Matching Items (70)
Description
Microzooplankton, mainly heterotrophic unicellular eukaryotes (protists), play an important role in the cycling of nutrients and carbon in the sunlit (euphotic) zone of the world’s oceans. Few studies have investigated the microzooplankton communities in oligotrophic (low-nutrient) oceans, such as the Sargasso Sea. In this study, I investigate the seasonal and interannual dynamics of the heterotrophic protists, particularly the nanoflagellate, dinoflagellate, and ciliate communities, at the Bermuda Atlantic Time Series site and surrounding areas in the Sargasso Sea. In addition, I test the hypotheses that the community is controlled though bottom-up and top-down processes. To evaluate the bottom-up hypothesis, that the protists are controlled by prey availability, I test whether the protist abundance co-varies with the abundance of potential prey groups. Predation experiments with zooplankton were conducted and analyzed to test top-down control on the protists. I found distinguishable trends in biomass of the different protist groups between years and seasons. Nanoflagellates and dinoflagellates had higher biomass during the summer (28 ± 5 mgC/m2 and 44 ± 21 mgC/m2) than during the winter (17 ± 8 mgC/m2 and 30 ± 11 mgC/m2). Ciliates displayed the opposite trend with a higher average biomass in the winter (15 ± 9 mgC/m2) than in summer (5 ± 2 mgC/m2). In testing my bottom-up hypothesis, I found weak but significant positive grazer/prey relationships that indicate that nanoflagellates graze on picophytoplankton in winter and on the pico-cyanobacterium Prochlorococcus in summer. I found evidence that ciliates graze on Synechococcus in winter. I found weak but significant negative correlation between dinoflagellates and Prochlorococcus in summer. The predation experiments testing the top-down hypothesis did not show a clear top-down control, yet other studies in the region carried out during our investigation period support predation of the protists by the zooplankton. Overall, my results suggest a combination of bottom-up and top-down controls on these heterotrophic protists, however, further investigation is necessary to reveal the detailed trophic dynamics of these communities.
ContributorsWolverton, Megan (Author) / Neuer, Susanne (Thesis advisor) / Hartnett, Hillary (Committee member) / Elser, James (Committee member) / Arizona State University (Publisher)
Created2016
Description
The greatest barrier to understanding how life interacts with its environment is the complexity in which biology operates. In this work, I present experimental designs, analysis methods, and visualization techniques to overcome the challenges of deciphering complex biological datasets. First, I examine an iron limitation transcriptome of Synechocystis sp. PCC 6803 using a new methodology. Until now, iron limitation in experiments of Synechocystis sp. PCC 6803 gene expression has been achieved through media chelation. Notably, chelation also reduces the bioavailability of other metals, whereas naturally occurring low iron settings likely result from a lack of iron influx and not as a result of chelation. The overall metabolic trends of previous studies are well-characterized but within those trends is significant variability in single gene expression responses. I compare previous transcriptomics analyses with our protocol that limits the addition of bioavailable iron to growth media to identify consistent gene expression signals resulting from iron limitation. Second, I describe a novel method of improving the reliability of centroid-linkage clustering results. The size and complexity of modern sequencing datasets often prohibit constructing distance matrices, which prevents the use of many common clustering algorithms. Centroid-linkage circumvents the need for a distance matrix, but has the adverse effect of producing input-order dependent results. In this chapter, I describe a method of cluster edge counting across iterated centroid-linkage results and reconstructing aggregate clusters from a ranked edge list without a distance matrix and input-order dependence. Finally, I introduce dendritic heat maps, a new figure type that visualizes heat map responses through expanding and contracting sequence clustering specificities. Heat maps are useful for comparing data across a range of possible states. However, data binning is sensitive to clustering cutoffs which are often arbitrarily introduced by researchers and can substantially change the heat map response of any single data point. With an understanding of how the architectural elements of dendrograms and heat maps affect data visualization, I have integrated their salient features to create a figure type aimed at viewing multiple levels of clustering cutoffs, allowing researchers to better understand the effects of environment on metabolism or phylogenetic lineages.
ContributorsKellom, Matthew (Author) / Raymond, Jason (Thesis advisor) / Anbar, Ariel (Committee member) / Elser, James (Committee member) / Shock, Everett (Committee member) / Walker, Sarah (Committee member) / Arizona State University (Publisher)
Created2017
Description
Surveys of carbon:nitrogen:phosphorus ratios are available now for major groups of biota and for various aquatic and terrestrial biomes. However, while fungi play an important role in nutrient cycling in ecosystems, relatively little is known about their C:N:P stoichiometry and how it varies across taxonomic groups, functional guilds, and environmental conditions. Here we present the first systematic compilation of C:N:P data for fungi including four phyla (Ascomycota, Basidiomycota, Glomeromycota, and Zygomycota). The C, N, and P contents (percent of dry mass) of fungal biomass varied from 38 to 57%, 0.23 to 15%, and 0.040 to 5.5%, respectively. Median C:N:P stoichiometry for fungi was 250:16:1 (molar), remarkably similar to the canonical Redfield values. However, we found extremely broad variation in fungal C:N:P ratios around the central tendencies in C:N:P ratios. Lower C:P and N:P ratios were found in Ascomycota fungi than in Basidiomycota fungi while significantly lower C:N ratios (p < 0.05) and higher N:P ratios (p < 0.01) were found in ectomycorrhizal fungi than in saprotrophs. Furthermore, several fungal stoichiometric ratios were strongly correlated with geographic and abiotic environmental factors, especially latitude, precipitation, and temperature. The results have implications for understanding the roles that fungi play in function in symbioses and in soil nutrient cycling. Further work is needed on the effects of actual in situ growth conditions of fungal growth on stoichiometry in the mycelium.
ContributorsZhang, Ji (Author) / Elser, James (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor)
Created2017-07-14
Description
Nutrient availability and ratios can play an important role in shaping microbial communities of freshwater ecosystems. The Cuatro Ciénegas Basin (CCB) in Mexico is a desert oasis where, perhaps paradoxically, high microbial diversity coincides with extreme oligotrophy. To better understand the effects of nutrients on microbial communities in CCB, a mesocosm experiment was implemented in a stoichiometrically imbalanced pond, Lagunita, which has an average TN:TP ratio of 122 (atomic). The experiment had four treatments, each with five spatial replicates – unamended controls and three fertilization treatments with different nitrogen:phosphorus (N:P) regimes (P only, N:P = 16 and N:P = 75 by atoms). In the water column, quantitative PCR of the 16S rRNA gene indicated that P enrichment alone favored proliferation of bacterial taxa with high rRNA gene copy number, consistent with a previously hypothesized but untested connection between rRNA gene copy number and P requirement. Bacterial and microbial eukaryotic community structure was investigated by pyrosequencing of 16S and 18S rRNA genes from the planktonic and surficial sediment samples. Nutrient enrichment shifted the composition of the planktonic community in a treatment-specific manner and promoted the growth of previously rare bacterial taxa at the expense of the more abundant, potentially endemic, taxa. The eukaryotic community was highly enriched with phototrophic populations in the fertilized treatment. The sediment microbial community exhibited high beta diversity among replicates within treatments, which obscured any changes due to fertilization. Overall, these results showed that nutrient stoichiometry can be an important factor in shaping microbial community structure.
ContributorsLee, Zarraz (Author) / Poret-Peterson, Amisha (Author) / Siefert, Janet L. (Author) / Kaul, Drishti (Author) / Moustafa, Ahmed (Author) / Allen, Andrew E. (Author) / Dupont, Chris L. (Author) / Eguiarte, Luis E. (Author) / Souza, Valeria (Author) / Elser, James (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / School of Earth and Space Exploration (Contributor)
Created2017-05-30
Description
Nitrogen (N) and/or phosphorus (P) availability can limit growth of primary producers across most of the world's aquatic and terrestrial ecosystems. These constraints are commonly overcome in agriculture by applying fertilizers to improve yields. However, excessive anthropogenic N and P inputs impact natural environments and have far-reaching ecological and evolutionary consequences, from individual species up to entire ecosystems. The extent to which global N and P cycles have been perturbed over the past century can be seen as a global fertilization experiment with significant redistribution of nutrients across different ecosystems. Here we explore the effects of N and P availability on stoichiometry and genomic traits of organisms, which, in turn, can influence: (i) plant and animal abundances; (ii) trophic interactions and population dynamics; and (iii) ecosystem dynamics and productivity of agricultural crops. We articulate research priorities for a deeper understanding of how bioavailable N and P move through the environment and exert their ultimate impacts on biodiversity and ecosystem services.
ContributorsGuignard, Maite S. (Author) / Leitch, Andrew R. (Author) / Acquisti, Claudia (Author) / Eizaguirre, Christophe (Author) / Elser, James (Author) / Hessen, Dag O. (Author) / Jeyasingh, Punidan D. (Author) / Neiman, Maurine (Author) / Richardson, Alan E. (Author) / Soltis, Pamela S. (Author) / Soltis, Douglas E. (Author) / Stevens, Carly J. (Author) / Trimmer, Mark (Author) / Weider, Lawrence J. (Author) / Woodward, Guy (Author) / Leitch, Ilia J. (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor)
Created2017-07-06
Description
The growth rate hypothesis predicts that organisms with higher maximum growth rates will also have higher body percent phosphorus (P) due to the increased demand for ribosomal RNA production needed to sustain rapid growth. However, this hypothesis was formulated for invertebrates growing at the same temperature. Within a biologically relevant temperature range, increased temperatures can lead to more rapid growth, suggesting that organisms in warmer environments might also contain more P per gram of dry mass. However, since higher growth rates at higher temperature can be supported by more rapid protein synthesis per ribosome rather than increased ribosome investment, increasing temperature might not lead to a positive relationship between growth and percent P. We tested the growth rate hypothesis by examining two genera of Neotropical stream grazers, the leptophlebiid mayfly Thraulodes and the bufonid toad tadpole Rhinella. We measured the body percent P of field-collected Thraulodes as well as the stoichiometry of periphyton resources in six Panamanian streams over an elevational gradient spanning approximately 1,100 m and 7°C in mean annual temperature. We also measured Thraulodes growth rates using in situ growth chambers in two of these streams. Finally, we conducted temperature manipulation experiments with both Thraulodes and Rhinella at the highest and lowest elevation sites and measured differences in percent P and growth rates. Thraulodes body percent P increased with temperature across the six streams, and average specific growth rate was higher in the warmer lowland stream. In the temperature manipulation experiments, both taxa exhibited higher growth rate and body percent P in the lowland experiments regardless of experimental temperature, but growth rate and body percent P of individuals were not correlated. Although we found that Thraulodes from warmer streams grew more rapidly and had higher body percent P, our experimental results suggest that the growth rate hypothesis does not apply across temperatures. Instead, our results indicate that factors other than temperature drive variation in organismal percent P among sites.
ContributorsMoody, Eric (Author) / Rugenski, Amanda (Author) / Sabo, John (Author) / Turner, Benjamin L. (Author) / Elser, James (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor)
Created2017-04-18
Description
For many species, migration evolves to allow organisms to access better resources. However, the proximate factors that trigger these developmental changes, and how and why these vary across species, remain poorly understood. One prominent hypothesis is that poor-quality food promotes development of migratory phenotypes and this has been clearly shown for some polyphenic insects. In other animals, particularly long-distance bird migrants, it is clear that high-quality food is required to prepare animals for a successful migration. We tested the effect of diet quality on the flight behaviour and morphology of the Mongolian locust, Oedaleus asiaticus. Locusts reared at high population density and fed low-N grass (performance-enhancing for this species) had enhanced migratory morphology relative to locusts fed high-N grass. Furthermore, locusts fed synthetic diets with an optimal 1 : 2 protein : carbohydrate ratio flew for longer times than locusts fed diets with lower or higher protein : carbohydrate ratios. In contrast to the hypothesis that performance-degrading food should enhance migration, our results support the more nuanced hypothesis that high-quality diets promote development of migratory characteristics when migration is physiologically challenging.
ContributorsCease, Arianne (Author) / Harrison, Jon (Author) / Hao, Shuguang (Author) / Niren, Danielle (Author) / Zhang, Guangming (Author) / Kang, Le (Author) / Elser, James (Author) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor)
Created2017-06-07
Description
The ASU School of Dance presents Undergraduate Projects Showing, October 25-26, with works by undergraduate dance students, performed at Margaret Gisolo Dance Studio.
ContributorsPinholster, Jacob (Director, Artistic director) / Koch, Carolyn (Production manager) / Rex, Melissa S. (Technical director, Lighting designer) / Swayze, William (Musician) / Benard, Jacqueline (Costume designer) / Mihaleva, Galina (Costume designer) / Dodt, Alli (Artistic director) / Edwards, Allison (Artistic director, Performer) / Levin, Felicia (Performer) / Hughes, Haylee (Performer) / Groom, Léla (Performer) / Gastelo, Jr., Gabriel (Lighting designer) / Singleton, Kiah (Choreographer, Lighting designer, Costume designer, Performer) / DeSantis, Kimberly (Performer) / Freirich, Gordon (Performer) / Harkey, Noah (Performer) / Nguyen, Dana (Performer) / Bartholomew, Jessica (Choreographer, Musician, Costume designer) / Dorrel, Kayla (Performer) / Johnson, Sarah (Performer) / LeBlanc, Casey (Performer) / Norris, Sarah (Performer) / Rivera, Paola (Performer) / Sammons, Rylee (Performer) / Soto, Jose (Performer) / Wardarski, Jessie (Performer) / Witzke, Nikki (Performer, Choreographer, Costume designer) / Moraco, Steve (Videographer, Videographer) / Jackson, Sydney (Choreographer, Costume designer) / Castronova, Naomi (Performer) / Garcia, Lacee (Performer) / Keefe, Shelby (Performer) / Kerr, Elena (Performer) / Waitz, Jessica (Performer) / Riojas, David (Choreographer, Costume designer) / Calvano, Jourdan (Performer) / Locker, Rain (Performer) / Pullman, Gracie (Performer) / Reis, Ashley (Performer) / Nunn, Jasmine (Choreographer, Costume designer) / Koji, Saito (Musician) / Avery, Vickie (Musician) / Salcido, Alejandro (Lighting designer) / Baker, Ashley (Performer) / Siegfried, Jordyn (Performer) / Yoder, Allyson (Performer) / Gallagher, Grace (Choreographer, Costume designer, Videographer, Performer) / Dix, Geoffrey (Musician) / Stephens, Alexis (Choreographer, Costume designer, Performer) / Keating, Zoe (Musician) / Hernandez, Martha "Patty" (Choreographer, Costume designer, Performer) / Yuen, Priscilla (Performer) / Herberger Institute School of Dance (Musician)
Created2012
Description
The ASU School of Dance presents School of Dance LIVE!, September 7-9, with works by dance faculty, performed at Galvin Playhouse.
ContributorsPinholster, Jacob (Director) / Koch, Carolyn (Artistic director, Production manager, Lighting designer) / Swayze, William (Musician, Performer, Composer) / Jones, Ben (Performer) / Mack, Austen (Performer) / Ortego, Garrett (Performer) / Benard, Jacqueline (Costume designer, Creator) / Burk, Ashley (Collaborator deprecated, use Contributor, Performer) / Arredondo, Julia (Performer) / Groom, Léla (Performer) / Giordano, Erin (Performer) / Bouey, Billie-Joe "J." (Performer) / Bartholomew, Jessica (Performer) / Chapman, Eric (Collaborator deprecated, use Contributor)) / Peterson, Haley (Collaborator deprecated, use Contributor)) / Vissicaro, Pegge (Collaborator deprecated, use Contributor)) / Mitchell, John D. (Designer, Musician) / Standley, Eileen (Designer, Choreographer, Performer) / Kyriakides, Yannis (Composer) / Tomooka, Kayla (Performer) / Waitz, Jessica (Performer) / McNutt, Eden (Costume designer, Performer) / DeWitt, Inertia (Musician, Performer) / Murphey, Claudia (Director, Interviewer) / Mumford, Jessica (Videographer, Editor) / Britt, Melissa (Choreographer, Costume designer, Performer) / Alvarez, Emily (Musician) / Salcido, Alejandro (Lighting designer) / Calleros, Vince (Performer) / Dimmick, Saza (Performer) / Granado, Michaela (Performer) / Kusch, Liz (Performer) / Lopez, Cassidy (Performer) / Kaplan, Rob (Composer, Performer) / Rex, Melissa S. (Choreographer, Lighting designer, Technical director) / Bocchino, Corinne (Performer, Performer) / Mihaleva, Galina (Costume designer, Creator) / Cooper, Carol (Performer) / Crissman, Angel (Performer) / Bouey, J (Performer) / Bouey, Majee (Performer) / Bouey, Najee (Performer) / Matthews, Emily (Performer) / Vago, Haley (Performer) / Witzke, Nikki (Performer) / Goodson, Naomi (Performer) / Levin, Felicia (Performer) / Gonzales, Anthony (Performer) / Hughs, Haylee (Performer) / Ling, Amanda (Performer) / Pourzal, Kristopher K. Q. (Performer) / Munoz, Jessica (Performer) / Peterson, Britta (Performer) / Poto, Ana Maria (Performer) / Rickert, Austin (Performer) / Schupp, Karen (Director, Costume designer, Performer) / McMahon Ward, Frances (Editor) / Khoilian, Jarek (Cinematographer) / Heath, Jason (Musician) / Page, Martin (Composer) / Fairweather, Brian (Composer) / Thornton, Trevor (Composer) / Richardson, Chris (Composer) / Fitzgerald, Mary (Choreographer, Performer) / Ford, Lindsey (Performer) / Garibay, Elissa (Performer) / Barrett, Kristen (Performer) / Herberger Institute School of Dance (Musician)
Created2012
Description
The ASU School of Dance presents Emerging Artists I, February 9-12, with works by guest artists, dance faculty, and students, performed at Dance Studio Theatre, PEBE 132.
ContributorsSedlack, Kate (Choreographer, Lighting designer, Costume designer) / Bormann, Megan (Dancer) / Brack, Ashley (Dancer) / Hauk, Chelsey (Dancer) / Koeppel, Alex (Dancer) / Pesque, Julia (Dancer) / Roberts, Cassie (Dancer) / Roethler, Eva (Dancer) / Spenceley, Jenni (Dancer) / Trujillo, David (Dancer) / Fitzgerald, Mary (Artistic director, Choreographer, Lighting designer, Costume designer) / Ammerman, Mark C. (Technical director, Set designer, Lighting designer) / Benard, Jacqueline (Costume designer) / Mihaleva, Galina (Costume designer) / Swayze, William (Sound designer, Composer) / Archambault, Jared (Stage manager) / King, Natalie (Dancer) / Skrentny, Adrian (Choreographer, Lighting designer, Costume designer, Set designer, Dancer) / Bajromovic, Saban (Musician) / Parsons, Niamh (Musician) / Cortez, Sarah (Dancer) / Galindo, Rolanda (Dancer) / Kenworthy, Julianna (Dancer, Choreographer, Costume designer) / Kriston, Jordan (Dancer) / Wong, Jennifer (Dancer) / Taylor, Michelle (Choreographer) / Hart, Keira (Lighting designer) / Smith, Vanessa (Costume designer, Dancer) / Chesley, Andrea (Choreographer, Lighting designer, Costume designer, Dancer) / Chappman, Richard (Composer, Performer) / Childers, Emily (Dancer) / Cortez, Maggie (Dancer) / Howe, Martha E. (Choreographer) / Blake, Casey (Lighting designer) / Blukis, Audrey (Dancer) / Holcman, Sarah (Choreographer, Lighting designer, Costume designer, Set designer) / Lecuona, Margarita (Musician) / Santaolalla, Gustavo (Musician) / Aste, Cuti (Musician) / Lobos, Jorge (Musician) / Zamora, Maria Esther (Musician) / González, Polito (Musician) / Lindl, Roberto (Musician) / Sternke, Amy (Dancer) / Anderson, Laurie (Musician) / McGloin, Aaron (Lighting designer) / Bingle, Meghan (Dancer) / Jordan, Paul (Dancer) / Kuo, Alexis I-Cheng (Dancer) / Lederman, Christiana (Dancer) / Lerner, Kristin (Dancer) / Parish, Sara (Dancer) / Hatzis, Amy E. (Choreographer, Composer, Costume designer, Lighting designer) / Dumont, Marguerite (Dancer) / Ebling, Brett (Dancer) / Kettner, Lauren (Dancer) / Pannier, Nicci (Dancer) / Kelley, Jean (Costume designer, Dancer) / Monk, Meredith (Composer) / Kriston, Micah (Choreographer, Lighting designer, Costume designer) / Fox, Stacey (Cinematographer) / Herberger Institute School of Dance (Musician)
Created2006