The field of vector-borne disease research uses multidisciplinary approaches to help understand complicated interactions. This dissertation, covers three different aspects of tick-borne disease research which all focus on exploring tick-borne diseases in the non-endemic areas of Denton, County Texas and the state of Texas with a focus on Rickettsia spp. These aspects include tick sampling, testing ticks for the presence of Rickettsia spp., and creating species distribution maps of the Rickettsia spp. Rickettsia amblyommatis and tick species Amblyomma americanum.

The Science Teaching and Research (STAR) Leadership Program at Austin College was designed to intentionally include leadership development into the science curriculum and provides an opportunity to determine the effects of student leadership development on the retention of students in science, technology, engineering, and mathematics (STEM). This dissertation used a quasi-experimental design to determine: 1) if STEM retention can be explained though the inclusion of leadership development into the curriculum; 2) if there is a difference between Austin College students who choose a STEM major compared to students who do not; and 3) if there is a difference between Austin College students who complete a STEM degree compared to students who do not. Census data were collected on 2,137 students who enrolled in STEM courses beginning in the fall of 2008 through the spring of 2017, and factors affecting retention were compared across three 3-year time periods that spanned before the program was initiated through wider implementation. A logistic regression showed that there was no significant positive association between leadership development and STEM retention when taking into account other pre-college and demographic factors that have been linked to retention in the literature. However, a one-way ANOVA showed that the academic …

Water quality of a stream or river is influenced by the surrounding landscape and vegetation. The Normalized Difference Vegetation Index (NDVI) is commonly used to characterize landcover and vegetation density. Benthic macroinvertebrates are ubiquitous in freshwater streams and are excellent indicators of the quality of freshwater habitats. Data from one NDVI remote sensing flight and one macroinvertebrate sampling event for eight wadeable stream study sites in the National Ecological Observatory Network (NEON) were acquired. Proportions of high, moderate, and sparse vegetation were calculated for each stream watershed using ArcGIS. Functional feeding groups and tolerance values were assigned to macroinvertebrate taxa. The Fourth-corner and RLQ methods of analysis, available in the ade4 package for R software, were used to evaluate the relationships of macroinvertebrate traits with environmental variables. Hypothesis testing using Model 6 in the ade4 package resulted in p-values of 0.066 and 0.057 for global (overall) significance. Mean NDVI values of moderately vegetated areas and proportion of sparse vegetation were found to be significant to percent shredders at alpha ≤ 0.05. Results of these methods of analysis, when combined with traditional macroinvertebrate sampling metrics, show that NDVI can be a useful, additional tool to characterize a watershed and its effects …

Using metacommunity theory, I investigated the mechanisms of meta-assemblage structure and assembly among medium- to large-bodied mammals in North Texas. Mammals were surveyed with camera-traps in thirty property units of the LBJ National Grasslands (LBJNG). In Chapter II the dispersal and environmental-control based processes in community assembly were quantified within a metacommunity context and the best-fit metacommunity structure identified. A hypothesis-driven modelling approach was used in Chapter III to determine if the patterns of species composition and site use could be explained by island biogeography theory (IBT) or the habitat amount hypothesis (HAH). Islands were defined as the LBJNG property unit or the forest patch bounded by the property unit. Forest cover was selected as the focal habitat for the HAH. Seasonal dynamics were explored in both chapters. Metacommunity structure changed with each season, resulting in quasi-nested and both quasi and idealized Gleasonian and Clementsian structures. Results indicated that the anthropogenic development is, overall, not disadvantageous for this assemblage, that community assembly receives equal contributions from spatial and environmental factors, and that the metacommunity appears to operate under the mass effects paradigm. The patterns of species composition and site use were not explained by either IBT or HAH. Likely because …

Ecosystem services are the varied goods and benefits provided by ecosystems that make human life possible. This concept has fostered scientific explorations of the services that nature provides to people with the goal of sustaining those services for future generations. As the world becomes increasingly urban, ecosystems are reshaped, and services are degraded. Provisioning and regulating ecosystem services, landscape planning, decision making, and agricultural systems and technologies play a distinctive role in feeding and sustaining the expanding urban population. Hence, the integrated assessment of these coupled components is necessary to understand food security and sustainable development. Nevertheless, frameworks that incorporate ecosystem services, urbanization, and human wellbeing are still scarce due to several conceptual and methodological gaps that challenge this assessment. As a consequence, these frameworks are not operationalized, and ecosystem services rarely receive proper attention in decision making. This dissertation seeks to improve our understanding of the role of ecosystem services at the landscape level and provides an approach for operationalizing decisions that affect sustainable practices and human wellbeing.