What Are the Differences in Trichome Density and Morphology Between Arabidopsis Lyrata Subsp. Lyrata Populations When Grown in A Northern Common Garden, Outside of Their Geographic Distribution?
Tue, 04/30/2019 - 15:23
Abstract: Trichomes are diverse among plants. There is evidence suggesting that environmental factors may influence these structures and their densities. Other evidence shows that weather may influence genetics and gene expression. Arabidopsis lyrata subsp. lyrata is a wild flower that is native to North America and Europe and has been extensively studied. Literature regarding Arabidopsis states that within the family and genus, there is evidence suggesting that trichomes can be either non-branched, twice branched or thrice branched. This study’s purpose was to analyze how trichome density, and morphology in Arabidopsis lyrata subsp. lyrata differs between populations when grown outside of the natural distribution limit. Four populations of Arabidopsis lyrata subsp. lyrata were studied based on latitude. After analyzing the outcomes, unexpectedly there are no major differences between the north and south populations; however, there are differences between the four populations. Based on the data gathered, it was determined that the population, North2 (07G) must be genetically different from the other three populations. The four populations were grown together in a common garden; thus, all variables were the same. The environment did not influence trichome density or morphology within the North2 population, therefore the structures were genetically pre-determined.
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File Attachments: Scarabaggio_A.docx
Walden Pond: Ecological and Anthropological History Reflected in the Sedimentary Record
Tue, 05/03/2016 - 23:13
Abstract: This study examined environmental changes reflected in the microfossil record of a sediment core taken in August 2015 from Walden Pond, Massachusetts spanning the last 600 years. In particular changes in the eutrophication status, inorganic sediment deposition due to land use, lake water depth and temperature were examined using phytoplankton indicator species—diatoms and chrysophytes— to reconstruct environmental conditions. The study site was a basin shallower and closer to the source of anthropogenic N and P inputs than the site of previous studies at Walden’s deepest basin, allowing for finer detection of changes in water level and organic content of sediment. A gravity corer was used to collect the sediment core to preserve topmost sediment layers for analysis, as more than a decade has passed since the last published study of this kind at Walden Pond by Köster et. al. (2005). Results show a significant increase in indicators of eutrophic lake conditions since European settlement ca. 1630, and especially since the 20th century. However, relative Asterionella formosa and Synedra nana abundances had not changed significantly in the last decade since Köster et. al.’s 2005 study, and have in fact decreased somewhat, suggesting water treatment efforts by the Massachusetts Dept. of Environmental Protection (DEP) have had some success. Loss on ignition (LOI) of organic content shows a precipitous decline from the mid 19th century from 37% to 22%, representing intensive land clearance and development until the 1970’s when DEP management began. After that point, LOI rose, perhaps due to increased lake productivity, and has fluctuated around 25%. Relative Discostella stelligera abundance, while used in the WAl-3 piston core as a proxy for water depth, could not be used in the WAL-1 gravity core from this study as eutrophication has significantly impacted their abundance. Chrysophyte scale:diatom ratios corroborate an observed trend of increasing abundance in lakes globally since the 20th century, perhaps in response to rising global temperatures over the same period.
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File Attachments: Capstone Paper.docx
Analysis of Forage Quality in Adirondack Macrophytes: Implications for Waterfowl Nutrition
Fri, 04/29/2016 - 14:48
Abstract: To understand the relative nutritional value of macrophyte food sources for Adirondack waterfowl, the forage quality of four common Adirondack macrophytes were assessed. An analysis of two native pondweeds (Potamogeton) and two invasive watermilfoil (Myriophyllum) was conducted to deduce how invasive and native macrophytes compare in their relative concentrations of nitrogen and mineral content; important indicators of forage quality for waterfowl. Nitrogen content is used as a metric for relative concentration of protein. Macrophyte species were sampled from four Adirondack lakes of the same trophic status to account for effects of lake nutrient characteristics on plant nutrient uptake and synthesis. Total nitrogen was determined with the Kjeldahl procedure using flow injection analysis. Ash (mineral) content was acquired through high-heat burning in a muffle furnace. The invasive watermilfoil species had a higher percentage of nitrogen than the native species. There was no significant difference in the ash content between the species. It is critical to understand the ecological function of these species in relation to wildlife populations. The nutritional value of these aquatic macrophytes may have implications for the fitness and distribution of breeding herbivorous waterfowl in Adirondack lakes. These results may indicate that invasive plants will serve as a viable food source for herbivorous waterfowl as watermilfoil continues to spread across Adirondack aquatic systems.
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File Attachments: Bianca Fournier Capstone Draft 4th Edit.docx