The primary vector for transmission of Yellow Fever, Chikungunya, Dengue Fever, and Zika viruses is the Aedes aegypti mosquito. This species exists in two forms—Aedes aegypti formosus (Aaf), an ecologically variable form found primarily in sub-Saharan Africa, and Aedes aegypti aegypti (Aaa), a human specialist found globally in tropical and subtropical regions. The two subspecies show mean differences in morphology, but there is substantial overlap, and they can only reliably be distinguished using genetics. To date, research conducted in Kenya, Senegal, Tanzania, and Cameroon has shed light on Aedes aegypti populations based on geography, body coloration, and genetic makeup. However, little is known about the morphology and host preference of Aedes aegypti mosquitoes across most of West Africa. The goal of this project was to characterize morphological and behavioral variation among Aedes aegypti populations in Ghana that may affect their ability to transmit human disease. Live Ae. aegypti eggs were collected in the field and carried back to the McBride lab at Princeton University in the U.S. Morphology and behavior were then examined using a standard dissecting microscope and an olfactometer, respectively. The olfactometer allowed for measurements of preference for human vs. non-human odor. Results of this study suggest that there is significant morphological variation within the subspecies Aaf found in Ghana (p<0.008). On the topic of host preference, each colony preferred the non-human host as oppose to the human host in each trial, suggesting that with increased urbanization and vector density in West Africa, non-human reservoirs can pose a severe threat to humans if effective vector control measures are not prioritized.

Young adult fiction is a genre of fiction that is aimed at readers between 12 to 18 years of age. This thesis is a narrative aimed at familiarizing young adult audiences about biological concepts and climate change through fiction. The story is influenced by climate models on extreme weather patterns, loss of biodiversity, projections of social effects of climate change, and effects on agriculture, and how they interact in a post-climate change world.

The following study investigated temporary declines in air pollution observed during the COVID-19 lockdown and potential changes in adult asthma prevalence across four urban U.S. East Coast cities: Boston, Massachusetts; Baltimore, Maryland; New York City, New York; and Washington, D.C. Leveraging the COVID-19 lockdown as a natural experiment, this research combined annual air pollutant data from the U.S. Environmental Protection Agency (EPA) with asthma prevalence data from the Center of Disease Control’s Behavioral Risk Factor Surveillance System from the years 2013 to 2023 and conducted multiple statistical analyses to determine associations between air pollutants and asthma prevalence. Regression and mediation models were utilized to assess the effects of nitrogen dioxide (NO2) and fine particulate matter (PM2.5) on asthma prevalence. Results showed that NO2 concentrations significantly declined during the COVID-19 period and were modestly associated with reduced asthma prevalence. Mediation analysis suggested that NO2 partially mediated the relationship between the COVID-19 period and observed decreases in asthma prevalence. PM2.5 did not demonstrate a significant mediating effect. Although asthma prevalence declined during the COVID-19 lockdown period, the decrease was not statistically significant. Additionally, the rebound in asthma prevalence after COVID-19 may reflect diagnostic delays or other non-environmental factors impacting the data. Nonetheless, these findings reinforce and inform previous research regarding the impact of air pollution on respiratory health outcomes and asthma prevalence. Furthermore, the results of this study support tactics to reduce NO2 emissions as a strategy to improve public health in urban environments.

Top carnivores impact prey species through extensive risk effects, beyond lethal predation, that reduce prey fitness even without direct interaction. Costs such as reduced foraging to compensate for increased vigilance, or exclusion from otherwise high-quality habitat due to risk, demonstrate the wide-reaching effects relatively low numbers of carnivores can have on large prey populations. As conservationists weigh possible methods of restoring degraded landscapes, including “rewilding” or reintroducing apex predators, it is important to know what kinds of responses that may elicit in existing prey populations. By taking advantage of the unique absence of large carnivores within Gorongosa National Park (GNP) in Mozambique—and the recent reintroduction of predatory African wild dogs (Lycaon pictus)—we were able to conduct research into the plasticity of antipredator behavior and concept of a “landscape of fearlessness.” In 2015, some of the park’s bushbuck (Tragelaphus sylvaticus) were found to have expanded beyond their natural woodland habitat into the more exposed floodplain area, which is at odds with the species’ typical secretive behavior. It was hypothesized, and supported by experimental research in 2016, that some bushbuck likely moved to the floodplain in response to reduced predation risk following several decades of carnivore absence. If and how those bushbuck would react to the reintroduction of predators, and whether that would result in a reinstatement of a landscape of fear, remained largely unexplored. This study aims to expand upon previous research by examining the effect of predator reintroduction on bushbuck restfulness, which serves as a more easily identifiable inverse measure of vigilance. By analyzing several years’ worth of camera trap footage, we were able to compare prey restfulness and other behavior before and after the reintroduction of wild dogs. We also looked at behavioral differences between bushbuck residing in the floodplain versus woodland areas to examine the effect of habitat on antipredator responses. We found that both carnivore reintroduction status and habitat are, among other included variables, factors which significantly influence bushbuck behavior. As might be expected, the renewed presence of wild dogs, in particular, seems to be highly associated with decreased bushbuck restfulness.

Cuticular hydrocarbons (CHCs) serve important roles in insects as barriers against desiccation and as chemical signals within and between species. In eusocial species such as Bombus impatiens, CHCs are known to be correlated with reproductive status, behavior, and caste, but the composition of chemical profiles across different body parts and between castes remains poorly understood. This study investigates caste-specific differences in the cuticular hydrocarbon profiles of the common eastern bumble bee, Bombus impatiens, focusing on the compound classes of alkanes, alkenes, esters, ketones, aldehydes, and terpenoids. I hypothesized that queens would exhibit higher overall levels of CHCs, particularly alkanes, alkenes, and esters, and that the thorax and abdomen would show the most pronounced differences due to their association with the biosynthesis of hydrocarbons. Small colonies were established and aged under controlled conditions, after which queens and workers were dissected and separated by antennae, head, thorax, abdomen, and legs. Pentane extractions of each body part were analyzed via gas chromatography-mass spectrometry. Statistical comparisons using NMDS and ANOSIM revealed strong caste-specific differentiation across all body regions, with queens exhibiting significantly greater abundances of alkanes across all tissues and enriched levels of alkenes and esters on most body parts. The thorax displayed the greatest chemical divergence between queens and workers. The results of this experiment reinforce the idea that reproductive roles strongly shape the composition of cuticular hydrocarbons in bumble bees. Understanding these differences in chemical profiles enhances broader comprehension of eusocial organization and communication and provides further insight into potential mechanisms by which queens maintain reproductive dominance.

Highly Pathogenic Avian Influenza (HPAI) is an emerging zoonotic disease of global concern, driven by transmission between wild avian hosts and commercial poultry. Understanding where these populations overlap is critical for predicting and mitigating spillover risk. This study aimed to identify geographic hotspots of potential HPAI spillover across the contiguous United States using a geospatial analysis. Relative abundance data for 157 wild avian host species were integrated with county-level poultry density data to construct a multiplicative spatial Risk Index. To identify extreme spillover interfaces, county-level risk values were standardized using Z-score normalization, with thresholds of Z > 3 and Z > 4 used to define high and extreme-risk counties, respectively. Spatial statistical analyses, including Spearman’s rank correlation and Global Moran’s I, were conducted to assess relationships and clustering patterns. All data analysis and associated code can be accessed through the GitHub repository (Appendix A). In addition, a field study in South Texas collected 111 avian fecal samples to test for the presence of HPAI and Avian Bornavirus (ABV) in urban bird communities (Appendix B). Results revealed no significant global correlation between poultry and wild host densities (ρ ≈ 0, p = 0.953), but a strong, significant spatial clustering of high-risk interfaces (Moran’s I = 0.610, p < 0.001). The Z-score analysis identified 53 high-risk counties (Z > 3) and 28 extreme-risk counties (Z > 4), representing less than 1% of U.S. counties. These high-risk areas were concentrated in major agricultural and migratory regions, including the Mississippi River Basin, Mid-Atlantic, Southeast, and California Central Valley. All field samples tested negative for both pathogens. These findings demonstrate that HPAI spillover risk is highly localized rather than uniformly distributed, highlighting the importance of targeted, spatially informed biosecurity strategies.

The common preclinical mouse models lack the mature immune system of humans, making them poor models for clinical research. Commensal microbes and pathogens, through their co-evolutionary history with the mammalian immune system, can shift the mouse immune system toward that of humans. Using rewilding and Trichuris muris helminth infection, we examined the independent and combined effects of microbial exposure and infection on immune functions and phenotypes in C57BL/6J (B6) and B10.BR (B10) mice. For immune phenotypes, we found that rewilding shifted the mouse blood lymphocyte to neutrophil proportions toward those of humans, and that infection increased spleen mass in B6 mice only. For immune function, we measured Interferon-γ (IFN-γ) and Tumor Necrosis Factor (TNF-α) production by splenocytes stimulated in vitro with the CD28 superagonist (CD28SA) that caused life-threatening cytokine storms in humans but not in mice. Most notably, T. muris infection alone was sufficient to drive ~23-fold higher IFN-γ production to CD28SA stimulation, while rewilding alone drove a more modest ~4-fold increase, and the combined effect was the most dramatic at an ~111-fold increase. These results highlight the importance of environmental experience and host genotype as determinants of immune phenotype and function, and suggest that a single defined helminth infection may offer an accessible means to mature the mouse immune system for more accurate and safe clinical research.

Mosquito host-seeking behavior depends on olfactory detection of human odor, yet functional analysis of individual receptors is limited by the technical difficulty of assembling multi-component donor plasmids for genome editing in Aedes aegypti. In this study, a modular HDR donor plasmid system was developed using the pJAT77 (Atalanta) backbone, incorporating a species-specific U6-driven guide RNA cassette and Gateway recombination for efficient insertion of locus-specific sequences. The system was validated through assembly of a donor construct targeting the IR75d locus, with sequence-confirmed integration of homology arms and reporter elements. Compared to traditional cloning approaches, this strategy reduced hands-on time and increased consistency across assemblies. By separating backbone preparation from locus-specific design, the system enables rapid and reproducible generation of donor constructs across multiple genomic targets. This platform provides a scalable method for genetic interrogation of olfactory receptors and supports efforts to link receptor function to mosquito host-seeking behavior.

The yellow fever mosquito Aedes aegypti is one of the primary vectors of human disease. Its global success as a vector hinges on the invasive nominate subspecies (Aedes aegypti aegypti) that specializes on human hosts and has spread around the world. The invasive Ae. aegypti aegypti lineage evolved in West Africa ~5,000 years ago from the ancestral African subspecies (Aedes aegypti formosus), which remains largely an animal-generalist and is confined to sub-Saharan Africa. Recent whole‑genome sequences of Ae. aegypti in varying regions around the globe uncovered a genetically unique population in Argentina that retains genetic signatures characteristic of the ancestral African Ae. aegypti formosus populations. So far, it is the only such Ae. aegypti population outside of Africa that has this genetic make up. Whether these Argentinian populations also retain animal-generalist host‑seeking behaviour is unknown. We quantified host-preference in three Argentinian Ae. aegypti populations using a two‑port olfactometer with a human hand and guinea pig as competing stimuli. We benchmarked these strains against a strongly human-preferring Ae. aegypti aegypti laboratory strain from Orlando, Florida (ORL), and an African generalist Ae. aegypti formosus strain from Uganda (ZIK). Our results showed ORL having the strongest human preference and ZIK showing only weak human preference to no preference. All three Argentinian strains slightly preferred human odor, with mean preference indices ranging between that of ORL and ZIK. In contrast, response rates of all three Argentinian strains were consistently lower than ORL and more similar to ZIK. Our results suggest that Argentinian Ae. aegypti populations combine weak human odor attraction with relatively low assay engagement for a behavioural phenotype consistent with heterogenous specialization on human hosts.

The phylogenetic relationships among early tetrapods (modern amphibians and their extinct relatives) remain ambiguous due to an absence of extant lineages and the resulting need to infer relationships solely using morphological data. One of the critical questions surrounding early tetrapods is the phylogenetic origin of modern amphibians, Lissamphibia (frogs, salamanders, and caecilians) and Amniota (reptiles, mammals, and birds), from this early stock of tetrapods. Three main hypotheses have been proposed to explain the origins of lissamphibians: the “temnospondyl hypothesis,” the “lepospondyl hypothesis,” and the “polyphyly hypothesis,” that different clades within lissamphibians originated from different groups, some from temnospondyls and some from lepospondyls. A phylogenetic dataset by Ruta and Coates (2007) is the largest morphological database produced to study determine lissamphibian origins, yet it has faced criticism for a combination of issues related to accuracy, including limitations in taxa sampled, algorithms employed, and errors in data input. Marjanović and Laurin (2019) sought to revise and improve this database, such as through thorough correction of data scoring errors, but with limited success. The present research builds on the work of Marjanović and Laurin (2019), particularly through revision of erroneous character constructions using the dataset construction framework proposed by Simões (2017). Analyses were completed on both the original dataset by Marjanović and Laurin (2019) and the updated dataset using maximum likelihood and Bayesian inference. The 277 original characters used by Marjanović and Laurin (2019) were reduced to 163 characters post-revision. Despite some discrepancies between analyses caused by differences in data and methods used, all results point to lepospondyl ancestry of Lissamphibia. All analyses place temnospondyls as a sister clade to lepospondyls, with one exception placing lepospondyls within the temnospondyl clade. Additionally, varying support for different possible outgroups to Lissamphibia are discussed, as well as differences in exact placement of groups often associated with crown lissamphibians, such as Aïstopoda and Eocaecilia.

Arboviral diseases such as dengue, Zika, and chikungunya remain significant global public health burdens, and traditional control methods are increasingly ineffective. The introduction of Wolbachia-infected Aedes aegypti mosquitoes has emerged as a promising alternative for reducing arboviral disease transmission. However, reported outcomes across studies vary substantially, highlighting the need to understand the factors driving variability. This systematic review examines variation in reported outcomes of Wolbachia-based interventions by synthesizing findings from empirical trials and mathematical modeling studies. A PRISMA-guided literature search was conducted across three major databases, and 42 studies were included in the final review. Selected studies were analyzed to compare patterns of Wolbachia establishment, spatial spread, and incidence reduction to identify key drivers of variation across studies. Across both empirical and theoretical approaches, substantial reductions in arboviral incidence were observed when Wolbachia achieved stable establishment. However, outcomes varied widely across implementations due to differences in environmental conditions, biological parameters, operational constraints, and surveillance methodologies. While modeling approaches capture key mechanisms, they often rely on fixed parameter assumptions that do not fully reflect the variability observed in field settings. These findings underscore the importance of integrating modeling and empirical approaches. Incorporating field-derived data into models, alongside the use of context-specific, model-informed intervention strategies in the field, can improve both predictive accuracy and implementation efficiency. A more integrated and context-dependent approach is essential for optimizing Wolbachia interventions and its applicability across diverse ecological and operational settings.

Our study found evidence of resource partitioning among the mesocarnivores at Gorongosa National Park, which could be predicted by the relative abundance of a species in the park as their body size. Using camera traps, set up at naturally occurring carcasses, we found that only 7 of the confirmed 13 mesocarnivore species at the park utilized 24 carcasses sites. The three most common mesocarnivores were civets, marsh mongoose, and side stripped jackals. The use of carcass was dominated by the largest mesocarnivore civet. We found a positive correlation between the proportion of civets and carcass decay. We did not find a correlation between carcass size and decay, however, unlike in landscape rich with apex predators, such as hyena, mesocarnivores were not excluded from the larger carcass. We found that tree coverage was an indicate of spatial partitioning. And mesocarnivores spent less time and visited less often carcass sites that were in open landscapes. There was large hourly temporal overlap, however the mesocarnivores were found to be activity only during the evening. By integrating our results with the current body of research, we understand the multifaceted nature of scavenger interactions at carcasses, driven by a combination of competitive, temporal, and spatial partitioning strategies.

Because of the environmental constraints placed on the evolution of communicative signals, marine mammals rely heavily on sound to receive and transmit information in their aquatic environment. According to the social complexity hypothesis for communication, social structure places various demands on the animals' recognition systems; therefore, complex social systems may require more complex communicative systems to navigate group interactions and meet the same intraspecific goals as terrestrial mammals. Although little is known about the communicative function of odontocete vocalizations, long-finned pilot whales provide a good, natural study system to explore how and what odontocete vocalizations may communicate. Long-finned pilot whales display matrilineal units, coupled with long-term individual associations of pairs or trios with heterogeneous affiliations. Under the framework of the social complexity hypothesis, the presence of this multi-layered social structure suggests that long-finned pilot whales need a communication system in which multiple levels of identity transmission are possible to maintain the integrity of the group as well as individual relationships. By considering individual vocal repertoire composition and response patterns from digital acoustic data collected from long- finned pilot whale populations in Strait of Gibraltar, this study suggests that (1) long-finned pilot whales use stereotyped, repeated call types, (2) these repeated call types are shared extensively, suggesting that they may transmit group identity information and maintain specific intra-unit associations, (3) long-finned pilot whales can discriminate between individuals within the matrilineal group and (4) the mother, the oldest female in the group, may be critical to information flow within the group. Inter and intragroup differences in vocal repertoires between subunits and call copying may allow for group identity transmission and discrimination in long-finned pilot whales but nuanced differences in these shared call repertoires or within these shared call types may allow for the individual identity transmission that leads to the individually specific response patterns observed. Future research is necessary to consider the possibility of more subtle individual differences within call types to tease apart the nuanced acoustic discrimination and recognition system of long-finned pilot whales.

Among social animal groups, consensus decision‐making is often important for the survival of the group. The decision-­making process consists of several facets of information that aggregate into one final decision. Sometimes, when the personal information of the group members and the public information available conflict, the group may split. Here, we look at how groups of zebrafish respond to the presence of various manipulations of risk and reward. We determine that when fish groups find reward in an area perceived as lower-­risk, they are likely to immediately choose that reward area as their optimal strategy. When fish groups find reward in areas perceived as higher-­risk, they are likely to spend time exploring the other areas before committing to a consensus decision to enter their high-­risk reward area.

Two Lampyridae species, Photinus and Photuris, have evolved the ability to safely produce and consume, respectively, lucibufagin, a cardiac glycoside toxin which targets the alpha subunit (ATPα) of sodium-potassium protein pumps. Photuris, the consumers of exogenous lucibufagin, have accumulated adaptive mutations in their ATPα to resist cardiac glycoside binding. The path of Photuris ATPα’s evolution has been shaped by negative pleiotropic constraints and gene duplication events. Previous studies have examined how these constraints and forces direct the speed and orientation of evolution, but debate continues over early models of gene duplicate maintenance and the significance of negative pleiotropy. I examined the amino acid sequences, cardiac glycoside binding affinities, and tissue-specific expression patterns of Photuris’ ATPα gene copies to better parse the constraints and forces guiding adaptive evolution. My findings show that Photuris have employed many of the same molecular strategies to evolve lucibufagin resistance as other insects which also safely consume cardiac glycosides (Zhen et al., 2012). This parallelism across ecological systems suggests that there are general rules governing adaptive evolution. Independent of ecological context, it seems that gene duplication eases constraints imposed by negative pleiotropy to allow for fixation of nonsynonymous mutations. In addition to providing insight into evolutionary dynamics, my findings have implications for treatment of human diseases involving the sodium-potassium pump, including Digitalis therapy for Congestive Heart Failure and several neural disorders.