An Exploratory Study of the Impact of Institutional Policies and Practices of Community and Technical Colleges in Texas on Student Persistence in Online Courses (open access)

An Exploratory Study of the Impact of Institutional Policies and Practices of Community and Technical Colleges in Texas on Student Persistence in Online Courses

Online education is the fastest growing form of course delivery of higher education in the United States. It has revolutionized how students and instructors interact in the educational process. Yet students in online courses continue to experience higher attrition rates than their counterparts in traditional face-to-face classes despite the advantages offered by the technology. This study examined the impact that institutional policies and practices at community colleges in the state of Texas have had on student persistence in online courses. It also examined how institutions collect and use data in addressing students' attrition. The findings were used to identify the most effective institutional practices to share with community college systems in Texas in an effort to improve student persistence in online courses across the state. The population for the study consisted of the 50 public two-year community college and the technical college systems in the state of Texas. The study used a mixed method. A theoretical model of institutional impact on online persistence was drawn from the literature review. This model's five categories were then used to construct a survey to collect data on institutional practices and measure the effectiveness in addressing student persistence. Four college systems were identified using …
Date: December 2010
Creator: Hills, Fred W.
System: The UNT Digital Library
The Relationship of Peer Leadership Employment to Academic Outcomes in Texas Institutions of Higher Education (open access)

The Relationship of Peer Leadership Employment to Academic Outcomes in Texas Institutions of Higher Education

The purpose of this quantitative study was to examine the relationship of participation and involvement in an undergraduate student success program to academic success and persistence among students in three programs sponsored by the Texas Higher Education Coordinating Board (THECB): the G-Force Collegiate Work-Study Mentorship Program, the Advancement Via Individual Determination (AVID) for Higher Education (AHE) program, and the THECB work-study program. The sample was identified using data from the THECB during the 2009-2013 academic years. Compared to THECB work-study students, significantly more AHE and G-Force students persisted toward graduation while engaged in the program (p < .001). ANOVA indicated that AHE students had a higher average GPA compared to G-Force and THECB work-study students, controlled for gender, race/ethnicity, pre-program GPA, and length of time in the position. Regression analyses found no statistically significant relationship between program associations and persistence towards graduation or GPA. Results suggest that although participation in a peer leadership programs such as AHE and G-Force encourage greater academic achievement and persistence, there is no direct relation to the achievement of these outcome variables. Implications of the study suggest the need for a deeper analysis into elements of peer leadership programs that contribute to student success, an …
Date: May 2015
Creator: Buggs, Michelle L.
System: The UNT Digital Library
Impact of Teacher and Student Ethnicity on Student Assessments (open access)

Impact of Teacher and Student Ethnicity on Student Assessments

The purpose of the study was to answer the questions: Do students show greater academic success in English language arts/reading as measured by the Texas Assessment of Knowledge and Skills (TAKS) exam scores in secondary education when their teachers are the same ethinicity? Do students show greater academic success in math as measured by the TAKS exam scores in secondary education when their teachers are the same ethnicity? Minority students' success on the TAKS test was compared to the assessment scores of White students from the 2010-2011, 2011-2012, and 2012-13 school year in thre suburban school districts. This topic has been a subject of discussion since the late 10970s when Cardenas and Cardenas (1977) studied the achievement among minority students and their White peers. The conversation continued through authors such as Takei and Shouse (2008), Hays (2011), Ladson-Billings (2006), Dee (2003, 2005), and Brown (2006). To answer these research questions, a hierarchical multiple regression analysis was conducted on the data collected. Although the study verified the achievement gap between minority students and White students, the study indicated no consistent pattern corroborating that minority students were more successful when taught by teachers of the same ethnicity. In many cases, students learned …
Date: May 2016
Creator: Barnes, Barbara (Principal)
System: The UNT Digital Library
Effects of a Water Conservation Education Program on Water Use in Single-family Homes in Dallas, Texas (open access)

Effects of a Water Conservation Education Program on Water Use in Single-family Homes in Dallas, Texas

The City of Dallas Environmental Education Initiative (EEI) is a hands-on, inquiry-based, K-12 water conservation education program that teaches students concepts about water and specific water conservation behaviors. Few descriptions and evaluations, especially quantitative in nature, of water conservation education programs have previously been conducted in the literature. This research measured the quantitative effects and impacts of the education program on water use in single-family homes in Dallas, Texas. A total of 2,122 students in 104 classrooms at three schools in the Dallas Independent School District received hands-on, inquiry-based water conservation education lessons and the average monthly water use (in gallons) in single-family homes was analyzed to measure whether or not there was a change in water use. The results showed that over a period of one calendar year the water use in the single-family homes within each school zone and throughout the entire research area in this study experienced a statistically significant decrease in water use of approximately 501 gallons per home per month (independent, t-test, p>0.001). Data from this research suggests that EEI is playing a role in decreasing the amount of water used for residential purposes. Additionally, this research demonstrates the use of a quantitative tool by …
Date: December 2014
Creator: Serna, Victoria Faubion
System: The UNT Digital Library
Professional Learning Community Dimensions in a North Texas Elementary School’s Culture and Their Impact on Reading and Math Student Growth Scores (open access)

Professional Learning Community Dimensions in a North Texas Elementary School’s Culture and Their Impact on Reading and Math Student Growth Scores

The purpose of this mixed methods study was to determine which dimensions, as represented by the Professional Learning Community Assessment – Revised dimensions, are present in the environment of North Texas elementary schools and their impact on student growth. A survey design was utilized in which elementary principals and teachers in a selected school district completed the Professional Learning Community – Revised survey developed by Hipp and Huffman (2009), to gather perceptions of PLC implementation within their school environments as well as reflect strengths and needs regarding each dimension. The results of the survey were analyzed and one-to-one interviews were completed to clarify and support survey results. Bivariate and multiple regression analysis were used to determine correlations between dimensions present in a school’s environment and their impact on student growth. The study found a statistically significant relationship between the dimensions of shared values and vision and shared personal practice and math growth. Although PLCA-R dimensions were not found to be statistically significant in predicting reading and math growth, the effect sizes were notable at 22.4% for reading growth and 15.8% for math growth. This study’s findings provide important information which educators can use to implement practical application of Professional Learning …
Date: May 2015
Creator: Patrick, Linda Denise
System: The UNT Digital Library
Use of Digital Fabrication Tools and Curriculum with Gifted Students in Rural Middle Schools (open access)

Use of Digital Fabrication Tools and Curriculum with Gifted Students in Rural Middle Schools

This study focuses on the use of American Invention Kits from the Smithsonian Institute in conjunction with a 3D printer. In conjunction with a large dataset from a study funded by the National Science Foundation (NSF), this innovative research focuses on the effect the digital fabrication curriculum unit has on gifted and talented students' knowledge and affinity toward the fields of science, technology, engineering, and mathematics (STEM). Students from two rural middle schools in north-central Texas (N = 190) took part in this quantitative study; the students were divided among four subgroups: gifted-contrast (n = 12), gifted-treatment (n = 8), nongifted-contrast (n = 76), and nongifted-treatment (n = 94). The surveys utilized include the STEM Semantics Survey, TIMSS-Limited, and a knowledge assessment for the specific curriculum unit focused on the solenoid. The STEM Semantics Survey is divided into five subsets. Thirty-two separate one-way repeated measures ANOVAs were performed across the surveys and subgroups. Statistically significant results were found on four comparisons. This research holds implications in the areas of advocating for gifted education, collecting field data, utilizing large datasets, and understanding rural schools.
Date: December 2018
Creator: Moore, Vince
System: The UNT Digital Library
Teacher Perceptions of Pay-for-Performance: An Investigation of Four Middle School Pay-for-Performance Programs in a Large Urban School District (open access)

Teacher Perceptions of Pay-for-Performance: An Investigation of Four Middle School Pay-for-Performance Programs in a Large Urban School District

In this study, I explored the different perceptions of teachers in a large urban school district in Texas towards a pay-for-performance program used on their respective campuses between 2011-2016. In total, 97 teachers from four different middle school campuses participated in this study. A descriptive analyst was conducted on teacher responses to an online survey to answer the research questions examined in this study: 1) What are teachers' perceptions of the pay-for-performance program's impact on teacher motivation?, 2) What are teachers' perceptions of the pay-for-performance program's impact on teacher retention?, and 3) What are the differences among teachers' perceptions of the pay-for-performance programs on the participating campuses? The results indicate 48.3% and 53.4% of the participants perceive pay-for-performance programs as having a positive impact on teacher motivation and teacher retention, respectively. Additionally, the results demonstrate 47.5% of participating teachers responded positively towards the pay-for-performance program on their respective campuses. This study has implications for policymakers and school district leaders who may consider implementing teacher pay-for-performance programs. Future research studies might explore school districts of different sizes throughout Texas and across the United States to gain a broader prospective of pay-for-performance programs.
Date: May 2017
Creator: Whitaker, Norbert L., Sr.
System: The UNT Digital Library
An Action Research Study of Community Building with Elementary Students in a Title I School (open access)

An Action Research Study of Community Building with Elementary Students in a Title I School

“In what ways does teaching with folk arts inspired visual arts-based instruction enhance community building among elementary students in a Title I school?” was the primary research question in this study. Agreeing with past and present day research that the construct of community is vital to social and cultural capital, this research attempts to determine how the notion of community benefits both students and teachers in the elementary art classroom. Folk art was utilized because this genre was accessible in terms of locality and familiarity among students and teachers. The purpose of this investigation was to produce teaching strategies and methods that show how community can be formed in the art classroom. The participants were elementary students, Grades 2 and 3, in a Title I school located in Denton, Texas. This investigation was conducted under an action research methodology. This approach to research is intended to be transformational, emergent, and accommodating. I recorded observations, field notes, and conversations from the participants. Emergent themes were discovered through content analysis and conceptual maps. Results from this investigation concluded transformation is only possible if the person wants change to happen. Data also showed that community and art education are symbiotic. Transformation, growth, and …
Date: May 2014
Creator: Dew, SaraBeth
System: The UNT Digital Library
Mineola (open access)

Mineola

Mineola is a poetic, observational, immersive documentary centered in the town of Mineola, Texas. The film provides an intimate, first person perspective of different locations in the town as well as underlying subversive beliefs and traditions. The film’s authoritative perspective guides the viewer not only in a direction of observation but personal connection to nostalgia of small communities.
Date: December 2015
Creator: Cater, Lauren
System: The UNT Digital Library
Levanten La Mano Si Me Entienden: Receptive Bilinguals’ Linguistic and Cultural Perceptions in Secondary Spanish Classes (open access)

Levanten La Mano Si Me Entienden: Receptive Bilinguals’ Linguistic and Cultural Perceptions in Secondary Spanish Classes

Receptive bilinguals have been in a dilemma of knowing just enough Spanish to write and aurally comprehend the curriculum at the beginning-intermediate levels of a Spanish language course. This dichotomy in classrooms with mixed-ability learners has created a need to reconsider placement and pedagogical structures tailored for these students in foreign language courses. Thus, this descriptive study examined the perceptions of receptive bilinguals, drawn from two secondary Spanish courses regarding receptive bilinguals’ language use, personal Spanish language abilities and confidence, personal beliefs about the language, and contentment with the course. For this study, 31 participants were selected from two public high schools in a suburb of a large metropolitan area in north Texas. Two surveys, a listening assessment and an online questionnaire, were administered at the end of the academic year. The Likert questionnaire items were analyzed using SPSS software, while open-ended questions were coded for recurrent themes. Analyses revealed four major findings. First, with regard to influence on language use, participants’ grandparents created the most interaction with the Spanish language when compared with the other family groups. In addition, Spanish influence through television, literature, radio, and music contributed to students’ early childhood Spanish learning. Second, as to language preference, …
Date: May 2015
Creator: Baker, Adelita Gonzales
System: The UNT Digital Library
Developing a Soil Moisture-Based Irrigation Scheduling Tool (SMIST) Using Web-GIS Technology (open access)

Developing a Soil Moisture-Based Irrigation Scheduling Tool (SMIST) Using Web-GIS Technology

Software as a service (SaaS) is a primary working pattern and a significant application model for next generation Internet application. Web GIS services are the new generation of the Software as a service that can provide the hosted spatial data and GIS functionalities to the practical customized applications. This study focused on developing a webGIS based application, Soil Moisture-Based Irrigation Scheduling Tool (SMIST), for predicting soil moisture in the next seven days using the soil moisture diagnostic equation (SMDE) and the upcoming seven precipitation forecasts made by the National Weather Service (NWS), and ultimately producing an accurate irrigation schedule based on the predicted soil moisture. The SMIST is expected to be capable of improving the irrigation efficiency to protect groundwater resources in the Texas High Plains and reducing the cost of energy for pumping groundwater for irrigation, as an essential public concern in this area. The SMIST comprised an integration of web-based programs, a Hydrometeorological model, GIS, and geodatabase. It integrates two main web systems, the soil moisture estimating web application for irrigation scheduling based on the soil moisture diagnostic equation (SMDE), and an agricultural field delineation webGIS application to prepare input data and the model parameters. The SMIST takes …
Date: May 2018
Creator: Nikfal, Mohammadreza
System: The UNT Digital Library
Community-based Participatory Research: HIV in African American Men Who Have Sex with Men (open access)

Community-based Participatory Research: HIV in African American Men Who Have Sex with Men

To date, traditional behavioral interventions have done little to reduce the prevalence and transmission of HIV among African American men who have sex with men (AAMSM), a highly at risk group. Some researchers theorize that the lack of success may be because these interventions do not address contextual factors among AAMSM. Community-based participatory research (CBPR) is one approach to research with the potential to lead to effective interventions in the future. CBPR is a collaborative, mixed-methods and multidisciplinary, approach to scientific inquiry, which is conducted with, and within, the community. The current study follows the CBPR approach to engage and develop a relationship with the African American communities in the Dallas/Fort Worth Metroplex. Contextual issues were discussed in order to identify emerging themes regarding HIV health related issues among AAMSM to provide the groundwork for continued CBPR research and future interventions with AAMSM in the Dallas/Fort Worth Metroplex. To accomplish this goal, researchers began the CBPR process by conducting interviews and focus groups with a sample of approximately 62 (34 from key informant interviews, 28 from focus groups [gender balanced]) AIDS service organization leaders and workers, advocates, medical doctors and community members with first-hand knowledge of HIV health issues in …
Date: August 2015
Creator: Miller, James MS
System: The UNT Digital Library
Exploring the Process of Developing a Glocally Focused Art Curriculum for Two Communities (open access)

Exploring the Process of Developing a Glocally Focused Art Curriculum for Two Communities

The world is becoming progressively interconnected through technology, politics, culture, economics, and education. As educators we strive to provide instruction that prepares students to become active members of both their local and global communities. This dissertation presents one possible avenue for engaging students with art and multifaceted ideas about culture, community, and politics as it explores the possibilities for creating a community-based, art education curriculum that seeks a merger of global and local, or "glocal" thinking. Through curriculum action research, I explored the process of writing site-specific curriculum that focuses on publicly available, local works of art and encourages a connection between global experiences and local application. I have completed this research for two communities, one in Ohio and one in Texas, and investigated the similarities and differences that exist in the process and resulting curriculum for each location. Through textual analysis, interviews, curriculum writing, and personal reflections, I identified five essential components of a community-based, glocal art education curriculum: flexibility, authenticity, connectedness, glocal understandings, and publicly available art. Additionally, I developed a template for writing glocally focused, community-based art education curriculum and produced completed curricular units for each of the communities. Finally, I have made suggestions for the future …
Date: December 2017
Creator: Hartman, Jennifer D
System: The UNT Digital Library
Cowboys, “Queers,” and Community: the AIDS Crisis in Houston and Dallas, 1981-1996 (open access)

Cowboys, “Queers,” and Community: the AIDS Crisis in Houston and Dallas, 1981-1996

This thesis examines the response to the AIDS crisis in Houston and Dallas, two cities in Texas with the most established gay communities highest number of AIDS incidences. Devoting particular attention to the struggles of the Texas’ gay men, this work analyzes the roadblocks to equal and compassionate care for AIDS, including access to affordable treatment, medical insurance, and the closure of the nation’s first AIDS hospital. In addition, this thesis describes the ways in which the peculiar nature of AIDS as an illness transformed the public perception of sickness and infection. This work contributes to the growing study of gay and lesbian history by exploring the transformative effects of AIDS on the gay community in Texas, a location often forgotten within the context of the AIDS epidemic.
Date: August 2014
Creator: Bundschuh, Molly Ellen
System: The UNT Digital Library
Strategic Design: Developing Community Relations in a Texas School District (open access)

Strategic Design: Developing Community Relations in a Texas School District

School leaders often contemplate implementing measures that will increase community and parent involvement in schools. There is a shortage of research that concisely takes school leadership through a process that details how to integrate parent and community input in a school transformation initiative and careful analysis of student outcomes. Within this study, I provide an in-depth look at one school district’s efforts to engage its community through strategic planning and mission and vision redesign. This process includes community involvement at every phase. For the purpose of this study, community refers to both community members who do not have children in the school system and parents of current students. In this study, I outline the inception of the transformation effort, the ongoing efforts to include community input in decision-making and campus implementation, and finally a review of the overarching impact on leadership, staff, students and community. Data collection analyzed in this study include assessment data, survey data, discipline data and walk through data collected by the school district.
Date: May 2016
Creator: Jund, Nicole C.
System: The UNT Digital Library
School and Community Partnerships: Effect on At-risk Elementary Student Populations (open access)

School and Community Partnerships: Effect on At-risk Elementary Student Populations

The purpose of this study was to investigate the current practices of school and community partnerships in five North Texas elementary schools. In addition, the study focused on the influence community partnerships have on at-risk students based on at-risk indicators data. The literature revealed that when schools, parents, and families work together, students tend to earn higher grades, attend school more regularly, stay in school longer, and enrolled in coursework beyond high school. The target population included approximately 350 administrators, teachers, and paraprofessionals from five North Texas elementary schools. Also included were the respective partners from each of the five elementary schools. This research included online survey instrument and data were gathered and analyzed through a combination of statistical procedures and descriptive and inferential statistics. The results may provide other schools with a profile of school and community partnerships that can be implemented as a method to help their at-risk student populations. Findings included a descriptive analysis of factors that contributed to the success of community engagement efforts as well as those factors that limited those efforts. A secondary purpose of this study was of continuous improvement in developing these approaches through a goal-setting approach. Schools included in the study …
Date: December 2015
Creator: Tucker, Linda Cavazos
System: The UNT Digital Library
Teachers’ Perceptions of Their Responsibilities in Teaching Social Emotional Skills: a Case Study (open access)

Teachers’ Perceptions of Their Responsibilities in Teaching Social Emotional Skills: a Case Study

This study investigated the beliefs of teachers at a particular elementary campus in North Texas during its first year of implementation of a social emotional curriculum regarding teaching social emotional skills and the influence of those beliefs on their classroom practices. The study drew from the works of Dewey and Bandura in the development of a framework for teacher decision making. A case study design incorporating multiple cases within the case study utilized a mixed-methods approach for data collection and analysis. Ten teachers volunteered and participated in the quantitative data collection, and four of those ten participated in the qualitative data collection through interviews and classroom observations. Data collection methods also included a demographic survey, a questionnaire on teacher beliefs about social emotional learning, and a self-ranking scale of practices related to teaching social emotional skills. Results indicated that although all participants believed social emotional skills instruction was part of their duties as teachers, their practices in teaching social emotional skills varied. Additionally, there was a mismatch between participants’ self-identified practices and the practices that were observed during the study. Administrative support for program implementation was high, but did not necessarily translate to effective practices during the first year of …
Date: August 2014
Creator: Madueke, Nkechi A.
System: The UNT Digital Library
The Perceptions of Policymakers on the Transfer Pathway in Texas Public Higher Education (open access)

The Perceptions of Policymakers on the Transfer Pathway in Texas Public Higher Education

Community college students transfer to public universities experiencing a pathway filled with complexity and inequity. Transfer students are not able to graduate at the same pace as native students at the university and complete their baccalaureate degrees 18% below the rate of native students. Policymakers have attempted to address the baccalaureate gap. This qualitative study explored the perspectives of Texas policymakers and policy influencers on the efficacy of policies intended to improve transfer outcomes. This study investigated what experience participants have with transfer policy, what their perceptions of the transfer pathway are, and how their voices can refine an understanding of policy development and ways to improve student persistence. Purposeful sampling was used to explore the perspectives of 14 Texas policymakers and those that influence policy. Findings revealed that significant gaps exist between expectations and student realities and that the completion agenda is driving policy decisions. Participants perceived that transfer students have been ignored in the completion metrics, which influence institutional priorities. Moreover, the decentralized system of independent, autonomous institutions is a major contributor to inefficiencies such as excessive student credit hours. Improving the transferability of courses was a priority recommendation of all participants both because it benefits the State’s …
Date: May 2016
Creator: Faris, Kimberly A.
System: The UNT Digital Library
Texas Principals’ Data Use: Its Relationship to Leadership Style and Student Achievement (open access)

Texas Principals’ Data Use: Its Relationship to Leadership Style and Student Achievement

This study applies an empirical research method determine whether Texas public school principals’ leadership styles, coupled with their use of real time data in a data warehouse, influenced their leadership ability as measured by student achievement. In today’s world of data rich environments that require campuses and districts to make data-driven decisions, principals find themselves having to organize and categorize data to help their school boards, campuses, and citizenry make informed decisions. Most school principals in Texas have access to data in multiple forms including national and state resources and a multitude of other data reports. A random sample of principals was selected to take the Multi Factor Leadership Questionnaire (MLQ5x) and the Principals Data Use Survey. The MLQ5x measured principals’ leadership styles as transformational, transactional, or passive avoidant. The Principals Data Use Survey measured how principals use data to inform campus decisions on student achievement, shaping the vision of the campus, and designing professional development. Data obtained from the survey were correlated to determine the relationship between principals’ use of data warehouses and their leadership styles on student achievement as measured by the Texas Assessment of Knowledge and Skills. The results yielded significant relationships between student achievement, principals’ leadership …
Date: May 2014
Creator: Bostic, Robert E.
System: The UNT Digital Library
The Identification and Participation of Latino Students in Advanced Mathematics Courses (open access)

The Identification and Participation of Latino Students in Advanced Mathematics Courses

Using a phenomenological approach, this qualitative study examined the perspectives of Latino parents and their involvement in the decision of their child to enroll in an advanced mathematics course in sixth grade. Since enrollment in Algebra I in high school is said to be a strong predictor of college attainment and with the growing number of Latino students across the nation, this study has the potential to help district and campus leaders establish whole-school systems for communicating with Latino parents to encourage their children to enroll in advanced mathematics courses at earlier grades. Participants in this study included four sixth-grade students enrolled in an advanced mathematics course, four enrolled in regular mathematics, their mother or father, two mathematics teachers, a school counselor, and two district administrators. Data analyzed included audio recordings of semi-structured interviews of each of the participants. The findings suggested that the district has proactively developed a systematic process of creating that includes six data points to create a student profile of students that will do well in advanced mathematics. This process is helping the district close the gap between total Latino school enrollment and the enrollment of Latino students in advanced mathematics. The findings also suggested that …
Date: May 2018
Creator: Blanchard, Myrna Elizabeth
System: The UNT Digital Library
Alignment of Middle School Core TEKS with Visual Arts TEKS (open access)

Alignment of Middle School Core TEKS with Visual Arts TEKS

This descriptive study uses a qualitative, content analysis to examine the middle school visual arts and core Texas Essential Knowledge and Skills (TEKS) to determine the potential common learning activities that can be aligned between the two. By performing an alignment of the potential common learning activities present in the middle school visual art TEKS and the middle school core TEKS, I demonstrate that there is a foundation for curriculum integration in the Texas middle school visual arts classroom.
Date: December 2010
Creator: Hartman, Jennifer
System: The UNT Digital Library
Developing a Forest Gap Model to Be Applied to a Watershed-scaled Landscape in the Cross Timbers Ecoregion Using a Topographic Wetness Index (open access)

Developing a Forest Gap Model to Be Applied to a Watershed-scaled Landscape in the Cross Timbers Ecoregion Using a Topographic Wetness Index

A method was developed for extending a fine-scaled forest gap model to a watershed-scaled landscape, using the Eastern Cross Timbers ecoregion as a case study for the method. A topographic wetness index calculated from digital elevation data was used as a measure of hydrologic across the modeled landscape, and the gap model modified to have with a topographically-based hydrologic input parameter. The model was parameterized by terrain type units that were defined using combinations of USDA soil series and classes of the topographic wetness index. A number of issues regarding the sources, grid resolutions, and processing methods of the digital elevation data are addressed in this application of the topographic wetness index. Three different grid sizes, 5, 10, and 29 meter, from both LiDAR-derived and contour-derived elevation grids were used, and the grids were processed using both single-directional flow algorithm and bi-directional flow algorithm. The result of these different grids were compared and analyzed in context of their application in defining terrain types for the forest gap model. Refinements were made in the timescale of gap model’s weather model, converting it into a daily weather generator, in order to incorporate the effects of the new topographic/hydrologic input parameter. The precipitation …
Date: August 2014
Creator: Goetz, Heinrich (Heinrich Erwin)
System: The UNT Digital Library
The Population Genetic Structure of Quadrula aurea (Bivalvia: Unionidae), A Threatened Freshwater Mussel in Central Texas (open access)

The Population Genetic Structure of Quadrula aurea (Bivalvia: Unionidae), A Threatened Freshwater Mussel in Central Texas

The anthropogenic alteration of riverine ecosystems has led to declines in the abundance and diversity of freshwater mussels (Bivalvia: Unionoida) worldwide. Central Texas is home to a diverse freshwater mussel fauna including three candidates for federal listing under the Endangered Species Act. Surveys conducted over the last few decades suggest many of the endemic freshwater mussel species in Texas exist in small isolated populations that may be vulnerable to the deleterious effects of genetic diversity loss. Microsatellite primers from two closely related species were used to identify a set of genetic markers that functioned in the Golden Orb (Quadrula aurea). Microsatellite markers were then applied to document the population genetic structure of Q. aurea within and among three connected river drainages in southeastern Texas. Gene flow within existing Q. aurea populations appears high indicating little potential for genetic issues stemming from isolation and inbreeding. Two weakly divergent admixed populations were identified occupying the San Antonio and Guadalupe/San Marcos rivers. Population genetic structure was related to river basin affiliation, but results for environmental factors were unresolved. Current effective population size estimates are large for the Guadalupe/San Marcos drainage and moderately large for the San Antonio drainage and there is no clear …
Date: May 2018
Creator: Mabe, Jeffrey A.
System: The UNT Digital Library