Life Sciences Commons^™

Resolving The Paradox Of Polyploidy: Underexplored Facets Of Polyploid Plants, Benjamin Gerstner

Biology ETDs

Polyploidy, or whole genome duplication, is a common phenomenon in plants, but the establishment and persistence of mixed-ploidy populations remains a paradox. This dissertation explores factors that contribute to the persistence and establishment of mixed-ploidy populations in nature. The first chapter investigates the role of unreduced gametes in neopolyploid establishment and finds that variability in their formation rate can have a significant impact on polyploid establishment and persistence. The second chapter searches for evidence of soil microbes exhibiting ploidy-specificity, a pre-condition for microbe-mediated niche differentiation, a possible stabilizing mechanism contributing to ploidy coexistence. Finally, the third chapter tests for microbe-mediated …

National Development And The Sustainability Of Mining In The Atacama Desert, Chile, Dakota Soleil Osgood

Capstone Collection

As climate change continues to intensify on a global scale, efforts have been made to implement renewable energies and progressive technologies. These tools are critical in the shift towards a more sustainable practice, and yet analysis of localized impacts from the development of these mechanisms is inadequate. Chile has been and continues to be a leading country in mineral extraction, with an economic history founded in the mining industry. The establishment of mining in Chile as a progressive tool has aided the social and economic development of the nation. Consequences of mining extraction, however, include intensive environmental degradation, human rights …

Effects Of Solar Arrays On Southwestern Desert Thermal Landscapes: Consequences For Terrestrial Ectotherms, Adrian Slade

All Master's Theses

Solar energy development in the Southwestern United States coincides with habitat for many sensitive and endemic species, including reptiles such as Mojave Fringe-toed Lizards and Mojave Desert Tortoises who are threatened by a warming and drying climate. While utility-scale solar energy reduces carbon emissions and should ultimately benefit climate-sensitive species, it locally destroys fragile desert habitat, displaces wildlife, and has been shown to incur local air and surface temperature changes. Mitigation-based translocation of wildlife species in the face of solar development yields mixed results, and the unprecedented pace of solar expansion in the desert highlights the need for alternative practices …

Extreme, Positive Geomorphic Change In A Historically Degraded Desert River: Implications For Imperiled Fishes, Tansy T. Remiszewski

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rivers comprise some of the most unique and biodiverse ecosystems on the planet with their waters supporting both human societies as well as the organisms that make these rivers their home. Large rivers like the Colorado are often highly regulated and diverted in order to support human residence in arid regions like the desert Southwest, and these water diversions often have dramatic, negative impacts on the natural flow regime of the river. These impacts leave large reaches of the river dry, reduce the river’s capacity to transport sediment, cause channel and habitat homogenization, and significantly reduce the amount of suitable …

Ectotherm Thermoregulation At Fine Scales: Novel Methods Reveal A Link Between The Spatial Distribution Of Temperature And Habitat Quality, Ian Axsom

Master's Theses

Investigating ecological questions at the scale of individual organisms is necessary to understand and predict the biological consequences of environmental conditions. For small organisms this can be challenging because we need tools with the appropriate accuracy and resolution to record and quantify their ecological interactions. Unfortunately, many of our existing tools are only appropriate for medium to large organisms or those that are wide ranging, inhibiting our ability to investigate the ecology of small organisms at fine scales.

In Chapter 1, I tested a novel workflow for recording animal movements at very fine spatial and temporal scales. The workflow combined …

Above- And Belowground Responses To Environmental Change In The Northern Chihuahuan Desert, Renée F. Brown

Biology ETDs

Drylands cover 45% of the terrestrial surface and are expanding rapidly due to anthropogenic drivers. Altered precipitation regimes, atmospheric nitrogen deposition, and wildfire will likely have significant consequences in these regions where ecological processes are limited by water and nitrogen. In this dissertation, I explored temporal dynamics of net primary production (NPP) and related above- and belowground processes under several environmental change drivers in the Sevilleta National Wildlife Refuge, central New Mexico, USA. Located in the northern Chihuahuan Desert, this region experiences strong seasonal precipitation patterns driven by the North American Monsoon, historically characterized by frequent small rain events hypothesized …

Biodiversity And Global Change In Terrestrial Ecosystems, Timothy J. Ohlert

Biology ETDs

Terrestrial ecosystems are critical to human and ecological processes but many gaps in our knowledge remain regarding how terrestrial plant communities assemble and respond to global change. I used field experiments distributed around the world, including long-term experiments from the Sevilleta National Wildlife Refuge (SNWR) in New Mexico and deserts of the southwestern U.S., to evaluate the consequences of drought and other abiotic stressors on plant communities. Dominant grasses were particularly important for the productivity and structure of grasslands at SNWR. In general, the structure of desert plant communities had high resistance to extreme drought, though grasses and other perennial …

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

Monitoring Mammals At Multiple Scales: Case Studies From Carnivore Communities, Kadambari Devarajan

Doctoral Dissertations

Carnivores are distributed widely and threatened by habitat loss, poaching, climate change, and disease. They are considered integral to ecosystem function through their direct and indirect interactions with species at different trophic levels. Given the importance of carnivores, it is of high conservation priority to understand the processes driving carnivore assemblages in different systems. It is thus essential to determine the abiotic and biotic drivers of carnivore community composition at different spatial scales and address the following questions: (i) What factors influence carnivore community composition and diversity? (ii) How do the factors influencing carnivore communities vary across spatial and temporal …

Global Population Divergence Of A Cosmopolian Desert Plant, Victor Ryan Alfaro

Biology ETDs

Genetic and phenotypic variation can have different patterns within a species if it has populations with contrasting histories. Populations can have discrete differences that are shaped by different evolutionary scenarios, but within each population, range, or region, traits and association with fitness can also be affected by both edaphic and landscape variation. For my dissertation, I surveyed and experimentally analyzed variation and adaptive potential in Sahara mustard (Brassica tournefortii), a desert annual that has endemic, invasive, and agricultural populations in Africa, Asia, and the Americas. Although my multi-trait analysis generated complex results, my findings can be applied to …

Dietary Shifts Related To Water Availability And The Demographic Response To Changing Prey Abundance Of Carnivores In The West Desert, Utah, Ashley E. Hodge

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The decrease in number and range of North American large carnivores, has often all owed smaller carnivores ( < 15 kg) to fill the role of the top predator. This has favored some carnivores such as coyotes (Canis latrans), who have expanded their distribution. Other small carnivores such as kit foxes (Vulpes macrotis) have experienced a range shrinkage and their population status throughout the United States is a concern. Historically, western U.S. natural resource management agencies installed artificial water sources to assist desert wildlife, but some researchers believe the access to water allowed more coyotes to live in Utah’s West Desert. In the late-1980s, research proposed that without free drinking water, coyotes would have to triple …

Effects Of Wetland Management And Associated Abiotic Factors On Rare Plant Communities Of Spring-Fed Arid Wetlands, Antonio Cantu De Leija

LSU Master's Theses

Spring-fed arid wetlands support high biological productivity and are hotspots for endemism and distribution of rare plants, making them areas of high conservation value. These systems are driven by complex interactions among groundwater discharge and the geomorphic and climatic features of the setting, which provide gradients of edaphic conditions, particularly soil moisture and salinity that influence the presence and abundance of rare plant communities. However, spring-fed arid wetlands are at particular risk of increases in salinity and drier hydrological regimes due to anthropogenic activities. Such alterations to abiotic conditions may jeopardize the distribution and abundance of rare plants by exceeding …

Habitat Heterogeneity Affects The Thermal Ecology Of The Federally Endangered Blunt-Nosed Leopard Lizard, Nicole Gaudenti

Master's Theses

Global climate change is already contributing to the extirpation of numerous species worldwide, and sensitive species will continue to face challenges associated with rising temperatures throughout this century and beyond. It is especially important to evaluate the thermal ecology of endangered ectotherm species now so that mitigation measures can be taken as early as possible. A recent study of the thermal ecology of the federally endangered Blunt-Nosed Leopard Lizard (Gambelia sila) suggested that they face major activity restrictions due to thermal constraints in their desert habitat, but that large shade-providing shrubs act as thermal buffers to allow them …

Effects Of Environmental Change On Ancestral Pueblo Fishing In The Middle Rio Grande, Jonathan W. Dombrosky Dr.

Anthropology ETDs

It has long been assumed that fishes were unimportant in the diet of past Pueblo people in the U.S. Southwest. Yet, small numbers of fish remains are consistently recovered from Late pre-Hispanic/Early Historic archaeological sites in the Middle Rio Grande of New Mexico. The end of drought conditions may have impacted food choice and fishing decisions during this time. I use behavioral ecology to understand how fishing could have been an optimal food-getting strategy for Ancestral Pueblo farmers. Stable isotope analysis offers a way to account for environmental change. I provide a refined ¹³C Suess correction model to support …

Some (Im)Material Girls, Living In (Im)Material Worlds, With Seeds, Stars, And Shit, Matthew Weiderspon

Theses and Dissertations

This writing situates material and gestural vocabularies cultivated in my artwork in relation to my lived experience; primarily my rural upbringing in Colorado. Scattered floor dispersals, calling sounds, and bodily movements desire reconsiderations of hope in precarity through a disorientation of place, association, scale, and language.

Interactive Effects Of Soil And Browsing On Big Sagebrush: Implications For Restoration Success, Kyle Nehring

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Heterogeneity in landscape conditions (e.g., soil types) precludes a “one size fits all” management strategy across large landscapes. New management approaches that explicitly account for heterogeneous landscapes (and the variable conditions therein) will be required to maintain habitat quality. In particular, we require an improved mechanistic understanding of how the outcomes of conservation and restoration actions are contingent upon a) contextual abiotic factors (e.g., moisture availability mediated by soils and precipitation) and b) their interactions with biotic factors (e.g., browsing wildlife).

We propose to answer fundamental questions about how big sagebrush (Artemisia tridentata), the foundational species for sagebrush …

Seed Bank Composition Within Two Sagebrush Communities: A Comparison Of Drought, Microsite, And Aboveground Community Effects, Allison Marie Nunes

Cal Poly Humboldt theses and projects

Soil seed banks are critical biodiversity repositories for many dryland plant communities. Understanding how environmental factors alter seed bank composition can provide valuable information on ecological processes within a community and be useful for creating land management strategies. Using the seedling emergence method, I characterized the seed bank of two adjacent dryland plant communities that vary in dominant sagebrush species, structure, and function. Specifically, within an Artemisia arbuscula dominated community and Artemisia cana dominated community, I assessed the influence of three environmental factors on each seed bank: experimentally imposed drought, shrub microsites (compared to interspaces), and aboveground vegetation. Within the …

A Historical Ecology Of Aridland Springs In Desert National Wildlife Refuge, Nuwu/Nuwuvi (Southern Paiute/Chemehuevi) Ancestral Territory, Nevada, Yarrow Sarah Valentine Geggus

Dissertations and Theses

Aridland springs are among the most threatened ecosystems in the world. Vital to desert ecologies and Indigenous cultures, these complex and individualistic ecosystems have layered histories. To inform management in the changing landscape of Desert National Wildlife Refuge, a 1.6 million acre protected area in Southern Nevada, I conducted a historical ecology study of a sample of ten upland springs. Through a six-part interdisciplinary methodology including interviews, archaeological survey, botanical survey, and archival research, I summarize findings into three broad eras: the Nuwu/Nuwuvi pre-Contact Era, the Settler Era, and the U.S. Fish and Wildlife Service Era.

For millennia, Nuwu/Nuwuvi drank …

Species Distribution Modeling For Arid Adapted Habitat Specialists In Zion National Park, Sam Driver, Chris M. Schalk, Daniel Unger, David Kulhavy

Electronic Theses and Dissertations

The Arizona toad (Anaxyrus microscaphus) and Jones’ waxy dogbane (Cycladenia humilis var. jonesii) are habitat specialists with historical ranges in the desert southwest and specifically, Zion National Park (ZION). The machine learning method, MaxEnt, constructed species distribution models (SDMs) in ZION for the two study species at 30 m and 900 m spatial resolutions using climate, topographic, and remotely sensed data. Additionally, 900 m forecasting models were constructed to observe the shifts in suitable habitat for the years 2050 and 2070, based off two representative concentration pathway scenarios. Results indicate promising predictive power for both high …

Population Structure Of A Federally Endangered Plant (Astragalus Jaegerianus Munz, Fabaceae) With Limited Range Using Microsatellites, Sueann Neal

Electronic Theses, Projects, and Dissertations

Studies on population genetics examine the relationship and effects of population structure, migration, gene flow and demographic history, and are therefore important in the conservation of endangered species. Astragalus jaegerianus, a critically federally endangered species found in a geographically restricted range is investigated to determine population structure and genetic variation. Previous research on A. jaegerianus focused on DNA sequence data for cpDNA and nrDNA showed no variation. Further research on A. jaegerianus utilizing AFLP’s on the whole genome indicated substantial gene diversity and population structure consistent with geographically widespread species. AFLP research is a cost-effective process to identify levels …

Inoculum Potential Of Pinus Edulis-Associated Ectomycorrhizal Fungi Across A Forest Extirpation Chronosequence, Annie M. Montes

Biology ETDs

Few studies have examined inoculum potential of ectomycorrhizal fungi (EMF) in the absence of plant hosts, yet persistence of these fungi may be paramount to resilience of Pinus edulis and other mycorrhizal plant species. We conducted a study in which seven sites were selected in northwestern New Mexico with known dates of P. edulis extirpation and a lack of regeneration. Age classes included: two sites extirpated 10-20 years ago, two extirpated 55-65 years ago, two extirpated 500+ years ago, and one extirpated 11,000+ years ago. At each site, two plots were paired: an extirpated plot and the nearest live adult …

Plant Litter Decomposition Differs With Species And Soil Resources In A Chihuahuan Desert Grassland, Andrea Lopez

Biology ETDs

Uncertainties surround the extent to which diversity can mitigate the effects of climate change and anthropogenic activity on ecosystem functions. In desert grasslands, changes to water availability and soil nitrogen, two primary resources that limit ecosystem processes, can have lasting impacts on nutrient cycling. We used grass litter from Bouteloua eriopoda, Bouteloua gracilis, Pleuraphis jamesii, and Sporobolus spp. to assess the effects of soil resources on single- and multi-species decomposition in a Chihuahuan Desert grassland in central New Mexico, USA. Litterbags were deployed in a factorial experiment that manipulated rain pulse size (5- vs. 20-mm) and frequency …

A Tale Of Two Cervids: Habitat Selection And Spatial Ecology Of Roosevelt And Tule Elk In California, Adam S. Mohr

Cal Poly Humboldt theses and projects

California’s Roosevelt (Cervus canadensis rooseveltii) and tule elk (C. c. nannodes) populations have experienced a remarkable recovery after over-hunting and habitat loss nearly extirpated them from the state. Greater clarity of Roosevelt and tule elk habitat selection patterns would help managers continue to effectively support the recovery of these two iconic subspecies. As the manner in which elk populations balance their competing resource needs is unique to each population (Skovlin et al. 2002), I have examined Roosevelt and tule elk habitat selection patterns in separate analyses and present these results in independent chapters. In both cases, …

Sampling The Local Fare: Fishes At The Sam Israel House Pit (45gr76), Soap Lake, Washington, Adam Fruge

All Master's Theses

The Sam Israel site is a precontact archaeological complex with numerous fish bones at the north end of Soap Lake, Washington. Excavated in 1976, the fish remains recovered from there were never fully analyzed prior to this research. Since this inland Columbia Plateau site had thousands of fish bones, it contained untapped potential for our understanding of ancient local fish procurement. As such, I conducted a detailed analysis of 2,862 fish bone specimens from the Sam Israel House Pit locus to: study a larger sample of fish bones in greater detail than was done before; compare the distribution of fishes …

Seed Predation By Owyhee Harvester Ants And The Potential Of Seed Introductions In Recovery Efforts For Slickspot Peppergrass, Jennifer A. Brown

Boise State University Theses and Dissertations

Slickspot peppergrass (Lepidium papilliferum) is a rare plant endemic to the sagebrush-steppe habitat in southwestern Idaho. Within sagebrush-steppe, the plant is restricted to microsites known as “slick spots”– shallow depressions of soil characterized by distinct clay layers and surface water retention that is higher than that of surrounding areas. Having one of the highest extirpation rates among rare plant taxa in Idaho, and considering its unique habitat requirements, limited range, and declining numbers, land managers and conservationists have voiced concern regarding the species’ long-term viability. While range-wide declines in slickspot peppergrass have been attributed largely to the loss …

Genomics Based Approaches To Fungal Evolution, Aaron J. Robinson, Donald O. Natvig

Biology ETDs

Advances in DNA sequencing and data analysis make it possible to address questions in population genetics and evolution at the genomic level. Fungi are excellent subjects for such studies, because they are found in diverse environments, have short generation times, can be maintained in culture and have relatively small genomes. My research employed genetic approaches using a variety of sequencing technologies and methods of analysis to explore questions in fungal evolution.

In one study, I explored the genetics behind differences in thermotolerance between isolates of Neurospora discreta from Alaska and New Mexico. Isolates from the two states exhibited differences in …

Evaluation Of Range-Wide Occupancy And Survey Methods For The Giant Kangaroo Rat (Dipodomys Ingens), Alyssa E. Semerdjian

Cal Poly Humboldt theses and projects

Though habitat suitability and occupancy are often correlated, they cannot always be inferred from each other. Therefore, a solid understanding of both is essential to effectively manage species. Recent studies have assessed range-wide habitat suitability for the giant kangaroo rat (Dipodomys ingens; GKR), but data regarding occupancy is lacking in parts of its distribution. Satellite and aerial imagery were used to identify GKR burrows across their known range, producing a range-wide occupancy map and non-invasive survey methods including track plates, manned flight, unmanned aerial vehicle, and sign surveys were conducted to determine effective methods for monitoring GKR occupancy. …

Drought And Coyotes Mediate The Relationship Between Mesopredators And Human Disturbance In California, Molly K. Parren

Cal Poly Humboldt theses and projects

Mesopredators in California are facing two major changes to their ecosystem: drought and the expansion of human disturbance. As a result, mesopredators are likely shifting their habitat use as well as their interspecies interactions to balance resource needs and risk-taking on the landscape. In response to severe drought, the California Department of Fish and Wildlife deployed 585 camera traps throughout the Mojave Desert and Central Valley documenting mammalian mesopredator presence in a drought year (2016) and a post-drought year (2017). The objectives of this study were to examine spatial patterns of mesopredator occurrence and co-occurrence with a dominant predator, the …

Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender

Student Theses 2015-Present

This paper aims to shed light on the dissonance caused by the superimposition of Dominant Human Systems on Natural Systems. I highlight the synthetic nature of Dominant Human Systems as egoic and linguistic phenomenon manufactured by a mere portion of the human population, which renders them inherently oppressive unto peoples and landscapes whose wisdom were barred from the design process. In pursuing a radical pragmatic approach to mending the simultaneous oppression and destruction of the human being and the earth, I highlight the necessity of minimizing entropic chaos caused by excess energy expenditure, an essential feature of systems that aim …

Seasonal Shifts In C3 And C4 Resource Use By A Small Mammal Community Under Changing Precipitation Regimes, Alaina D. Pershall

Biology ETDs

In light of climate change and projections of increasing temperatures and aridity in the North American southwest, it is essential to understand how consumer populations will respond to changes in the resource landscape. Rainfall varies in timing and intensity and therefore the timing, proportion, phenology, and abundance of C₃ and C₄ plant resources vary seasonally and annually. Here we examine rodent resource use in the Chihuahuan desert and focus on two distinct precipitation pulses in this system, where spring C₃ plants increase production in response to winter rains and C₄ plants respond to summer monsoons. We …