Life Sciences Commons^™

Comparison Of Bacterial And Archaeal Communities In The Subsurface Versus Surface: Implications For Nitrogen Cycling, Jason C. Kimble 5059801155

Biology ETDs

Arid-land caves are thought to be extremely nitrogen-limited, but almost nothing is known about how microbes in subsurface arid-land environments obtain this essential element to meet cellular demand. The depth of caves beneath the surface may represent a critical factor affecting microbial nitrogen cycling in these environments. Percolation of water and nutrients from a precipitation pulse event would affect deep arid-land carbonate caves at a much slower rate. To obtain nitrogen in deep, carbonate caves, microorganisms could use fixed N in the host rock for assimilatory biochemical pathways or for a respiratory electron acceptor. However, the latter process leads to …

Forage Selection And Habitat Architecture As Drivers Of Small Mammal Community Dynamics In An Arid, Nutrient Limited, Highly Stochastic Ecosystem, Jennifer Darby Noble

Biology ETDs

In the Northern Chihuahuan desert, grassland and shrubland co-occur as separate stable states under similar climatic conditions. In this bottom up (resource driven) system, the magnitude and timing of precipitation events drives primary production which varies from year to year and season to season. Climate change is predicted to alter precipitation regimes, and increase aridity, facilitating shrub encroachment which results in increased landscape heterogeneity and a decrease in plant biodiversity. These changes will likely result in a restructuring of small mammal communities.

We used long-term data on precipitation, primary production, and abundances of small mammals in adjacent grassland and shrubland …

Bacterial Siderophore Production In Lechuguilla And Spider Caves, Carlsbad National Park (Ccnp) Carlsbad, New Mexico, Tammi R. Duncan

Biology ETDs

Lechuguilla and Spider caves, Carlsbad Caverns National Park, contain a rich microbial diversity. Despite oligotrophic conditions, the microorganisms in these caves have developed strategies to acquire essential nutrients. I hypothesized that cave bacteria use siderophores, a ferric iron chelating compound, to acquire iron for essential life processes. To understand the backdrop against which the cave bacteria would produce siderophores, I examined the bacterial physiological characteristics, determined whether cave bacteria have an ability to produce siderophores, and investigated a possible correlation between iron and manganese concentrations in cave deposits and siderophore production by bacteria cultured from the same site. I carried …

Dynamics Of Community Composition And Ecological Processes In Mesic And Semiarid Grasslands, Sydney K. Jones

Biology ETDs

Grassland communities change in response to disturbance and chronic resource alterations. Temporal community dynamics were examined within mesic tallgrass prairie at Konza Prairie in northeastern Kansas, and semiarid desert grassland and shrubland in central New Mexico. In both grasslands, producer and consumer communities changed over time in response to fire frequency and shrub encroachment. Directional change was driven by changes in abundances of species already in the community, rather than turnover in species composition. Despite directional change, species richness was highly stable, making species abundance rather than richness a better indicator of future community change. Species reordering also occurred during …

Diet Specialization Does Not Explain Occupancy Or Abundance In A Test Of The Resource Breadth Hypothesis In A Small Mammal Community, Deborah R. Boro

Biology ETDs

The abundance-occupancy relationship (AOR) is a recurrent pattern in ecology and biogeography, in which species with expansive distributions are locally common while those with restricted distributions are locally rare. Despite occurring across a wide variety of taxa and spatial scales, the mechanisms underlying AORs are not well understood. I tested two such mechanisms regarding dietary generalism in a guild of 8 small, herbivorous African mammals: (1) the degree to which diet was explained by food availability, and (2) population-level diet breadth. I expected that food availability would better predict diet for abundant, widespread species than rare, restricted species. Additionally, I …

The Impact Of Climate And Elevation On The Growth And Mortality Of Piñon Pine, Alice M. Fretz

Biology ETDs

The Southwestern United States is currently experiencing severe drought, resulting in the mortality of many tree species. Piñon-juniper woodlands are an extensive biome in the Southwest, and are highly vulnerable to extended periods of drought that lead to tree mortality. Specifically, Pinus edulis populations are decreasing due to increasingly arid conditions. I used dendrochronology to investigate how tree growth rings of Pinus edulis reflect severe drought in living and dead trees. I also investigated how severe drought affects Pinus edulis along an altitudinal gradient. Tree core samples were taken from currently living and dead trees, as well as from trees …

Nutrient Additions Alter Semi-Arid Grassland Response To Fire, Alec A. Carrigy

Biology ETDs

Knowledge of how multiple global change drivers interact to affect community structure is critical for predicting future community states, especially when community structure drives ecosystem function. Disturbances such as fire and nutrient additions often shift communities away from their mean composition, but less is known about how disturbances affect spatial variation among local patches of the community over time (spatiotemporal dispersion). Dispersion may increase (local communities diverge in composition), stay the same, or decrease (communities converge) in response to disturbance. We compared patterns of spatiotemporal dispersion and temporal trajectories in community composition across three sites in a northern Chihuahuan Desert …

Genetic Approaches To Population Ecology And Conservation Of The Sacramento Mountain Salamander, Samantha Jo Nicole Cordova

Biology ETDs

Aneides hardii (Sacramento Mountain salamander) is restricted to high-elevation habitat that is fragmented by low-elevation piñon-juniper woodland. Aneides hardii is a species of conservation concern in New Mexico, in part, because disease and climate change endanger its long-term persistence. In this study, we use sequence data from the mitochondrial cytochrome b gene and a microsatellite locus of A. hardii to addresses the timing and scale of population subdivision. We also calculated genetic diversity measures and compared them among mountain ranges to explore demographic history of A. hardii. Twenty-six haplotypes and three genetically distinct lineages were identified, and each haplotype …

Dengue Vaccination Modulates The Dengue-Zika Viral System Via Immunogenic Cross-Talk, Noah J. B. Silva

Biology ETDs

A vaccine for dengue, a viral disease which is a major driver of morbidity and mortality in tropical and subtropical regions, has recently been approved by eleven countries. While vaccination has the potential to reduce disease burden, the approved vaccine faces challenges due to the interactions between the four serotypes of dengue virus (DENV1-4) and the potential interactions with Zika virus (ZIKV), a related flavivirus. In this study, we propose a mathematical model incorporating both DENV and ZIKV in order to investigate the effects of viral competition on dengue vaccine performance, the potential for change in incidence of Zika due …

Evaluating The Relationship Of Temperature And Growth Of A Larval Colorado River Catostomid, C. Latipinnis, Through Otolith Aging And Stable Isotopes (Δ18o), Adam Lawrence Barkalow

Biology ETDs

Knowledge of early life history strategies and ecological dynamics of larval fish growth and development is invaluable for effectively managing and conserving common and endangered fish species. Isotopic analysis of otoliths (bony structures of the inner ear) from larval Flannelmouth Suckers Catostomus latipinnis obtained from the Colorado River in Grand Canyon could greatly facilitate understanding of thermally-regulated growth rates, thermal preferences, and ontogenetic habitat use by these fishes. Colorado River water temperatures in the Grand Canyon are highly modified from projected historic water temperatures present before closure Glen Canyon Dam. Cold water as result of Glen Canyon dam and hypolimnetic …

Phylogeography And Population Dynamics Of North American Wolverines (Gulo Gulo Luscus) In Alaska And Western Canada, Dianna Krejsa

Biology ETDs

The circumboreal wolverine (Gulo gulo sp.) is ideal for studying responses to environmental perturbation in the North due to a history of persistence in glacial refugia and subsequent glacial recolonization. Wolverines are also excellent indicators of human influence on the environment due to their close association with remote areas and cold, snowy climes. Through the use of genetic tools (i.e., nuclear microsatellite loci and mitochondrial sequences), I examined population structure of wolverines in Alaska and western Canada to identify signatures of glacial refugia, bottlenecks, and distinctive populations, sex-biased dispersal, gene flow, and source and sink population dynamics. I identified genetic …

Final Report: Status Of The Arizona Toad (Anaxyrus Microscaphus) In New Mexico, Mason J. Ryan, Jacek Tomasz Giermakowski, Ian M. Latella, Howard L. Snell

Biology Faculty & Staff Publications

This report covers the fourth consecutive year (2013-2016) of research on the population dynamics, ecology, and conservation status of the Arizona Toad (Anaxyrus microscaphus) in New Mexico. The year 2016 represented the rare opportunity to study the effects of El Niño, which typically brings above average precipitation to New Mexico, on the breeding behavior and ecology of the Arizona toad. We expected that the El Niño-driven above average precipitation during the winter of 2015 and spring of 2016 would result in increased detection of toads at breeding sites, especially those sites that were dry in 2013, 2014, and …

Natural History And Evolution Of An Elevational Generalist, The Cinereous Conebill (Conirostrum Cinereum), Andrea N. Chavez, Chandresekhar Natarajan, Jay F. Storz, Angela Fago, Christopher C. Witt

Biology ETDs

Elevational generalism is relatively rare in the tropical Andes Mountains, likely owing to the inherent requirements of enduring a high degree of climatic zonation and coping with hypoxic stress. The Cinereous Conebill (Conirostrum cinereum) appears to be an exception, and inhabits a continuous elevational distribution that spans over 4,500 m. Two subspecies, cinereum and fraseri, are restricted to high elevations and may be isolated, whereas the third and most widespread, littorale, occurs continuously along the western slope of the Andes from 0 to over 4,500 m. First, we aim to characterize the morphology, genetics, and climatic …

The Effects Of Atmospheric Pressure On Inter-Specific Competition And The Morphological And Hematological Characteristics Of Elevational Distributions Of Hummingbirds, Ariel M. Gaffney

Biology ETDs

Species diversity in mountainous regions is strongly influenced elevational range limits of species, but it is generally not known which abiotic or biotic factors maintain these limits. Using Black-chinned and Broad-tailed Hummingbirds, species with offset but overlapping elevational ranges in the southwestern USA, we investigate the role barometric pressure plays in influencing these limits. In chapter one, we used a hypobaric chamber to test the effects of variable air pressures on interspecific competitive dominance. We sequenced the genes that encode the two adult isoforms of haemoglobin and measured the O₂-binding affinity of each isoform. In chapter two, we …

Precipitation Patterns And Fungal Community Succession In A Seasonally Dry Secondary Tropical Savanna, Sara R. Lopez

Biology ETDs

Life in seasonally dry areas strongly depends on pulses of precipitation during certain portions of the year. This is particularly relevant for Tropical savannas on the Caribbean coast of Colombia that have been converted from Tropical Dry Forests and subjected to permanent agricultural and grazing practices that in turn induce changes in nutrient status in these systems. Several studies have presented evidence for a shift in C and N dynamics following forest conversion, including a decrease in total soil organic carbon and changes in nitrogen status, but the consequences of forest conversion on soil microbial processes are poorly understood. No …

Immunology Of The Gray Short-Tailed Opossum During Pregnancy And Prenatal Development, Victoria L. Hansen

Biology ETDs

Vertebrate species that bear live young have overcome the evolutionary challenge of maintaining both a functional adaptive immune system and viviparous life cycle. In normal pregnancy, viviparous mothers are able sustain and nourish a fetus that is genetically half non-self without mounting an immunological attack. In 1953 Sir Peter Medawar brought attention to the “enigma of the fetal graft” and immunologists have been puzzling out the intricacies of fetal tolerance ever since. Although viviparity has evolved in all jawed vertebrate lineages aside from Aves, the vast majority of reproductive immunology research has been limited to eutherian mammals. There are insights …

Plant-Microbial Interactions Are Strong Determinants Of Plant Population And Community Dynamics, Y. Anny Chung 9485698

Biology ETDs

Plant-microbial interactions are ubiquitous and yet the consequences of these interactions on plant population and community dynamics are relatively unknown. Here, we used two different classes of plant-microbial interactions to examine their effects on key plant population and community characteristics such as commonness and rarity, competition and coexistence, as well as community stability.

Vertically-transmitted endophytes had stage-dependent effects on the population growth of two grass species Poa sylvestris and Poa alsodes, and generally increased host population growth rates. However, it was the intrinsic demographic advantage of P. sylvestris that allowed its population to grow at a much faster rate …

Pattern And Process In The Radiation Of Ground-Dwelling Squirrels, Bryan S. Mclean

Biology ETDs

What causes biological diversity to be unevenly apportioned across the Tree of Life? The pattern is widespread and well-characterized; but our understanding of processes underlying the taxonomic, phenotypic, and ecological disparities of clades remains incomplete. At least some of this disparity is due to clade-specific differences in the ability to respond to ecological opportunity, whereby access to, and exploitation of, different resources in ecological time drives evolutionary divergence and adaptive radiation. However, not all clades respond equivalently to ecological opportunity, and considerable heterogeneity therefore exists in diversification patterns across radiations.

This dissertation focuses on patterns and processes of diversification in …

Novel Indices To Quantify Freeze Tolerance In Amphibians, Jolene R. Rearick

Biology ETDs

We propose Freeze Endurance (F_end) as a new measure of the ability of amphibians to tolerate internal freezing, allowing integration of time and temperature to describe each freeze event. Use of freeze endurance as a descriptor allows direct comparison between individuals, populations, and species, and may be scaled by body size, or other characteristics, to determine if abilities to survive freezing are significantly different between groups. Thermal limit examinations have long suffered from lack of comparability between publications due to differing endpoints, measurements, equipment, and organism availability, despite the value of information yielded by such studies to understanding …

Novel Approaches To Exploring Silk Use Evolution In Spiders, Rachael Alfaro

Biology ETDs

Spider silk is enigmatic, and web structure, design, and adult morphology of the spinning apparatus of spiders once informed how systematists approached the spider phylogeny. The orb-web and adaptation of viscous silk was considered a key innovation leading to rapid diversification of spiders. However, the advent of molecular techniques including recent phylogenomics studies, overturned this major paradigm in spider evolution. Clades once considered monophyletic are no more. The orb-web is not a pinnacle of evolution, and the former sister group, using cribellate silk (loops of fibrils combed from a specialized silk plate on the abdomen), is now sister to the …

Where The Wild Things Are: Investigating Body Size As A Mechanism For Persistence, Meghan A. Balk

Biology ETDs

Body size is a trait under selection. Genetic drift, climate, diet quality, and biotic interactions all select upon body size at the population, species, and community levels. These factors can be important in the context of rapidly changing climate. One of the ways an animal can persist in its environment is through morphological adaptation in situ. Here, I investigate four questions relating to the evolution of body size: (1) what is the limit in body size change in response to climatic change; (2) how does body size influence the thermal tolerances of animals; (3) how does body size evolve …

Introducing A Theory Of Neutrosophic Evolution: Degrees Of Evolution, Indeterminacy, And Involution, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

During the process of adaptation of a being (plant, animal, or human), to a new environment or conditions, the being partially evolves, partially devolves (degenerates), and partially is indeterminate i.e. neither evolving nor devolving, therefore unchanged (neutral), or the change is unclear, ambiguous, vague, as in neutrosophic logic. Thank to adaptation, one therefore has: evolution, involution, and indeterminacy (or neutrality), each one of these three neutrosophic components in some degree. The degrees of evolution/indeterminacy/involution are referred to both: the structure of the being (its body parts), and functionality of the being (functionality of each part, or inter-functionality of the parts …