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Consequences Of The Megafauna Extinction: Changes In Food Web Networks On The Edwards Plateau Across The Pleistocene–Holocene Transition, Quentin A. Smith Jr.

School of Biological Sciences: Dissertations, Theses, and Student Research

We are experiencing biodiversity loss due to climate change and human impacts, which is not only harmful to the environment but can also alter the composition of communities and interactions among species. The late Pleistocene experienced a loss of large-bodied mammals which resulted in significant changes in community structure due to changes in body size, diet, and species associations. The impact of these changes on species interactions and community structure across the Pleistocene-Holocene transition remains poorly understood. Using a robust data set of species composition, stable isotopes, body size, and climate variables, we constructed and compared ecological networks of mammal …

Seasonal Climate And Environmental Conditions Associated With Physiological Variations Of Southwestern United States Pines, Taylor Brewer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Juvenile and adult conifers in the southwestern United States are vulnerable to a range of different abiotic and biotic factors, yet it is unclear how their stress tolerance varies across environments. Predicted increases in the frequency and intensity of disturbance as well as greater climate and weather variability across the region highlight the potential for differential physiological responses across tree species and populations. This thesis focuses on two physiologic mechanisms, hydraulic vulnerability and mortality, that could be altered by climate change in two broadly distributed southwestern United States conifers: ponderosa pine and pinyon pine.

In chapter 2, I measured the …

Increasing Swim Instructors' Perceived Knowledge Of Sensory-Based Strategies When Coaching Children Who May Have Sensory Differences, Gabrielle Palmer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Although swim instructors are solely taught water safety regulations and correct swimming techniques, they are nonetheless viewed as mentors by the kids they work with. They are required to finish both their basic swim instructor (BSI) course and their cardiopulmonary resuscitation (CPR) certification, which primarily covers the fundamentals (American Red Cross Training Services, 2023; Kraft & Leblanc, 2018). However, neither provides a method of teaching swimming to children who might have sensory processing differences. This lack of education may affect both the child's participation and the swim instructor's capacity to impart knowledge. Research revealed that swim instructors are not very …

Plant-Plant Interaction In Early- Vs. Late-Successional Varieties Of The Hawaiian Landscape-Dominant Tree, Metrosideros Polymorpha, Tomoko Sakishima

UNLV Theses, Dissertations, Professional Papers, and Capstones

Plant-plant interactions play an important role in assembling plant communities. Interactions between neighboring plants can vary as a result of the genetic relatedness of neighbors, impacting rates of growth and patterns of resource allocation. When growing alongside close relatives, some species decrease their growth in a form of cooperation, while others grow faster through facilitation. A complication of plant interaction studies arises because decreased growth in the presence of close relatives can also be due to competition for resources, which increases with phenotypic similarity. Further complicating matters, mycorrhizal fungi, through their connections with plant roots, may strongly influence plant interactions. …

The Effects Of Aboveground Herbivory On Root Traits And Root Decomposition, Emily A. Chavez

All Graduate Theses and Dissertations, Fall 2023 to Present

Soil holds more carbon (C) than the Earth's atmosphere and vegetation combined. Soil loses carbon through soil respiration and releases CO₂ from the soil. The soil respiration rate can vary based on the chemistry of the plant litter inputs and physical factors, such as soil temperature and nutrient content. In Alaska's Yukon-Kuskokwim (YK) Delta, grazing by geese affects the chemistry of plants and the soil's physical qualities, thus altering the rate of soil respiration. Although we know that goose herbivory leads to changes in the rate of soil respiration, we know very little about how goose herbivory affects the …

Evaluating Aspen Seedling Outplanting Success Following High Severity Wildfire In The Southwest, Sarah M. Kapel

All Graduate Theses and Dissertations, Fall 2023 to Present

Quaking aspen (Populus tremuloides Michx.) is an ecologically important forest species in the western U.S. Aspen forests host a variety of understory species, are critical wildlife habitat, and are considered a "natural fuel break" since they are less likely to support crown fires than conifers. Because of climate change and altered disturbance regimes, populations are declining, and innovative strategies are needed to restore aspen. Planting aspen seedlings is a solution, though not a common practice in the West and has been met with high mortality in past experiments. For aspen planting to be more broadly implemented, managers need guidance …

Spatiotemporal Dynamics Of Disease: Social And Environmental Drivers Of Movement, Connectivity, And Disease Transmission In Bighorn Sheep, Lauren E. Ricci

All Graduate Theses and Dissertations, Fall 2023 to Present

Movement is a fundamental component of animal ecology. Animals move in order to access resources and avoid risk. Movement decisions aggregated across time determine how individuals use space, contact dynamics between individuals within a population, and connectivity across a species range. These patterns that emerge from movement decisions have downstream implications for many ecological processes and a mechanistic understanding of movement can help answer broader questions about ecology.

Disease dynamics are intrinsically tied to movement. Understanding the mechanisms that drive movement can elucidate how disease will spread and impact host populations. In this vein, I employed a suite of movement …

Relationships, Species Boundaries, And Speciation Of Piper Section Enckea, Cara Jean Hastings

Boise State University Theses and Dissertations

Species are fundamental biological units but defining what constitutes a species has been debated by biologists, philosophers, and other scholars. Our concept of what constitutes a species has evolved over time, reflecting progress and advances in technology and types of data available as well as increased understanding of the complexity of the speciation process. To understand how extant species evolved, it is useful to evaluate their relationships using molecular data in a phylogenetic framework. By pairing phylogenetic data with other types of data including morphological and fossil data as well as topographical and climatic history, we can gain understanding of …

The Functional Dynamics Of Bacterial Communities In Relation To Environmental Selection And Host Health In A Pitcher Plant Model System, Jessica Rae Bernardin

Boise State University Theses and Dissertations

Our research investigates the function and composition of microbial communities across various conditions, shedding light on microbial community dynamics and plant-microbe interactions. Despite the crucial role microbes play in Earth's ecosystems, many questions remain about how microbiomes function and their direct impact on host health.

The first chapter explores the links between bacterial community function and the growth of purple pitcher plants (Sarracenia purpurea). We introduced three distinct bacterial communities into sterile pitchers to assess their effects on plant health. Different bacterial functions influenced plant traits, with communities rich in decomposition and secondary metabolite production traits leading to significantly larger …

Causes And Consequences Of Space-Use Behavior Under Predation Risk In A Free-Living System, Brian J. Smith

All Graduate Theses and Dissertations, Fall 2023 to Present

Predators can have important ecological effects through killing and eating their prey, the so-called consumptive effect, but predators can also have a nonconsumptive effect (NCE) on their prey – this happens when the risk of predation itself causes prey to alter their behaviors or other traits and these alterations ultimately reduce prey survival, reproduction, or population size. While scientists understand the consumptive effects of predators well, we are still unsure whether NCEs are important in free-living systems. In this dissertation, I sought to better understand the potential NCEs of predators (wolves and cougars) on elk in northern Yellowstone National Park …

Movement Behavior And Habitat Selection Of Juvenile Mountain Lions (Puma Concolor) During Three Behavioral States Of Dispersal, John F. Randolph

All Graduate Theses and Dissertations, Fall 2023 to Present

Juvenile dispersal, the act of moving from their natal range to the place where they eventually reproduce and establish an adult home range is hazardous. Juveniles must travel and find food across unfamiliar landscapes, where they must also cross roads, avoid harvest, and navigate developed landscapes. Despite the inherent dangers of dispersal, this demographic process is important for finding suitable mates and reducing inbreeding depression. Wildlife conservation concerns arise when individuals are unable to disperse due to a loss of connectivity, as this can negatively impact population demographics and genetic diversity. We explored the effects of hunting and human-developed landscapes …

Revegetation Strategies For Native Wetland Plant Restoration In The Face Of Phragmites Australis Reinvasion And Hydrologic Extremes, Maddie Houde

All Graduate Theses and Dissertations, Fall 2023 to Present

Reestablishing native plant communities in degraded habitats through seeding or planting ("revegetation") is a necessary step to restore ecosystems and their functions (e.g., supporting biodiversity, nutrient cycling, etc.). Globally, wetlands have suffered high rates of degradation and also experience numerous invasions. Invasive species are those that cause environmental, economic, or societal harm. Phragmites australis is a widespread invasive species that outcompetes native plants and reduces habitat diversity. Reestablishing native plant communities can limit P. australis invasion, yet effective methods to do so remain somewhat untested in wetlands. Additionally, stressful environmental conditions can increase plant mortality in revegetation efforts. In semi-arid …

Experimental Nonnative Wood Addition Enhances Instream Habitat For Native Fishes And Investigating Dryland River Alterations, Benjamin J. Miller

All Graduate Theses and Dissertations, Fall 2023 to Present

The rivers of the Colorado River Basin (CRB) have been degraded by human activities such flow regulation, water overallocation, and the introduction of invasive riparian vegetation (primarily tamarisk tamarix spp. and Russian olive Elaeagnus angustifolia). These stressors have resulted in widespread habitat loss and simplification, which is a major contributor to the endangerment of native fishes in the CRB.

The objectives of this study were to 1) assess the effectiveness of enhancing native fish habitat by experimentally adding cut wood from nonnative Russian olive to the San Juan River, a highly degraded dryland river, and 2) determine the …

Mapping Quaking Aspen Using Seasonal Sentinel-1 And Sentinel-2 Composite Imagery Across The Southern Rockies, Usa, Maxwell Cook, Teresa Chapman, Sarah Hart, Asha Paudel, Jennifer Balch

Aspen Bibliography

Quaking aspen is an important deciduous tree species across interior western U.S. forests. Existing maps of aspen distribution are based on Landsat imagery and often miss small stands ( < 0.09 ha or 30 m²), which rapidly regrow when managed or following disturbance. In this study, we present methods for deriving a new regional map of aspen forests using one year of Sentinel-1 (S1) and Sentinel-2 (S2) imagery in Google Earth Engine. Using observed annual phenology of aspen across the Southern Rockies and leveraging the frequent temporal resolution of S1 and S2, ecologically relevant seasonal imagery composites were developed. We derived spectral indices and …

Modelling And Mapping Of Forest Biodiversity Indicators Using Sentinel-2 And Planetscope Remotely Sensed Data, Diana L. Tesha, Ernest W. Mauya, Sami D. Madundo

Tanzania Journal of Science

Tropical montane forests harbour exceptionally high biodiversity yet face severe threats from human activities. Assessing forest biodiversity over large areas is crucial yet extremely challenging. Remote sensing provides an efficient monitoring solution, but few studies have focused on Tanzania's diverse, montane forests. We collected field data on tree species composition within 159 plots across montane forests in Tanzania's West Usambara region. We calculated species richness, evenness, and Shannon diversity index as indicators of tree diversity. Using Sentinel-2 and PlanetScope satellite imagery, we derived spectral, textural, and vegetation index predictors to model these indices via generalized additive models and extreme gradient …

Notes On North American Butterflies, 1, Harry Pavulaan

The Taxonomic Report of the International Lepidoptera Survey

New natural history elements and distribution records of several North American butterflies are reported. Taxonomy is often driven by geographical analyses. Cartography, coupled with internet-based imagery, opens up a promising wealth of information, allowing avocational researchers a tool by which inconvenient visits to institutional collections are no longer necessary for resolving some basic questions. While diversity and distribution of butterflies in North America are commonly believed to be fully known, the findings presented here show that much is yet to be learned of our butterfly fauna.

Monitoring Selenium Bioaccumulation In False Map Turtles (Graptemys Pseudogeographica), Grant M. Budden

Honors Thesis

Selenium is an element that becomes bioactivated in aquatic environments. Selenium bioaccumulation may threaten a South Dakota state-threatened species, the False Map Turtle (Graptemys pseudogeographica). Invertebrate filter feeder species like zebra mussels (Dreissena polymorpha) uptake selenium via exposure. Previous laboratory work has found that False Map Turtles consume large amounts of zebra mussels throughout the summer, leading to selenium bioaccumulation from selenium transfer from prey to predator. A myriad of adverse effects, like selenosis, reproductive infertility, and death, are associated with high selenium concentrations. Sampling was completed on False Map Turtles in the summer of 2022. …

Ecosystem Response To Increasing Hurricane Disturbance: Comparing Nutrient Cycling Dynamics Associated With Early- And Late-Successional Tree Species In A Wet Tropical Forest, Miriam Kleit

Biology Honors Projects

Puerto Rico has seen changes in the frequency and severity of disturbances in recent years as hurricanes become more frequent and more intense under climate change. In ecosystems experiencing increasing disturbances, we expect that species composition will shift as early successional trees become more common. These changes to species composition and community ecology are likely to affect terrestrial nutrient cycling both directly and indirectly, and it is still not well understood how shifting community composition may alter ecosystem functioning. To address this gap, I measured carbon (C) and nitrogen (N) variables in soils, microbial biomass, roots, leaves, and soil greenhouse …

New Records Of Mesobuthus Mesopotamicus (Penther, 1912) In Iraq And Mesobuthus Faiki Sp. Nov. From Turkey (Scorpiones: Buthidae), Ersen A. Yağmur, František Kovařík, Victor Fet, Ridvan Kurt, Fenik S. Hussen, Azhar M. Al-Khazali, Hamid S. Kachel, Ali A. Al-Fanharawi

Euscorpius

New locality records for Mesobuthus mesopotamicus (Penther, 1912) are given from Iraq. The populations from southeastern Turkey, earlier identified as M. mesopotamicus by Kovařík et al. (2022), are examined and compared with the specimens from the area close to the type locality of M. mesopotamicus. These populations are described as a new species, Mesobuthus faiki sp. nov. Detailed illustrations of both species and a map are given.

An Examination Of The Eastern Nebraska And Western Iowa Flash Flood Event Of 6-7 August 1999, Catherine M. Zapotocny

National Oceanographic and Atmospheric Administration: Technical Reports and Related Materials

Flash flooding occurs each summer in eastern Nebraska and western Iowa. While 10-inch rains are extraordinary, it is not uncommon to have at least one excessive rain event during the annual convective season. A significant flash flood occurred in east central Nebraska and western Iowa the night of August 6, 1999 into the morning of August 7, 1999. Antecedent hydrologic conditions limited the loss of life, however considerable property damage resulted as the heavy rain fell over the urbanized areas in eastern Nebraska and western Iowa.

Several flash flood ingredients came together over the area. These meteorological factors are typical …

Using Edna To Assess Impacts Of Oyster Restoration On Ecosystem Biodiversity At A Heavily Impacted Coastal Lagoon, Dominique Di Domenico, Emily Bonacchi, Elizabeth Suter

Molloy Multidisciplinary Undergraduate Research Conference

The Great South Bay (GSB), a bar-built, temperate, coastal lagoon on the south shore of Long Island, New York, USA, is a highly modified estuary due to heavy urbanization and suburbanization in the last century. GSB historically provided up to 50% of the nation’s hard clam (Mercenaria mercenaria) harvest, and is the legal home of the “Blue Point” oyster (eastern oyster; Crassostrea virginica). However, due to overexploitation as well as persistent stress from ongoing nitrogen pollution and harmful algal blooms, shellfish populations are fractions of their original abundances. Restoration efforts in GSB, driven both by community efforts …

Net Fluxes Of Broadband Shortwave And Photosynthetically Active Radiation Complement Ndvi And Near Infrared Reflectance Of Vegetation To Explain Gross Photosynthesis Variability Across Ecosystems And Climate, Kanishka Mallick, Joseph Verfaillie, Tianxin Wang, Ariane Arias Ortiz, Daphne Szutu, Koong Yi, Yanghui Kang, Robert Shortt, Tian Hu, Mauro Sulis, Zoltan Szantoi, Gilles Boulet, Joshua B. Fisher, Dennis Baldocchi

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

A significant challenge in global change research is understanding how vegetation interacts with the environment to influence ecosystem gross primary productivity (GPP) through carbon assimilation. One emerging objective is to consistently predict GPP fluctuations worldwide by establishing a robust scaling relationship between GPP measured at flux towers and satellite spectral reflectance data. However, a major hurdle in achieving this goal is the discrepancy in spatial resolution between early satellite measurements and eddy flux measurements. By using a large set of growing season data covering 100 site-years in North and Central America, we explored the potential of transforming incident and reflected …

Scorpions Of The Horn Of Africa (Arachnida: Scorpiones). Part Xxxii. Barbaracurus Hofereki Sp. N. From Djibouti, František Kovařík

Euscorpius

Barbaracurus hofereki sp. n. from Djibouti is described and compared with other species of the genus. B. hofereki sp. n. is the only species of the genus with pedipalp movable finger with 8 rows of granules and pectinal tooth count 27–28 in female. Also, its pedipalp chela with very narrow manus (chela length/width ratio 6.07 in female), narrower than in all other African species of the genus. A map of the distribution of the genus in the Horn of Africa and the Arabian Peninsula is provided.

Euhaplorchis Sp. A Effect On Social Behavior And Familiarity Of Gulf Killifish (Fundulus Grandis), Hannah Bauman

All HCAS Student Capstones, Theses, and Dissertations

Trophically transmitted parasites may manipulate their hosts’ phenotype (e.g., behavior, physiology, morphology) to increase the likelihood of transmission to the definitive host. In fishes, stable social groups develop familiarity over time through repeated interactions among individuals, and social preferences are often developed due to familiarity. Consequently, fishes often shoal with familiar fishes, a behavior that is likely to be protective against predation. Parasites may alter fish social dynamics in two ways: by decreasing association with familiar individuals, thereby isolating infected fish and making them more susceptible to predation by definitive hosts; and/or by incentivizing uninfected individuals to avoid infected fish …

Trophic Ecology Of Black Swallowers (Scombriformes: Chiasmodontidae: Chiasmodon) In The Deep-Pelagic Gulf Of Mexico, Travis J. Kirk

All HCAS Student Capstones, Theses, and Dissertations

The ecology of deep-pelagic predatory fishes remains poorly understood despite their importance as ecosystem regulators and energy transfer vectors. This study investigated the trophic ecology of three species of the predatory fish genus Chiasmodon (“black swallowers”) in the Gulf of Mexico, a region that serves as an analog for the global low-latitude deep pelagial, the world’s largest cumulative ecosystem. Foraging habits (e.g., selectivity, chronology, daily ration) of an “advanced” evolutionary fish in a system that is otherwise dominated by basal fish taxa, were quantitatively estimated via high-resolution stomach content analysis. A quantitative dataset of both predator and prey abundance, the …

Quantifying How Natural History Traits Contribute To Bias In Community Science Engagement: A Case Study Using Orbweaver Spiders, John Deitsch, Angela Chuang, David R. Nelsen, Michael Sitvarin, David Coyle

Achieve

Online citizen science platforms can be crucial to the scientific and regulatory community, but inherent biases based on organism traits can influence the likelihood of a species being reported and accurately identified. We explored how traits of orb weaving spiders impact data in iNaturalist, using the invasive Jorō spider as a case study. This species is an outlier among orbweavers due to its large size and bright coloration, and was the most frequently reported species, with the most identifications and research-grade observations. It was also reported by less experienced users on average, highlighting its potential role as a gateway species …

Assessment Of Thermal Preferences And Critical Temperature Tolerance Polygons On Mangrove Fish And Invertebrates From South Florida, Jailynn Konkler

All HCAS Student Capstones, Theses, and Dissertations

Mangroves serve as important nursery habitats for several species of subtropical fishes and invertebrates. Southeastern Florida mangrove environments have experienced an increasing frequency of strong hot and cold weather front systems, but little information is known about the temperature thresholds for mangrove-associated prey species that lethally disrupts homeostasis. To assess the vulnerability of mangrove-associated prey species to these short-duration temperature fluctuations, critical thermal methodology (CTM) was used to determine thermal tolerances for two fishes and two invertebrates, using loss of equilibrium (LOE) as the endpoint to determine CTmax and CTmin values as a survivable proxy for death. Physiological tolerances were …

The Decline In Monarch Butterfly, Danaus Plexippus, Populations: An Example Of The Global Threat To Biodiversity, Olivia Sidoti

Honors Projects

Biodiversity encompasses the variety of all life on Earth and how these aspects of nature interact with each other. To have stable and abundant biodiversity, vast amounts of species and organisms are required within an ecosystem. As a result of the increase in negative impacts of human activities and behaviors on the health of nature, biodiversity has been decreasing. An example of the decrease in biodiversity is depicted by the recent decline of the monarch butterfly species. The monarch butterfly is an iconic North American insect that is experiencing a decline in its population due to threats such as deforestation, …

Influence Of Forest Management On Bumblebee-Plant Networks And Community Compositions In Eastern Kentucky Forest Openings, Kassandra Carter

Online Theses and Dissertations

Both the productivity of agricultural systems and functioning of terrestrial ecosystems are reliant on animal pollinators to facilitate plant reproduction. Yet the integrity of these pollination services is threatened by the declines of pollinators. Mounting evidence indicates landscape homogenization in agricultural, urban, and most notably in natural systems have corresponded with substantial changes in bumblebee distribution, abundance, composition, and forage resource availability. Naturally occurring forest openings, barrens, and grasslands have historically provided important habitat for native bees across the otherwise forested landscape in the eastern United States. Fire suppression and the loss of these important habitats are well-documented, but it …

Sustainability And Drivers Of Populus Tremuloides Regeneration And Recruitment Near The Southwestern Edge Of Its Range, Connor D. Crouch, Nicholas P. Wilhelmi, Paul C. Rogers, Margaret M. Moore, Kristen M. Waring

Aspen Bibliography

Quaking aspen (Populus tremuloides Michx.) ecosystems are highly valued in the southwestern United States because of the ecological, economic, and aesthetic benefits they provide. Aspen has experienced extensive mortality in recent decades, and there is evidence that many areas in Arizona, United States lack adequate recruitment to replace dying overstory trees. Maintaining sustainable levels of regeneration and recruitment (i.e. juveniles) is critical for promoting aspen ecosystem resilience and adaptive capacity, but questions remain about which factors currently limit juvenile aspen and which strategies are appropriate for managing aspen in an increasingly uncertain future. To fill these critical knowledge gaps, …