Life Sciences Commons^™

An Elevational Gradient In Thermal Tolerance Among Daphnia From Western Maine Lakes, Wheeler Lowell

HON 499 Honors Thesis or Creative Project

With climate change threatening biodiversity worldwide, it is important to understand species’ physiological responses to changing thermal environments. This study examined whether thermal tolerance (measured as time to immobilization, Timm) in the zooplankton Daphnia catawba and D. schødleri varied along an elevational gradient in Western Maine. Specimens collected from five lakes were subjected to heat stress trials to look for inter-population variation. Thermal tolerance was strongly correlated with several elevation-driven lake temperature variables, with the percent of variation explained ranging from 13-37%. Daphnia from cooler, high-elevation lakes were more sensitive to elevated temperatures. While latitudinal gradients have been examined extensively, …

Three Lc-Ms Plant Metabolomics Studies Of Hop (Humulus) Species: Wild H. Neomexicanus, Drought Stress, And Agricultural Terroir, Taylan Morcol

Dissertations, Theses, and Capstone Projects

The hop plant (Humulus L., Cannabaceae) is a dioecious, perennial, twining vine with a long history of human use. Nowadays, hop plants are generally grown for their inflorescences (“cones”), which are used in brewing for their phytochemical metabolites. Many of these metabolites are involved in plant stress response and communication. Genetics and environment are two major factors that affect plant metabolism. In three separate metabolomics studies, this project examined the effects of both genetic and environmental factors on hop phytochemistry.

In the first study, 23 hop genotypes were grown in two different locations in the Pacific Northwest region of …

Investigating Local Adaptation To Hypoxia Stress In The Eastern Oyster Through Comparative Transcriptomics, Heather Nichole Smith

LSU Master's Theses

Climate change represents one of the most important challenges to biodiversity, therefore it is important to understand the mechanisms that allow species to respond to rapid environmental change. Here, we compared two populations of eastern oysters, Crassostrea virginica, from the Gulf of Mexico to study the mechanisms underlying hypoxia tolerance. Using a common garden experiment and comparative transcriptomics, we identified sets of genes involved in the hypoxia response and found differences in both the timing and baseline expression of hypoxia-responsive genes between tolerant and sensitive populations, consistent with a scenario of local adaptation. These genes include the signaling transcription factor …

Examining The Links Between Environmental Variation, Foraging Behaviour And Foraging Success In An Arctic Seabird, Alyssa Eby

Electronic Theses and Dissertations

Arctic regions are experiencing increasing variability in inter-annual sea ice dynamics ultimately impacting marine Arctic ecosystems. Arctic-breeding seabirds, such as thick-billed murres (Uria lomvia) are thus likely to be negatively impacted by fluctuating environmental conditions through its influence on prey availability. Additional extrinsic factors (colony size and chick demand) and intrinsic factors (sex) are also likely to impact foraging behaviour and success of murres in combination with environmental conditions. First, we tested the effect of colony size on colony sensitivity to environmental change at two low Arctic colonies of varying sizes, Coats Island, Nunavut and Digges Island, Nunavut …

Climate-Driven Impacts On Himalayan Aquatic Biodiversity: A Case Study Involving Snowtrout (Cyprinidae: Schizothorax), Riri Wiyanti Retnaningtyas

Graduate Theses and Dissertations

Monitoring biodiversity, to include its relative dispersal and contraction, has become a conservation task of great importance, particularly given the catastrophic and ongoing loss of habitat due to climate change. However, the timing, direction, and magnitude of these rates vary across taxa and ecosystems. Predicting specific impacts of climate change can thus be difficult and this, in turn, hampers management action. Metrics are needed to not only quantify contemporary requirements of species, but also predict potential distributions that fluctuate in lockstep with climate.

Montane ecosystems in the Himalayas are highly impacted by climate change, yet remain largely understudied due to …

Effects Of Tropical Cyclones On Incubation And Hatch Frequency Of Marine Turtles In Broward County, Fl: An Exploratory Look For Potential Cues Of Environmentally Cued Hatching (Ech), Alexis Peterson

All HCAS Student Capstones, Theses, and Dissertations

Due to climate change and warming sea surface temperatures (SST), the intensity and frequency of tropical cyclones in the North Atlantic are continuing to increase. Tropical cyclones have many direct and indirect effects on coastal and marine species, such as sea turtles. Sea turtles are extremely vulnerable to climate change, due to having life history, physiology, and behavioral traits that are heavily influenced by environmental factors (Fuentes and Porter 2013). This study examined whether tropical cyclones serve as a triggering event for environmentally cued hatching (ECH) in loggerhead (Caretta caretta) and green (Chelonia mydas) turtle nests …

Effect Of Temperature On Growth And Gene Expression In The Marine Diatom, Thalassiosira Pseudonana, John M. Foster

USF Tampa Graduate Theses and Dissertations

Diatoms are unicellular, eukaryotic, photosynthetic algae responsible for the production of 20% of our atmospheric oxygen. Diatoms contribute to several important biogeochemical functions. Diatoms contribute to the carbon cycle, sequestering carbon and forming oxygen as a product of photosynthesis. Moreover, by converting abiotic forms of energy such as sunlight into organic compounds (i.e., sugars, starches and lipids), primary producers including diatoms, plants, and phytoplankton feed organisms at higher trophic levels. Consequently, changes in temperature, light intensity, nutrients, salinity and other stress factors that affect primary producers can generate a potentially catastrophic ripple effect at higher trophic levels In this study …

Shorebird Response To Human-Induced Changes At Three Pinellas County Beaches, Rebecca J. Ruthberg-Campagna

USF Tampa Graduate Theses and Dissertations

Worldwide, shorebird habitat is being destroyed and degraded by development and sea level rise. Shorebirds depend on availability of pristine, undisturbed coastal habitats for resting and feeding during migration as well as for reproduction. Migratory shorebirds using the East Atlantic Flyway visit the Gulf of Mexico Beaches of Pinellas County, Florida as a stopover site during Fall and Spring migration. In addition to hosting migratory species, Pinellas County beaches are home to several year-round resident species that breed during Summer. Pinellas County is the most densely populated county in Florida, and its Gulf Coast is heavily developed with commercial and …

Benthic Microalgae Response To A Warming Climate And Shift In Foundational Vegetation Species In A Saltmarsh-Mangrove Ecotone, Gabriela Canas

UNF Graduate Theses and Dissertations

The ecotone in Northeast Florida is experiencing rapid change as mangroves begin to encroach northward into saltmarsh dominated coastal wetlands. This is especially prevalent within the boundaries of the Guana Tolomato Matanzas National Estuarine Research Reserve where studies are attempting to understand the consequences of more mangroves. Although we are beginning to understand some of the implications of this shift in dominant vegetation, the true effects and the accompanying sustained climatic warming effects on the resilience of wetland habitats and their associated communities remains unknown. Primary producers such as benthic microalgae (BMA) are important food sources in both mangrove and …

Heat And Chemical Cues Enhance Germination Rates In Fire-Dependent Chaparral Species, Zachary Litwinowicz

Senior Honors Projects

Climate change has caused an increase in the frequency and intensity of fire cycles in chaparral ecosystems. In environments impacted by wildfires, some plant species depend on complex fire cues to germinate. Determining how to best replicate wildfire cues is essential to using fire-recruiter species in restoration efforts. This study examines the effects of various simulated fire cues on four chaparral species: Arctostaphylos manzanita, A. viscida, Ceanothus cuneatus, and C. jepsonii. Seeds were exposed to heat, charate, liquid smoke, or combinations of treatments. Other germination cues, such as cold exposure for all species and acid exposure for Arctostaphylos species, were …

Assessing Short-Term Microalgal Community Responses Over Altering Hydrological Conditions In Experimental Wetlands Of Costal Georgia, Maggie M. Kuhn

Electronic Theses and Dissertations

Wetlands provide valuable ecosystem services such as nutrient cycling and carbon storage. Microalgae (i.e., diatoms) provide the foundation of primary production and determine rates of energy transfer throughout the system. Climate change models predict an increase in frequency of intense storms and severe drought conditions that pose a threat to known hydrological regimes and wetland ecosystem stability. The purpose of my study was to assess the effects of water permanence (i.e., duration of flooding) on diatom community structure in experimental wetlands. I predicted that wetlands with prolonged periods of flooding (i.e., permanent) would harbor a consistent diatom community throughout flooding …