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Full-Text Articles in Life Sciences
Investigating The Role Of Carbon Stress In The Mortality Of Tamarack Seedlings Under A Warming Environment, Bridget K. Murphy
Investigating The Role Of Carbon Stress In The Mortality Of Tamarack Seedlings Under A Warming Environment, Bridget K. Murphy
Electronic Thesis and Dissertation Repository
Climate warming is increasing the frequency of climate-induced tree mortality events. While drought combined with heat is considered the primary cause of this tree mortality, little is known about whether high temperatures alone can induce mortality, or whether rising CO2 will increase survival. I grew tamarack in two experiments combining warming (0-8 ˚C above ambient) and CO2 (400-750 ppm) to investigate whether high growth temperatures led to carbon limitations and mortality. Using glasshouses, +8 ˚C warming with ambient CO2 (8TAC) led to 40% mortality despite thermal acclimation of respiration. Dying 8TAC seedlings had lower needle carbon concentrations …
Effects Of Elevated Temperature And Elevated Co2 On Leaf Carbon Fluxes In Boreal Conifers: Lab And Field Studies, Mirindi Eric Dusenge
Effects Of Elevated Temperature And Elevated Co2 On Leaf Carbon Fluxes In Boreal Conifers: Lab And Field Studies, Mirindi Eric Dusenge
Electronic Thesis and Dissertation Repository
Rising CO2 may warm northern latitudes up to 10 °C by the end of the century. However, responses of plant physiological processes (such as photosynthesis and respiration) and growth to climate change remain uncertain. Seedlings and mature trees of tamarack (a deciduous species) and black spruce (an evergreen species), North America dominant conifers, were exposed to combined warming (up to +9 ˚C) and elevated CO2 (up to +300 ppm). In seedlings, stomatal conductance (gs) tended to increase with warming in tamarack seedlings, while gsdeclined with warming in spruce. In both species, CO2 had …
Analyzing Avian Incubation With A Computer Algorithm, Tanya T. Shoot
Analyzing Avian Incubation With A Computer Algorithm, Tanya T. Shoot
Electronic Thesis and Dissertation Repository
A stable nest environment is necessary for incubation and development of offspring. Birds vary behaviour to regulate temperature for successful hatchlings. I used a hidden Markov model (HMM) to test how environmental conditions affect incubation behaviour. I examined nest temperatures and behaviours collected from Zebra finches that incubated at 30 °C or 14 °C, then incubated in the same or opposite condition for a second clutch. Data loggers and cameras recorded nest temperature and number of parents on nest. The HMM inferred behaviour from recorded behaviours and temperatures. Temperature and offspring success affected incubation duration. Birds that had successful offspring …
Thermal Biology Of Temperate And High-Latitude Arachnids, Susan E. Anthony
Thermal Biology Of Temperate And High-Latitude Arachnids, Susan E. Anthony
Electronic Thesis and Dissertation Repository
Temperate and high latitude terrestrial ecosystems have high thermal variability, and the ectotherms that inhabit these regions must have thermal tolerances that mirror these temperatures. However, the thermal limits of many high-latitude arachnids are unknown, as well as any underlying mechanisms of seasonal plasticity for any arachnid. The objective of my thesis is to measure the thermal tolerances of temperate, Arctic, and sub-Arctic arachnids, and identify if they have thermal plasticity, either seasonally or following acclimation. I collected the high-latitude pseudoscorpion Wyochernes asiaticus streamside from the Yukon Territory, where besides large thermal variability, they are also inundated with spring flooding. …
Growth And Toxicity Of Geographically-Distinct Isolates Of The Fish-Killing Phytoflagellate, Heterosigma Akashiwo, Veerta Singh
Growth And Toxicity Of Geographically-Distinct Isolates Of The Fish-Killing Phytoflagellate, Heterosigma Akashiwo, Veerta Singh
Electronic Thesis and Dissertation Repository
Harmful Algal Blooms (HABs)—an accumulation of toxic phytoplankton—often result from environmental changes reflecting the increasing global human footprint and climate change. One HAB species drawing attention is Heterosigma akashiwo, a fish-killing flagellate that can cause extensive fish loss or be benign, depending on location or environmental conditions. Here, I investigate if this difference in toxicity is regulated by environmental conditions or differences in cellular physiology. Six strains were examined. Three originate from the Salish Sea, where fish-kills are common, and three from Japan, where blooms of Heterosigma are common but fish-kills are rare. By measuring growth and toxicity of cells …
Effects Of Water Temperature, Rearing Temperature And Population On Swimming Performance And Temperature Preference In Atlantic Salmon (Salmo Salar), Nicole Zathey
Electronic Thesis and Dissertation Repository
Understanding how animals respond to environmental temperatures is important for the survival and reintroduction of species. My objectives were to determine how swim performance responds across water temperatures, and how rearing temperature or population would affect this performance and temperature preference. Juvenile Atlantic salmon (Salmo salar) from two populations that are currently used for stocking in Lake Ontario (LaHave, Sebago) were reared at two temperatures (11°C, 19°C). I measured critical swim speed and burst swim speed across eight water temperatures (11 – 25°C). Water temperature had no effect on burst speed, while critical swim speed increased with increased …
Elevated Temperature And Co2 Concentrations Affect Carbon Flux In Two Boreal Conifers, Sasha Madhavji
Elevated Temperature And Co2 Concentrations Affect Carbon Flux In Two Boreal Conifers, Sasha Madhavji
Electronic Thesis and Dissertation Repository
Elevated temperatures and CO2 will alter carbon flux in two dominant boreal tree species Picea mariana (black spruce) and Larix laricina (tamarack). Trees were grown in three temperature treatments (ambient, ambient +4 °C, and ambient +8 °C) at either 400 ppm or 750 ppm CO2, to simulate climate conditions between now and the year 2100. Spruce acclimated to increasing temperature detractively; warming scenarios reduced spruce net carbon gain. Tamarack maintained comparable levels of net photosynthesis (Anet) across warming treatments and both species acclimated respiration (Rdark) with increasing growth temperature. Elevated CO2-grown …
Winter Warming Affects The Onset Of Reproduction But Not Cognition Or The Hippocampus In Black-Capped Chickadees (Poecile Atricapillus), Robert J. Martin
Winter Warming Affects The Onset Of Reproduction But Not Cognition Or The Hippocampus In Black-Capped Chickadees (Poecile Atricapillus), Robert J. Martin
Electronic Thesis and Dissertation Repository
The effects of overwinter temperature on behaviour and cognition, hippocampal volume, and reproductive timing were studied in Black-capped chickadees (Poecile atricapillus). I hypothesized that overwinter temperature would have varied effects for Black-capped chickadees that overwinter in northern climates. I found that temperature had no effect on behaviour and cognition, or hippocampal volume, but temperature did influence reproductive timing. Birds that experienced warmer winter conditions had significantly more developed gonads than birds that experienced colder conditions. These results suggest that while birds are clearly sensitive to ambient winter temperature, temperature only modulates some processes and not all. These studies …
Weather And Photoperiod Indices Of Autumn And Winter Dabbling Duck Abundance In The Mississippi And Atlantic Flyways Of North America, Lena M. Van Den Elsen
Weather And Photoperiod Indices Of Autumn And Winter Dabbling Duck Abundance In The Mississippi And Atlantic Flyways Of North America, Lena M. Van Den Elsen
Electronic Thesis and Dissertation Repository
Climate change may influence autumn and winter distributions of dabbling ducks throughout the Atlantic and Mississippi Flyways of North America. To determine how weather and photoperiod influenced autumn-winter abundances of dabbling ducks at staging areas in eastern North America, I modeled weather and photoperiod variables with rate of change in relative abundance of various dabbling duck species over space and time. Latitude was incorporated into models to determine if changes in duck abundance in relation to weather severity were influenced by locale. Changes in abundance were best described by weather models incorporating temperature and snowfall variables for all species except …
Nitrogen Fixation By The Cyanobacterium Nostoc Punctiforme In Response To Variation In Nitrogen Availability, Temperature, And Atmospheric Co2 Concentrations, Danielle A. Griffith
Nitrogen Fixation By The Cyanobacterium Nostoc Punctiforme In Response To Variation In Nitrogen Availability, Temperature, And Atmospheric Co2 Concentrations, Danielle A. Griffith
Electronic Thesis and Dissertation Repository
The predominant input of available nitrogen (N) in boreal forest ecosystems originates from moss-associated cyanobacteria, which fix unavailable atmospheric N2, contribute to the soil N pool, and thereby support forest productivity. Although increases in N availability, temperature, and atmospheric CO2 concentrations are expected in Canada’s boreal region over the next century, little is known about the combined effects of these factors on N2 fixation by axenic cyanobacteria or the associated mechanisms. I assessed changes in N2 fixation by Nostoc punctiforme under different global environmental change scenarios and examined correlations between the response and changes in …
The Plastic And Evolutionary Responses Of Fish To Anthropogenic Stressors, Ross D. Breckels
The Plastic And Evolutionary Responses Of Fish To Anthropogenic Stressors, Ross D. Breckels
Electronic Thesis and Dissertation Repository
Ecosystems are being altered at unprecedented rates with little knowledge of the potential impacts on biodiversity. Two of the most pressing contemporary anthropogenic stressors are pollution and global warming. Species can respond to these stressors via dispersal, phenotypic plasticity, or evolutionary adaptation. Many species, especially aquatic organisms, experience ecological or physical barriers to dispersal and will therefore have to respond via phenotypic plasticity or evolutionary responses. I examined the responses of multiple traits associated with fitness in fish to pollution and increased temperature using a 2 × 2 common garden experimental design. I examined the effects of pollution on behaviour …
The Effects Of Extrinsic And Intrinsic Factors On The Reproductive Biology Of Male Western Bean Cutworm Moths, Striacosta Albicosta (Smith), Jasmine Farhan
The Effects Of Extrinsic And Intrinsic Factors On The Reproductive Biology Of Male Western Bean Cutworm Moths, Striacosta Albicosta (Smith), Jasmine Farhan
Electronic Thesis and Dissertation Repository
Pheromones are important in the mating systems of nocturnal moths as they are relied on to find and/or assess mates. Extrinsic and intrinsic factors have been shown to influence female emission of and male response to pheromones. My thesis focuses on the reproductive biology of males of the western bean cutworm, Striacosta albicosta, a pest of beans and corn that has recently began expanding its range eastwardly. I conducted a field-based experiment to determine the effects of extrinsic factors on pheromone trap catches. I also conducted laboratory based mating experiments to determine the effect of male age on acceptance …