Three Minute Thesis Competition

McKinley Nevins

Integrating above and belowground perspectives to understand the drivers of tree demography in the northwestern United States

Tree survival and growth is dependent upon acquiring resources like water and nutrients. Aboveground, trees may experience competitive and facilitative effects from close tree neighbors in acquiring or conserving resources. Belowground, trees benefit from symbioses with mycorrhizal fungi that increase water and nutrient uptake. Therefore, the drivers of tree survival and growth can be understood as a series of nested abiotic factors and biotic interactions occurring at levels of both the individual tree and the surrounding neighborhood. Yet we still lack a full understanding of how this biotic context, particularly belowground, influences tree demography and responses to environmental stress and disturbance. Filling this knowledge gap is essential in light of changing environmental conditions in the northwestern United States, which are becoming increasingly stressful and altering the availability of resources essential to tree performance. My dissertation research has aimed to elucidate the drivers of tree demography by expanding the consideration of linkages between aboveground and belowground contexts.

My dissertation uses trait-based approaches as a mechanistic way to understand species interactions and responses to the environment. I examined how the leaf and root traits of neighboring trees interact with drought and wildfire stress to influence the survival and growth of focal trees across 56 tree species in the region. These neighborhood-environment interactions produced highly variable demographic responses. To further explore the belowground context, I again applied a trait-based framework to determine how the taxonomic and functional composition of mycorrhizal fungal communities varied with environmental conditions and host tree species across the region. Then I linked tree leaf and root traits with fungal functions to assess the contribution of mycorrhizal communities and tree neighborhoods to the performance of focal trees in an old growth experimental forest. I found that tree hosts and their fungal symbionts displayed variable strategies to cope with local environmental conditions that explained variation in tree growth.

Overall, my research integrates lesser studied belowground traits and biotic interactions of trees to provide a more holistic understanding of the drivers of tree demography and responses to environmental stress in the northwestern United States. These findings underscore that understanding how trees will respond to future environmental conditions requires looking both above and belowground.

Joseph Akowuah

Electoral Fraud, Regionalism, and the Mobilization of Opposition Violence in Africa

Why do allegations of election fraud result in large-scale post-election violence in some African countries but not others? While existing research emphasizes incumbent-led post-election violence or treats fraud as an exogenous variable, it offers a limited explanation for cross-national variation in the escalatory actions of opposition actors in response to allegations of election fraud. This study advances an electoral geographic theory that explains opposition post-election violence as a function of allegations of election fraud and enduring regional patterns of election support (regionalism). I argue that allegations of election fraud generate collective grievances across opposition constituencies, but these grievances escalate into large-scale violence when opposition parties possess territorially concentrated support bases. In highly regionalized party systems, dense subnational networks lower coordination costs, intensify collective grievances, and provide the organizational capacity needed to sustain mass post-election violence. Where party support is geographically diffuse, similar grievances are less likely to produce coordinated escalation. I test this theory using causal process tracing in two African cases: Ghana and Nigeria. The evidence indicates that the post-electoral conflict in Nigeria in 2011 was driven by dense social networks of party supporters, who quickly and readily translated allegations of electoral fraud by party elites into large-scale violence. In Ghana, where these mechanisms did not exist, despite similar stakes and allegations of electoral fraud, the country remained peaceful after its 2012 elections. This paper contributes to the existing literature on how narratives about electoral integrity translate into escalatory action and potentially civil wars.

Shamila Gopalakrishnan

Track! Target! Treat! Ovarian Cancer

Ovarian cancer stands out as one of the most lethal types of gynecological cancer, primarily due to its late diagnosis, aggressive progression, and the development of chemoresistance. Traditional chemotherapeutic agents, such as methotrexate, often lack specificity, resulting in potential harm to healthy tissues.

The primary focus of this thesis was to develop a multifunctional nanotherapeutic platform capable of achieving metabolic targeting, receptor-mediated delivery, and effective chemotherapy. An engineered dendrimer-based nanocarrier was modified to include 2-deoxy-D-glucose (2DG), which targets the high glucose uptake characteristic of ovarian cancer cells. Additionally, folic acid (FA) was incorporated to exploit the overexpression of folate receptors in these cancer cells, while methotrexate (MTX) was used as the therapeutic agent.

This innovative combinational design facilitates the selective tracking, transportation, and delivery of the drug to ovarian cancer cells using two distinct targeting strategies: one that leverages glucose metabolism and another that capitalizes on receptor specificity. By targeting these pathways, the approach aims to minimize side effects, simultaneously depriving cancer cells of their nutrient source while delivering chemotherapy more precisely. The findings of this study present a rationally designed nanoplatform whereby the metabolic dependencies and receptor overexpression in cancer cells are transformed into strategic therapeutic advantages, highlighting a promising avenue for targeted therapy in the treatment of ovarian cancer.