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Global Change Effects On Carbon Cycling In Terrestrial Ecosystems, Guopeng Liang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since terrestrial ecosystems store approximately 3 times more carbon (C) than the atmosphere, they have a significant effect on the atmospheric CO₂ concentration. Although many studies have been conducted to determine global change effects on C cycling in terrestrial ecosystems, the underlying mechanisms remain uncertain. To address this knowledge gap, I utilized meta-analysis, laboratory experiments, and soil microbial community analysis.

In chapter 2, I conducted a meta-analysis to examine whether effects of long-term N addition on plant productivity can shift over time. I found that 44% of studies showed a marked trend (increase or decrease) in the strength of …

Keeping Your Cool: Thermoregulatory Performance And Plasticity In Desert Cricetid Rodents, Richard W. Ramirez, Eric A. Riddell, Steven R. Beissinger, Blair O. Wolf

Biology ETDs

Small mammals in hot deserts often avoid heat via nocturnality and fossoriality and are thought to have a limited capacity to dissipate heat using evaporative cooling. Research to date has focused on thermoregulatory responses to air temperatures (T_a) below body temperature (T_b). Consequently, the thermoregulatory performance of small mammals exposed to high air temperatures is poorly understood, particularly responses across geographic and seasonal scales. We quantified the seasonal thermoregulatory performance of four cricetid rodents (Neotoma albigula, N. lepida, Peromyscus eremicus, P. crinitus) exposed to high T_a, at four sites …

Fish Community Assembly At Multiple Spatial Scales In East Texas Streams, Jake R. Swanson

Electronic Theses and Dissertations

Stream communities are structured by environmental processes that vary in strength across different spatiotemporal scales. Therefore, revealing how stream fish communities are influenced by environmental gradients may clarify how communities respond to disturbance associated with anthropogenic change. I investigated the relative role environmental variables play in the processes that structure the taxonomic and functional diversity of stream fish communities, as well as historical trends in occurrence and local habitat associated with a species of greatest conservation need within east Texas. The results of this study indicate that stream sites with more habitat complexity and stability support a more taxonomically and …

Oystershell Scale: An Invasive Threat To Aspen Conservation, Amanda M. Grady, Connor D. Crouch, Nicholas P. Wilhelmi, Richard W. Hofstetter, Kristen M. Waring

Aspen Bibliography

Aspen decline is an acute and chronic problem in Arizona, where high levels of overstory mortality and a lack of recruitment continue to be observed. Oystershell scale (Lepidosaphes ulmi; OSS), an invasive sapsucking insect, has recently become widespread in native aspen stands in the southwestern U.S., further contributing to aspen mortality. Damage is severe in lower elevation stands and within ungulate exclosures created to conserve aspen. Young recruiting aspen that are rare on the landscape incur high levels of OSS-caused mortality when infested (Fig. 1). OSS has only recently become a pest of concern in the Southwest and …

Using Community Science To Assess The Effect Of Wing Pattern And Weather On Butterfly Behavior, Abbigail Merrill

Animal Science Undergraduate Honors Theses

Signaling in insects is used as communication and for attraction of mates. The physical appearance of the insect as well as conditions such as weather can play a role in visual signaling, by influencing the wavelengths of light available, and subsequent signal detection. We do not know, however, whether signals butterflies present broadly correlate with how they behave. In this study, we looked at the wing patterns and behavior of butterflies in Northwest Arkansas over a 3.5-year period to assess the relationship between wing pattern, weather, and behavior. We used observational data collected by hundreds of University of Arkansas students …

Native And Non-Native Ant Impacts On Soil Microbes, Hannah A. Stewart

Biology Theses

Organisms produce chemical weapons for defense, but target organisms can develop resistance. In their introduced range, non-native species may bring “novel weapons” against which native organisms have not co-evolved resistance. The invasive European fire ant (Myrmica rubra) may have brought antimicrobial secretions to the Northeastern United States that are novel weapons against native fungal and bacterial soil organisms. I hypothesized that M. rubra would better inhibit seed pathogens resulting in greater emergence of native myrmecochorous Viola sororia seeds and, as a side effect, more strongly inhibit arbuscular mycorrhizal fungi than a native seed dispersing ant (Aphaenogaster picea …

Plant-Pollinator Communities Responsive To Local And Landscape Level Factors In Grassland Restorations., Aaron Sexton

Electronic Theses and Dissertations

As humans continue to degrade natural ecosystems via greenhouse gas emissions and habitat destruction, many species are being pushed to the brink of extinction. In hopes to offset this degradation, habitat restoration attempts to restore ecosystem function to an improved state resembling intact, remnant values. This is a difficult, but important, undertaking with factors to consider at multiple spatial and temporal scales. The restoration and conservation of pollinator communities has garnered heightened attention because of the valuable ecosystem services they provide. This dissertation investigates the local and landscape level factors of grassland restorations that influence plant-pollinator communities. I used a …

Nitrogen Availability In Dune Systems And Its Effect On Root Fungal Endophyte Communities., Haley E. Sage

College of Arts & Sciences Senior Theses

As global change persists, changes in resource availability can influence plant-microbe interactions. To understand how resource availability can influence these interactions and species diversity, I focused this research on how varying nitrogen (N) levels affect root endophyte communities in the plant species Ammophila breviligulata, an ecosystem engineer in the dune system. I analyzed the relationship between nitrogen addition and microbial community composition across 60 plots treated with three nitrogen addition levels (control, low, and high) in a long-term experimental field site in the Lake Michigan dunes. I identified Ammophila breviligulata's root endophyte community after creating a culture collection and …

Incorporating Human Effects In Quantifying Mechanisms Of Stream Fish Community Structure Using Metacommunity Theory, Lauren E. Stoczynski

All Dissertations

Metacommunity theory incorporates local and regional factors to understand how biotic communities are structured across the landscape. Despite established knowledge of how humans impact aquatic systems, inclusion of anthropogenic factors in metacommunity studies have been largely ignored. Additionally, alpha, beta, and gamma diversity can all be explored at the metacommunity level to investigate mechanistic drivers of community structure. Beta diversity can be further partitioned into turnover and richness difference components, each with different mechanistic drivers. Streams provide an excellent study system for metacommunity research because of the dendritic structure of watersheds and the natural delineation that watershed boundaries provide. Large-extent …

Examining The Invasion Of Bush Honeysuckle Through A Phylogenetic Analysis, Phoebe Bruffett

Biological Sciences Undergraduate Honors Theses

The mechanisms underlying the continual spread of invasive plants within their respective non-native ranges is a major focal point to invasion research. Many theories have been proposed to understand these invasions, each with different implications for the predicted range for invasive plants. Lonicera maackii provides an exceptional opportunity to examine the effectiveness of these theories to explain the trends of invasive plants. Lonicera maackii is native to eastern Asia, but has invaded much of the eastern United States, presenting a severe threat to the health of forest and other natural areas. Recent analysis of the climatic envelopes uncovered a significant …

Investigating The Potential Role For The Nervous System In Controlling Regeneration In Nematostella Vectensis, Kristen Malir

Biological Sciences Undergraduate Honors Theses

Nematostella vectensis is a marine sea animal that has become a model for developmental and evolutionary research. Included in the phylum Cnidaria, N. vectensis’ was chosen as the model for this research. Not only can this animal go through asexual and sexual reproduction, but it also has the ability to regenerate. Although much research has been put forth in an effort to understand regeneration better, much is still unknown. The underlying mechanisms of regeneration in Cnidaria are illusive; however, studies within vertebrates have shown the substantial role of the nervous system. The objective of this experiment is to test if …

The Synchronization Of Nocturnal Pollinator Behavior And Apple Flower Nectar Production, Madison Jennings

Biological Sciences Undergraduate Honors Theses

Insects perform an essential ecological service by facilitating the pollination of crops for food production worldwide. Recent declines in diurnal bee populations threaten food security and has led to growing concerns about existent pollination methods. Pollination contributions by native nocturnal insects have been documented to occur in a variety of systems, thought to be supported by the plant’s attractant and reward system. If this is the case, pollination of flowers by nocturnal vectors may be influenced by circadian cycles of nectar production and insect activity. To test this hypothesis, we recorded insect abundance of nocturnal pollinators periodically throughout the night …

Using Ai To Examine Nocturnal Moth Pollination, Conor Moriarty

Biological Sciences Undergraduate Honors Theses

The importance of insect-mediated agriculture cannot be understated especially in the wake of pollinator population declines. Most research of insect-mediated pollination is focused on diurnal pollinators like the honeybee (Apis mellifera). Deepening our understanding of how other pollinators, such as nocturnal pollinators, can benefit agriculture and ecosystems will be very important as honeybee populations decline. I explored nocturnal moth interactions with flowering apple flowers during their pollination season to better understand how these nocturnal pollinators interact with the plants. To accomplish this, I used a University of Arkansas farm area with a dedicated apple orchard. I gathered my raw data …

Winter Cover Crop Impacts On Weed Dynamics In Eastern And Central Nebraska, Elizabeth Ann Oys

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Reducing tillage in cropping systems causes weed management to be dependent on chemical and cultural methods for weed control. Over time, herbicide-resistant weeds have developed due to the continuous selection pressures from herbicides, particularly in the Midwest Corn Belt. Integrated weed management strategies, such as cover crops, can be used to mitigate some of these issues. Cover crops are primarily known for their soil health benefits, but there is evidence that cover crops can suppress weeds. However, less research has been done at the field-scale level to address cover crop impacts on the weed seedbank and aboveground weeds during the …

Effects Of Vegetation Heterogeneity On Multiphasic Treatment Outcomes In Sagebrush Steppe, Rebecca Donaldson

Boise State University Theses and Dissertations

Exotic annual grass invasion into western North America has led to significant loss of native perennials, altering the structure and function of sagebrush-steppe ecosystems. Monitoring and assessment of necessary restoration treatments have provided mixed evidence of success. We hypothesized that treatment outcomes would be influenced by restoration strategy (e.g., the timing of herbicide or drill seeding) and by within-treatment vegetation heterogeneity. We evaluated exotic annual grass and exotic perennial forb response to three replicate treatments of the pre-emergent herbicides indaziflam and imazapic, and a combination treatment of both herbicides, followed with the broadleaf herbicide, aminopyralid, at a highly invaded site …

Sex, Body Size, And Winter Weather Explain Migration Strategies In A Partial Migrant Population Of American Kestrels (Falco Sparverius), Sadie Claire Ranck

Boise State University Theses and Dissertations

Partially migratory systems describe populations that consist of both individuals that migrate away from the breeding grounds for the winter, and others that remain resident near their nesting sites year-round. Partial migration is the most common type of migration across all animal taxa, but the evolution, maintenance, and consequences associated with different movement strategies are still poorly understood. Studying the factors that drive migratory strategies and the associated consequences of those decisions is important to understand how migratory animals may adapt to climate change. Partial migrant populations offer a great opportunity for which to study these questions because individuals with …

The Effects Of Roads On Movement, Flight Dynamics, Occupancy, And Productivity In Barn Owls (Tyto Alba), Brian Thomas Busby

Boise State University Theses and Dissertations

Barn Owls (Tyto alba) are a species of conservation concern in many portions of their cosmopolitan range. One important factor contributing to population declines and sometimes local extirpations is roads, which can cause direct mortality through Barn Owl-vehicle collisions, fragment habitat, limit dispersal and movement, and imperil long-term population viability. However, the effects of roads on Barn Owl reproduction are less clear. Further, the cumulative effects of roads on Barn Owls can be dependent on how they respond to them. Road and traffic responses of animals have been classified into four categories: 1) speeders, who increase speed to …

Reconstructing Bison And Mammoth Migration During The Late Pleistocene And Early Holocene Of Central Texas Using Strontium Isotopes, Joshua John Porter

Graduate Theses and Dissertations

During the Late Pleistocene (LP; past 130,000 years), over two-thirds of large mammal (>45kg) species went extinct globally. While the role of humans is hotly debated, the effect of these extinctions is growing clearer; the extinctions resulted in widespread and lasting faunal community reorganization. However, the impact of these extinctions on dietary and migratory behavior within faunal communities is unknown. Our study examines the impact of the megafaunal extinctions on the dietary and migratory behavior of surviving Bison individuals in Texas using carbon, oxygen, and strontium isotopes. Strontium isotopes are incorporated into mammalian enamel during their tooth development and …

The Effects Of Dissolved And Suspended Solids On Freshwater Meiofauna, Jessica Cline

Honors Theses

Meiofauna include small-sized animals (< 1mm) distributed in all aquatic ecosystems on Earth, where they play fundamental trophic and ecological roles. The biodiversity of marine meiofauna and its links with anthropogenic activities is routinely investigated, however, freshwater communities are less known. This is particularly true for the Southeastern United States, which is greatly investigated and elected a hotspot of biodiversity for larger species but very little is known about the meiofauna. The purpose of this research is to reveal the biodiversity of meiofauna from the Tennessee River and test for potential correlations with anthropogenic activities. As a proxy for pollution, dissolved and suspended solids were considered in this study. The research hypothesis is that meiofaunal biodiversity would be affected by possible changes of dissolved and suspended solids in the water column. Possible mechanisms causing biodiversity shifts could be ascribed to osmotic stresses of animals to cope with variation in dissolved solids or, more indirectly, because different sunlight penetration caused by suspended solids would affect primary production. To test the hypothesis, water samples were collected from nine stations located along the Tennessee River in Hamilton County. Each station was visited three times, and, during each visit, environmental parameters (including dissolved and suspended solids) were measured. Meiofauna biodiversity (estimated as richness, community composition, and phylogenetic diversity) was revealed using a metagenomic approach. Statistical analyses were applied to test for possible correlations between the biodiversity estimates and the measured environmental parameters. Results show a high biodiversity of meiofauna with more than 200 amplicon-sequence variants distributed across 10 metazoan phyla. Environmental conditions are highly variable among stations and statistical analyses show that while both dissolved solids (TDS) and turbidity (suspended solids, NTU) did not significantly affect meiofauna biodiversity in the collected samples, various other water, and sediment metrics were found to be significant predictors of meiofauna biodiversity. In conclusion, the results of this project not only reveal for the first time the meiofauna biodiversity from the Tennessee River, but also suggest that meiofauna could be used as bioindicators for several anthropogenic activities in freshwater ecosystems.

Habitat Preference Of F. Notatus And F. Olivaceus From A Reversed Hybrid Zone, Elizabeth Hart Williams

Honors Theses

Understanding the mechanisms driving habitat preference throughout an organism’s life opens doors to the further understanding of the origins of diversity. Two species of minnow, Fundulus notatus and Fundulus olivaceus, are ideal for ecological research on habitat preference. Ordinarily, F. notatus and F. olivaceus display habitat preferences of downstream and upstream, respectively, with minimal coexistence at confluences. However, in some drainages, these preferences are flipped, like those in the Tombigbee River basin. Members of both species were collected from the Tombigbee River, tagged with species and sex specific colored elastomer marks, and placed in either a homogeneous control or …

Understanding The Role Of Small Mammals In Arctic Biogeochemical Cycling, Austin Roy

Open Access Theses & Dissertations

Small mammals play an integral role in their ecosystems. This is especially true in northern ecosystems, where small mammals represent both top-down and bottom-up forces and can have strong effects on ecosystem function through affecting biogeochemical cycling. Despite these important effects, the role of small mammals in influencing biogeochemical cycling has been largely underappreciated in the understanding of arctic ecosystems, leading to a call to better understand how small mammal herbivores impact ecosystem processes including carbon cycling. The overarching goal of this dissertation is to assess how biogeochemical cycling is affected by small mammal herbivore presence, behavior, and population dynamics …

Relative Palatability And Efficacy Of Brodifacoum-25d Conservation Rodenticide Pellets For Mouse Eradication On Midway Atoll, Peter J. Kappes, Shane R. Siers, Israel L. Leinbach, Robert T. Sugihara, Wesley J. Jolley, Jonathan H. Plissner, Elizabeth N. Flint, Kelly L. Goodale, Gregg R. Howald

United States Department of Agriculture Wildlife Services: Staff Publications

Invasive mice (Mus spp.) can negatively impact island species and ecosystems. Because fewer island rodent eradications have been attempted for mice compared to rats (Rattus spp.), less is known about efficacy and palatability of rodenticide baits for mouse eradications. We performed a series of bait acceptance and efficacy cage trials using a standard formulation of brodifacoum-based rodenticide on wild-caught mice from Sand Island, Midway Atoll, to help inform a proposed eradication there. Mice were offered ad libitum brodifacoum pellets along with various alternative food sources, and a “no choice” treatment group received only bait pellets. Mortality in the no choice …

Risk-Prone And Risk-Averse Foraging Strategies Enable Niche Partitioning By Two Diurnal Orb-Weaving Spider Species, Mitchell D. Long

Electronic Theses and Dissertations

Niche partitioning is a major component in understanding community ecology and how ecologically similar species coexist. Temporal and spatial partitioning and differences in foraging strategy, including sensitivity to risk (variance), likely contribute to partitioning as well. Here, we approach this partitioning with fine resolution to investigate differences in overall strategy between two species of diurnal, orb-weaving spiders, Verrucosa arenata and Micrathena gracilis (Araneae: Araneidae), that share similar spatial positioning, temporal foraging window, and prey. Through field observation, we found that V. arenata individuals appear to increase spatial and temporal sampling to compensate for an overall risk-prone strategy that depends on …

Intercontinental Movement Of Highly Pathogenic Avian Influenza A(H5n1) Clade 2.3.4.4 Virus To The United States, 2021, Sarah N. Bevins, Susan A. Shriner, James C. Cumbee Jr., Krista E. Dilione, Kelly E. Douglass, Jeremy W. Ellis, Mary Lea Killian, Mia K. Torchetti, Julianna B. Lenoch

United States Department of Agriculture Wildlife Services: Staff Publications

We detected Eurasian-origin highly pathogenic avian influenza A(H5N1) virus belonging to the Gs/GD lineage, clade 2.3.4.4b, in wild waterfowl in 2 Atlantic coastal states in the United States. Bird banding data showed widespread movement of waterfowl within the Atlantic Flyway and between neighboring flyways and northern breeding grounds.

Evolution Of Floral Microbes And The Resulting Effects On Pollinator Preference, Hailey Hatch

Undergraduate Honors Capstone Projects

Floral microbes are an overlooked aspect of the extended floral phenotype. Through altering floral nectar chemistry, they can mediate interactions between flowers, pollinators, and other floral microbes, with significant implications for plant and pollinator health. Interactions between floral microbes and pollinators are critically important to understand, as pollinators provide important ecosystem services in both natural and agriculture systems. Here, I explored how floral nectar traits affected both evolution and competition within the floral yeast Metschnikowia reukaufii, the floral bacterium Bacillus subtilis, and other microbes isolated from Brassica rapa nectar, an important plant model system and oilseed crop. To …

Study Of Adaptive Radiation Effects On Sprint Performance In Anolis Ecomorphs, Alexander J. Bergeson

Honors Thesis

Anolis lizards have become model organisms for the study of adaptive radiation and convergent evolution due to repeated patterns of specialization that allow them to live in different environmental niches within the habitats they occur. As part of a suite of adaptations for living in specific habitats, many species have repeatedly evolved specific changes in anatomy and physiology that make them better able to perform and survive in their surroundings. These specialized forms are referred to as “ecomorphs” based on their preferred habitats and have been well documented among Caribbean anoles. Mainland species, on the other hand, are less studied. …

Site Fidelity Of Bottlenose Dolphins (Tursiops Truncatus) Using Elemental Analyses And Photo-Identification, Lauren R. Clance

Graduate Theses and Dissertations (2019 - present)

The objective of this study was to determine if bottlenose dolphins (Tursiops truncatus) in Alabama waters acquire location-specific elemental signatures indicative of site fidelity. I measured trace metal concentrations (Chapter II) and stable isotope ratios (Chapter III) in skin from free-ranging dolphins remotely biopsied in Mobile Bay, the northern Gulf of Mexico (Gulf) and eastern Mississippi Sound (EMSS). Elemental findings were corroborated with photo-identification data. I found that dolphins acquired some location-specific elements indicative of site fidelity, with the greatest differences at geographic extremes, particularly relative to salinity. For trace metals, highest concentrations were found in winter, consistent with higher …

Alfred Russel Wallace Notes 21: Wallace & The Doorway To The Universe, Charles H. Smith

Faculty/Staff Personal Papers

An important yet largely unrecognized theme in the thought of Alfred Russel Wallace (1823−1913) was his insistence that all dependably-reported phenomena, even those of aberrant nature, were worthy of a respectful kind of attention: that is, a kind which did not automatically banish difficult subjects to the realm of myth or superstition. In this work, Wallace’s philosophy in this direction is documented, and linked to the world of post-Age-of-Enlightenment revisionism.

Severe Hypoxia Up-Regulates Gluconeogenesis In Daphnia, Morad C. Malek

Undergraduate Honors Theses

Hypoxia is a significant low oxygen state that has complex and diverse impacts on organisms. In aerobes, various adaptive responses to hypoxia are observed that vary depending on the level of oxygen depletion and previous adaptation, hence the continued attention to hypoxia as an important abiotic stressor. Adaptive responses to hypoxia are primarily governed by the hypoxia-inducible factors (HIFs), which activate downstream genetic pathways responsible for oxygen transport and metabolic plasticity. In aquatic habitats, oxygen availability can vary greatly over time and space. Therefore, aquatic organisms’ adaptation to hypoxia is likely pervasive, especially in genotypes originating from waterbodies prone to …

Epidemiology And Impacts Of A Leaf Spot Disease In Veratrum Viride (Melanthiaceae), Leeah R. Sutton, Foster Levy

Undergraduate Honors Theses

Fungal phytopathogens can cause disease epidemics in crops, weeds, and
populations of native plants. To investigate the impact of a foliar phytopathogen on the native herbaceous species, Veratrum viride, a demographic and disease assessment was carried out on two high elevation grassy bald populations on Roan Mountain, Tennessee. A leaf spot disease impacted all plants in both populations, causing widespread premature senescence of leaves and stems. Disease severity increased over the course of the growing season. Based on host disease symptoms and fungal conidia morphology, Pseudocercosporella sublineolata was shown to be the causal pathogen. A study of herbarium specimens …