Honors-Thesis

Assessing The Harmful Impacts Of Increased Commercial Shipping On Arctic Marine Mammals: A Systematic Literature Review - Hayley Wuestenberg - 2021

Anonymous — Mon, 28 Jun 2021 04:35:35 +0000

Assessing The Harmful Impacts Of Increased Commercial Shipping On Arctic Marine Mammals: A Systematic Literature Review - Hayley Wuestenberg - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:35

Abstract

The endemic species of marine mammals that live in the Arctic year-round have been increasingly threatened by melting Arctic sea ice over the past several decades. Reduction in sea ice has led to increases in multiple commercial Arctic shipping routes, such as the Northwest Passage and the Northern Sea Route. This paper systematically reviews peer-reviewed literature to assess the impacts of melting sea ice and increased use of Arctic shipping routes on key species of Arctic marine mammals. Further, I also discuss several proposed solutions to mitigate the negative effects of these issues. I find that the most highly documented impacts of commercial shipping activity are noise pollution, oil spills, and ship strikes. Harmful effects of these activities include behavioral change, in which mammals alter their feeding, breeding, and pupping behaviors due to the presence of commercial ships, toxicological effects from ingestion of pollutants, and mortality. Multiple shipping regulations have been proposed, including altering vessel routes and reduction of ship speeds, but many studies do not analyze the potential effects of these regulations and therefore fall short of providing adequate and descriptive policy suggestions. Even though 65% of papers discuss shipping regulation in some form, only 58% propose future regulations, and 46% evaluate the effect of that regulation. While climate change is frequently mentioned in papers considering Arctic shipping, climate policy is especially neglected. This literature review reveals crucial gaps in the current body of knowledge, both in animal and ship monitoring data and policy effectiveness, and highlights important areas for future research to inform policymaking in light of climate change. Modifying and creating new policies for the mitigation of harmful shipping impacts is important for the protection of Arctic marine mammals as climate change continues to worsen.

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Harmful Algal Blooms As A Possible Cause Of Late Cretaceous Vertebrate Mortality Events In Northwestern Madagascar - Christopher Mulligan - 2021

Anonymous — Mon, 28 Jun 2021 04:34:37 +0000

Harmful Algal Blooms As A Possible Cause Of Late Cretaceous Vertebrate Mortality Events In Northwestern Madagascar - Christopher Mulligan - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:34

Abstract

Many localized vertebrate die offs have been found in the Anembalemba Member in the Maevarano Formation of Northwestern Madagascar during Late Cretaceous (~70 Ma) - microbialites found immediately below the fossil beds suggest seasonal blooms of algae could have introduced toxins into the dry season's shrinking water sources. The ecosystem was a semi-arid floodplain with violent seasonal monsoons - and contained an amazing biodiversity: large theropods, titanosaurs, many crocodiles, and a number of birds and mammals. Biomarkers, the degradation products of cell membrane lipids, preserved in the rocks offer a glimpse into the microbial ecology of this system. By using evidence from paleontology, organic geochemistry, and comparisons with similar ecosystems in modern-day Sub-Saharan Africa, the seasonal cycles in the basin can possibly be outlined and importantly when toxic algal blooms may have happened. The Anembalemba Member’s yearly climate, like many subtropical semi-arid ecosystems, alternated between dry seasons and monsoon seasons. During the dry season the river dried up and microbial mats formed in the remaining ponds. As rains started to return, nutrient pulses carried by upstream water and by wildlife might have created conditions perfect for photosynthetic algae and cyanobacteria, but significantly toxin-producing dinoflagellates and to a lesser extent cyanobacteria could have bloomed - as animals drank from the potentially poisoned water they died and were left to decompose on the dry floodplain. Once monsoon season was in full swing, violent floods swept up the often articulated animal remains and deposited them in a poorly-sorted sandstone. To justify the harmful algal bloom (HAB) cycle, the biomarkers of dinoflagellates and cyanobacteria were found to change in a similar pattern to known modern blooms in analogous ecosystems. The Maevarano Formation may contain some of the oldest documented HAB events, and organic geochemistry can help shed light on the nuanced paleoecology of Late Cretaceous Madagascar.

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Population Structure Of The Endangered Mud Shrimp Upogebia Pugettensis - Madeleine Horan - 2021

Anonymous — Mon, 28 Jun 2021 04:33:29 +0000

Population Structure Of The Endangered Mud Shrimp Upogebia Pugettensis - Madeleine Horan - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:33

Abstract

The blue mud shrimp (Upogebia pugettensis) is a vital ecosystem engineer in estuaries along the west coast of North America. Under normal circumstances, this species fulfils several important roles, including nutrient cycling, estuary aeration, and habitat provision for a number of commensal species. Unfortunately, nearly all populations of this species have undergone an extreme decline in recent years due to the anthropogenic introduction of an invasive isopod parasite (Orthione griffenis). In order to preserve U. pugettensis for the sake of estuary health, the population structure of the species must be considered. However, the genetic distribution of U. pugettensis is almost entirely unknown. This study analyses the population structure of the blue mud shrimp through genomic sequencing, PCA, TESS, and isolation-by-distance analyses, based on the supposition that at least one major genetic barrier exists for this species along its natural range. Results indicated the presence of one major and one minor genetic barrier for this species within the range of locations sampled: the larger barrier is present in northern California, while the less defined barrier is located near northern Washington. Isolation-by-distance did not play as important a role in determining U. pugettensis’ population structure; however, a moderate amount of genetic variation in the species could still be attributed to physical distance. From this, conservation implications and future research on U. pugettensis are discussed, providing insight into the preservation and recovery of this endangered species.

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Exploring The Biogeographic Relationship Between Variation In Parasites And Pathogens And Host Plant Dispersal Traits - Patrick Heffernan - 2021

Anonymous — Mon, 28 Jun 2021 04:32:27 +0000

Exploring The Biogeographic Relationship Between Variation In Parasites And Pathogens And Host Plant Dispersal Traits - Patrick Heffernan - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:32

Abstract

Plants rely on seed dispersal to track favorable habitats and escape unsuitable conditions in variable environments. One likely driver of phenotypic dispersal trait plasticity is the prevalence and intensity of parasites and pathogens in the plant’s environment. If the effects of parasites and pathogens follow broad scale biogeographic patterns, and plant dispersal traits vary with parasite and pathogen prevalence and intensity, then corresponding biogeographic patterns in dispersal trait variation will likely be observed. To test this, I explored the literature to identify potential biogeographic trends in parasites and pathogens and evaluate support for the hypothesis that biotic interactions increase with decreasing latitude. In parallel, I reviewed and synthesized empirical studies that have tested for intraspecific variation in dispersal traits and evaluated the extent of evidence for a latitudinal gradient in dispersal propensity. These literature surveys revealed that there is mixed evidence at best for the hypothesis that parasite and pathogen pressure increase with decreasing latitude, and—consistent with these mixed results—there was little support for a consistent latitudinal gradient in plant dispersal propensity. However, very few studies have quantified biogeographic variation in dispersal, and I found that none of these studies simultaneously tested for covariation between dispersal traits and disease pressure. Nonetheless, it is clear that both disease pressure and plant dispersal traits each show high spatial variation. I propose an experimental design that tests if host plants exhibit phenotypic plasticity in their dispersal traits in response to the presence of parasites or pathogens, as well as the genetic and environmental sources of dispersal trait variation across geographic gradients. Understanding the relationship between dispersal and the presence of parasites and pathogens will be key to predicting the responses of these relationships and the species evolved to a rapidly changing world.

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Flowering Time And Related Genes In Cannabis - Zachary Girard - 2021

Anonymous — Mon, 28 Jun 2021 04:30:19 +0000

Flowering Time And Related Genes In Cannabis - Zachary Girard - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:30

Abstract

The transition from the vegetative stage to the reproductive stage is a crucial process for all flowering plants. The optimal timing for the development of flowering tissue not only increases fertility and reproductive success, but also improves pollination, seed formation, and seed dispersal. This timing of this transition is initiated by a network of a few hundred regulatory genes which respond to changes in the plant’s environment, as well as other factors. The collection of these genes is referred to as the Flowering Time Regulatory Pathway. The genomic nature of this pathway has been studied for several decades in model species of Arabidopsis and Brassica, as well as important crop species like wheat, barley, and sunflowers. The identification of these genes in other novel crop species, like Cannabis, remains an important step in describing the presence/absence and variation of the flowering time pathway. Using protein alignment tools and publicly available genomic data, this research identified 618 candidate flowering time genes present in Cannabis for future investigation into expression, variation, and selection. The information gained on these candidate flowering time genes within Cannabis can now be used to develop molecular primers to amplify these regions of the genome for experimental purposes. The increasing economic importance of Cannabis propelled by recent legalization movements in the US states and other countries makes the timing of this research particularly relevant for growers, breeders, and geneticists aiming to understand the genomic nature of flowering time in Cannabis.

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May Physical Activity Ameliorate Symptoms And Comorbidities Associated With Human Immunodeficiency Virus (Hiv) Infection? - Elizabeth Enichen - 2021

Anonymous — Mon, 28 Jun 2021 04:28:32 +0000

May Physical Activity Ameliorate Symptoms And Comorbidities Associated With Human Immunodeficiency Virus (Hiv) Infection? - Elizabeth Enichen - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:28

Abstract

The human immunodeficiency virus (HIV) was discovered in the 1980s. Development of HIV treatment has since been accompanied by decreased attention to HIV in Europe and North America. Yet, while treatment for HIV increased the life expectancy of at least some people living with HIV (PLWH), the available treatment is not a cure and the quality of life of PLWH remains impaired. Even in the era of treatment, research on how to ameliorate symptoms in PLWH thus remains crucial. This thesis investigates the potential of exercise to ameliorate symptoms and comorbidities associated with HIV, especially those acting though a key gene regulator of the immune response (the transcription factor NF-kB) in interaction with the gut microbiome (community of gut bacteria), and specifically butyrate-producing bacteria. Comprehensive literature review of these different focus areas supports the conclusion that moderate exercise may be a beneficial therapy for PLWH, although more research is necessary to fully elucidate how exercise-driven increases in butyrate levels affect those with HIV. Overall, the findings of this thesis suggest that exercise has the potential to enhance quality of life in PLWH.

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Nest Insulative Capacity Varies Between Chickadee Species But Not Along An Elevation Gradient - Shay Ding - 2021

Anonymous — Mon, 28 Jun 2021 04:27:11 +0000

Nest Insulative Capacity Varies Between Chickadee Species But Not Along An Elevation Gradient - Shay Ding - 2021 Anonymous (not verified) Sun, 06/27/2021 - 22:27

Abstract

Black-capped (Poecile atricapillus) and mountain (P. gambeli) chickadees are common backyard birds native to the Colorado Front-Range with broadly overlapping distributions in western North America. Black-capped chickadees are more common at lower elevations, and mountain chickadees are more common at higher elevations . The nests of these two species, which they construct in cavities, can be distinguished by either having more moss and plant material (black-capped chickadees) or more animal hair and feathers (i.e., “fluff;” mountain chickadees). I examined nests that I collected from field sites spanning an elevation gradient from 1600 to 3000 meters above sea level. I then investigated their thermoregulatory capacity and composition to understand if species or elevation had an effect on how well nests maintain heat. I found that there is a significant difference in thermoregulatory capacity between species, but that thermoregulatory capacity does not increase with increasing elevation. I also found that mountain chickadee nests, whose nests plateau at higher temperatures, have, on average, higher proportions of fluff than plant material compared to black-capped chickadee nests. As climate changes, particularly in high elevation mountain systems, understanding whether species have the capacity to rapidly respond is important. My results indicate that nest thermoregulatory capacity varies by species but not with elevation, and provides a baseline for understanding whether chickadees will alter their nests in response to warming temperatures. Adaptive responses may be unlikely given that chickadees do not build warmer nests at higher elevations and additional work should examine correlations between nest thermoregulation, climate, and the success rate of clutches.

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