Sewanee Senior Honors Theses 2022

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    The Impact of Parental Size on The Effectiveness of Parental Care
    (University of the South, 2022-05-08) Parker, Hughes
    In animals with parental care the amount or quality of care the parent provides can have a large impact on the development of the offsprings phenotype and ultimately it’s fitness. Variation in the quality of parental care is often associated with variation in other aspects of the parental phenotype. For example, in the burying beetle (Niceophorus vespilloides) the effectiveness of parental care is determined by maternal size. The large mother is providing better care than small mothers. In the study, I conducted to experiment to test whether they’re similar size base parental effects in another burying beetle, Nicrophorus orbicollis. The species differs from. N. vespilloides in two important ways. First, parental care in N. orbicollis is obligate while it is facultative in N. vespilloides. Second, biparental care is beneficial in N. orbicollis while males do not appear to contribute much in N. Vespilloides. My first experiment focused solely on the impact of female body size on the effectiveness of parental care. I phenotypicslly engineered females to be large or small and then measured their reproductive performance. I found that large female broods produced broods of larger offspring than small females, consistent with the pattern seen in previous studies of N. vespilloides. My second experiment examined the joint effects of female and male body size on the effectiveness of parental care. I conducted crosses in which I factorially manipulated parental body size, and for each cross, I recorded the number and size of offspring that were produced. I found the female body size influence, the offspring size at dispersal; however, there were no affects of male size or the interaction between male and female size. My results demonstrate size dependent maternal effects in N. orbicollis, with bigger mothers providing more effective parental care than smaller mothers. Furthermore, male body size does not appear to influence the number or size of offspring produced, either directly or through an interaction with female size. These results show that mothers have the primary influence over offspring size.
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    The Effect of Dune Age and Microtopography on Triadica sebifera (Chinese tallow tree) Recovery from Hurricane Disturbance
    (University of the South, 2022-05-08) Burruss, George
    The distribution and density of invasive species is a function of dispersal combined with the effects of disturbance. Disturbance is a necessary prerequisite for the colonization of most invasive species. Coastal dune communities experience a high frequency of disturbance, such as associated with hurricanes, making them susceptible to invasion by non-native species. Due to a rapid growth rate, high fecundity, stress tolerance, and persistent seed bank the non-native Triadica sebifera (Chinese tallow tree) is an aggressive invader of the southeastern coastal plain. We examined tallow population recovery after hurricane disturbances in 2017 as a function of three variables; microtopography (swale, slope, ridge), dune age (young, intermediate, old), and time since disturbance (pre-hurricane, post, and 4 years out). We investigated whether the initial tallow invasion on the island in the early 1990s had been facilitated by hurricane disturbance. We hypothesized that mechanisms of population persistence would vary as a function of microtopography and dune age. We predicted that adult survivorship would increase with dune age and would be restricted to slopes and ridges. We found that tallow, unlike most invasive species, had invaded without the facilitation of major disturbances. We found that after four growing seasons all tallow populations had recovered to pre-hurricane densities regardless of dune age. Adult survivorship was significantly higher in slopes and ridges as compared to swales. Population recovery in swales was almost exclusively a result of recruitment of new individuals from the buried seed pool despite the salt water inundation from the hurricanes. Our results show that tallow was able to successfully invade and establish populations across a barrier island dune chronosequence in the absence of a major disturbance event. Following a major hurricane, tallow was resilient to disturbance allowing it to persist and maintain pre-hurricane abundance.
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    Language and Hybridity: The Reconstruction of Mapuche Culture in Post-Dictatorship Chile
    (University of the South, 2022-12-11) Ball, Anna
    The Mapuche make up almost 90% of the 700,000 indigenous in Chile. While the Spanish named these people Araucanians and the region Arauco, terms that carry connotations of imperial biases, the vast community calls themselves Mapuche (mapu ‘land’, che ‘people’). Throughout the history of the Mapuche in Chile, significant and ongoing threats to cultural autonomy have persisted for centuries. First with the arrival of the Spanish to colonize the region, and then by the Chilean state, Mapuche have found ways to adapt and reconstruct sociopolitical structures in a way that has preserved their culture within a global arena full of complex power dynamics, such as the dictatorship from 1973-1990, and the consolidation of neoliberal policies. The use of Mapuche poetry, oral traditions, and media outlets through the preservation of their native language, Mapudúngun, have offered ways to reclaim indigenous voices and affirm Mapuche cultural autonomy. Using hybridity in the adoption of Chilean and European language and written traditions, the Mapuche have adapted in a way that ensures cultural continuity through expression. Because much of the content of Mapuche poetry challenges the Chilean nation-state and seeks recognition of their own rights to ancestral lands, its identification as global intellectual history also proves the power of this cultural export in reconstructing Mapuche culture to secure a place in the national and global arenas. Because of the vast and complex history of Mapuche in Chile, a focus on the post-dictatorship era allows for more in depth analysis of the use of Mapuche cultural expression in creating a space for Mapuche existence within Chilean society. The era following the dictatorship fostered a flourishing of cultural exports, as there was more room for the expression and widespread support of the different identities that were marginalized by the oppressive socio-political system. The complex history of marginalization of Mapuche in Chile has continuously been overcome by indigenous representation in linguistic policies, poetry, and media. While these reconstructions of Mapuche cultural expression have not yet produced a realization of political and cultural sovereignty, they have served to place Mapuche at the forefront of contemporary discussions in Chile.
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    Generation of HiBiT-tagged recombinant murine coronaviruses to quantitatively study early events during virus replication
    (University of the South, 2022-05-08) Wilson, Natalie; Sterling, Cade; Smith, Everett Clinton
    Coronaviruses (CoVs) are a large family of single-stranded, positive-sense RNA viruses that infect a wide range of vertebrate hosts. Along with SARS-CoV-2, the etiological agent of the COVID-19 pandemic, there are six other characterized human CoVs (HCoVs). Infection by the four endemic HCoVs (e.g., -OC43, -NL63, -229E, -HKU1) can cause cold-like illness, while infection with epidemic HCoVs (e.g., SARS-CoV and MERS-CoV) can result in severe disease with high mortality. A comprehensive understanding of viral biology is required to develop effective therapeutics, such as vaccines and antiviral drugs. Early steps during viral replication, such as cell-surface binding and entry, are challenging to study in a quantitative manner. To circumvent some of these technical challenges, we developed tagged recombinant murine coronaviruses expressing a small, N-terminal portion of the luciferase enzyme (NanoLuc) encoded by the deep-sea shrimp Oplophorus gracilirostris. The small size of this tag (HiBiT, 11 amino acids), relative to the remaining catalytic portion of NanoLuc (LgBiT, ~170 amino acids), reduces the risk that the tag interferes with viral protein function. Complementation of the viral protein-HiBiT fusion with LgBiT results in a catalytically active complex referred to as NanoBiT. Because even small amino acid tags can disrupt protein function, we generated constructs that tagged either the N- or C-terminus of each CoV structural protein (N, E, and M), excepting Spike (S), which was only C-terminally tagged. Three of the seven recombinant viruses were recovered, and two showed evidence of replication but were unable to be propagated further. Serial dilution of these viral stocks demonstrated several log10 of linear signal, indicating that they will be useful tools to quantitatively investigate early events during viral replication.
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    Forms of Feeling: Bronte's Language of the Heart
    (University of the South, 2022) Stephens, Lilly