Biology Commons^™

Olfactory Detection Of Viruses Shapes Brain Immunity And Behavior, Aurora Kraus

Biology ETDs

Olfactory sensory neurons (OSNs) directly contact the environment and are

exposed to pathogens, such as viruses. When OSNs detect a virus, they coordinate antiviral immune responses locally to stop virus progression into the brain, termed the central nervous system (CNS). For example, in COVID-19 patients the SARS-CoV-2 virus replicates in the olfactory epithelium resulting in loss of olfaction, yet viral presence in the CNS is rare. However, neuronal detection of a virus by OSNs may send electrical signals to the CNS via the olfactory bulb (OB) and shape our CNS. Because the OB is the nexus between the pathogen exposed …

Relating Plant Community Structure To Carbon Dynamics In Semiarid Grasslands, Theodore D. Roper

Biology ETDs

Understanding how fine-scale changes in soil characteristics and plant community composition affect ecosystem functioning is key to predicting how biome shifts will affect regional and global carbon cycling. This is crucial in the dryland biomes of the US Southwest, projected to be one of the regions most affected by climate change. We examined fine-scale drivers of ecosystem function within two biomes – a Chihuahuan Desert grassland and Plains/Chihuahuan Desert ecotone – via long-term vegetation data, micrometeorological data, eddy covariance carbon flux measurements, and soil water and texture, finding that the ecotone site had over 30% higher soil water content, over …

Sierra Nevada Mixed-Conifer Regeneration Response To Repeated Burning Varies By Species, Carolina J. May

Biology ETDs

Fire-exclusion has acted as a major perturbation on dry conifer forests, increasing tree density and, in mixed-conifer forests, the dominance of shade-tolerant species. Restoration efforts aim to reverse these effects by reducing stand density, restoring relative proportions of tree species, and reintroducing recurrent fire, but the long-term effects of repeated burning on tree regeneration have not been quantified. We analyzed two decades of seedling and overstory data from the Teakettle Experimental Forest in the southern Sierra Nevada to determine how thinning and repeated burning affect seedling establishment and overstory recruitment. Across treatments, pine seedling densities remained much lower than shade-tolerant …

Thermoregulation And Spatial Distribution Of Lizards In The Southwestern Usa: Adaptation To A Changing Climate, Caleb Lee Loughran

Biology ETDs

Lizards rely heavily on environmental temperatures to thermoregulate and maintain a body temperature (Tb) that optimizes physiological function and maximizes surface activity time. While early research noted the propensity for lizards to thermoregulate by shuttling between different thermal environments, it was long assumed that evaporative cooling via panting was an ineffective means of thermoregulation. However, evaporative cooling can potentially lower a lizard’s Tb significantly below air temperature, and thus allow lizards to extend activity periods during prolonged heat exposure. In this dissertation, I explore the varying abilities of lizards to thermoregulate while panting. I describe the metabolic and evaporative water …

Biodiversity And Global Change In Terrestrial Ecosystems, Timothy John 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 …

Traits And Functional Diversity Of A Hyperdiverse Bee Assemblage Are Linked To Aridity, Benjamin D. Turnley

Biology ETDs

Climate change in the American Southwest is altering the composition of species assemblages. However, the resulting patterns in mean trait values and functional diversity are poorly understood. Bees assemblages in Southwestern drylands are exceptionally diverse, and vary greatly in their morphologic traits. In this study we focused on two questions: Have community-weighted mean trait values shifted over time and/or with aridity, consistent with the hypothesis that aridification is driving bee assemblage change? Has the functional diversity of the Sevilleta bee assemblage declined over time and/or with aridity, consistent with the hypothesis that pollination services could be declining? To address these …

Ontogenetic Niche Shift As A Driver Of Community Structure And Diversity In Non-Avian Dinosaurs, Katlin M. Schroeder

Biology ETDs

As some of the most charismatic megafauna to ever walk the earth, the physiology, morphology, growth and evolution of non-avian theropods has been studied exhaustively, yet little is understood about their roles in ecosystems as juveniles. For carnivorous megatheropods, which exceed 1,000kg in mass yet hatched from eggs of limited size, the likelihood of utilizing different prey through ontogeny was high, simply by proxy of the immense difference in size between adults and juveniles. We found these ontogenetic niche shifts, evidenced by significantly different dental microwear in Tyrannosaurids, to have excluded dinosaurian mesocarnivores from Mesozoic communities. The few dinosaurian mesocarnivores …

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 …

The Consequences Of Climate Change For Native Bee Assemblages, Melanie R. Kazenel

Biology ETDs

Recent declines in terrestrial arthropod biodiversity highlight the need to pinpoint which taxa and ecosystem services are most threatened, and why. But, for most of the world’s ~20,000 bee species, we lack robust evidence of population trends, and the role of climate change remains surprisingly little studied. I used long-term bee monitoring data from the Sevilleta Long-Term Ecological Research Program (Socorro, NM, USA), along with complementary experimental and observational data, to examine how climate relates to bee abundance and diversity patterns over time and space, and to identify the traits that govern bees’ climate sensitivities. Under climate change, drylands worldwide …

Improving Photosynthetic Efficiency In Microalgae Through The Genetic Engineering Of Energy Sensors And Photoreceptors, Taylor L. Britton

Biology ETDs

Through photosynthesis microalgae can convert sunlight, water, and CO₂ into chemical energy that can be used to generate carbon neutral biofuels and biomass. With an ever-increasing demand and need for petroleum substitutes it is imperative that we improve the output of industrial-relevant crops such as microalgae. One important way of improving output in algae is by understanding the roles that stress and energy conversion is regulated in these organisms. Photosynthetic organisms fundamentally depend on light- and sugar-driven metabolic and signaling networks, which integrate environmental cues to govern and sustain growth and survival. SnRKs (SNF1-related protein kinases) and the photoreceptor …

A Diverse Flea (Shiponaptera) Assemblage From The Small Mammals Of Central New Mexico, Dianne Esther Peterson

Biology ETDs

The geographical ranges of many mammals and their associated parasites are dynamic. Comprehensive documentation of these communities over time provides a foundation for interpreting how changing environmental conditions, driven by accelerating climate change, other anthropogenic disturbances, and natural events may influence host-parasite interactions. Fleas (Order Siphonaptera) are obligate, hematophagous parasites of birds and mammals with medical interest due to their role in transmitting pathogens. From 2016 to 2019, we sampled the small mammal and associated flea communities in El Malpais National Conservation Area (El Malpais) in Cibola County, New Mexico. Among 898 mammalian specimens, 925 fleas representing 29 species were …

Rapid Source To Sink Transition In A Mixed-Conifer Forest Following Stand-Replacing Fire, Ryan Matthew Schulze

Biology ETDs

Mixed-conifer forests play an important role in the Southwestern USA’s regional carbon cycle by sequestering and storing large amounts of atmospheric carbon onto the landscape. Despite this, little is known about how large, stand-replacing fire alters ecosystem carbon sink-source dynamics. In this study, we used eddy covariance to quantify how stand-replacing fire altered forest sink strength, and the sensitivity of carbon uptake to soil and atmospheric drought in a mixed-conifer forest located in The Valles Caldera National Preserve, NM. We found that the post-burn ecosystem returned to an annual net sink of carbon in the year immediately following the fire, …

Sex- And Age - Specific Migratory Strategies Of Blue Whales In The Northeast Pacific, Christina Blevins

Biology ETDs

Sequential subsampling of blue whale baleen plates can yield information of individual migratory plasticity of this endangered species in the northeast Pacific Ocean. We measured δ13C and δ15N isotope values along baleen from thirteen whales of different age and sex. Results showed sex/age-specific migratory strategies. Adult females exhibited relatively stable cyclical movements between temperate and subtropical regions. Adult males exhibited two strategies, most remained within temperate latitudes, whereas two migrated to subtropical latitudes. Movement patterns in juveniles were erratic. These patterns are potentially driven by energetic requirements of females, intraspecific competitions among adult males, and inexperience in locating prey in …

Comparative Phylogeography Across Multiple Scales: Small Mammals, Their Ecology, Pathogens, And Drivers Of Diversification, Schuyler W. Liphardt

Biology ETDs

Comparative phylogeography has historically been defined as the study of how genetic variation of co-distributed species has been shaped by biogeographical history. This is a mature field of study out of which several techniques have been developed directed at identifying the role ecology and geography in diversification patterns across time. I employ the tools developed in classical comparative phylogeography across multiple taxonomic scales and across regions that historically have been understudied. My first two chapters study the complex history of host-switching, codiversification, and reassortment of hantaviruses in their mammal hosts across North America. By taking a host-centric comparative phylogeographic approach …

Quantification Of Soil Microbial Biomass In The Mcmurdo Dry Valleys, Antarctica, Emily Ruth Reynebeau

Biology ETDs

Quantifying microbial biomass is important for understanding microbial contribution to nutrient cycling and population flux. Widely accepted biomass estimation methods are sufficient for well-studied and high biomass systems, though are often not sensitive enough for systems with extremely low biomass. The McMurdo Dry Valleys of Antarctica are characterized as an extremely harsh environment with severe restrictions on life, with perhaps some of the lowest biomass in the world. We measured prokaryote biomass across Taylor and Wright Valleys using four estimation metrics to determine the most appropriate method for this ecosystem. The chloroform fumigation method was not sensitive enough for the …

Breathing Can Be Dangerous: Coccidioides And The Diverse Community Of The Lung Mycobiome, Paris S. Salazar-Hamm

Biology ETDs

Coccidioidomycosis, caused by soil-dwelling species of Coccidioides, is endemic to the Southwestern United States. It can present as a mild respiratory illness to life-threatening disseminated infections.Multi-gene phylogenetics and tracing patient histories revealed the presence of both Coccidioides species in New Mexico, and Native Americans may represent an unrecognized risk group. A PCR method developed distinguishes Coccidioides species by targeting regions of the mitochondrial genome. Recent advancements in molecular genetics solidifies lungs are not sterile. Illumina community data from 199 small mammals from Arizona, California, and New Mexico demonstrated a great diversity of fungi inhabiting lung tissues. One dominant order, Onygenales, …

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 …

Mud Binds Mitotic Kinesins Non-Claret Disjunctional And Pavarotti In D. Melanogaster, Vincent Cutillas

Biology ETDs

The cytoskeleton is crucial to maintaining an even distribution of chromosomes and subsequently to divide the cell during every cell cycle. During mitosis, spindle structure and movement dictates how chromosomes will be separated and act as the sole mechanism for even distribution of these chromosomes. The cytoskeleton also remains a major cellular component during cytokinesis when the cell must cleave the membrane in order to form two resulting daughter cells. Both processes require an extensive use of the immobile structures of the cytoskeleton, such as microtubules (MTs), intermediate filaments, and microfilaments, but also the mobile units, which are the motor …

The Role Of Toxoplasma Gondii Dense Granule Protein Gra24 In Signaling And Immunity During Infection, Heather L. Mercer

Biology ETDs

Toxoplasma gondii is a pathogen whose control partly depends upon Toll-like receptors (TLR) 11 and 12, that signal through MyD88. Yet, human TLR11 and TLR12 are nonfunctional, motivating us to investigate MyD88-independent immune pathways. Parasite dense granule protein GRA24 activates p38 MAPK independently of MyD88 in macrophages. Using wild-type and GRA24-deleted T. gondii strains, I demonstrate GRA24 activates p38 MAPK, resulting in IL-12 production, and protective immunity. Furthermore, GRA24 triggers p38 MAPK-dependent CX3CL1 production. GRA24 also induces CCL17 and Ppbp independently of p38 MAPK. Additionally, I demonstrate GRA24 downregulates CCL12. Furthermore, IL-15 is negatively regulated by GRA24 through activation …

What Does The Future Look Like? Plant Community Change At The Recruitment Life Stage, Brooke E. Wainwright

Biology ETDs

Species ranges are shifting due to anthropogenic climate change. However, it is unclear how climate variability affects species recruitment, an essential step in range expansion. Recruitment is challenging in drylands, where soil moisture is highly unpredictable. In Southwestern North America, creosotebush (Larrea tridentata) has expanded into Chihuahuan Desert grassland (CDG) dominated by black grama (Bouteloua eriopoda), and black grama is expanding into Great Plains grassland (GPG) dominated by blue grama (Bouteloua gracilis). To evaluate how precipitation variability affects germination and survivorship, we added blue and black grama seeds into a climate variability experiment in GPG in 2019 and 2020 and …

Into The Neotropics: Perspectives On The Evolution Of Neotropical Myotis, Carlos Alberto Carrión Bonilla Mr

Biology ETDs

In my dissertation, I used morphological, sanger sequencing and next-generation sequencing data sets to explore the evolutionary relationships and study cryptic diversity of a extant Neotropical myotine radiation. Using a integrative approach, I described a new species of Myotis from the montane and premontane forest of Panama, Costa Rica and Eastern Ecuador, refining our undestanding of the taxonomy and systematics of the Myotis pilosatibialis complex of bats. Then, using a single locus barcoding approach I explored genetic diversity partitioning across the Myotis radiation with a focus on Neotropical species, ilustrating the phylogenetic relationships of Neotropical species and exploring their species …

The Impacts Of Disturbance On Submerged Aquatic Macrophytes Populations Of The Jemez Mountains, New Mexico, Virginia Frances Thompson

Biology ETDs

This dissertation investigates the effects of disturbance (a catastrophic forest fire and decadal-level multi-day flood) on populations of submerged aquatic macrophytes (SAMs) in the streams and rivers of the Jemez Mountains of northern New Mexico, USA. Research conducted and reported in this dissertation addresses the following research questions: 1.) What factors influence the presence or absence of SAMs in Jemez Mountain streams? 2.) How does disturbance (catastrophic wildfire and decadal-level flood) change the amount of aboveground SAM biomass? and 3.) How does that disturbance change the nutrient content (%C, %N, %P) and nutrient stoichiometry of SAMs? These disturbance events had …

The Phylogeography And Molecular Systematics Of Woodrats (Genus: Neotoma) In The American Southwest, Katrina M. Derieg

Biology ETDs

The American Southwest is a region where many biomes converge, harboring a wide variety of habitats ranging from desert to alpine environments. Habitat heterogeneity and the confluence of multiple species ranges make the American Southwest a biodiversity hotspot. Climate cycling throughout the Quaternary has driven the dynamics of changes in species’ ranges that are recorded by genetic signatures. For example, range expansion may lead to secondary contact between previously isolated populations or species. Contact can result in multiple evolutionary outcomes, including hybridization or the reinforcement and maintenance of independent lineages. I used multi-locus species tree methods to re-examine the nominal …

Heterogeneity In Hosts And Environment: Implications For Schistosomiasis Control, Larissa Celeste Anderson

Biology ETDs

Schistosomiasis is a widespread neglected parasitic disease, endemic in 54 countries, for which 290 million people needed treatment in 2018. A major Schistosoma species, Schistosoma mansoni, is sustained via a life cycle that includes both human and snail hosts. Mathematical models of S. mansoni transmission are an integral tool for elucidating the complexities of the transmission cycle, interactions between parasite species and for the estimation of the impact of intervention efforts. We designed both deterministic and stochastic mathematical models to understand the impact of heterogeneity in host and parasite composition on projected infection control. These models indicate the impact of …

Molecular Studies On The Interactions Between Biomphalaria Snails And Schistosoma Mansoni, Lijun Lu

Biology ETDs

Biomphalaria snails serve as vectors for Schistosoma mansoni, a trematode causing human schistosomiasis. Control of Schistosoma mansoni involves chemotherapy of affected people, but new control methods built on improved understanding of schistosome-snail interactions are needed. My dissertation applies molecular and bioinformatics approaches to understand such interactions. Chapter 1 shows that significant differences exist among Biomphalaria species in Africa with respect to their ability to support schistosome development. Chapters 2 and 3 reveal the transcriptional responses of Biomphalaria glabrata susceptible (SUS) or resistant (RES) to Schistosoma mansoni. Chapter 2 identifies a new family of snail immune factors, the AIG …

A New Species Of Ant-Mimicking Sac Spider Castianeira Reiskindi (Araneae: Corinnidae: Castianeirinae) From Nicaragua And A Phylogenetic Analysis Of The Australian Castianeirinae, Matthew P. Leister

Biology ETDs

Ant-mimicking spiders in the subfamily Castianeirinae have had a number of taxonomic revisions and species descriptions. Despite these advancements, more species exist await formal scientific description and little scientific progress has been made in terms of reconstructing their evolutionary histories. This study 1) describes a new species Castianeira reiskind sp. n. from cloud forests in Nicaragua; and 2) presents a first look of the Australian Castianeirinae taxa in a phylogenetic framework. This analysis is used to explore the origins of Hymenoptera mimicry in this group, test the monophyly of this subfamily compared to the Corinninae and to test the current …

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 …

Spatio-Temporal Dynamics Of Fungal Communities And Their Effects On Plants, Kel Cook

Biology ETDs

Fungi perform several critical functions in the environment. Spatiotemporal distributions of fungal communities will mediate when and where these functions happen and how they vary across the landscape. I first explored tropical tree canopy fungal community variation at small spatial scales and documented near total turnover of fungi across sub-meter distances and among adjacent substrates. The second chapter analyzed fungal turnover over the course of three years, where community stability was driven primarily by abundant fungi. In the third chapter, I tested effects of the environment, including host plant and habitat, on canopy fungal communities and found only small effects, …

Mucosal Immune System Of African Lungfish, Ryan D. Heimroth

Biology ETDs

Conquering land was an apex moment in the evolution of vertebrates. Physiologically, the first vertebrates to transition to life on land had to adapt in order to survive in an oxygen-rich environment where gravitational forces and limited water prevailed. Several extant vertebrates including anurans and lungfish, survive droughts by undergoing aestivation. Unfavorable environmental conditions trigger lungfish to aestivate. Aestivation is a process of metabolic torpor wherein the fish will encase itself in a mucus cocoon and not move until favorable environmental conditions (food and water) are reintroduced. Aestivation can be reproduced in laboratory settings and, thus, lungfish can be used …

Characterization Of The Overexpression Of The Native H+-Pumping Pyrophosphatase In The Microalga Picochlorum Soloecismus, Kimberly T. Wright

Biology ETDs

Microalgae are of interest for the creation of sustainable and cost competitive alternatives to petroleum-based fuels and chemicals. However, cultivation, extraction and processing of algal biomass requires improved yields to achieve economic feasibility. The advancement of microalgal biotechnology and various genetic engineering techniques allow the improvement of microalgae biomass for this purpose. Here, the characterization of the overexpression of the native vacuolar H+ pumping pyrophosphate (AVP1) in Picochlorum soloecismus was examined. AVP1 overexpression causes biomass increase in relevant plant crops. When overexpressed in this microalga it increases carbon storage in the form of starch in a closed laboratory photobioreactor. However, …