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Articles 1 - 16 of 16
Full-Text Articles in Life Sciences
Sphenoidal Sinuses And Spherical Harmonics: Variation And Covariation Of The Most Morphologically Diverse And Least Understood Paranasal Sinus, Katharine Grace Josephine Ryan
Sphenoidal Sinuses And Spherical Harmonics: Variation And Covariation Of The Most Morphologically Diverse And Least Understood Paranasal Sinus, Katharine Grace Josephine Ryan
Doctoral Dissertations
Understanding the shape variation of the human sphenoidal sinus is important to several areas of research. This includes clinical investigation (sinus pathology and safe endoscopic endonasal surgical practice) and paranasal sinus evolution (for which there is still no consensus). Yet, the sphenoidal sinus has high morphological variation, prohibiting its quantification through traditional geometric morphometric landmarking methods. The sphenoid body, and thus also the sinus contained within, is located directly at the developmental center of the basicranium in humans, where the three cranial fossae meet at the midline, and adjacent to the three synchondroses which are the sites of cranial base …
Water Availability As A Cross-Scale Driver Of Microbial Functions And Free Viral Abundance In Soil, Aubrey K. Fine
Water Availability As A Cross-Scale Driver Of Microbial Functions And Free Viral Abundance In Soil, Aubrey K. Fine
Doctoral Dissertations
Viral infection is widespread in natural microbial communities, with extensive study in aquatic ecosystems demonstrating direct influence on host physiology, functional activity, and mortality. While similar dynamics are assumed to occur across ecosystems, soils are distinct microbial habitats where soil physiochemical structure and water availability constrain resource availability. These unique environmental conditions have been widely demonstrated to affect microbial distribution, diversity, and functional activity in bulk soil, while their influence on virus-microbe interactions and free viral abundance remains limited. To address this knowledge gap, this research had three broad aims: i) to investigate variability in microbial responses to drying-rewetting cycles …
Applications Of Statistical Physics To Ecology: Ising Models And Two-Cycle Coupled Oscillators, Vahini Reddy Nareddy
Applications Of Statistical Physics To Ecology: Ising Models And Two-Cycle Coupled Oscillators, Vahini Reddy Nareddy
Doctoral Dissertations
Many ecological systems exhibit noisy period-2 oscillations and, when they are spatially extended, they undergo phase transition from synchrony to incoherence in the Ising universality class. Period-2 cycles have two possible phases of oscillations and can be represented as two states in the bistable systems. Understanding the dynamics of ecological systems by representing their oscillations as bistable states and developing dynamical models using the tools from statistical physics to predict their future states is the focus of this thesis. As the ecological oscillators with two-cycle behavior undergo phase transitions in the Ising universality class, many features of synchrony and equilibrium …
Flexible Phenotypes, Energetics, And Whole-Animal Performance Of Migratory Songbirds, Michael Griego
Flexible Phenotypes, Energetics, And Whole-Animal Performance Of Migratory Songbirds, Michael Griego
Doctoral Dissertations
Animal life has evolved innumerable strategies to adapt to a great range of environmental conditions present on earth. The physiology of free-living animals has thus been shaped to allow for maximal performance under challenging conditions and has given rise to traits that enable animals to overcome daunting ecological pressures. Few life history stages in the animal kingdom rival the intensity of annual avian migration: the extreme metabolic requirements of long-distance flight coupled with navigating vast and hostile ecological barriers results in enormously high mortality for young birds. It is therefore the main focus of this thesis to identify physiological traits …
Constraints Of The Imagination: How Phenotypes Are Shaped Through Genetics, The Environment, And Development, Michelle Gilbert
Constraints Of The Imagination: How Phenotypes Are Shaped Through Genetics, The Environment, And Development, Michelle Gilbert
Doctoral Dissertations
Phenotypic constraints are ubiquitous throughout nature, being found throughout all stages of life and at multiple different biological levels including cellular, genetic, environmental, behavioral, evolutionary, and developmental. These constraints have shaped, not only the natural world, but the way that we perceive what is possible, or impossible, an observation made clear by François Jacob in his 1977 paper “Evolution and Tinkering”. This is reflected in the literature, repeatedly, by the regular occurrence of densely packed visualization of phenotypic space that seemingly always have large areas that go unoccupied. Despite constrained regions of space being observable across countless taxa, identifying the …
Ecology And Phytochemistry Of The Non-Native Plant Thlaspi Arvense (Brassicaceae) In Subalpine Meadows Of Colorado, Usa, Elsa Cousins
Ecology And Phytochemistry Of The Non-Native Plant Thlaspi Arvense (Brassicaceae) In Subalpine Meadows Of Colorado, Usa, Elsa Cousins
Doctoral Dissertations
Climate change is altering ecosystems at multiple scales. Globally, warming temperatures and increasing irregularity of precipitation will have large scale impacts on species distribution and success. Locally, understanding species response to fine scale microhabitat variation can provide key insights into population adaptation. Non-native plants represent an opportunity to investigate population level response and adaptation to relatively novel combinations of biotic and abiotic environments. Subalpine meadows are at the intersection of biotic and abiotic change, as large-scale climatic shifts alter water and temperature regimes and species range shifts become increasingly common and larger in scale. This dissertation addresses these questions of …
The Influence Of Traits On Species Responses To Climate Change: Does Warming Negatively Impact Native Species More Than Invasive Species?, Margaret Anne Mamantov
The Influence Of Traits On Species Responses To Climate Change: Does Warming Negatively Impact Native Species More Than Invasive Species?, Margaret Anne Mamantov
Doctoral Dissertations
Current climate change is increasing global temperatures so that many organisms are now experiencing temperatures outside of their thermal tolerance, which threatens their survival. Organisms respond to physiologically stressful temperatures to reduce this threat. Organisms respond to warming through three main mechanisms: range shifts, adjustments via phenotypic plasticity, and evolutionary adaptation. Organisms vary in their ability to utilize these three mechanisms, leading to differences in the magnitude and success of their adjustments to temperature change. Here, I examine how organismal traits influence variation in species response to climate change. Chapter one addresses how physiological tolerance may influence the rate of …
Broadscale Outcome And Monitoring Assessment To Evaluate Protected Area Effectiveness In Northern Patagonia, Maria Daniela Rivarola
Broadscale Outcome And Monitoring Assessment To Evaluate Protected Area Effectiveness In Northern Patagonia, Maria Daniela Rivarola
Doctoral Dissertations
Biomes worldwide have been affected by biodiversity loss and habitat degradation for more than a century. Protected Areas (PAs) have been established in almost every country, as they represent one of the most important tools in biodiversity conservation. Nevertheless, the relentless biodiversity loss trend has not stopped. Concern about PA effectiveness has risen, and several methods to evaluate it have been implemented over the last few decades. Nahuel Huapi National Park (NHNP) is the first PA in Argentina and one of the largest. The area is considered a biodiversity hotspot, and its conservation is essential, as unique ecological and evolutionary …
Making Sense Of Soil Microbiome Complexity For Plant And Ecosystem Function In A Changing World, Kendall K. Beals
Making Sense Of Soil Microbiome Complexity For Plant And Ecosystem Function In A Changing World, Kendall K. Beals
Doctoral Dissertations
Soils contain the highest biodiversity on Earth. While the importance of the soil microbiome for larger-scale ecological phenomena such as nutrient and carbon cycling, plant growth and plant community dynamics is well-established, the fundamental question of the ecological and evolutionary function of this immense belowground microbial diversity for plant and ecosystem function still remains a great challenge in microbial ecology research. The objective of this dissertation is to understand how the importance of soil microbial community composition for plant and ecosystem function and how changes to soil microbial community composition from climate change-induced disturbance events, specifically fire, influence plant and …
Elk Abundance, Survival, And Health In The Cumberland Mountains Of Tennessee, Katherine Kurth
Elk Abundance, Survival, And Health In The Cumberland Mountains Of Tennessee, Katherine Kurth
Doctoral Dissertations
Managing sustainable wildlife populations requires insight into population abundance and health. Since reintroduction, elk (Cervus canadensis) at the North Cumberland Wildlife Management Area (NCWMA) in Tennessee have shown marginal population growth using low-precision abundance estimates. Limited research investigating possible population limiting factors has occurred since evaluations conducted directly after translocation. To provide information necessary for effective population management, we estimated abundance, identified survival rates, and conducted mortality and health surveillance. Precise abundance estimates of eastern elk populations are challenging to obtain using traditional capture-recapture due to invasive handling of individuals and low detection in forested landscapes. Therefore, we …
Plant Community Responses To Interactive Anthropogenic Disturbances Along A Natural-Wildland-Urban Gradient And Undergraduate Students’ Attitudes Toward Disturbances, Mali M. Hubert
Doctoral Dissertations
Anthropogenic disturbances are defined as any change caused by human activity that alters biodiversity. Wildfire and urbanization disturbances are among the most influential on the landscape because of their individual and interactive properties. Areas deemed wildland-urban interfaces (WUI; area where environment intermingles with human-built structures) are increasing near protected lands because of human population growth and movement, which often facilitates fire ignitions by humans. Houses that are adjacent to or overlap with wildland vegetation can complicate protection of urban development and wildlands from fires. The expansion of the WUI due to population growth will exacerbate fire risk, which can ultimately …
The Influence Of Climate Change On The Ecology Of The Arctic Ground Squirrel In Denali National Park, Ak., Nigel A. Golden
The Influence Of Climate Change On The Ecology Of The Arctic Ground Squirrel In Denali National Park, Ak., Nigel A. Golden
Doctoral Dissertations
This dissertation research focuses on the ecology of the Arctic ground squirrel (Urocitellus parryii) in Denali National Park and Preserve, AK. The Arctic ground squirrels is a species of interest for monitoring efforts under the National Park Services’ Vital Signs Monitoring Program under the Vital Signs Monitoring program. The focus of this program is to monitor what is considered to be the most significant indicators of ecological conditions of the specific park resources that are of the greatest concern. The CAKN designated the Arctic ground squirrel (Urocitellus parryii) as one indicator species of park ecosystems. Despite being easy to observe …
The Spatial Distribution Of Invasive Plant Presence, Abundance, And Impact, Evelyn M. Beaury
The Spatial Distribution Of Invasive Plant Presence, Abundance, And Impact, Evelyn M. Beaury
Doctoral Dissertations
Across the globe, native ecosystems are increasingly threatened by the spread and negative impacts of non-native, invasive plants. While many hypotheses explore what contributes to the damage caused by invasive species, few studies have tested these hypotheses at the macroscale. My dissertation addresses this knowledge gap by synthesizing thousands of vegetation surveys from ecosystems across the United States. I leverage existing, as well as explore new macroecological methods to deepen our understanding of the spatial ecology of plant invasions. My dissertation also asks how effective management and policy has been at reducing plant invasions. The primary introduction pathway for invasive …
Drivers And Direct Impacts Of Lean Mass Dynamics On The Stopover Ecology And Migratory Pace Of Nearctic-Neotropical Migrant Songbirds In Spring, Mariamar Gutierrez Ramirez
Drivers And Direct Impacts Of Lean Mass Dynamics On The Stopover Ecology And Migratory Pace Of Nearctic-Neotropical Migrant Songbirds In Spring, Mariamar Gutierrez Ramirez
Doctoral Dissertations
Annual migration in songbirds is one of the most demanding life-history stages. It represents a period of high mortality, yet there is still much unknown about the ecological correlates that influence its successful completion. After long non-stop migratory flights, birds require a stopover period to rest and replenish depleted energy reserves. Birds use fat as the primary fuel to power long-distance flights. However, birds also burn lean tissue, which results in significant reductions in muscle and organ masses. The discovery and quantification of lean mass catabolism represented a paradigm shift in migration ecology because non-fat components were thought to remain …
Thermal Ecophysiology Of Juvenile Anadromous River Herring, Lian W. Guo
Thermal Ecophysiology Of Juvenile Anadromous River Herring, Lian W. Guo
Doctoral Dissertations
Temperature controls the rate of all biochemical processes, and thus can significantly influence the physiology and ecology of all living organisms on earth. Understanding how temperature influences fitness can therefore provide insight into mechanisms affecting population size, dynamics, and geographic distributions, especially in the context of climate change. Early life stages of fishes experience significant selective pressure to grow large and accumulate energy reserves in order to avoid predation and starvation. Increasing temperatures will increase routine metabolic rates, which may result in less energy being available for growth and energy storage. In this thesis, I examine the effects of temperature, …
Developing A Restoration Strategy For Brook Floater (Alasmidonta Varicosa) In Massachusetts, Ayla Skorupa
Developing A Restoration Strategy For Brook Floater (Alasmidonta Varicosa) In Massachusetts, Ayla Skorupa
Doctoral Dissertations
The brook floater (Alasmidonta varicosa) is a freshwater mussel (Order: Unionida) native to Atlantic Slope drainages from Canada (Nova Scotia and New Brunswick) to Georgia, U.S. The precipitous loss of brook floater populations and extant low densities in many regions evokes an urgency to establish conservation initiatives for the species. A targeted approach to population restoration is critical in Massachusetts (MA) where brook floater remain in low abundances in only 4 of the 11 originally occupied watersheds (Hydrologic unit code-12). A succinct strategy to restore a rare freshwater mussel species is unavailable yet critical to aid restoration. The …