses do not regulate internal water conditions separate from that of their environment and as a result, evolved mechanisms to survive in a terrestrial world out of water. Yet, there is a widely accepted dogma that moss reproductive success is solely dependent on rainfall events carrying swimming, bi-flagellate sperm across the landscape to reproductively mature and receptive female mosses--but this classic view of moss reproduction may be too simplistic. In this dissertation I test the assumptions of reproductive limitation in mosses and present novel findings in a basal, yet understudied terrestrial …

Agricultural Management Decisions Impact Isoprene Emission And Physiology Of Arundo Donax, An Emerging Bioenergy Crop, Jason Charles Maxfield

Dissertations and Theses

Arundo donax (Giant Reed) is quickly being developed as a rapidly-growing, robust, and highly productive bioenergy crop, with large scale cultivation of this species planned for the Columbia River basin of the Pacific Northwest (USA). Despite its potential as a next generation biomass crop, relatively few studies have examined the physiological performance of A. donax under agricultural conditions. Unlike traditional crops, A. donax is known to be a high-emitter of the volatile compound isoprene, which may significantly impact regional air quality, but it has not been widely cultivated in North America and little is known about how this species will …

Effects Of Arbuscular Mycorrhizal Fungal Infection And Common Mycelial Network Formation On Invasive Plant Competition, Rachael Elizabeth Workman

Dissertations and Theses

Understanding the biotic factors influencing invasive plant performance is essential for managing invaded land and preventing further exotic establishment and spread. I studied how competition between both conspecifics and native co-habitants and arbuscular mycorrhizal fungal (AMF) impacted the success of the invasive bunchgrass Brachypodium sylvaticumin early growth stages. I examined whether invasive plants performed and competed differently when grown in soil containing AMF from adjacent invaded and noninvaded ranges in order to determine the contribution of AMF to both monoculture stability and spread of the invasive to noninvaded territory. I also directly manipulated common mycelial network (CMN) formation by AMF …

Interspecific Variation In Leaf-Level Biogenic Emissions Of The Bambuseae, Andrea Natalie Melnychenko

Dissertations and Theses

Plants emit a diverse range of biogenic volatile organic compounds (BVOCs) into the atmosphere, of which isoprene is the most abundantly emitted. Isoprene significantly affects biological and atmospheric processes, but the range of isoprene and BVOCs present in bamboos has not been well characterized. In this thesis I explore the range of isoprene emission found in bamboos and relate it to plant morphological and physiological characteristics. In addition, I measure and relate the entire suite of BVOCs present in the bamboos to their fundamental isoprene emission rate.

Interspecific variation in isoprene emission documented in a comprehensive survey of bamboos. Two …

Distance And Sex Determine Host Plant Choice By Herbivorous Beetles, Daniel J. Ballhorn, Stefanie Kautz, Martin Heil

Biology Faculty Publications and Presentations

Background: Plants respond to herbivore damage with the release of volatile organic compounds (VOCs). This indirect defense can cause ecological costs when herbivores themselves use VOCs as cues to localize suitable host plants. Can VOCs reliably indicate food plant quality to herbivores?

Methodology: We determined the choice behavior of herbivorous beetles (Chrysomelidae: Gynandrobrotica guerreroensis and Cerotoma ruficornis) when facing lima bean plants (Fabaceae: Phaseolus lunatus) with different cyanogenic potential, which is an important constitutive direct defense. Expression of inducible indirect defenses was experimentally manipulated by jasmonic acid treatment at different concentrations. The long-distance responses of male and female beetles to …

Evidence Of Reduced Arbuscular Mycorrhizal Fungal Colonization In Multiple Lines Of Bt Maize, Tanya E. Cheeke, Todd N. Rosenstiel, Mitchell B. Cruzan

Biology Faculty Publications and Presentations

Premise of the Study: Insect-resistant Bacillus thuringiensis (Bt) maize is widely cultivated, yet few studies have examined the interaction of symbiotic arbuscular mycorrhizal fungi (AMF) with different lines of Bt maize. As obligate symbionts, AMF may be sensitive to genetic changes within a plant host. Previous evaluations of the impact of Bt crops on AMF have been inconsistent, and because most studies were conducted under disparate experimental conditions, the results are difficult to compare. Methods: We evaluate AMF colonization in nine Bt maize lines, differing in number and type of engineered trait, and five corresponding near-isogenic parental (P) base hybrids …

Effects Of Light Limitation On Plant-­Rhizobia And Plant-Mycorrhiza Interactions, Jess A. Millar

Anthós

Plants respond with a sink stimulation of photosynthesis when colonized by bacterial and fungal mutualists, which compensates for costs of carbohydrate allocation to the microbes. Problems may arise when light is limited and plants cannot increase photosynthesis. We hypothesize that under such conditions the costs for maintaining the mutualism outweigh the benefits, which ultimately turns the beneficial microbes into parasites exploiting resources and reducing host fitness. We study these plant-­‐microbe interactions under different light availabilities using lima bean plants, rhizobia (nitrogen-­‐fixing bacteria), and mycorrhizal fungi. In our study, we apply two levels of light (full light and light intensity reduced …

Sex-Specific Variation In The Interaction Between Distichlis Spicata (Poaceae) And Mycorrhizal Fungi, Sarah M. Eppley, Charlene Ashley Mercer, Christian Haaning, Camille Brianne Graves

Biology Faculty Publications and Presentations

Associations between mycorrhizal fungi and plants can influence intraspecific competition and shape plant population structure. While variation in plant genotypes is known to affect mycorrhizal colonization in crop systems, little is known about how genotypes affect colonization in natural plant populations or how plant sex might influence colonization with mycorrhizal fungi in plant species with dimorphic sexual systems. In this study, we analyzed mycorrhizal colonization in males and females of the wetland dioecious grass Distichlis spicata, which has spatially segregated sexes. Our results suggest that D. spicata males and females interact with mycorrhizal fungi differently. We discuss the implications for …

Investigating The Relationship Between Cryptococcus Fagisuga And Fagus Grandifolia In Great Smoky Mountains National Park, Ashley B. Morris, Randall L. Small, Mitchell B. Cruzan

Biology Faculty Publications and Presentations

Focuses on a study which investigated the relationship between Cryptococcus fagisuga and Fagus grandifolia in Great Smoky Mountains National Park. Potential for genetic resistance; Methods; Results and discussion.

Seasonal Patterns Of Photosynthesis In Douglas Fir Seedlings During The Third And Fourth Year Of Exposure To Elevated Co2 And Temperature, James D. Lewis, Melissa S. Lucash, David M. Olszyk, David T. Tingey

Environmental Science and Management Faculty Publications and Presentations

The interactive effects of elevated atmospheric CO₂ and temperature on seasonal patterns of photosynthesis in Douglas fir (Psuedotsuga menziesii (Mirb.) Franco) seedlings were examined. Seedlings were grown in sunlit chambers controlled to track either ambient (~400 p.p.m.) CO₂ or ambient +200 p.p.m. CO₂, and either ambient temperature or ambient +4 °C. Light-saturated net photosynthetic rates were measured approximately monthly over a 21 month period. Elevated CO₂ increased net photosynthetic rates by an average of 21% across temperature treatments during both the 1996 hydrologic year, the third year of exposure, and the 1997 hydrologic year. Elevated …

Internal Temperature Of Douglas-Fir Buds Is Altered At Elevated Temperature, Martha E. Apple, Melissa S. Lucash, David M. Olszyk, David T. Tingey, Donald L. Phillips

Environmental Science and Management Faculty Publications and Presentations

Pseudotsuga menziesii (Douglas-fir) saplings were grown in sun-lit controlled environment chambers at ambient or elevated (4°C above ambient) temperature. We measured internal temperatures of vegetative buds with thermocouple probes and compared temperatures of normal buds and abnormal buds with loosened, rosetted outer scales in elevated temperature chambers. The abnormal buds had higher and earlier peak daily temperatures than normal buds. Elevated temperature may influence the internal temperature of buds and contribute to the development of abnormal, rosetted buds with loosened outer scales. Abnormal bud development may alter branching patterns and allometry of Douglas-fir trees subjected to climatic change.

Morphogenesis Of Douglas Fir Buds Is Altered At Elevated Temperature But Not At Elevated Co2, Martha E. Apple, Melissa S. Lucash, David M. Olszyk, David T. Tingey

Environmental Science and Management Faculty Publications and Presentations

Global climatic change as expressed by increased CO₂ and temperature has the potential for dramatic effects on trees. To determine what its effects may be on Pacific Northwest forests, Douglas-fir (Pseudotsuga menziesii ) seedlings were grown in sun-lit controlled environment chambers at ambient or elevated (+4°C above ambient) temperature, and at ambient or elevated (+200 ppm above ambient) CO₂. In 1995–1996 and 1996–1997, elevated CO₂ had no effect on vegetative bud morphology, while the following unusual morphological characteristics were found with greater frequency at elevated temperature than at ambient: rosetted buds with reflexed and loosened outer …

Intrapopulation Sex Ratio Variation In The Salt Grass Distichlis Spicata, Sarah M. Eppley, Maureen L. Stanton, Richard K. Grosberg

Biology Faculty Publications and Presentations

In many dioecious plant populations, males and females appear to be spatially segregated, a pattern that is difficult to explain given its potentially high costs. However, in asexually propagating species, spatial segregation of the sexes may be indistinguishable from superficially similar patterns generated by random establishment of a few genets followed by extensive clonal spread and by gender-specific differences in rates of clonal spread. In populations where a significant fraction of individuals are not flowering and gender cannot be assigned to this fraction, apparent spatial segregation of the sexes may be due to differential flowering between the sexes. We confirm …

Genetic Markers In Plant Evolutionary Ecology, Mitchell B. Cruzan

Biology Faculty Publications and Presentations

Genetic markers have provided plant ecologists with a method of assessing levels of genetic relatedness among individuals and populations. In recent years a number of techniques based on DNA sequence variation have been developed to complement allozyme methods that are already widely used. Some of these new markers are more variable than protein-based markers, allowing more precise estimates of genetic differences among individuals and populations. Other DNA-based markers are based on organelle genomes that are inherited uniparentally. These cytoplasmic markers can provide a method for assessing the separate effects of seed and pollen dispersal on gene flow within and among …

Temporal Patterns Of Nectar And Pollen Production In Aralia Hispida: Implications For Reproductive Success, James D. Thomas, Mary A. Mckenna, Mitchell B. Cruzan

Biology Faculty Publications and Presentations

Large plants of Aralia hispida present their pollen and nectar in hundreds of small flowers than open sequentially over 2—3 wk in a pattern of synchronized protandry that alternates male and female phases. The primary pollinators, bumble bees, are able to discover individual plants with elevated levels of either nectar or pollen, and to return to them more often than to less rewarding plants. Both pollen and nectar are presented gradually over time in such a way as to favor traplining behavior by the bees, with many, frequent visits. In controlled environments, lifetime sugar production per flower varies among plants, …

The Effect Of Dwarf Mistletoe (Arceuthobium Americanum) Upon A Portion Of The Carbon Budget Of Lodgepole Pine (Pinus Contorta), Nancy Ellen Broshot

Dissertations and Theses

Arceuthobium americanum is a vascular plant which is parasitic upon Pinus contorta var. murrayana. Its documented effects include reductions in host growth, vigor and wood quality. The specific physiological changes that occur in the host are, for the most part, unknown.

In an attempt to understand the manner in which the mistletoe alters its host's carbon budget, a model is proposed which states that the host plant has priorities for carbon allocation. The model proposes that the parasite will access the host's carbon initially in terms of carbon intended for storage, next, in terms of carbon intended for growth, …

Variation In Branch Growth Characteristics Of Pinus Contorta Infected With Arceuthobium Americanum, Lynn Anne Larsen

Dissertations and Theses

Arceuthobium americanum is a flowering plant which parasitizes Pinus contorta (Lodgepole pine). This study examined branch performance of P. contorta infected to varying degrees with A. americanum.

The Allelopathic Potential Of Rhododendron Macrophyllum In A Western Cascades Clearcut, Ivan W. Clark

Dissertations and Theses

The purposes of this study were to determine if Rhododendron macrophyllum has the potential to inhibit the growth of other species through the production of water-soluble toxins which are leached out of its litter by rainfall, and to determine if this potential is realized in the field. The study was therefore composed of two part: 1) a series of bioassays to determine the presence an activity of water-soluble phytotoxins in R. macrophyllum leaf litter, and 2) a field study to describe vegetational patterns associated with R. macrophyllum in a western Cascades clearcut.

A Taxonomic Study Of The Marine Algae Of Netarts Bay, Oregon, Charles Jerome Kunert

Dissertations and Theses

Gathering taxonomic data is fundamental to any biological or ecological research. It was the intent of this paper to increase the storehouse of taxonomic information by studying the marine algae of one section of the Oregon coastline. Netarts Bay was chosen because of its accessibility and generally primitive nature. It is in an area of Oregon largely untouched by phycologists and so offered an opportunity for original research.

Techniques of collecting and preserving specimens were kept as simple as possible, thus allowing a proportionately greater amount of the available time to be spent in the classification of the organisms. The …

Mutual Exclusion Between Salmonberry And Douglas-Fir In The Coast Range Of Oregon, Kenneth Ray Still

Dissertations and Theses

One serious problem faced by the forest industry in the Pacific Northwest is poor regeneration of commercial trees on land which is harvested and subsequently dominated by brush species. In Coastal Oregon, salmonberry is one of these brush species. Detailed investigations of field sites indicate that light intensity in the brush stands was low but sufficient for germination and early growth of Douglas-fir seedlings and soil moisture percentages and nutrient levels were high enough to support early Douglas-fir growth. Laboratory tests demonstrated the presence of leachable phytotoxins in the leaves of salmonberry. The hypothesis resulting from this study is that …

The Effect Of Antibiotics On Thermophilic Blue-Green Algae, Erleen Blanche Christenson

Dissertations and Theses

The nature of the action of penicillin on the cell walls of bacteria is reviewed. The composition of bacterial cell walls is compared to cell walls of blue-green algae.

The test organisms used were thermophilic: Anacystis nidulans grew optimally at 35⁰C, whereas Synechococcus lividus grew best at 45⁰ C. Growth was recorded by reading optical densities.

Cells of these two thermophilic blue-green algae were treated with varying dosages of penicillin and streptomycin. Penicillin inhibited growth of Anacystis nidulans and Synechococcus lividus in concentrations of 3.0 µg/ml and 0.03 µg/ml respectively. However, when 0.3 µg/ml of penicillin was added to Anacystis …

Observations On The Establishment Of Seedlings Of Phoradendron Californicum On Prosopis Juliflora, Richard L. Null

Dissertations and Theses

The mistletoe Phoradendron californicum is a common parasite on the mesquite plant Prosopis juliflora. Seeds of the parasite are deposited upon the host plant by birds and perhaps other agents. Normally seedlings of the parasite become established when the elongating radicle of the embryo comes into contact with a host branch and forms a holdfast. From the underside of the holdfast the primary haustorium enters the host tissue and establishes the parasitic union. Later the aerial portion of the parasite develops. Some seeds of P. californicum follow a different sequence; they stimulate the host to produce gum in the tissue …