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Description
Many studies over the past two decades examined the link between climate patterns and discharge, but few have attempted to study the effects of the El Niño Southern Oscillation (ENSO) on localized and watershed specific processes such as nutrient loading in the Southwestern United States. The Multivariate ENSO Index (MEI) is used to describe the state of the ENSO, with positive (negative) values referring to an El Niño condition (La Niña condition). This study examined the connection between the MEI and precipitation, discharge, and total nitrogen (TN) and total phosphorus (TP) concentrations in the Upper Salt River Watershed in Arizona. Unrestricted regression models (UMs) and restricted regression models (RMs) were used to investigate the relationship between the discharges in Tonto Creek and the Salt River as functions of the magnitude of the MEI, precipitation, and season (winter/summer). The results suggest that in addition to precipitation, the MEI/season relationship is an important factor for predicting discharge. Additionally, high discharge events were associated with high magnitude ENSO events, both El Niño and La Niña. An UM including discharge and season, and a RM (restricting the seasonal factor to zero), were applied to TN and TP concentrations in the Salt River. Discharge and seasonality were significant factors describing the variability in TN in the Salt River while discharge alone was the significant factor describing TP. TN and TP in Roosevelt Lake were evaluated as functions of both discharge and MEI. Some significant correlations were found but internal nutrient cycling as well as seasonal stratification of the water column of the lake likely masks the true relationships. Based on these results, the MEI is a useful predictor of discharge, as well as nutrient loading in the Salt River Watershed through the Salt River and Tonto Creek. A predictive model investigating the effect of ENSO on nutrient loading through discharge can illustrate the effects of large scale climate patterns on smaller systems.
ContributorsSversvold, Darren (Author) / Neuer, Susanne (Thesis advisor) / Elser, James (Committee member) / Fenichel, Eli (Committee member) / Arizona State University (Publisher)
Created2012
Description
Phosphorus (P), an essential nutrient for growth of all organisms, is often in limited biological supply for herbivore consumers compared to other elements, such as carbon (C). Ecological stoichiometry studies have assessed responses of filter-feeding zooplankton from the genus Daphnia to single and multi-species food resources that are P-limited, finding decreased growth as a result to changes in metabolic processes and feeding behavior. Conversely, recent laboratory studies have shown that P-rich algal food resources also result in decreased growth rates for Daphnia, though the possible mechanisms behind this maladaptive response is understudied. Moreover, no published study tests the existence of the “stoichiometric knife edge” hypothesis for low C:P under field conditions. To address this lack of information, I measured growth rate as well as respiration and ingestion rates for D. magna, D. pulicaria, and D. pulex that were fed natural lake seston experimentally enriched with different levels of PO43-. I found heterogeneous effects of high dietary P across Daphnia species. Growth rate responses for D. magna were strong and indicated a negative effect of high-P, most likely as a result to decreased ingestion rates that were observed. The seston treatments did not elicit significant growth rate responses for D. pulex and D. pulicaria, but significant responses to respiration rates were observed for all species. Consumer body stoichiometry, differences in seston C:P for each experiment, or differential assimilation by producer types may be driving these results. My study suggests that the stoichiometric knife edge documented in laboratory studies under low C:P conditions may not operate to the same degree when natural seston is the food source; diet diversity may be driving complex nuances for consumer performance that were previously overlooked.
ContributorsCurrier, Courtney M (Author) / Currier, James (Thesis advisor) / Harrison, Jon (Committee member) / Neuer, Susanne (Committee member) / Arizona State University (Publisher)
Created2015
Description
Cellular and molecular biologists often perform cellular assays to obtain a better understanding of how cells work. However, in order to obtain a measurable response by the end of an experiment, the cells must reach an ideal cell confluency. Prior to conducting the cellular assays, range-finding experiments need to be conducted to determine an initial plating density that will result in this ideal confluency, which can be costly. To help alleviate this common issue, a mathematical model was developed that describes the dynamics of the cell population used in these experiments. To develop the model, images of cells from different three-day experiments were analyzed in Photoshop®, giving a measure of cell count and confluency (the percentage of surface area covered by cells). The cell count data were then fitted into an exponential growth model and were correlated to the cell confluency to obtain a relationship between the two. The resulting mathematical model was then evaluated with data from an independent experiment. Overall, the exponential growth model provided a reasonable and robust prediction of the cell confluency, though improvements to the model can be made with a larger dataset. The approach used to develop this model can be adapted to generate similar models of different cell-lines, which will reduce the number of preliminary range-finding experiments. Reducing the number of these preliminary experiments can save valuable time and experimental resources needed to conduct studies using cellular assays.
ContributorsGuerrero, Victor Dominick (Co-author) / Guerrero, Victor (Co-author) / Watanabe, Karen (Thesis director) / Jurutka, Peter (Committee member) / School of Mathematical and Natural Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Vitellogenin (vg) is a precursor protein of egg yolk in honeybees, but it is also known to have immunological functions. The purpose of this experiment was to determine the effect of vg on the viral load of deformed wing virus (DWV) in worker honey bees (Apis mellifera). I hypothesized that a reduction in vg expression would lead to an increase in the viral load. I collected 180 worker bees and split them into four groups: half the bees were subjected to a vg gene knockdown by injections of double stranded vg RNA, and the rest were injected with green fluorescent protein (gfp) double stranded RNA. Half of each group was thereafter injected with DWV, and half given a sham injection. The rate of mortality in all four groups was higher than expected, leaving only 17 bees total. I dissected these bees' fat bodies and extracted their RNA to test for vg and DWV. PCR results showed that, out of the small group of remaining bees, the levels of vg were not statistically different. Furthermore, both groups of virus-injected bees showed similar viral loads. Because of the high mortality rate bees and the lack of differing levels of vg transcript between experimental and control groups, I could not draw conclusions from these results. The high mortality could be caused by several factors: temperature-induced stress, repeated stress from the two injections, and stress from viral infection. In addition, it is possible that the vg dsRNA batch I used was faulty. This thesis exemplifies that information cannot safely be extracted when loss of sampling units result in a small datasets that do not represent the original sampling population.
ContributorsCrable, Emma Lewis (Author) / Amdam, Gro (Thesis director) / Wang, Ying (Committee member) / Dahan, Romain (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
Triops (Branchiopoda: Notostraca) and Streptocephalus (Branchiopoda: Anostraca) are two crustaceans which cohabitate in ephemeral freshwater pools. They both lay desiccation resistant eggs that disperse passively to new hydrologically isolated environments. The extent of genetic distance among regions and populations is of perennial interest in animals that live in such isolated habitats. Populations in six natural ephemeral pool habitats located in two different regions of the Sonoran Desert and a transition area between the Sonoran and Chihuahuan Deserts were sampled. Sequences from Genbank were used for reference points in the determination of species as well as to further identify regional genetic distance within species. This study estimated the amount of within and between genetic distance of individuals from each region and population through the use of a neutral marker, cytochrome oxidase I (COI). We concluded that, although the method of passive dispersal may differ between the two genera, the differences do not results in different patterns of genetic distances between regions and populations. Furthermore, we only found the putative species, Triops longicaudatus "short", with enough distinct speciation. Although Triops longicaudatus "long" and Triops newberryi may be in the early stages of speciation, this study does not find enough support to conclude that they have separated.
ContributorsMurphy Jr., Patrick Joseph (Author) / Rutowski, Ronald (Thesis director) / Cartwright, Reed (Committee member) / Lessios, Nikos (Committee member) / School of Life Sciences (Contributor) / School of Human Evolution and Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The Beauty Within is a ceramics show displaying human body anatomy, which seeks to bridge aspects of my biological sciences major in the School of Life Sciences with aspects of my studio art minor in the Herberger Institute for Design and the Arts. My goal in creating the show was to change the opinion of people on human body organs from unease to admiration by recreating these organs in an artistic light. By stylizing the construction of the pieces and bringing in the contemporary form of art \u2014 makeup art \u2014 I hoped to bring a new light to the pieces and highlight the beauty within the human body. By leaving the pieces partly unfinished I further hoped to draw attention to the natural beauty within the pieces regardless of the makeup that covers them. By holding the show in the human anatomy lab room on campus and having both animal and human organs on display I was able to create that sense of disgust toward the organs in the viewers. The beauty of my created pieces was then directly contrasted with the disgust felt about the real organs by displaying each of my pieces next to a real organ. The reactions of the viewers reflected a change in view from the actual organs to my re-created organs, and therefore the goal of the show was achieved.
ContributorsThomas, Brandon Lee (Author) / Weiser, Kurt (Thesis director) / Chung, Samuel (Committee member) / School of Art (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This study focused on the connection between the EnvZ/OmpR two-component regulatory system and the iron homeostasis system in Escherichia coli, specifically how a mutant form of EnvZ11/OmpR is able to reduce the expression of fepA::lacZ, a reporter gene fusion in E. coli. FepA is one of several outer membrane siderophore receptors that allow extracellular siderophores bound to iron to enter the cells to power various biological processes. Previous studies have shown that in E. coli cells that expressed a mutant allele of envZ, called envZ11, which led to altered expression of various iron genes including down regulation of fepA::lacZ. The wild type EnvZ/OmpR system is not considered to regulate iron genes, but because these envz11 strains had downregulated fepA::lacZ, this study was undertaken to understand the connection and mechanisms of this downregulation. A large number of Lac+ revertants were obtained from the B32-2483 strain (envz11 and fepA::lacZ) and 7 Lac+ revertants that had reversion mutations not directly correcting the envZ11 allele were further characterized. With P1 phage transduction genetic mapping that involved moving a kanamycin resistance marker linked to fepA::lacZ, two Lac+ revertants were found to have their reversion mutations in the fepA promoter region, while the other five revertants had their mutations mapping outside the fepA region. These two revertants underwent DNA sequencing and found to carry two different single base pair mutations in two different locations of the fepA promoter region. Each one is in the Fur repressor binding region, but one also may have affected the Shine-Dalgarno region involved in translation initiation. All 7 reveratants underwent beta-galactosidase assays to measure fepA::lacZ expression. The two revertants that had mutations in the fepA promoter region had significantly increased fepA activity, with the revertant with the Shine-Dalgarno mutation having the most elevated fepA expression. The other 5 revertants that did not map in the fepA region had fepA expression elevated to the same level as that found in the wild type EnvZ/OmpR background. The data suggest that the negative effect of envZ11 can be overcome by multiple mechanisms, including directly correcting the envZ11 allele or changing the fepA promoter region.
ContributorsKalinkin, Victor Arkady (Co-author) / Misra, Rajeev (Co-author, Thesis director) / Mason, Hugh (Committee member) / Foy, Joseph (Committee member) / Biomedical Informatics Program (Contributor) / School of Life Sciences (Contributor) / W. P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Honey bees (Apis mellifera) are responsible for pollinating nearly 80\% of all pollinated plants, meaning humans depend on honey bees to pollinate many staple crops. The success or failure of a colony is vital to global food production. There are various complex factors that can contribute to a colony's failure, including pesticides. Neonicotoids are a popular pesticide that have been used in recent times. In this study we concern ourselves with pesticides and its impact on honey bee colonies. Previous investigations that we draw significant inspiration from include Khoury et Al's \emph{A Quantitative Model of Honey Bee Colony Population Dynamics}, Henry et Al's \emph{A Common Pesticide Decreases Foraging Success and Survival in Honey Bees}, and Brown's \emph{ Mathematical Models of Honey Bee Populations: Rapid Population Decline}. In this project we extend a mathematical model to investigate the impact of pesticides on a honey bee colony, with birth rates and death rates being dependent on pesticides, and we see how these death rates influence the growth of a colony. Our studies have found an equilibrium point that depends on pesticides. Trace amounts of pesticide are detrimental as they not only affect death rates, but birth rates as well.
ContributorsSalinas, Armando (Author) / Vaz, Paul (Thesis director) / Jones, Donald (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This paper explores the relationship between wildfire management and the consideration of ecological and environmental concerns in Arizona. To get a proper perspective on the current state of wildfire management in Arizona, information on two wildfire management programs, the Four Forests Restoration Initiative and FireScape, was researched and analyzed, as well as contemporary fire policy, a history of wildfire in Arizona, and two recent fires in Sedona, AZ. The two fires in Sedona, the Brins Fire of 2006 and the Slide Fire of 2014, act as a focal point for this ecological management transition, as even within an 8-year period, we can see the different ways the two fires were managed and the transition to a greater ecological importance in management strategies. These all came together to give a full spectrum for the factors that have led to more ecologically-prominent wildfire management strategies in Arizona.
ContributorsGeorge-Sills, Dylan (Author) / Pyne, Stephen (Thesis director) / Hirt, Paul (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2015-05
Description
The giant green sea anemone, Anthopleura xanthogrammica, hosts two different endosymbiotic algae. One is a unicellular chlorophyte, Elliptochloris marina; the other is Symbiodinium muscatinei, a dinoflagellate. Hosting these different symbionts influences the life history strategy of A. xanthogrammica's congener A. elegantissima, directly impacting its reproductive strategy (asexual vs. sexual). My study sought to examine whether the type and density of symbiont also affects the reproductive condition of A. xanthogrammica, which reproduces only sexually. Gonad development was measured in anemones from Slip Point, Clallam Bay, WA and Tongue Point, WA along with symbiont type and density per mg of anemone protein. The results indicate a trend towards brown anemones having more developed gonads, especially in males. This may mean that A. xanthogrammica anemones that host zooxanthellae are more reproductively fit than zoochlorellate anemones. Thus, it may be favorable for anemones to host zooxanthellae. This is especially true in summer months when the high temperatures and mid-day low tides coincide with the period of most rapid gonad development.
ContributorsGasbarro, Ryan Patrick (Author) / Neuer, Susanne (Thesis director) / Rutowski, Ronald (Committee member) / Bingham, Brian (Committee member) / Barrett, The Honors College (Contributor) / School of Earth and Space Exploration (Contributor) / School of Life Sciences (Contributor)
Created2015-05