Ecology and Evolutionary Biology Commons^™

Investigating The Impact Of Psychoactive Plant Alkaloids On Bumblebee Behavior, Skylar Mathieson

Electronic Theses and Dissertations

The relationship between plants and their pollinators is often framed as a food-for-service exchange in which plants provide pollinators with nutrients in exchange for transport of their gametes. However, in addition to essential nutrients, many floral rewards (nectar, pollen) also contain defensive toxins such as alkaloids, with largely unexplored consequences for plant-pollinator interactions. I investigated how three psychoactive and addictive plant alkaloids — caffeine, nicotine, and morphine — affect foraging behavior in generalist bumblebees (Bombus impatiens) using robotic flowers. Each of these chemicals affected pollinator foraging behavior, influencing the number and duration of their visits to flowers in …

Drivers And Consequences Of Changes In Nectar Microbiome Composition Across Spatial And Biological Scales, Daniel A. Barker

Electronic Theses and Dissertations

Microbial communities inhabiting floral nectar, known as the nectar microbiome, are important mediators of plant-pollinator interactions. However, the ecological and environmental factors that shape the composition of these microbial communities remain poorly understood. While previous studies have examined the effects of a few microbial groups, typically independent of one another, on one plant or pollinator species, this dissertation takes a wide-scale approach to explore how abiotic conditions and biotic interaction’s structure microbial communities within floral nectar. Furthermore, I also quantify how variation in microbial richness and identity influences pollinator behavior and plant reproductive success.

This dissertation shows that microbial abundance …

Effects Of Sediment Composition On Spartina Alterniflora And Juncus Roemerianus Productivity In Coastal Virginia: A Thin-Layer Sediment Placement Experiment, Caitlin Hemphill

Biological Sciences Theses & Dissertations

Climate change poses a major threat to the health of estuaries and their coastal wetland systems. The Chesapeake Bay’s coastal salt marshes are at high risk of inundation due to sea-level rise and land subsidence. Restoration techniques for maintaining coastal marsh resistance to sea-level rise are being developed and refined, with thin layer placement (TLP) emerging as a feasible solution in many areas of the United States. Despite TLPs use across the country, additional research is needed on species-specific responses, sediment types, and geographically focused studies in the lower Chesapeake Bay. My research addresses these gaps by combining both greenhouse …

Assessing Long-Term Changes In Aspen Forest Cover In Northern Yellowstone National Park Before And After Carnivore Recovery, Nicholas J. Bergeron

All Graduate Theses and Dissertations, Fall 2023 to Present

The recovery of large carnivores (wolves, bears, cougars) in Yellowstone National Park and the subsequent decline of the area's elk herd have raised key questions about ecosystem restoration—particularly for species such as aspen, which are heavily browsed by elk. Following wolf reintroduction in the mid-1990s, scientists began tracking changes in browsing intensity and height of young aspen within sampling plots, assuming reduced browsing and taller stems were signs of population recovery. However, no studies have measured whether the total area covered by aspen stands actually increased, as would be expected with broader recovery. Moreover, the potential influence of climate change …

Endotherm Energetics Under Environmental And Physiological Constraints, Zachary Andrew David

Biological Sciences Theses & Dissertations

Metabolic rate governs how animals allocate energy toward maintenance, activity, growth, and reproduction, linking physiology to environmental context. This dissertation investigates how two endothermic mammals regulate metabolic rate in response to environmental variability, focusing on thermoregulatory flexibility and physiological constraints. Using flow-through respirometry, I measured resting metabolic rates (RMRs) in two complementary systems: tropical bears housed in semi-natural outdoor enclosures and marsh rice rats (Oryzomys palustris) exposed to controlled thermal treatments. Asiatic black bears (Ursus thibetanus) exhibited unexpectedly low mass-specific metabolic rates even under high ambient temperatures, yet their RMR increased with temperature, suggesting proximity to their …

Spatial And Thermal Aspects Of The Ecology Of Three Sympatric Rattlesnakes In The Montane Northern Chihuahuan Desert, Joshua James Mead

Open Access Theses & Dissertations

To understand how animals coexist on the landscape, the individual aspects of a species life history must first be understood. Animals need to find locations that provide the resources they need to survive. Movement, microhabitats, and temperature can alter such areas where animals occur. Understanding animal movements provide important information on space use and microhabitats on the landscape. Ectothermic animals must acquiesce to ambient temperatures or use behavioral modifications to alter their body temperature. The ability to maintain suitable body temperature is essential for physiological function, reproduction, and ability to avoid predation. Research on the variation in a species ecology …

Systematics Of African River Frogs (Anura: Pyxicephalidae: Amietia) In Central Africa, With The Description Of Two New Species, Jesus Manuel Reyes

Open Access Theses & Dissertations

Amietia is a pyxicephalid anuran genus that is prevalent throughout central, southern, and eastern portions of sub-Saharan Africa. Recent phylogenetic studies have been in conflict regarding the validity and composition of several Amietia species in the Albertine Rift region. The goals of this study are to: (1) generate an updated molecular phylogeny for Central African Amietia with new sampling; (2) clarify the relationship between the previously unsampled taxa A. amieti and A. chapini; (3) clarify the status of A. desaegeri; and (4) confirm the taxonomic status of potentially new species. Maximum likelihood and Bayesian inference methods were used to generate …

Phylogenetics And Integrative Taxonomy Of The Lang's Reed Frog Species Complex (Anura: Hyperoliidae: Hyperolius Langi), Dominic Troiani

Open Access Theses & Dissertations

The genus Hyperolius (Rapp, 1842) is the most speciose amphibian genus in sub-Saharan Africa. The genus has a complex taxonomic history because of its extensive intraspecific and interspecific morphological variation, large geographic distribution of many taxa, gaps in sampling, and the discovery of significant cryptic diversity within many species. The goal of this study is to understand the relationships and taxonomy of Hyperolius langi via an integrative taxonomic approach that combines molecular, morphological, and bioacoustics data to clarify the systematics of the geographically widespread species Hyperolius langi. Two mitochondrial (16S and cyt b) and one nuclear (RAG1) gene were used …

Coal Mining Reclamation: Lessons Learned From Tropical And Subtropical Countries, Priyaji Agung Pambudi, Suyud Warno Utomo, Roni Setyo Handoko

Journal of Environmental Science and Sustainable Development

This study addresses the persistent environmental challenges associated with coal mining in tropical and subtropical regions, where complex microclimates and ecological variability hinder effective reclamation. Despite the increasing global coal demand, comparative cross-country insights remain limited. This research fills the gap by evaluating the best practices. This study employs a qualitative methodology with a comparative case study design, uses systematic literature review to evaluate ecology based reclamation policies and implementation practices. Data were sourced from peer-reviewed journals from Scopus and the Web of Science database and institutional reports, and analyzed using McHarg’s landscape ecology theory to evaluate reclamation policies, ecological …

Methodology For Environmental Toxicology: Assessing Feeding And Rearing Strategies In Largemouth Bass (Micropterus Nigricans) Larvae, Amber Hitchins, Hannah Mcneese, Deise Cruz, Andrew Todd, Maria Sepúlveda, Tyler Hoskins

Discovery Undergraduate Interdisciplinary Research Internship

Poly- and perfluoroalkyl substances (PFAS) are an anthropogenic group of chemicals known for their persistence in the environment and their potential to bioaccumulate. PFAS can bioaccumulate in largemouth bass (Micropterus nigricans), yet the effects of exposure on bass larvae are unknown. While largemouth bass are commonly raised for aquaculture, techniques for rearing bass which enable controlled experiments at known densities, a necessity for toxicity studies, are poorly understood. Furthermore, the live prey typically used in existing approaches are not suitable for PFAS studies due to high background concentrations. The objective of this project was to assess different venues …

Assessing The Ecological Drivers And Consequences Of Partial Migration In Hudson River Striped Bass Over Three Decades, Caitlin Egan Zimmer

Biology ETDs

Climate change and shifts in human land use have caused extensive impacts to the connectivity, structure, and resilience of aquatic populations. Partial migration (PM), where only some individuals from a population migrate while the rest remain resident, can mitigate population-level responses to environmental stressors. However, little is known of the underlying mechanisms promoting variation in migration and whether these shift over time. In the Hudson River Estuary, striped bass (Morone saxatilis) are known to exhibit anadromous PM behavior. Here, I measured carbon isotopes (δ¹³C) of essential amino acids in striped bass scales to determine variation in …

The Island Biogeography Of Mangrove-Dwelling Vertebrates: Isolation, Specialisation, And Extinction, Jian Xiong David Tan

Biology ETDs

Mangroves are highly dynamic ecosystems that are widely distributed across the coastlines of the tropics and subtropics. Despite their low plant diversity, mangroves host a disproportionately high number of terrestrial vertebrate taxa. However, mangrove specialists — taxa that only occur in mangrove habitats — exhibit a global distribution that is incongruous with the broader background distribution patterns of mangrove-associated fauna, exhibiting higher diversity in Australia and Southeast Asia. This dissertation therefore aims to assess how the diversity and distribution of mangrove specialist fauna may have been shaped by the historical biogeography of mangroves, and the effects of mangrove specialisation on …

Plant Reproductive Strategies Shift In Response To Restoration Using Beaver Dam Analogs, Laurel F. Martinez

Biology ETDs

As riparian communities become increasingly degraded, restoration treatments are being implemented in streams to recover ecosystem functions. In the Jemez Mountains, beaver dam analogs (BDAs) are used to restore degraded streams by connecting the floodplain and increasing the extent of anoxic soil conditions. These environmental disturbances are expected to alter how riparian plants recruit, particularly their allocation to seed-based and vegetative regeneration strategies. We investigated whether BDAs and associated changes in soil water filled pore space (WFPS) affected riparian plant recruitment. We investigated the number of flowering stems as a proxy for seed-based regeneration and rhizome length and mass as …

Using Triple Oxygen Isotopes To Investigate Water Usage In Desert Ecosystems, Cloe V. Knutson

Earth and Planetary Sciences ETDs

In arid environments, maintaining water balance can be more critical for survival than obtaining food. As droughts intensify, understanding how animals manage body water is essential. Triple oxygen isotope analysis provides a novel way to trace water sources in animals, distinguishing contributions from free water, food-derived oxygen, and atmospheric O₂. We developed an equilibration method using CO₂–H₂O oxygen exchange and measured δ^’18O and Δ^’17O values via tunable infrared laser direct spectroscopy (TILDAS). Validated against traditional fluorination methods, this technique enables streamlined analysis of whole blood and plant samples. Applied to …

Nitrogen Addition Additively Boosts Climate-Driven Salsola Tragus (Russian Thistle) Invasion Into Southwestern Usa Grasslands, Melissa A. Bacigalupa

Biology ETDs

Effective management of invasive, non-native plants requires understanding key drivers of invasion, including nitrogen enrichment from atmospheric deposition and agriculture. Long-term studies are essential for capturing complex invasion dynamics yet remain uncommon. We used 22 years of observations and 14 years of nitrogen experiments to examine invasion by Salsola tragus (Russian thistle) into three semi-arid grasslands of central New Mexico. Invasion patterns varied, with rapid expansion in Chihuahuan Desert grassland and the Desert-Plains ecotone but stability in Plains grassland. Under ambient nitrogen, precipitation most strongly correlated with Russian thistle biomass and high native grass biomass was associated with Russian thistle …

Distributional Records Of Blanding’S Turtles (Emydoidea Blandingii) In Nebraska, Sam Thede, Dan Fogell, Keith Geluso

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

Blanding’s Turtle (Emydoidea blandingii) is a species of concern in North America as many populations have declined across its distribution. Environmental factors associated with alteration of natural ecosystems have played a role in declines leading to many isolated populations. Most populations exist in the Great Lakes region with a number of outlying populations, such as Nebraska. Understanding the current distribution of the species will facilitate regional management strategies to protect this species into the future. In Nebraska, Blanding’s Turtles were known from 23 counties prior to this study. Herein, we report on eight new county records, five (Blaine, …

Simulated Walleye Responses To Various Harvest Regulations In A Nebraska Reservoir, Mikael Ranta, Melissa Wuellner, Keith D. Koupal

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

Recreational fishing provides sociological and economic benefits, and fish populations are managed by state agencies to meet angler expectations. One of the most popular species in Midwest reservoirs are walleye (Sander vitreus), and most of these fisheries have established restrictions on the number and sizes of fish harvested. Regulations are set based on population structure and dynamics and management goals, but often agencies have incomplete information needed to establish regulations. Predictive models can provide insight on population responses and inform managers of the tradeoffs between angler restrictions and population sustainability. Lake McConaughy, Nebraska, supports a popular walleye fishery. …

Changing Aspen Stand Structure Following Large Carnivore Restoration In Yellowstone, Luke E. Painter, Robert L. Beschta, William J. Ripple

Aspen Bibliography

Restoration of large carnivores in northern Yellowstone National Park in the late 20th century resulted in a sustained reduction of Rocky Mountain elk (Cervus canadensis) and their herbivory, facilitating new growth of quaking aspen (Populus tremuloides) saplings. In 2020–21, we examined 87 randomly selected, previously sampled aspen stands across northern Yellowstone, combining random plots with stand-wide observations. Forty-three percent of stands contained a new cohort of small trees (5–10 cm dbh), the first documented recruitment of overstory aspen trees in northern Yellowstone since the 1940s. Both aspen saplings ( ≥2 m tall) and small trees were …

Scorpions Of The Horn Of Africa (Arachnida: Scorpiones). Part Xli. Pandinops Sahil Sp. N. From Somaliland (Scorpionidae), František Kovařík

Euscorpius

Pandinops sahil sp. n. from Somaliland is described and compared with other species of the genus, fully complemented with color photos of specimens of both sexes of the new species, as well as of their habitat. Pandinops bambii Rossi, 2017 is synonymyzed with Pandinops turieli Kovařík, 2016, syn. n. A key for the species of Pandinops and a map of the distribution of the genus are provided.

Scorpions Of The Horn Of Africa (Arachnida: Scorpiones). Part Xl. Barbaracurus Lowei Sp. N. From Ethiopia (Buthidae), František Kovařík, Hassan Sh A. Elmi

Euscorpius

Barbaracurus lowei sp. n. from Ethiopia is described and compared with other species of the genus, fully complemented with color photos of specimens of both sexes of the new species, as well as of their habitat. Included is a key for Barbaracurus and a map of the distribution of the genus in the Arabian Peninsula and the Horn of Africa.

Canopy Insect Communities Are Shaped By The Genes And Phenotypes Of Their Aspen Hosts, Clay J. Morrow, Jennifer Lind-Riehl, Christopher T. Cole, Kennedy Rubert-Nason, Cécile Ané, Richard L. Lindroth

Aspen Bibliography

1. Community genetics research aims to identify genetic and phenotypic mechanisms that shape communities as extended phenotypes. To date, most progress has been made identifying variation in herbivore communities associated with intraspecific variation in plants, with little focus on identifying specific genes or traits responsible for that variation. Here, we identify how extended phenotype variation of a foundation tree species, Populus tremuloides, arises from trait variation among individuals and specific genes. 2. We quantified heritability for 13 tree traits -- including phenology, defense chemistry, reproduction, and morphology -- and for 18 associated insect species (640,557 individuals). We performed genomic …

Post-Wildfire Erosion And Sedimentation: An Escalating Threat For Utah Fisheries, Colton James, Kendall Becker, Scott Hotaling, Aish Chandrasekaran, Alex Fiedler, Timothy E. Walsworth, Patrick Belmont

All Current Publications

Wildfires are a natural part of the western U.S. landscape and provide numerous benefits, including enhanced nutrient cycling and habitat rejuvenation. Utah’s fish populations evolved with wildfire as a common disturbance. However, the increasing size and severity of wildfires, combined with Utah’s heavily engineered and fragmented stream networks, pose a contemporary risk to fish populations. This fact sheet reviews wildfire impacts on erosion and Utah's watersheds and fisheries. It outlines measures we can take to prevent post-wildfire fish die-offs.

Watching The Grass Grow: Expanding Outreach And Accessibility Of Itex-Aon, Justin Blough

Masters Projects

Science has an accessibility problem. Though results are published and the component data is archived and made publicly available, distrust in and misunderstanding of science by the lay populace remains common. This work focuses on bolstering the outreach component of the International Tundra Experiment (ITEX)—Arctic Observing Network (AON) to increase public awareness, interactivity, and ultimately, the understanding of how the science of ITEX-AON takes place. This project uses several component methods to further outreach goals of ITEX-AON. These include: documentary photography of researchers, study sites, subjects and the surrounding environments, 360-degree imaging and interactive virtual tour building, building interactive data …

Update To: Advancing Butterfly Systematics Through Genomic Analysis, Jing Zhang, Qian Cong, Jinhui Shen, Leina Song, Nick Grishin

The Taxonomic Report of the International Lepidoptera Survey

In this update, we propose (type species or type localities in parentheses): Lochris Grishin, nom. nov. (Lasaia oileus Godman, 1903; Lepidoptera: Riodinidae) as a new substitute name for Locris Grishin, 2025 preoccupied by Locris Stål, 1866 (Cercopis rubra Fabricius, 1794; Hemiptera: Cercopidae), 5 new species, and 5 new subspecies: Emesis (Mandania) mandarina Grishin, sp. n. (Brazil: Santa Catarina) and Emesis (Mandania) mandela Grishin, sp. n. (Venezuela, Carabobo) in Riodinidae Grote, 1895 (1827); others in Hesperiidae Latreille, 1809: Telegonus (Rhabdoides) flavifimbro Grishin, sp. n. (Colombia), Urbanus (Urbanoides) dolus Grishin, sp. n. (Colombia: …

Niche Conservatism And Sympatric Parallel Evolution May Help To Maintain Eight Nascent Tree Taxa Along A Sharp Elevation Gradient, Elizabeth A. Stacy, Rebecca Ostertag

Life Sciences Faculty Research

1. Patterns of niche partitioning among closely related taxa, such as those in incipient adaptive radiations, can provide clues into how niches are created, partitioned, and integrated over ecological and evolutionary time scales. Hawaiian Metrosideros is a ~3-MYO adaptive radiation of trees that dominates the Hawaiian Islands in continuous stands within islands and allows examination of niche partitioning at the early stages of adaptive radiation.
2. We monitored growth and survivorship over 2 years of seedlings derived from open-pollinated fruits of eight Metrosideros taxa distributed along the elevation gradient of Koʻolau Volcano, Oʻahu, under four combinations of light and phosphorus. We included …

Aspen Impedes Wildfire Spread In Southwestern United States Landscapes, Matthew P. Harris, Jonathan D. Coop, Jared A. Balik, Jessika R. Mcfarland, Sean A. Parks, Camille S. Stevens-Rumann

Aspen Bibliography

Aspen (Populus tremuloides) forests are generally thought to impede fire spread, yet the extent of this effect is not well quantified in relation to other vegetation types. We examined the influence of aspen cover on interpolated daily fire spread rates, the relative abundance of aspen at fire perimeters versus burn interiors, and whether these relationships shifted under more fire-conducive atmospheric conditions. Our study incorporated 314 fires occurring between 2001 and 2020 in the southwestern United States and a suite of gridded vegetation, topography, and fire weather predictor variables. We found that aspen slows fire progression: as aspen cover …

Examining The Performance Of An Insect Generalist Reared On Unused Host Plants In Colorado, Maxwell J. Meyer, Kanshita Dam, Kailey G. Hicks, Emma J. Sellers, Mykaela M. Tanino-Springsteen, Jd Reigrut, Dhaval K. Vyas, Shannon M. Murphy

DU Undergraduate Research Journal Archive

Dietary generalist insects are important to ecological communities because they are commonly found in many environments and play important roles in ecosystem services like pollination and decomposition. Although dietary generalist herbivores eat a broad range of plant species, regional populations of these species may have significantly narrower or specialized diet breadths. Fall webworm (Hyphantria cunea, hereafter FW) is a dietary generalist at the species level, but we do not know if there is dietary generalism at the population level or how generalism varies across populations. In Colorado, FW larvae feed on only a few plant species, but many plant species …

Planetary Thinking: Hellbenders As Emissaries Of Appalachia, Tierra R. Curry

Critical Humanities

Hellbenders are prehistoric salamanders that have thrived in cold rivers since before the continents divided. Once found throughout Appalachian watersheds, due to exploitation and habitat degradation only a few dozen healthy populations survive. Monstrous yet fascinating, hellbenders were often reviled historically, but in recent decades they have gained iconic status and are now celebrated as charismatic indicators for clean rivers. Hellbenders are symbols of the wild because of their ancient history, elusive nature, and contribution to ecosystem resilience. The same forces that drove the decline of these amphibian sentinels have sacrificed public health in Appalachia. Their demise echoes the struggle …

The Astrobiological Figure Of Humboldt As Pioneer In The Rock Varnish Research, Jose Jordan-Soria

Homage to Alexander von Humboldt: Travels to and from Spain Throughout the Centuries / Homenaje a Alexander von Humboldt: Viajes hacia y desde España de todos los siglos

From Humboldt is particularly interesting -and little know- his description of mineral coatings on rocks 200 years ago, reported in his book Personal Narrative of Travels to the Equinoctial Regions of the New Continent during the years 1799-1804, co-written with Aimé Bonpland, for which is considerate the father of rock coating research. On June 5th 1799 set sail from A Coruña -Spain- to Cumaná -Venezuela- beginning five years of expedition. While they explored the Orinoco River system, in th eriver basin waterfalls, Humboldt observed the presence of dark coating depositions. He ascertained a manganese-rich accretion, reporting similar structures in other …

Response Of Various Body Parts Of House Flies, Musca Domestica, To Sucrose, Panchalie B. Gunathunga, Merveille Muyizere, Bethia H. King

Faculty Articles, Papers, and Other Scholarship

Insects use multiple body parts, not just their mouth, to taste. Whether a particular body part has a taste function can be determined by examining the morphology or electrophysiological response of its sensilla (sense organs) or by its behavioral response. The present study investigated taste response of each of the three pairs of tarsi, tibiae, femurs, as well as the antennae and wings, in house flies, Musca domestica L. (Diptera: Muscidae). This was done by measuring the proboscis extension response (PER), and in the case of the wings, also the grooming behavior. PER is a visible precursor to consumption. The …