Matching Items (23)
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- All Subjects: Ecology
- Creators: School of Life Sciences
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
- Resource Type: Text
Description
Ephemeral and intermittent streams are valuable sources of surface water support in the arid ecosystems of the Southwestern United States. These streams account for over 80% of the streams in the American Southwest and their importance has been indicated in many studies. Ephemeral and intermittent streams support a wide range of plant and animal species in both continuous and episodic fashions. This study aimed to gain a better understanding of the relationship between streamflow permanence and patterns of biomass and secondary production of the riparian fauna these ecosystems support. This was accomplished through a yearlong survey in the Huachuca Mountains of Southeastern, Arizona where macroinvertebrates were collected at various sites along a gradient of streamflow permanence before, during, and after the three month monsoon season that supplies most of the annual rainfall in this region. The results of my surveys indicate that 1) Sites characterized by low streamflow permanence were more responsive to changes in precipitation than sites characterized by relatively high streamflow permanence 2) In ephemeral streams, there is a significant peak in terrestrial macroinvertebrate production and biomass both during and after the monsoon season 3) streamflow permanence may convey consistent but not exceptional secondary production whereas seasonality in rainfall may convey exceptional but episodic secondary production—more so in sites where streamflow is not consistent.
ContributorsMcCartin, Michael Patrick (Author) / Sabo, John (Thesis director) / Stromberg, Juliet (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2014-05
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
It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients can also reduce animal growth. In ecological stoichiometry, this phenomenon is known as the "stoichiometric knife edge," but its underlying mechanisms are not well-known. Previous work has suggested that the crustacean zooplankter Daphnia reduces its feeding rates on phosphorus-rich food, causing low growth due to insufficient C (energy) intake. To test for this mechanism, feeding rates of Daphnia magna on algae (Scenedesmus acutus) differing in C:P ratio (P content) were determined. Overall, there was a significant difference among all treatments for feeding rate (p < 0.05) with generally higher feeding rates on P-rich algae. These data indicate that both high and low food C:P ratio do affect Daphnia feeding rate but are in contradiction with previous work that showed that P-rich food led to strong reductions in feeding rate. Additional experiments are needed to gain further insights.
ContributorsSchimpp, Sarah Ann (Author) / Elser, James (Thesis director) / Neuer, Susanne (Committee member) / Peace, Angela (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2014-05
Description
The Community Action Research Experiences program integrates the research and teaching mission of Arizona State University by providing services to the community by fostering professional and leadership development of students. It is hoped that the results of the collaborations with CARE will serve to further an organization's goals and effectiveness. VALLEYLIFE (VL) is a non-profit organization striving to help people with disabilities. VL develops Action Programs for each of its clients, whom they call members, to improve their independent or social skills. Examples of programs that members may work on include tasks such as computer training, visual arts, or writing. VALLEYLIFE lacked the data to evaluate if the developed and implemented Action Programs are properly carried out by the staff in ways that are beneficial to members. Given the problem, this research project sought to conduct a process evaluation of the staff regarding their implementation of the Action Programs. This involved observations of employee-member interactions in performing the Action Programs and an interview of staff measuring their preparedness and confidence in performing the program and their feelings of the programs and how things are run. This research provided the following implications to VALLEYLIFE. VL might consider performing periodic observations and reviews of the program implementation to monitor quality. VL may consider involving staff in program development and revision to create programs that better serve members. VL may consider generating ideas for how they may cooperate when a peer is struggling to keep up with events that happen through the day in the interest of better serving the members. Overall, employees are doing well as they are efficient in carrying out the written programs during program time. They are comfortable with what they are doing, use time effectively, and do their best to help the members. There is always room for improvement however and by considering some of the implications mentioned, VALLEYLIFE and their employees may be able to take action that may hold potential for further improvements in effectiveness.
ContributorsAbalos, Cherylene Sales (Author) / Bradley, Robert (Thesis director) / Dumka, Larry (Committee member) / Goldblatt, Lois (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / T. Denny Sanford School of Social and Family Dynamics (Contributor)
Created2013-05
Description
Optometry is an important field in medicine as it allows people a chance to have their vision corrected and it serves as a health screening opportunity for those who receive a dilated eye examination. One of the largest barriers to receiving a dilated eye exam is insurance coverage. Most health insurance policies have limited optometric coverage. By expanding health insurance plans to be more inclusive of optometric care, people who use these health insurance plans will have a better access of care.
ContributorsFurey, Colleen (Author) / Ruth, Alissa (Thesis director) / Mullen, Tyler (Committee member) / School of Life Sciences (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
The bull shark, Carcharhinus leucas, is a large species that it is commonly distributed worldwide in tropical and subtropical waters. Despite the bull sharks global distribution, little is known about its life history. In particular, the limited reproductive information suggests the bull shark is placental viviparous, assumed to have a biennial cycle, and that newborn pup nurseries are near the coast. In order to conserve and protect any species, an understanding of the habitats where reproductive events occur is needed. In order to better understand the habitat use in Biscayne bay, Fla, and whether certain areas are critical during the reproductive cycle of bull sharks, I will evaluate circulating levels of the hormones progesterone, estradiol, and testosterone using radioimmunoassay. These samples were collected by the University of Miami opportunistically between 2012-2020 shipped to Arizona State University, where they were analyzed. For my study a total of 73 mature samples, 27 females and 46 males, were collected over the sampling period. The results indicated that Biscayne bay is an important gestation area for bull sharks. The hormonal trends for males and females demonstrated an interesting reproductive cycle, which were further supported through other placental viviparous reproductive patterns. Females had a low level of estradiol throughout most of the year, besides in the summer where there were no sharks in the bay due to movement to estuaries. During their return to the bay, there was a peak in progesterone indicating early pregnancy. Male testosterone levels indicated that there was a production in sperm right before females speculated peak in estradiol.
ContributorsJara-Aguirre, Nisi G (Author) / Sulikowski, James (Thesis director) / Ferry, Lara (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Water is the main driver of net primary productivity (NPP) in arid ecosystems, followed by nitrogen and phosphorous. Precipitation is the primary factor in determining water availability to plants, but other factors such as surface rocks could also have an impact. Surface rocks may positively affect water availability by preventing evaporation from soil, but at higher densities, surface rocks may also have a negative impact on water availability by limiting water infiltration or light availability. However, the direct relationship between rock cover and aboveground net primary productivity (ANPP), a proxy for NPP, is not well understood. In this research we explore the relationship between rock cover, ANPP, and soil nutrient availability. We conducted a rock cover survey on long-term fertilized plots at fifteen sites in the Sonoran Desert and used 4 years of data from annual plant biomass surveys to determine the relationship between peak plant biomass and surface rock cover. We performed factorial ANCOVA to assess the relationship among annual plant biomass, surface rocks, precipitation, and fertilization treatment. Overall we found that precipitation, nutrients, and rock cover influence growth of Sonoran Desert annual plants. Rock cover had an overall negative relationship with annual plant biomass, but did not show a consistent pattern of significance over four years of study and with varying average winter precipitation.
ContributorsShaw, Julea Anne (Author) / Hall, Sharon (Thesis director) / Sala, Osvaldo (Committee member) / Cook, Elizabeth (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
The amphibian pathogen Ambystoma Tigrinum Virus (ATV) has been an important topic of study within the amphibian community since its discovery. ATV threatens many salamander populations across the US, including those in east-central and southeast Arizona. These populations remain at risk since there are no treatments available. In this thesis, a novel method of inactivation is tested to produce a vaccine with the aim of safely eliciting an immune response within the salamander host. This novel form of inactivation has been tested on several human pathogens but has yet to be used on amphibian pathogens. It has the potential to revolutionize our traditional approach to inactivating viruses. After laser treatment, viral plaque assays suggested that inactivated ATV ceased to grow completely, pointing to the possibility of creating a vaccine. Animal challenge trials were conducted with 60 juvenile Ambystoma tigrinum, but surprisingly there was no protective effect from viral inactivation. Further study is needed to clarify why in vitro and in vivo tests of viral inactivation produced contradictory results.
ContributorsVazquez, Luis Ernesto (Author) / Collins, James (Thesis director) / Tsen, Kong-Thon (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Nitrogen (N) and phosphorus (P) are important limiting or co-limiting nutrients in many aquatic ecosystems. Consumers such as fishes can significantly impact the balance and redistribution of these nutrients through consumer-driven nutrient recycling. Intraspecific variation in nutrient excretion rates can therefore have significant ecosystem impacts. Among individuals of sexually dimorphic consumers, variation in population size structure and sex ratio could potentially have impacts of similar magnitude. We tested for the effects of body size and sex on consumer-driven nutrient recycling by measuring N and P excretion rates from eight species of poeciliid fishes. We found a strong positive effect of size on N excretion rates, as has been previously described among species. However, we found no effect of size on P excretion rates, nor did we find any difference in N or P excretion rates between sexes. Our work provides a preliminary analysis of how sexual dimorphism can lead to disparate nutrient excretion rates within consumer populations. These results indicate that variation in population sex ratios of sexually dimorphic consumers could have impacts at the ecosystem scale.
ContributorsAmbus, Nicholas George (Author) / Jon, Harrison (Thesis director) / Eric, Moody (Committee member) / Jordan, Okie (Committee member) / Dean, W.P. Carey School of Business (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
I am evaluating the genomic basis of a model of heat tolerance in which organisms succumb to warming when their demand for oxygen exceeds their supply. This model predicts that tolerance of hypoxia should correlate genetically with tolerance of heat. To evaluate this prediction, I tested heat and hypoxia tolerance in several genetic lines of Drosophila melanogaster. I hypothesized that genotypes that can fly better at high temperatures are also able to fly well at hypoxia. Genotypes from the Drosophila Genetic Reference Panel (DGRP) were assessed for flight at hypoxia and normal temperature (12% O2 and 25°C) as well as normoxia and high temperature (21% O2 and 39°C). After testing 66 lines from the DGRP, the oxygen- and capacity-limited thermal tolerance theory is supported; hypoxia-resistant lines are more likely to be heat-resistant. This supports previous research, which suggested an interaction between the tolerance of the two environmental variables. I used this data to perform a genome-wide association study to find specific single-nucleotide polymorphisms associated with heat tolerance and hypoxia tolerance but found no specific genomic markers. Understanding factors that limit an organism’s stress tolerance as well as the regions of the genome that dictate this phenotype should enable us to predict how organisms may respond to the growing threat of climate change.
ContributorsFredette-Roman, Jacob Daniel (Author) / Angilletta, Michael (Thesis director) / VandenBrooks, John (Committee member) / Youngblood, Jacob (Committee member) / School of Life Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05