Terrestrial and Aquatic Ecology Commons^™

From Flight To Hatching: Adult Sexual Dimorphism, Life History, And Egg-Stage Ecology Of Pseudocotalpa Giulianii, Mandylene Mountain

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Nevada endemic dune beetle Pseudocotalpa giulianii is currently known only from two dune systems in Amargosa Valley, Nevada, yet much of its life cycle occurs below the sand surface and remains poorly documented. This thesis addresses key gaps in adult-stage biology and egg-stage development that are relevant to understanding reproduction, vulnerability, and habitat requirements in this dunerestricted species.

To characterize adult sexual dimorphism and life history, I quantified morphological differences between males and females and measured sex-specific adult survival under laboratory conditions relative to the aboveground flight season. Males and females overlapped broadly in external body size, but tarsal …

Thermal Physiological Ecology Of The Relict Leopard Frog At Hot And Cold Springs, Robert P. Pelletier Iii

UNLV Theses, Dissertations, Professional Papers, and Capstones

The relict leopard frog (Rana onca) once ranged across drainages in southern Nevada, northwestern Arizona, and southwestern Utah. Following a decline, the species only persisted in a few geothermally influenced hot springs, which led to the perspective that hot springs were high-quality habitat. Rana onca has been under intensive, multiagency management and the species has been translocated to establish additional populations, including at cold-water sites. Three research studies are presented into the thermal physiological ecology of R. onca with the aim of informing conservation strategy. The research was focused at a thermally influenced hot spring and a cold-water spring to …

Modeling The Mojave: A Multiphase, Mixed Methods Phenomenological Investigation Of Novice Understanding Of A Complex Ecological System, Nicole Juliana Thomas

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores early college science majors’ conceptions of the Mojave Desert ecosystem as a complex system. A multi-level, explanatory sequential mixed methods design was employed to study college science majors’ understanding of the Mojave Desert ecosystem to better inform science pedagogy. The first level, the quantitative phase of the study, consisted of developing a mathematical representation of twelve ecosystem variables present within the Mojave Desert. The second level, the qualitative phase of the study, consisted of phenomenological semi-structured interviews with 23 early college science majors. The findings of this research suggest that the Mojave Desert operates as a complex, …

Enviromental Dna (Edna) Tools For Invasive Mosquitofish (Gambusia Affinis) Surveillance At The Shoshone Pupfish (Cyprinidon Nevadensis Shoshone) Refugium, Yusuf Olamilekan Umar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring-fed aquatic ecosystems of the North American Southwest and U.S. Great Basin hosts a plethora of endemic fish species due to the effects of hydrologic fragmentation that resulted from Pleistocene aridification. Threats to endemic fishes worldwide include human intentional or unintentional release of exotic species into their habitats. Early detection of invasive species, while corrective actions are still possible, is critical for management, yet traditional survey methods are often disruptive to sensitive ecosystems, costly, and limited in sensitivity. The recent development of environmental DNA (eDNA) approaches offers powerful alternatives for invasive species monitoring in aquatic systems. In this study, a …

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 …

Uvc And Planetary Habitability: Insights From Desert Lichens And Cyanobacteria, Tejinder Singh

UNLV Theses, Dissertations, Professional Papers, and Capstones

An important question in astrobiology is whether life can exist under the levels of UVC radiation found on Archean Earth, Mars, and exoplanets. We investigated this question by studying the UVC survival of colonial cyanobacterium and lichens that grow in harsh desert environments and possess natural sunscreens. We irradiated them nonstop in a desiccated state with a UVC flux closely representing the upper limit on those planets: 55-60 W/m². After irradiation, we rehydrated and assessed their survival using chlorophyll fluorometry and by counting the number of viable colonies that formed on agar plates. All three study organisms survived two to …

Effects Of Climate Change On (Semi)-Arid Ecosystems In The Southwestern United States, Charlotte Van Der Nagel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Climate change is considered amongst the most severe threats to terrestrial and aquatic ecosystems globally. Ecosystems in the southwestern United States have specifically been impacted by intense drought conditions since 2000. Higher temperatures combined with altered precipitation stresses many ecosystems; however, ecosystem specific responses to such stressors may vary. Here, the effects of climate change on semi-arid ecosystems are analyzed for some of the most vulnerable ecosystems in the southwestern United States: lacustrine, riparian, and dryland ecosystems.

Lakes and reservoirs in arid environments often serve as drinking water sources and recreational areas where high water quality is essential. Climate change …

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 Habitat Isolation On Fine-Scale Genetic And Geographic Structure Of Populations Of Two Threatened Endemic Insects In Southern Nevada, Pseudocotalpa Giulianii And Icaricia Shasta Charlestonensis, Kristen Tovar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Assessing the role geographic isolation and ecological specialization have on phylogeographic patterns contributes to our understanding of the evolutionary history of a species and the processes that erode genetic diversity. I used mitochondrial and nuclear genomic sequences to assess whether habitat isolation has shaped the fine-scale patterns of present-day genetic structure and diversity in two threatened insect species endemic to southern Nevada. Pseudocotalpa giulianii (Coleoptera; Scarabaeidae) is a dune obligate scarab beetle endemic to only two small, isolated sand dunes in Nye County, Nevada, with a usable habitat of less than 4.2 km sq that is impacted by on-going degradation. …

Quantifying The Effect Of Disturbance On Native Mojave Desert Shrubs, Tamara J. Wynne

UNLV Theses, Dissertations, Professional Papers, and Capstones

Disturbance can come in many different forms. In our studies, we looked at the impact of a solar photovoltaic facility on native plants growing inside and outside of the facility, alteration in precipitation (simulated) on four native shrubs and the impact of applying supplemental water as a function of volume and frequency to establish native shrubs such as might occur at restoration sites. Disturbance is becoming a more common phenomenon in many ecosystems throughout the world, increasing the need for studies that quantify the impact at the plant and ecosystem level. Each research project revealed different plant responses, such as …

The Aboveground And Belowground Growth Characteristics Of Juvenile Conifers In The Southwestern United States, N. L. Pirtel, R. M. Hubbard, J. B. Bradford, T. E. Kolb, M. E. Litvak, Scott Abella, S. L. Porter, Matthew Petrie

Life Sciences Faculty Research

Juvenile tree survival will play an important role in the persistence of coniferous forests and woodlands in the southwestern United States (SWUS). Vulnerability to climatic and environmental stress declines as trees grow, such that larger, more deeply rooted juveniles are less likely to experience mortality. It is unclear how juvenile conifers partition the aboveground and belowground components of early growth, if growth differs between species and ecosystem types, and what environmental factors influence juvenile carbon allocation above- or belowground. We developed a novel data set for four juvenile conifer groups (junipers, piñon pines, ponderosa pines, firs; 1121 juveniles sampled, 221 …

Climate And Soil Moisture Dynamics Inform Potential Climate Change Impacts On Available Moisture And Juvenile Tree Survival In Semiarid Forests, Carolyn R. Koehn

UNLV Theses, Dissertations, Professional Papers, and Capstones

Trees in semiarid forests and woodlands of the western United States need soil moisture to transpire and function. Juvenile trees are especially vulnerable during periods of low soil moisture as their rooting zones are smaller and shallower than those of adult trees. This thesis focuses on two soil moisture-driven aspects of semiarid forests that may be modified by climate change: seasonal soil moisture patterns and juvenile tree survival.

In chapter 1, I investigated the influence of precipitation on soil moisture across seasons, elevations, soil layers, and periods of low and high precipitation. I developed time-varying definitions of winter (snow accumulation), …

Linking Extreme High Air Temperature Events To Wildfire And Environmental Variation To Water Balance Partitioning In The Western Us, Neil Savage

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chapter 1

Wildfire activity has increased across the western United States in recent decades, causing significant damage to ecosystem services and human communities. The Sierra Nevada region, in particular, has experienced substantial increases in the ignition frequency, severity, and extent of large wildfires. To partly disentangle the complex processes underlying wildfire risk, I developed a simple approach to link natural wildfire ignition patterns to changing seasonal temperatures and extreme high and low air temperature events across the Sierra Nevada region from 1992—2015. Extreme event analyses focused on the association between the magnitude and frequency of occurrence of extreme temperature events …

Distributions And Habitat Associations Of Blue Point Pyrgulopsis And Blue Point Tryonia, Chenoa Janine Wilcox

UNLV Theses, Dissertations, Professional Papers, and Capstones

Springsnails and other crenophilic species are often of conservation concern due to endemism, narrow habitat requirements, and susceptibility to habitat degradation. Because there is a distinct lack of natural history information for many of these organisms, management of species that are of concern is often based on data from non-target species related to the species of interest. In this thesis, I provide background information regarding springsnails in western North America (Chapter 1), describe a study investigating the distribution and habitat associations of two springsnails endemic to a single spring (Chapter 2), and provide supplemental information on habitat characteristics associated with …

Juvenile Conifer Growth And Regeneration Across Diverse Climatic And Environmental Conditions In The Southwestern United States, Nikki L. Pirtel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Juvenile conifer germination, growth, and survival will play important roles in the persistence of coniferous forests and woodlands in the southwestern United States (SWUS), yet it is unclear how juvenile conifers allocate aboveground and belowground early growth and if growth differs between conifer and ecosystem types. Descriptions of growth characteristics may allude to the types of stress juveniles experience in their environments, how they morphologically respond to stress, and how they may be able to survive stress to persist in their current locations or expand into new areas. In Chapter 1, I described the growth characteristics of 4 juvenile conifer …

Light Conditions During Desiccation And Rehydration Impact The Recovery Of Cultured Timmiella Crassinervis, Sotodeh Ebrahimi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many terrestrial mosses of xeric environments experience excess light during extended periods of desiccation. While dry or hydrated, excess light energy can lead to formation of reactive oxygen species and photoinhibition (e.g. damage to Photosystem II) which affects photosynthetic stress and efficiency. This study aimed to determine the effect of duration dry and light intensity (PAR) on cultured shoots of the chaparral moss Timmiella crassinervis, as well as to elucidate the optimal rehydration light conditions for this species. I hypothesized that 1) mosses exposed to higher light intensities during desiccation would incur more damage upon rehydration than those exposed to …

Effects Of Wildfire On Plant And Insect Pollinator Communities In The Mojave Desert, Nha Trang Vivian Sam

UNLV Theses, Dissertations, Professional Papers, and Capstones

The changing fire regime of landscapes across the Mojave Desert has prompted considerable research on its effects on plant community recovery, but it has not been widely studied what effects wildfire may have on native pollinators and the vital ecosystem services they provide. Ecological changes from increased wildfire severity from invasive exotic annual grasses will likely continue influencing pollinator habitats and floral resources. Understanding the effects that wildfires have on pollinators is valuable to make decisions as to whether active management and restoration activities are required to conserve ecologically vital pollinator functions. The intention of this thesis was to examine …

Microbiome Shifts Associated With The Introduction Of Wild Atlantic Horseshoe Crabs (Limulus Polyphemus) Into A Touch-Tank Exhibit, Ariel D. Friel, Sean A. Neiswenter, Cale O. Seymour, Lauren Rose Bali, Ginger Mcnamara, Fabian Leija, Jack Jewell, Brian P. Hedlund

Life Sciences Faculty Research

The Atlantic horseshoe crab (Limulus polyphemus) is a common marine aquarium species and model organism for research. There is potential monetary and conservation value in developing a stable captive population of horseshoe crabs, however, one major impediment to achieving captivity is a lack of knowledge regarding captive diseases. We utilized 16S rRNA gene amplicon sequencing to track changes in the microbiomes of four body locations in three wild-caught (tracked over 14 months in captivity) and three tank-acclimated (>2 years in captivity) adult L. polyphemus in a touch tank at Shark Reef Aquarium at Mandalay Bay in Las Vegas, NV. …

Can Desert Mosses Hide From Climate Change? The Ecophysiological Importance Of Habitat Buffering & Water Relations To A Keystone Biocrust Moss In The Mojave Desert, Theresa Ann Clark

UNLV Theses, Dissertations, Professional Papers, and Capstones

Empirical and observational studies suggest a keystone biocrust moss, Syntrichia caninervis, may be sensitive to future climate change in the American Southwest due to its uniquely sensitive water relations that appear particularly challenged during summer hydration-desiccation cycles. However, the potential mitigating roles of habitat buffering, acclimatization, and winter recovery on the vulnerability of this species remain largely unexplored. I investigated potential abiotic and biotic resiliency factors driving summer stress resistance and recovery in S. caninervis along present-day aridity gradients in the Mojave Desert to strengthen the climate change vulnerability assessment for this species common to biocrusts of North America, northern …

Mojave Desert Ecosystem Recovery: Potency Of Biotic And Abiotic Restoration Methods In Low Elevation Plant Communities, Mary Amanda Balogh

UNLV Theses, Dissertations, Professional Papers, and Capstones

The historic and current state of land in the Mojave Desert, including land managed by the National Park Service with fundamental goals of natural resource conservation and preservation, been severely degraded by a variety of anthropogenic disturbances. Due to increasingly sporadic and unpredictable precipitation patterns, land managers struggle to implement restoration projects with high success rates and are resource-limited for post-treatment monitoring. In this study, I examined success rates of biotic (outplanting, seeding) and abiotic (soil manipulation, vertical mulch) restoration treatments on various disturbance types in the creosote-bursage (Larrea tridentata-Ambrosia dumosa), blackbrush (Coleogyne ramosissima), and Joshua tree woodland (Yucca brevifolia) …

Landscape Scale: Inter- And Intraspecific Variation In Plant Interactions Along A Stress Gradient In The Sheep Range Of Nevada, Jordan Dowell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Impending threats to shrubland ecosystems, posed by climate change, necessitate niche modeling efforts to project vegetation range shifts. However, efforts often remain unguided by individual-scale interspecific plant interactions. The stress gradient hypothesis posits that facilitation should increase in areas of high abiotic stress, only if the individuals are able to ameliorate the surrounding area via functional traits. The Sheep Range of Nevada was used to assess the role of functional traits as predictors of plant association. Larrea tridentata, Coleogyne ramosissima, and Artemisia nova were selected as shrubs with variable life history strategies and ranges in order to identify general patterns …

Mojave Desert Plant Community Long-Term Response To Disturbance, Dominic M. Gentilcore

UNLV Theses, Dissertations, Professional Papers, and Capstones

All vegetation communities have been shaped by disturbances. This dissertation consists of three separate chapters: Blackbrush (Coleogyne ramosissima) natural regeneration in the Great Basin-Mojave Desert Transition Zone on two fires, Long-term Response to Fire in Eastern Mojave Desert semi-arid shrubland communities, and an Annotated Checklist of Gold Butte National Monument in the Mojave-Colorado Plateau Transition Zone. The section on blackbrush natural regeneration was a long-term dataset from two fires in Basin and Range National Monument that burned in 2008 with monitoring events in 2009, 2010, 2011, 2018 and 2019. The monitoring documented some of the strongest post-fire regeneration for the …

Phytoplankton Community And Algal Toxicity At A Recurring Bloom In Sullivan Bay, Kabetogama Lake, Minnesota, Usa, Victoria G. Christensen, Ryan P. Maki, Erin A. Stelzer, Jack E. Norlan, Eakalak Khan

Civil and Environmental Engineering and Construction Faculty Research

Kabetogama Lake in Voyageurs National Park, Minnesota, USA suffers from recurring late summer algal blooms that often contain toxin-producing cyanobacteria. Previous research identified the toxin microcystin in blooms, but we wanted to better understand how the algal and cyanobacterial community changed throughout an open water season and how changes in community structure were related to toxin production. Therefore, we sampled one recurring bloom location throughout the entire open water season. The uniqueness of this study is the absence of urban and agricultural nutrient sources, the remote location, and the collection of samples before any visible blooms were present. Through quantitative …

Heterogeneity In Surface Sensing Suggests A Division Of Labor In Pseudomonas Aeruginosa Populations, Catherine R. Armbuster, Calvin K. Lee, Jessica Parker-Gilham, Jaime De Anda, Aiguo Xia, Kun Zhao, Keiji Murakami, Boo Shan Tseng, Lucas R. Hoffman, Fan Jin, Caroline S. Harwood, Gerard Cl Wong, Matthew R. Parsek

Life Sciences Faculty Research

The second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition between planktonic and biofilm growth in many bacterial species. Pseudomonas aeruginosa has two surface sensing systems that produce c-di-GMP in response to surface adherence. Current thinking in the field is that once cells attach to a surface, they uniformly respond by producing c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in …

Muscular Apoptosis But Not Oxidative Stress Increases With Old Age In A Long-Lived Diver, The Weddell Seal, Kaitlin N. Allen, Jose Pablo Vazquez-Medina, John M. Lawler, Jo-Ann E. Mellish, Markus Horning, Allyson G. Hindle

Life Sciences Faculty Research

Seals experience repeated bouts of ischemia–reperfusion while diving, potentially exposing their tissues to increased oxidant generation and thus oxidative damage and accelerated aging. We contrasted markers of oxidative damage with antioxidant profiles across age and sex for propulsive (longissismus dorsi) and maneuvering (pectoralis) muscles of Weddell seals to determine whether previously observed morphological senescence is associated with oxidative stress. In longissismus dorsi, old (age 17–26 years) seals exhibited a nearly 2-fold increase in apoptosis over young (age 9–16 years) seals. There was no evidence of age-associated changes in lipid peroxidation or enzymatic antioxidant profiles. In pectoralis, 4-hydroxynonenal-Lys (4-HNE-Lys) levels increased …

Effects Of Ecological Restoration Techniques In Glen Canyon National Recreation Area, Simone Ka-Voka Jackson

UNLV Theses, Dissertations, Professional Papers, and Capstones

A better understanding of key ecological restoration techniques can inform land management in the Southwest on restoration options for areas infested by invasive grasses that can pose threats to ecosystems, from changes in nutrient cycling to altered fire regimes. In the semi-arid desert of Glen Canyon National Recreation Area (GLCA), several exotic grasses pose risks to local ecosystems: Saccharum ravennae, a relatively new invasive perennial grass, and Bromus rubens and Bromus tectorum, widespread annual grasses. In this study, multiple ecological restoration techniques were implemented to assess their effects on native and nonnative vegetation on sites invaded by the non-native grasses …

Assessing Minimal-Input Restoration Strategies For Desert Soil And Vegetation Restoration, Audrey Jean Rader

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Mojave and Sonoran Deserts have been negatively impacted by anthropogenic disturbances. Considering that these ecosystems may recover on millennial timescales, research has shown that restoration techniques can be fairly successful in initiating long-term recovery processes in these sensitive environments. However, uncertainty remains as to which techniques are effective in different circumstances, such as in different climates or across different soil properties, and which techniques may best avoid unintended consequences, such as facilitating non-native plants. To reduce fugitive dust as a human health hazard, increase soil stability, and enhance wildlife habitat, further work is necessary to develop restoration techniques for …

Long-Term Monitoring Of Rare Gypsum Communities In The Eastern Mojave Desert: A Study In Science And Art, Tiffany Jane-Marie Pereira

UNLV Theses, Dissertations, Professional Papers, and Capstones

For land managers, reliable estimates of soil seed banks, and more specifically, change in seed banks over time, provide insight into the restoration and regeneration potential of the landscape, site history and disturbance mapping, and, invasive and rare plant management. To understand the intricacies of desert soil seed banks in relation to aboveground vegetation change, my research evaluated long-term change in soil seed banks, fertile islands, and plant communities of conservation-priority gypsum rare plant habitat of the eastern Mojave Desert. Research found significant spatial and temporal differences in seed bank composition and density over an 11-year period; however, the gypsum …