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Climate change

2018

Theses/Dissertations

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Articles 1 - 21 of 21

Full-Text Articles in Life Sciences

Understanding The Impacts Of Current And Future Environmental Variation On Central African Amphibian Biodiversity, Courtney A. Miller Dec 2018

Understanding The Impacts Of Current And Future Environmental Variation On Central African Amphibian Biodiversity, Courtney A. Miller

University of New Orleans Theses and Dissertations

Global climate change is projected to impact multiple levels of biodiversity by imposing strong selection pressures on existing populations, triggering shifts in species distributions, and reorganizing entire communities. The Lower Guineo-Congolian region in central Africa, a reservoir for amphibian diversity, is predicted to be severely affected by future climate change through rising temperatures and greater variability in rainfall. Geospatial modelling can be used to assess how environmental variation shapes patterns of biological variation – from the genomic to the community level – and use these associations to predict patterns of biological change across space and time. The overall goal of this dissertation ...


Plant Evolutionary Response To Climate Change: Detecting Adaptation Across Experimental And Natural Precipitation Gradients, Jacqueline J. Peña Dec 2018

Plant Evolutionary Response To Climate Change: Detecting Adaptation Across Experimental And Natural Precipitation Gradients, Jacqueline J. Peña

All Graduate Theses and Dissertations

Global climate change is a real-time problem that presents threats to many species. Climate change can alter ecosystems and may lead to species extinction. Species can respond to climate change by moving to a better environment or adapting. Therefore, it is necessary to rely on several approaches and perspectives to anticipate ecological impacts of climate change. A common strategy uses models to understand how populations respond to different climate scenarios. Ecological models have helped usunderstand population persistence, but they often ignore how populations adapt to environmental stress. Adaptive evolution has been ignored because it was assumed that evolution was too ...


Landscape Planning For Climate Change Resilience In The Southern Rockies, Jeffrey D. Haight Dec 2018

Landscape Planning For Climate Change Resilience In The Southern Rockies, Jeffrey D. Haight

All Graduate Theses and Dissertations

The unique species, ecosystems and landscapes of the Western United States are experiencing unprecedented pressures from climate change, creating new challenges for conservation. As temperatures rise and patterns of precipitation shift, plant and wildlife species have been shifting their ranges to new areas in search of more suitable climates, building groupings of species that are historically unfamiliar. These climate -driven migrations place an additional burden on species that are already threatened from habitat loss and other human-related activities. The impacts of climate change are of particular concern in landscapes that have long been conserved and managed based on the ecological ...


Impacts Of Ammonia And Temperature On Freshwater Snail Behavior And Physiology., Megan Christine Dewhatley Dec 2018

Impacts Of Ammonia And Temperature On Freshwater Snail Behavior And Physiology., Megan Christine Dewhatley

Electronic Theses and Dissertations

Gastropods are one of the most imperiled groups of animals in North America, yet there are major gaps in the literature pertaining to pollutants and climate change, and especially sublethal impacts. This dissertation assesses the effects of climate warming and unionized ammonia (NH3), one of the most abundant water pollutants, on the behavior and physiology of two caenogastropod snails: fine-ridged elimia (Elimia semicarinata) and Shawnee rocksnails (Lithasia obovata) (Gastropoda: Neotaenioglossa: Pleuroceridae). Righting behavior, or the movement used by snails to turn themselves right-side-up, was used as the main endpoint; delays in this behavior compromise fitness via lost feeding time ...


Coastal Wetland Dynamics Under Sea-Level Rise And Wetland Restoration In The Northern Gulf Of Mexico Using Bayesian Multilevel Models And A Web Tool, Tyler Hardy Aug 2018

Coastal Wetland Dynamics Under Sea-Level Rise And Wetland Restoration In The Northern Gulf Of Mexico Using Bayesian Multilevel Models And A Web Tool, Tyler Hardy

Master's Theses

There is currently a lack of modeling framework to predict how relative sea-level rise (SLR), combined with restoration activities, affects landscapes of coastal wetlands with uncertainties accounted for at the entire northern Gulf of Mexico (NGOM). I developed such a modeling framework – Bayesian multi-level models to study the spatial pattern of wetland loss in the NGOM, driven by relative RSLR, vegetation productivity, tidal range, coastal slope, and wave height – all interacting with river-borne sediment availability, indicated by hydrological regimes. These interactions have not been comprehensively investigated before. I further modified this model to assess the efficacy of restoration projects from ...


Atmospheric Change Promotes Increasing Cyanobacteria Dominance In Swedish Lakes, Erika Christiane Freeman Aug 2018

Atmospheric Change Promotes Increasing Cyanobacteria Dominance In Swedish Lakes, Erika Christiane Freeman

Electronic Thesis and Dissertation Repository

The frequency and intensity of cyanobacteria blooms are increasing globally. The interacting effects of environmental drivers, including increased temperature, altered precipitation, reduced acidification-with associated shifts in nutrient limitation- and increased dissolved organic matter loads to lakes are predicted to create favourable environmental conditions for cyanobacteria in northern lakes. This prediction was tested in 28 nutrient-poor Swedish lakes over 16 years (1998-2013). Increases in cyanobacteria abundance were identified in 21% of the study sites, composed mostly of increases in three specific genera: Merismopedia, Chroococcus, and Dolichospermum. Increases in temperature favoured Merismopedia dominance in lakes with low pH and high nitrogen to ...


Climate Driven Range Shifts Of North American Small Mammals: Species’ Traits And Phylogenetic Influences, Katie Nehiba Aug 2018

Climate Driven Range Shifts Of North American Small Mammals: Species’ Traits And Phylogenetic Influences, Katie Nehiba

All NMU Master's Theses

Current anthropogenically-driven climate change is accelerating at an unprecedented rate. In response, species’ ranges may shift, tracking optimal climatic conditions. Species-specific differences may produce predictable differences in the extent of range shifts. I evaluated if patterns of predicted responses to climate change were strongly related to species’ taxonomic identities and/or ecological characteristics of species’ niches, elevation and precipitation. I evaluated differences in predicted range shifts in well-sampled small mammals that are restricted to North America: kangaroo rats, voles, chipmunks, and ground squirrels. I used species distribution modeling to develop predictions for the distributions of species under current and future ...


Spatial Distribution And Stock-Recruitment Analysis Of The Atlantic Surfclam, Spisula Solidissima, In The Mid-Atlantic Bight And On Georges Bank, Jeremy Timbs Jul 2018

Spatial Distribution And Stock-Recruitment Analysis Of The Atlantic Surfclam, Spisula Solidissima, In The Mid-Atlantic Bight And On Georges Bank, Jeremy Timbs

Master's Theses

Atlantic surfclams, Spisula solidissima, are long-lived bivalve molluscs with dispersive larval stages. Surfclam patchiness throughout the U.S. Exclusive Economic Zone (EEZ) has declined from the 1980’s to the present in all assessed regions (Delmarva, New Jersey, Long Island, Southern New England, and Georges Banks). Warming of Mid-Atlantic bottom waters is driving the surfclam stock into new habitat and extirpating the surfclams from nearshore areas. Based on a species distribution function model, the small surfclams appear to inhabit a greater area than the large market-size surfclams across the entire stock. The wider distribution of recent recruits relative to the ...


Plant Functional Groups And Success In A Changing Environment: Modeling Physiological Niches Of Colorado Plateau Plants, Anne Thomas May 2018

Plant Functional Groups And Success In A Changing Environment: Modeling Physiological Niches Of Colorado Plateau Plants, Anne Thomas

Undergraduate Honors Theses

Quantifying the environmental and physiological niches of plant species is crucial to predicting their sensitivity to global change, and aggregating plant species by functional type is fundamental both to ecological theory and to the practicality of large-scale efforts to predict the consequences of global change. However, traditional functional types are not always predictive of individual species’ responses to change. Here, an inverse species distribution modeling approach is used to identify functionally similar species based on physiological niche in order to better anticipate the consequences of climate change on the Colorado Plateau, USA. The Colorado Plateau is a semiarid region particularly ...


Developing A Risk Assessment Protocol To Quantify Distribution And Uptake Of Persistent Organic Pollutants In Glacial Outflows, Kimberley Rain Miner May 2018

Developing A Risk Assessment Protocol To Quantify Distribution And Uptake Of Persistent Organic Pollutants In Glacial Outflows, Kimberley Rain Miner

Electronic Theses and Dissertations

Pollutants released by industrialized nations between 1960 and 2004 have been transported northward through atmospheric processes and deposited into glaciated alpine ecosystems. Many of these chemicals retain their original structure and are absorbed into the biota thousands of miles away from where they were originally utilized. With a warming climate increasing the melt of alpine glaciers, these glaciers may be introducing growing amounts of toxins into the watershed. While studies have demonstrated the existence of resident pollutants within glaciated ecosystems, no one has developed a risk assessment to identify sources and quantity of risk posed by these compounds when released ...


Linking Climate Change And Mortality In Piñon-Juniper Woodlands, From Leaf To Ecosystem, Amanda I. Liebrecht May 2018

Linking Climate Change And Mortality In Piñon-Juniper Woodlands, From Leaf To Ecosystem, Amanda I. Liebrecht

Biology ETDs

As global climate changes, the Southwestern US is predicted to experience more frequent and intense drought events. Extreme droughts can drive decreases in both physiological and ecosystem function, and can result in widespread tree mortality. Piñon-juniper (PJ) woodlands are a prevalent ecosystem in the region, co-dominated by two tree species, piñon (Pinus edulis) and juniper (Juniperus monosperma). Drought-induced piñon mortality has occurred over the past few decades, coinciding with outbreaks of a piñon-specific bark beetle. Piñon and juniper have different hydraulic strategies (isohydry and anisohydry, respectively) that should affect the way each species responds to drought. In this dissertation, I ...


Geospatial Analysis Of Eastern Oyster Habitat And Disease In The Chesapeake Bay, Hannah Bradley May 2018

Geospatial Analysis Of Eastern Oyster Habitat And Disease In The Chesapeake Bay, Hannah Bradley

Senior Honors Projects, 2010-current

Crassostrea virginica, common name eastern oyster, in the Chesapeake Bay is currently at 1% of its peak annual landings in 1884 (600,000 metric tons). This decline is in spite of being considered a resilient species. Causes of the decline include overharvesting, disease, and habitat loss. While efforts have been made to combat each cause, the key element to recovering the population is coordinated habitat restoration. This study aims to develop a GIS-based habitat model for the eastern oyster in the Chesapeake Bay. The first goal of this study was to determine the water quality parameters necessary for successful oyster ...


Phenology Of A Southern Population Of Mountain Pine Beetle (Dendroctonus Ponderosae), Anne Elise Mcmanis May 2018

Phenology Of A Southern Population Of Mountain Pine Beetle (Dendroctonus Ponderosae), Anne Elise Mcmanis

All Graduate Theses and Dissertations

Mountain pine beetle (Dendroctonus ponderosae, Hopkins) is a major disturbance agent in pine ecosystems of western North America. Adaptation to local climates has resulted in primarily univoltine (one generation per year) generation timing across a thermally diverse latitudinal gradient. We hypothesized that this pattern in total development time is shaped by selection for slower developmental rates, altered developmental thresholds, or oviposition rates in southern populations inhabiting warmer climates. To investigate traits responsible for latitudinal differences we measured lifestage-specific development of southern mountain pine beetle eggs, larvae and pupae across a range of temperatures. We also describe and model oviposition of ...


Climate Change And Wildfire: Implications For Forest Management In The Blue Mountains Of Eastern Oregon, Angela Elaine Boag Jan 2018

Climate Change And Wildfire: Implications For Forest Management In The Blue Mountains Of Eastern Oregon, Angela Elaine Boag

Environmental Studies Graduate Theses & Dissertations

Shifting climate and wildfire regimes are changing forest structure and function globally. In the western US, future forest structure will be determined by interactions between climate change and disturbance, including increasingly frequent large wildfires, as well as the forest management actions of landowners and managers. While research on the ecological impacts of these changes is rapidly expanding, there is limited focus on how forest vulnerability may vary across land ownerships, which may have varying capacities for climate-adaptive forest management. In this dissertation, I explored how coniferous forests in the Blue Mountains of eastern Oregon are vulnerable to climate and wildfire ...


The Effects Of Human Trampling Disturbance, Plant-Plant Interactions, And Climate On The Performance And Distribution Of The Alpine Cushion Plant Silene Acaulis, Nathalie Isabelle Chardon Jan 2018

The Effects Of Human Trampling Disturbance, Plant-Plant Interactions, And Climate On The Performance And Distribution Of The Alpine Cushion Plant Silene Acaulis, Nathalie Isabelle Chardon

Environmental Studies Graduate Theses & Dissertations

Delineating the abiotic and biotic processes that set species geographic distributions has been a central theme in ecological research for hundreds of years, yet we still do not understand many aspects of this broad question. Discerning what processes determine past and current range limits is particularly critical for predicting how species distributions will respond to climate change. In Chapters 2 and 3, I address how the interactions of climate, inter-species interactions such as competition, and human disturbances together influence range limits. I show that disturbance has positive effects on the alpine cushion plants Silene acaulis and Minuartia obtusiloba at the ...


Modeling The Abundance And Distribution Of Terrestrial Plants Through Space And Time, Caroline Curtis Jan 2018

Modeling The Abundance And Distribution Of Terrestrial Plants Through Space And Time, Caroline Curtis

Doctoral Dissertations

Anthropogenically-driven changes threaten ecosystems and species over regional to global scales. I addressed several questions related to how species ranges will respond to these changes over large spatial and temporal extents to better understand what determines where a species occurs.

First, I modeled presence and abundance of two widespread invasive plants in the southwest U.S. under current and projected future climatic conditions, from which I inferred impact risk. These results provide more insight than presence modeling alone and highlight the possibility of increased invasion pressure in the future.

Second, I tested the assumption that expert-based climatic tolerance data will ...


Estimating The Heritability Of Thermal Tolerance In Acropora Cervicornis And The Physiological Basis Of Adaptation That Correlates To Survival At Elevated Temperatures, Kelsey L. Yetsko Jan 2018

Estimating The Heritability Of Thermal Tolerance In Acropora Cervicornis And The Physiological Basis Of Adaptation That Correlates To Survival At Elevated Temperatures, Kelsey L. Yetsko

UNF Graduate Theses and Dissertations

Human activities have substantially increased the atmospheric concentrations of greenhouse gases, resulting in warmer ocean temperatures that are having a negative impact on reef corals, which are highly susceptible to changes in temperature. Understanding the degree to which species vary in their tolerance to elevated temperatures and whether this variation is heritable is important in determining their ability to adapt to climate change. In order to address this, Acropora cervicornis fragments from 20 genetically distinct colonies were kept at either ambient or elevated temperatures, and mortality was monitored for 26 days. Heritability of thermal tolerance was estimated using a clonal ...


Growth Dynamics Of Black Spruce (Picea Mariana) Across Northwestern North America, Anastasia E. Sniderhan Jan 2018

Growth Dynamics Of Black Spruce (Picea Mariana) Across Northwestern North America, Anastasia E. Sniderhan

Theses and Dissertations (Comprehensive)

The impacts of climate change have been widely documented around the world. One of the most rapidly changing areas is the boreal forest of North America. The extent of change has been such that there have been shifts in long-standing climate-growth relationships in many boreal tree species; while the growth of many of these high-latitude forests were formerly limited by temperature, warming has increased the evapotranspirative demands such that there is widespread drought stress limiting productivity in the boreal forest. With the importance of the boreal forest as a global carbon sink, it is imperative to understand the extent of ...


Drivers Of Post-Fire Vascular Plant Regeneration In The Conifer-Dominated Boreal Forest Of Southern Northwest Territories, Alison White Jan 2018

Drivers Of Post-Fire Vascular Plant Regeneration In The Conifer-Dominated Boreal Forest Of Southern Northwest Territories, Alison White

Theses and Dissertations (Comprehensive)

In recent years, climate warming has led to an increase in the severity and frequency of naturally occurring fires in boreal ecosystems globally. In 2014, an unprecedented 3.4 million hectares of boreal forest burned in the Northwest Territories (NWT). While much research has focused on post-fire succession of serotinous tree species such as Picea mariana (black spruce) and Pinus banksiana (jack pine), the understory community of vascular plants play an important role in ecosystem functioning but less is known about the response of this component of the system to changing fire regimes. Regeneration strategies such as the ability to ...


Remote Sensing Methods And Applications For Detecting Change In Forest Ecosystems, David James Gudex-Cross Jan 2018

Remote Sensing Methods And Applications For Detecting Change In Forest Ecosystems, David James Gudex-Cross

Graduate College Dissertations and Theses

Forest ecosystems are being altered by climate change, invasive species, and additional stressors. Our ability to detect these changes and quantify their impacts relies on detailed data across spatial and temporal scales. This dissertation expands the ecological utility of long-term satellite imagery by developing high quality forest mapping products and examining spatiotemporal changes in tree species abundance and phenology across the northeastern United States (US; the ‘Northeast’).

Species/genus-level forest composition maps were developed by integrating field data and Landsat images to model abundance at a sub-pixel scale. These abundance maps were then used to 1) produce a more detailed ...


Evaluating Current And Future Range Limits Of An Endangered, Keystone Rodent (Dipodomys Ingens), Ivy V. Widick Jan 2018

Evaluating Current And Future Range Limits Of An Endangered, Keystone Rodent (Dipodomys Ingens), Ivy V. Widick

Theses and projects

Climate is often considered the single most important factor limiting species’ ranges. Other factors, such as biotic interactions, are often assumed to be included via abiotic proxies. However, differential responses to climate change may decouple these relationships or lead to adaptation to novel environments. Accounting for competition and local adaptation should more accurately describe environmental factors influencing current distributions and increase the predictive accuracy of future distributions. Modeling the endangered giant kangaroo rat (Dipodomys ingens) is an excellent application of these model improvements, as the species range consists of geographically and genetically isolated populations experiencing disparate climatic change. From eight ...