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Articles 1 - 12 of 12
Full-Text Articles in Life Sciences
Evidence Of Ancient Maya Agriculture In The Bajos Surrounding Tikal, Guatemala, Adam Calvin Parker
Evidence Of Ancient Maya Agriculture In The Bajos Surrounding Tikal, Guatemala, Adam Calvin Parker
Theses and Dissertations
Current Central American agricultural practices are environmentally and economically unsustainable, yet the ancient Maya who lived in the same region thrived for thousands of years. Archaeologists have attempted to understand the factors enabling the prolonged success and ultimate collapse of the Maya societies. Some have proposed that the karst seasonal wetlands, called bajos, that border many Maya sites in the region were an influential factor in the Maya's ability to flourish. For the past decade, researchers have used carbon isotope analyses to identify areas of ancient maize agriculture at Maya archaeological sites. In this study, we collected soil samples from …
Maternal Denning Phenology And Substrate Selection Of Polar Bears (Ursus Maritimus) In The Southern Beaufort And Chukchi Seas, Jay Wesley Olson
Maternal Denning Phenology And Substrate Selection Of Polar Bears (Ursus Maritimus) In The Southern Beaufort And Chukchi Seas, Jay Wesley Olson
Theses and Dissertations
Loss of sea ice due to global warming may affect the phenology and distribution of polar bear (Ursus maritimus) denning by altering access to denning habitats. We examined trends in the selection of maternal denning substrate (land versus sea-ice denning) in the southern Beaufort Sea (SB), addressing the potential influence of summer land-use and fall sea-ice conditions on substrate selection. We developed an algorithm based on statistical process control methods to remotely identify denning bears and estimate denning phenology from temperature sensor data collected on collars deployed 1985–2013 in the SB and Chukchi Sea (CS). We evaluated cub …
Control Of Alternaria Solani Resistance To Boscalid, Fluopyram, And Chlorothalonil, Andrew K. Hollingshead
Control Of Alternaria Solani Resistance To Boscalid, Fluopyram, And Chlorothalonil, Andrew K. Hollingshead
Theses and Dissertations
Alternaria solani, cause of early blight, threatens potato yields. Fungicide resistance has made control of early blight difficult and there are concerns that in-season fungicide use results in resistance to boscalid, fluopyram, and chlorothalonil. Concern of high levels of resistance to boscalid a group 7 fungicide may confer cross-resistance to fungicides of the same group such as fluopyram. From 2014 to 2015, A. solani isolates were collected from field plots treated with boscalid, fluopyram, and chlorothalonil to test resistance levels. Isolates were determined resistant if EC50 values were higher than 5 µg ml-1. Boscalid and chlorothalonil mean EC50 values decreased …
Mountain Big Sagebrush (Artemisia Tridentata Ssp Vaseyana) Seed Production, Melissa L. Landeen
Mountain Big Sagebrush (Artemisia Tridentata Ssp Vaseyana) Seed Production, Melissa L. Landeen
Theses and Dissertations
Big sagebrush (Artemisia tridentata Nutt.) is the most widespread and common shrub in the sagebrush biome of western North America. Of the three most common subspecies of big sagebrush (Artemisia tridentata), mountain big sagebrush (ssp. vaseyana; MBS) is the most resilient to disturbance, but still requires favorable climactic conditions and a viable post-fire seedbank for successful unassisted recovery. This study was designed to assess MBS seed production throughout post-fire recovery. We performed 2 pilot studies to develop methods for estimating seed production and plant age. The results of the pilot studies and a space-for-time substitution strategy were used to measure …
Mating-Type Locus Characterization And Variation In Pyrenophora Semeniperda, Julie Leanna Henry
Mating-Type Locus Characterization And Variation In Pyrenophora Semeniperda, Julie Leanna Henry
Theses and Dissertations
Pyrenophora semeniperda is a generalist fungal pathogen that occurs primarily on monocot seed hosts. It is in the phylum Ascomycota, which includes both self-compatible (homothallic) and self-incompatible (heterothallic) species. Homothallic fungal species contain complementary mating-type (MAT) idiomorphs in a single unikaryotic strain, while heterothallic strains contain a single MAT idiomorph requiring interaction between strains of complementary mating-types for sexual reproduction to occur. Because the majority of P. semeniperda strains contained either MAT1 or MAT2, this species was provisionally categorized as heterothallic. However, many strains contain both MAT idiomorphs and appear to be homothallic. These results warranted a closer look at …
Drought And Nitrogen Effects On Maize Canopy Temperature And Stress Indices, David A. Carroll
Drought And Nitrogen Effects On Maize Canopy Temperature And Stress Indices, David A. Carroll
Theses and Dissertations
Increased water scarcity due to changing climate, population growth, and economic development is a major threat to the sustainability of irrigated agriculture in the Western United States and other regions around the world. Management practices, such as controlled deficit irrigation, that seek to maximize the productivity of a limited water supply are critical. When using controlled deficit irrigation, remote sensing of crop canopy temperature is a useful tool for assessing crop water status and for more precise irrigation management. However, there is potential that nutrient deficiencies could compound the interpretation of water status from leaf temperature by altering leaf color …
Factors Constraining The Reproductive Output Of Baptisia Alba Macrophylla, Ashley Morgan Hembrough
Factors Constraining The Reproductive Output Of Baptisia Alba Macrophylla, Ashley Morgan Hembrough
Theses and Dissertations
Baptisia alba macrophylla, a native, herbaceous perennial legume, produces inflorescences with a large number of flowers, yet matures relatively few fruits. We hypothesized that the number of seeds matured by B. alba macrophylla is maximized based on resource availability at each stage of development, but this optimal number is further compromised by extrinsic factors including pollen limitation and pre-dispersal seed predation by the weevils Apion rostrum and Tychius sordidus. To test this hypothesis, we conducted a field experiment at two sites: (i) the John English Prairie, located in Hudson, IL, and also (ii) the Sugar Grove Nature Center and Funks …
The Amaranth (Amaranthus Hypochondriacus) Genome: Genome, Transcriptome And Physical Map Assembly, Jared William Clouse
The Amaranth (Amaranthus Hypochondriacus) Genome: Genome, Transcriptome And Physical Map Assembly, Jared William Clouse
Theses and Dissertations
Amaranthus hypochondriacus is an emerging pseudo-cereal native to the New World which has garnered increased attention in recent years due to its nutritional quality, in particular its seed protein, and more specifically its high levels of the essential amino acid lysine. It belongs to the Amaranthaceae family, is an ancient paleotetraploid that shows amphidiploid inheritance (2n=32), and has an estimated genome size of 466 Mb. Here we present a high-quality draft genome sequence of the grain amaranth A. hypochondriacus. The genome assembly consisted of 377 Mb in 3,518 scaffolds with an N50 of 371 kb. Repetitive element analysis predicted that …
Descriptive Analyses Of Pollen Surface Morphologies In The Model Systems Brassica Rapa And Arabidopsis Thaliana And Three Arabidopsis Pollen Wall Mutants By Scanning Electron Microscopy, Andrew B. Kirkpatrick
Descriptive Analyses Of Pollen Surface Morphologies In The Model Systems Brassica Rapa And Arabidopsis Thaliana And Three Arabidopsis Pollen Wall Mutants By Scanning Electron Microscopy, Andrew B. Kirkpatrick
Theses and Dissertations
The mechanisms behind the construction of the pollen wall are equally elaborate and mysterious. Previous studies primarily used sectioned tissue to elucidate the events involved in proper pollen development. This study proposed and evaluated a protocol for exposing developing microspores to be examined by Scanning Electron Microscopy (SEM). Utilizing this protocol, comparative analyses of the superficial features present at the early, middle, and late tetrad as well as at released microspore stages of the model plants Brassica rapa and Arabidopsis thaliana were conducted. The utility of the technique was then evaluated through the examination of three Arabidopsis pollen wall mutants …
Tree Islands Of Fertility Structure Bacterial Community Assembly And Functional Genes Contributing To Ecosystem Processes, Tayte Paul Campbell
Tree Islands Of Fertility Structure Bacterial Community Assembly And Functional Genes Contributing To Ecosystem Processes, Tayte Paul Campbell
Theses and Dissertations
In arid and semi-arid ecosystems, dominant tree species create dramatic mosaics of plant islands of fertility and relatively barren plant interspaces that exert immense pressure on ecosystem processes and offers an ideal opportunity to explore the impact of bacterial communities. We evaluated potential links between soil respiration and N mineralization, and community co-occurrence networks and predicted gene function across three tree island microsites (i.e., beneath tree canopies, at the canopy edge, and in interspaces) in a replicated field experiment in thirty-eight woodlands sites in the Great Basin Desert in UT, USA. Additionally, we potentially intensified the effects of tree islands …
Assessing The Perceptions Of Faculty Advisors And Green Industry Professionals On The Value Of Student Participation In A Professional Development Competitive Event, Katelynn Diane Clement
Assessing The Perceptions Of Faculty Advisors And Green Industry Professionals On The Value Of Student Participation In A Professional Development Competitive Event, Katelynn Diane Clement
Theses and Dissertations
The purpose of this study was to evaluate the impact Professional Landcare Network (PLANET) Student Career Days (SCD) professional development experience has on conceptual learning, job opportunities and placement, and job retention in the green industry. Student participants, PLANET judging team faculty advisors, and green industry professionals who attended the career fair were surveyed on their perceptions of PLANET Student Career Days and its related events. A block style survey was sent out to the participant groups. Depending on the participant's affiliation with PLANET Student Career Days, participants were asked a different set of questions in the survey. Each survey …
Dispersal: A Multidisciplinary Investigation Of Plant Life, Alexandra E. Arzt
Dispersal: A Multidisciplinary Investigation Of Plant Life, Alexandra E. Arzt
Theses and Dissertations
Using plants as a basis for exploring the interstices between the human and nonhuman, this thesis investigates ideas of awareness, intelligence, deep time, animism, and the fluctuating human perception of the agency of Nature. It outlines environmental art practices since the 1950s involving vegetal life. In addition, the paper provides a critical analysis of plant perception of Jakob von Uexküll’s work and theories of vital materialism and “critical plant studies” while noting recent studies in plant neurobiology. In my work, plants become active participants via their movement, seeding, and smell. This study takes the form of imitation, purposeful symbiosis, anthropomorphism, …