Touch is an extremely important sense to any organism’s understanding of their environment. The anatomy of the touch system is well-characterized: sensory neurons project axons to the skin where they form complexes with many specialized cells. One such specialized skin cell is the Merkel cell, known for its ability to sense gentle touch and texture. Although Merkel cells have been well studied in rodents during adult stages, little is known about Merkel cells during development. The Rasmussen lab recently identified a novel population of zebrafish skin cells sharing many characteristics of mammalian Merkel cells. In both zebrafish and mammals, Merkel cells arise from basal keratinocytes, a stem cell population in the epidermis, during normal skin development. However, the precise mechanisms involved in this process remain unclear. Stem cells can undergo two types of cell division: asymmetric or symmetric division. I hypothesize that Merkel cells develop from asymmetric division of basal keratinocytes, which would allow the production of new Merkel cells while also maintaining a certain level of stem cells. To test my hypothesis, I examined the Merkel cell lineage during zebrafish scale regeneration (to simulate recovery after injury) which we have established as an experimentally tractable system to study Merkel cell differentiation. Testing of my hypothesis has been conducted through two methods: EdU labeling/antibody staining of Merkel cells and photoconversion of Merkel cells. Preliminary results suggest asymmetric division to be occurring, with no “doublets” of recently divided Merkel cells shown in either method to support the occurrence of symmetric division. My results provide novel insights into the lineage connecting basal keratinocytes to differentiation of specialized sensory cells in the skin. I hope these findings can be used to better our understanding of the restoration of touch systems after injury.

The mechanistic target of rapamycin (mTOR) pathway is a central nutrient signaling pathway involved in regulating cell proliferation and metabolism. Targeting this pathway has promising implications for treating a variety of diseases, especially cancer and age-related diseases. Rapamycin is an allosteric inhibitor of mTOR that has been shown to extend longevity in the fruit fly Drosophila melanogaster. Despite this, rapamycin can interfere with healthy mTOR pathways necessary for survival, which is why further research on rapamycin’s mechanism is necessary to improve clinical usage. Previous research has shown that larval size is significantly decreased in fly larvae following inhibition of the mTOR pathway. However, this effect has not been studied across fly strains with differing levels of rapamycin sensitivity. In the Promislow Lab, we have found that fly strains vary in sensitivity to the effect of rapamycin on developmental timing. We are now comparing variation in sensitivity of development time with variation in rapamycin’s effect on larval size. Using D. melanogaster, we are able to selectively expose larvae to rapamycin from embryogenesis to model the effects of rapamycin. We are collecting larvae at various time points throughout their development, comparing individuals exposed to rapamycin or control conditions. We use ImageJ software to quantify larval size. Because of mTOR’s involvement in growth pathways, we hypothesized that larvae with greater rapamycin sensitivity would have significantly smaller sizes at the same time points compared with larvae with lesser rapamycin sensitivity following rapamycin exposure. These experimental results will provide insight into how rapamycin sensitivity is linked to the phenotypic effects of rapamycin on larval size. They will also help us investigate what contributes to the sensitivity differences seen between genotypes. The spectrum of rapamycin resistance in humans is unknown and so our work could help us identify targets for treatments and therapies of age-related diseases.

Skin is a very important organ that facilitates our sense of touch. The touch system is complex and versatile. For example, specialized cells detect a variety of tactile stimuli, including temperature, pain, and textures. Merkel cells are specialized skin cells responsible for detecting light touch and textures in most vertebrates. Despite being discovered over a hundred years ago, their development remains poorly understood. Zebrafish are a good model organism for studying Merkel cells because the fish skin is transparent and easy to image. In wildtype zebrafish, Merkel cells are distributed in clusters, corresponding to the location of scales. The ectodysplasin (Eda) signaling pathway regulates the formation of many types of skin appendages, including mammalian hair follicles and zebrafish scales. In eda mutants lacking scales, Merkel cells appear at a lower density and are uniformly distributed across the trunk. This suggests that blocking Eda-dependent scale formation inhibited Merkel cell development, but what would be the effect of altering scale shape and size? To address this question, we examined the skin of hagoromo mutant fish. The hagoromo mutation is a viral insertion that causes an overexpression of fgf8a, another important signal pathway for scale formation. By imaging transgenic zebrafish with marked Merkel cells and osteoblasts, we used ImageJ to calculate Merkel cell density, scale area, scale Feret’s diameter, and scale aspect ratio. We found that juvenile zebrafish with the hagoromo mutation had highly variable scale shapes and sizes. Interestingly, the clusters of Merkel cells expanded or shrank to match the new scale shapes in the mutants. However, there seemed to be no significant difference in Merkel cell density. We expect to see similar results in adult zebrafish. Our research will help us understand the development of Merkel cells, therefore helping us understand skin development in vertebrates better. 

Trait-based plant ecology can serve as a means to better understand shifts in ecological strategies within plant communities and how that affects greater ecosystem processes, such as productivity, across a period of major climate change. The most recent major global warming event prior to modern anthropogenic influences was the Miocene Climatic Optimum (MCO) ca. 17-14 million years ago. This event was a short aberration to a long-term cooling trend of the last 53 million years, with global temperature averages up to 8°C warmer than preindustrial averages. Changing climate conditions during the MCO may have led to plant community reshuffling, with many ecosystems possibly restabilizing with notably different optimal trait distributions. Functional traits such as leaf shape, size, and toothedness can be indicative of a plant’s ecological strategy. These leaf morphology variables have been shown to closely correlate with climate, highlighting their role in plant function and strategy, and can thus be used to statistically analyze community diversity across the MCO. I hypothesize that the MCO caused an overall increase in functional trait diversity through an increase in favorable environments, allowing plant reshuffling or migration of plants with new ecological strategies into existing communities. We expect to see this through trait distributions in a community diversifying as the MCO progresses. This study uses leaf functional trait data measured digitally from a range of Miocene fossil sites to assess trends and variances from before, during, and after the MCO. Statistical analysis will make use of a previously developed R package to assess functional diversity. These results will be crucial information in understanding the ecological response to today’s far more rapid climate change, as well as humanity’s response to the possible need for human-assisted plant community reshuffling by providing an example of how global warming affected vegetation in Earth’s past.

Grasses are a diverse group of plants that play a significant role in many terrestrial ecosystems globally. Despite their importance, very little is known about where and when grasses originated. In particular, it remains unclear in which environment early grasses evolved. Current hypotheses, based primarily on phylogenetic work, suggest that early grasses emerged in closed habitats, such as forests, or in more open habitats along forest margins. However, there is little direct paleobotanical evidence to support either option. To understand the environmental context grasses evolved in, I will be reconstructing canopy openness using phytoliths from Argentinian fossil sites. Phytoliths are microscopic silica bodies deposited in or around plant cells, which can be preserved in the fossil record and used to reconstruct past vegetation. The phytoliths that I am analyzing are from the Las Violetas Formation (57.9-50.6 Ma) of Argentine Patagonia, a rock formation within an area known to hold the oldest records of grass phytoliths in South America. As a proxy for vegetation structure, I am using reconstructed Leaf Area Index (rLAI), which takes the area to perimeter ratio of non-grass phytoliths originated in the leaf epidermis and determines a value that corresponds to how much light passes through a canopy. A canopy with a high leaf coverage correlates to a high rLAI value and vice versa. Based on preliminary rLAI results, I expect to find that ancestral grasses lived in habitats with semi-open canopies, similar to modern shrublands. Investigating the ancestral environment of grasses can help us better understand their evolutionary history and potential environmental drivers that led to their success in terrestrial ecosystems. This information can help us gain insight on the vulnerability of grasses and grass-dominated habitats to environmental changes in the past, present and future.

The geologic record has become an increasingly important source of information for scientists to observe how plant communities of the past have responded to disturbance. Currently, there is a limited ability to recognize disturbance as a primary driver of plant community change, as there is limited evidence of how functional traits – plant traits that relate directly with plant function and ecological strategy – that can be measured in fossil leaves vary across succession. In this study I will measure a functional trait to help better identify disturbance in the fossil record, the carbon stable isotopic composition (δ13C) of bulk organic matter in leaves sampled across a successional gradient following a disturbance. This trait is often preserved during leaf fossilization and is representative of a plant's water use efficiency (WUE), or the amount of carbon dioxide used by the plant during photosynthesis for a given amount of water that is lost during transpiration. It is currently not known the extent to which carbon isotopes measured at the community-scale reflect the successional stage of a plant community. In an effort to develop this tool, I hypothesize that the WUE of plant species within a community will become more conservative in later successional stages. In support of this hypothesis, I predict that the abundance-weighted community average of leaf δ13Cwill increase through succession. In addition, I hypothesize that δ13C as a proxy for WUE will be most confounded in early succession, before a tree canopy forms, due to seedling utilizing water resources more rapidly without having established root systems and thus predict a higher variance of δ13Cvalues in this earliest stage of succession (Cernusak 2020). This research will help develop a method of identifying disturbances within geologic records which can give guidance on management decisions regarding modern ecosystems.

Over the past decade, we have seen major forest loss due to events like deforestation and tree die off. Previous studies have examined ways in which the distribution of plant types and how they function impact local and global climate. Local climate can be impacted because plants alter fluxes of water, energy, and momentum between the land surface and the atmosphere. Global climate can be impacted because local changes influence atmospheric response in clouds, humidity, and gradients in energy which drive changes in circulation. This project aims to identify if observed forest loss has a measurable effect on the noisy climate system. We have compiled spatial data of actual forest loss derived from satellite observations and test the climate impact of forest loss in simulation experiments using an Earth system model. We will assess differences between simulations with and without forest loss to identify how forest loss impacted the atmosphere and surface climate over land. We use the identified impacts as hypotheses for the expected climate response to forest loss and will subsequently analyze if these patterns can be seen in observed environmental conditions following forest loss. We expect to see some effect in the climate due to the observed forest loss. This project serves to advance our understanding of the effect of forest loss on global climate, atmospheric circulation, and energy balance, and thus will help to coordinate efforts to mitigate climate change by identifying potential unwanted impacts of forest change due to human actions.

In this study I investigate potential changes in plant community ecology in response to Earth’s most recent major global warming event, the Miocene Climatic Optimum (MCO). During the MCO (from 17-14 million years ago) global temperatures increased by approximately 8° C and CO2 levels increased by 300-400ppm. In assessing these ecological changes, I use minor leaf vein density (mLVD), a leaf functional trait correlated with photosynthetic rate, as a proxy for understanding plant community strategies. This trait corresponds with the spectrum of “fast” versus “slow” growing strategies described in plant physiology, with high mLVD in fast-growing plants facilitating higher photosynthetic rates, and low mLVD reflecting slow-growing persistence strategies with lower rates of photosynthesis. I hypothesize that global warming led to long growing seasons that enabled the dominance of ecological strategies that prioritize persistence over productivity (i.e., slow growing strategies), and more favorable climates increased the diversity of ecological strategies present within the community. Currently, I am measuring fossil leaf mLVD from specimens collected in the Pacific Northwest from sites representing before, during and after MCO. I examine the community-level distribution of this trait (mean, variance, kurtosis) and compare these values between sites, and thus across the MCO. I predict that plant community ecological diversity would increase during this global warming event; I also expect to see higher variance in distribution of mLVD values as warming temperatures opened new ecological niches, while mean mLVD would decrease due to an increase in persistence strategies correspondent with low mLVD. This work will help us not only to understand how plant communities responded to rising temperatures in the past but also how plant communities could potentially respond to changing climates in the future.

Herbivory is a concern for agriculture because it results in loss of crops. Plants have innate immune systems that allow them to defend against pests that once better understood, can be utilized to help mitigate this loss. In Steinbrenner et al.’s 2020 work, the authors identified an herbivore-specific immune receptor termed INR in Vigna unguiculata (cowpea) which induces plant defenses upon perception of the protein inceptin, found in the oral secretions of caterpillars. To further investigate the herbivory defense signaling pathway, we acquired EMS (ethyl methanesulfonate) mutagenized seeds, which contain mutations called single nucleotide polymorphisms (SNPs). These F1 parent seeds were allowed to self-propagate, producing M2 seeds. We did this because the F1 seeds likely have a SNP in only one allele of their chromosome, thus being heterozygous at a particular loci where the SNP occurred. When the F1 seeds self-propagate, we expect to get a ratio of 1:2:1 of homozygous for the wildtype allele (HH), heterozygous (H*H) and homozygous for the mutated allele (H*H*). This would give us a more varied phenotypic response when screened for sensitivity to inceptin. Individuals that exhibited a compromised inceptin response will be further investigated to determine causative mutations. We identified a number of families with abnormal immune responses, rescreened those families and verified specific families. Next we will self-propagate individuals from verified families, and expect phenotypes to segregate in a 3:1 ratio if a single dominant mutation is causative. Then bulked segregant resequencing will be used to determine which mutations are co-associated with phenotype. After knowing the genotype, we can begin to determine the molecular mechanisms behind the phenotype. This would further our understanding of plant immune responses, which we can harness to better develop more resilient crops, thus mitigating crop loss due to herbivory.
 

The COVID-19 pandemic caused many college courses to shift to emergency remote instruction and instructors had to alter their in-person teaching methods for an online format. For example, some active-learning instructors opted to embed questions in recorded lectures, asking students to pause the video and attempt to answer on their own, and then continue playing the video to hear the answer. We hypothesize that if a professor has a video “autopause” before the video provides the answer (instead of asking the students to pause a video themselves), then students will be more likely to try the question on their own. Further we hypothesize that if students generate their own answer, they will develop a stronger understanding of the material. We investigated these hypotheses in Introductory Biology III. Students (n=550) completed “lecture follow alongs (LFAs)” assignments as they watched the video. Half of the students were randomly assigned to the control group, in which they were asked to pause lecture videos and answer the questions. The other half were part of the treatment group, in which lecture videos autopaused, and the students had to positively affirm they answered the question before the video continued. We are investigating differences in exam performance, LFA responses, interview transcripts, Panopto video data, and pre- and post-surveys. Preliminary statistical analyses show that autopause did not impact student exam performance. However, preliminary analyses of LFAs indicate that autopausing can decrease copying behavior and increase the chance that students try to answer a question on their own. Through further analysis, our results can give insight into the effectiveness of autopause questions in reducing copying, which can help encourage independent student thinking. At the same time, our results will teach us how to adapt autopause questions, so they might improve student performance, in addition to encouraging student thinking.

Throughout our lives, we generally base our idea of age upon someone’s ‘chronological age’, or how many years they’ve been alive. This, however, is not always the best indicator of aging, as people reach social and biological milestones at different ages. As an alternative, someone’s ‘biological age’ can be more representative of their progression through life. As such, research has focused on identifying biomarkers of biological age to help us better understand aging. Recent work in our lab has sought to determine the impact of several metabolites - biomolecules used for metabolism - on the biological age of the fruit fly, Drosophila melanogaster. Among the metabolites studied, histamine - a neurotransmitter involved in wakefulness and visual processing - had one of the strongest correlations with lifespan, suggesting that it plays a role in aging. In this study, we attempted to manipulate the biological age of female D. melanogaster by altering either their metabolic levels of histamine, or their perception of histamine. To do this, flies were given food supplemented with histamine or with the antihistamine hydroxyzine, a competitive inhibitor of histamine receptors. These experimental conditions were compared to control food that lacked additives. Treatment was administered continuously starting at 4 weeks and the lifespans of flies in each condition were measured. Based on our previous results, we expected to see a negative effect of added histamine on lifespan and an increase in lifespan in response to antihistamine. Our study could highlight histamine’s role in aging and lay the foundation for demonstrating that biological age can be influenced by a single metabolite.

 In humans, gait changes with age; changes that have been associated with the onset of disease. We also see age-related changes in the fruit fly, Drosophila melanogaster, which shows a decrease in the ability to climb vertically. However, the effects of age on walking patterns of flies on a flat surface, which more closely mimics human walking, have not been fully characterized. In my research, I use D. melanogaster as a model to investigate such effects. During the past year, I followed cohorts of D. melanogaster over their lifespans and recorded videos of them walking in an enclosed arena. A wide-field camera captured the entire arena while a higher resolution camera captured the leg movements of individual flies. I analyzed the trajectories of each fly from the wide-field videos to evaluate walking velocity and duration. Based on my preliminary analysis, I have discovered that flies walk less frequently and at slower average speeds with increasing age. As a next step, I am analyzing the high resolution videos to investigate the possibility that changes in gait might explain the slower walking velocities at older age. To do this, I trained a neural network using multi-pose animal estimation software to track the movement of individual legs in relation to the fly’s thorax. This will allow me to look at gait (step length, swing duration, stance duration) as well as coordination. I expect to see age-related changes in gait and a loss of limb coordination over fly lifespan, which might explain why flies walk slower with increasing age. With the findings from my study, I hope to establish a foundation for how gait changes with age in D. melanogaster.

Plants have a variety of pathways and receptors to defend against herbivores, pathogens, and damage. While receptors involved in damage and pathogen perception are well studied, receptors involved in defense against herbivorous pests are not well understood. The first known receptor involved in plant-herbivore interactions is the inceptin receptor (INR). INR recognizes inceptin, a short 11 amino acid polypeptide found in the oral secretions of caterpillars. When inceptin binds INR, the plant produces ethylene, peroxidases, and reactive oxygen species to reduce herbivory. However, only some legume species express INR. To confer novel resistance against herbivores to other plant species, we designed plasmids containing INR as well as its coreceptors to reconstruct the cell surface signaling pathway. These plasmids enable transgenic expression of the INR cell surface signaling network in the model organism Arabidopsis thaliana. After constructing these plasmids, I transformed them into Arabidopsis thaliana via Agrobacterium-mediated transformation, which allows for assessment of immune activation in response to inceptin treatment by measuring ethylene and reactive oxygen species production. If this strategy successfully transfers INR function into Arabidopsis thaliana, then this same approach may be used to transfer INR into crops. Higher resistance to herbivory would limit pesticide use while increasing crop yield, reducing the amount of land and water needed to sustain populations.

The mechanistic target of rapamycin (mTOR) is a protein kinase that is closely linked to growth and nutrient control in a multitude of organisms. Inhibiting TOR with the drug rapamycin has been shown to increase lifespan in many species. In the fruit fly, Drosophila melanogaster, rapamycin slows development, an outcome that is perhaps closely related to its effect on lifespan. Recent work in the Promislow lab on larval development has shown that the effect of rapamycin varies greatly across different genotypes, from no impact in the time of development to a nearly doubling of development time. However, it has not yet been determined which of the three larval stages is most sensitive to rapamycin. My project attempts to answer this question. I tested the delay in larval development of larvae treated with rapamycin across six different fly genotypes, four that are known to be sensitive to rapamycin treatment, and two that are resistant. After transferring eggs to food containing rapamycin or control food, I collected larvae over three days and staged them based on specific characteristics of each stage. The data were compared between treatments and genotypes to see if there was a delay in specific larval stage development that resulted in the overall delay seen in previous experiments. These data were analyzed using R, and the results indicate that there is a significant delay in development of the first instar larvae of the sensitive strains, and no delay in the resistant strains. Based on these results, I will next use single cell sequencing of first instar larvae raised on rapamycin-treated or normal food, with the goal of better understanding the specific mechanisms by which rapamycin leads to a decrease in larval development time, and the genetic basis of variation in the response to this treatment.

Organisms are required to maintain genome stability for the correct propagation of genetic information. Glycation damage is one of the most important types of DNA damage that cause genome instability. Glycation damage in organisms is caused by the covalent attachment of parts of sugar molecules to proteins and DNA. Accumulation of the Advanced Glycation End (AGE) products may cause Parkinson's disease, cancer, and other oxidative stress-induced diseases. The protein deglycase, known as DJ-1 in plants and Parkinson Disease Protein 7 (PARK7) in animals, can prevent glycation damages in many organisms. In maize, plastid genome stability is maintained by Whirly ssDNA-binding proteins. Our lab recently showed that the demise of plastids and their DNA is associated with increased DNA damage due to oxidative and glycation damages during maize seedling development. Here, our objective is to understand the role of Whirly proteins in glycation damage. Our approach involves quantifying the glycation and deglycation levels in maize plastids. We isolated plastids and their proteins from the wild-type (wt) and whirly (why) mutant maize seedlings and performed glycation and deglycation assays. We find a significant difference in deglycation levels between wt and why mutant plants. Our study should provide a better understanding of the role of ssDNA binding proteins in glycation damage. 

From their ability to perch perfectly on nearly any surface to their capability of balancing on any perch, birds are phenomenal animals. Avian anatomy includes mysterious features like the lumbosacral organ (LSO) within the spinal cord. Research surrounding the LSO has led to the discovery of a mysterious network of nerve fibers that seem to cross the midline of the spinal cord only in the LSO. The goal of my research was to identify the neuron cell bodies giving rise to these axons and to track their targets. To do so, I used immunohistochemistry (IHC) and tracing. A tracer was injected into the glycogen body, where the surrounding neurons took up the tracer and transported it both retrogradely, toward the cell body, and in the anterograde direction, toward the axon endings. Tracing revealed the structure of the circuit. IHC was subsequently used to test if proteins indicative of sensory nerves were present in the glycogen body, such as CGRP and substance P. These methods, thus far, have indicated the presence of CGRP and substance P in nerve fibers across the glycogen body. These findings suggest the mysterious nerve network in the LSO is a network of sensory neurons abundant in substance P and CGRP, also implicating the glycogen body as a facilitator for the passing of these nerve fibers.

Why do identical twins have different lifespans? Beyond genes, what else might influence the aging process? Variation in any phenotype is due to the combined effects of genetic variation and environmental variation. In fact, there are two types of environmental variation—one is extrinsic environmental variation, such as food, temperature, etc., and the other is intrinsic environmental variation, which can lead to subtle differences in behavior, such as how much an individual eats, how long it sleeps, etc. We hypothesize that these differences can be predicted by an individual’s underlying metabolism. There are thousands of molecules that make up the structural and functional building blocks of all organisms, a domain known as the metabolome. Previously, many studies have shown that genotypes vary in lifespan, but even within a single genotype there is enormous variation in lifespan. Here we address how intrinsic environmental variation influences aging by controlling the genetic and extrinsic environmental variation under lab conditions. We designed an experiment using Drosophila melanogaster, and since Drosophila has a natural tendency to climb upwards against gravity, and climbing ability of flies decreases with age, we hypothesized that we might use climbing ability as a biomarker of future mortality risk. Using mid-life climbing ability, we separated genetically-identical flies and then analyzed each group’s lifespan. We found that within a genotype, strong climbers had a longer lifespan than non-climbers. Finding strong support for this hypothesis led us to propose that the metabolome between climbers and non-climbers might be different. Our goal is to understand the role of intrinsic variation in aging. If we can find metabolites that associate with climbing ability, and as we have shown, climbing ability is associated with aging, we might be a step closer to explaining how intrinsic environmental variation influences aging.

This research aims to explore the link between mRNA translation and cancer growth specifically in bladder. Using genetically engineered mouse models, this work demonstrates that protein synthesis is essential for efficient urothelial cancer formation and growth but dispensable for bladder homeostasis. Through a candidate gene analysis for translation regulators implicated in this dependency, we discovered that phosphorylation of the translation initiation factor eIF4E at serine 209 is increased in both murine and human bladder cancer, and this phosphorylation corresponds with an increase in de novo protein synthesis. Employing an eIF4E serine 209 to alanine knock-in mutant mouse model (in vivo), we show that this single posttranslational modification is critical for bladder cancer initiation and progression, despite having no impact on normal bladder tissue maintenance. Using murine and human models of advanced bladder cancer and immunostaining techniques, we demonstrate that only tumors with high levels of eIF4E phosphorylation are therapeutically vulnerable to eFT508, the first clinical-grade inhibitor of MNK1 and MNK2, the upstream kinases of eIF4E. Our results show that phospho-eIF4E plays an important role in bladder cancer pathogenesis, and targeting its upstream kinases could be an effective therapeutic option for bladder cancer patients with high levels of eIF4E phosphorylation.

The human brain is highly sophisticated and its functions are influenced by a multitude of factors, many of which play a role in the complex aging process. Certain individuals appear to possess more resilience to environmental and biological stressors as they age compared to others. However, why they are more resilient is not understood. Resilience refers to an individual's capacity to respond to stress (physically, psychologically, emotionally) by resisting damage and bouncing back. In my research in the Promislow lab, I use the fruit fly, Drosophila melanogaster, to explore the intricate process of aging. In this experiment, I applied a biological stressor on the flies halfway through their lives and examined mortality and motor function as measures of health to study resilience throughout the fly’s lifespan. I stressed the flies with a sublethal dose of paraquat, a neurotoxin that causes oxidative stress and mitochondrial dysfunction upon acute exposure. If the stressed flies return to the mortality and motor function levels of the control flies, this tells us the flies are resilient. I hypothesize that all of the flies that receive the paraquat dosage will experience an increase in mortality and a decrease in motor function when compared to the control flies. While I think the majority of the flies will fail to recover from these stressed levels, I hypothesize a small number of flies will return to the mortality and motor function of the control flies, demonstrating resilience. In my project, I aim to understand how flies can recover from biological stressors, and how their ability to recover changes throughout their lives. My long-term goal is to understand how exposure to biological stressors affects the aging process, and in particular, how and why resilience varies with age.

Studying mesocarnivore interactions is vital to understanding ecosystem function, particularly in the absence of apex predators. Competition and niche partitioning between bobcats (Lynx rufus) and coyotes (Canis latrans), two abundant mesocarnivores, is poorly understood but may have significant impacts on prey dynamics and ecosystem structure. Understanding how bobcats and coyotes coexist will provide insights into the context and occurrence of intraguild exploitative competition. This study aims to determine if exploitative competition between bobcats and coyotes is occurring in the Eastern Cascades of Washington state by analyzing the diet and habitat use of sympatric and allopatric bobcat and coyote populations. I hypothesize that sympatric bobcat and coyote populations will occupy smaller niche spaces than allopatric bobcat and coyote populations due to the niche partitioning of shared resources. To test this hypothesis, I will compare the frequency of occurrence of food items in bobcat and coyote scats using DNA metabarcoding and Next-Generation sequencing. Using microsatellite analysis, I will genotype a subset of coyote and bobcat scat samples to determine the number of individuals and their home range size. I will also determine the habitat type of the georeferenced scat using geographic information systems. This will be the first study comparing allopatric and sympatric bobcat and coyote populations and will clarify the conflicting literature on the occurrence of exploitative competition between bobcats and coyotes.

Bats are the only mammals capable of powered flight and have correspondingly specialized body plans, apparent in the limbs. These specialized morphologies are thought to be the result of adaptations for the demands of flight; the skeletal elements of the bat forelimbs are elongated in order to support flight membranes and increase aerodynamic efficiency, whereas bat hind limbs are relatively short and specialized for hanging and catching prey in flight. Due to a deficient fossil record, the evolution of bat flight is still not fully understood but is hypothesized to be the result of an ancestral transition from gliding to flying. This hypothesis is plausible considering the morphological similarities between bat and glider forelimbs (both elongated) and the contrast between bat and glider hind limbs (shorter versus elongated). In this study, I collected linear measurements of the forelimb and hind limb skeletal elements of bats to add to a dataset of gliding, arboreal, and terrestrial mammals. I then fit evolutionary models to the data to test the hypothesis that A) selective pressures for flight drove the evolution of bat forelimb skeletal elements from glider-like forelimbs and that B) bat hind limbs evolved to become morphologically distinct from those of other mammals. Based on this hypothesis, I predict that A) bat and glider forelimb trait optima will fall progressively farther from arborealist optima and B) bat hind limb trait optima will be located in a unique region of morphospace. Preliminary results show that forelimb long bone lengths have evolved to be progressively longer from arborealists to gliders to flyers, supporting my hypothesis. This research helps address the longstanding question of how bats may have evolved flight from ancestral gliding mammals.

Accurate information on species identities and distributions is critical for informing state land use and conservation policies. However, it can often be difficult to determine species identity using morphological data alone. Using phylogenetic methods, we determined the identity of Sceloporus lizards occupying the Laramie Mountains of Wyoming, between known ranges for Sceloporus tristichus and Sceloporus consobrinus. The ND1 mitochondrial gene was sequenced for 10 individuals from the Laramie Mountains and analyzed using maximum likelihood with 23 other samples of S. tristichus and S. consobrinus from throughout their ranges. The mtDNA gene tree places the Laramie Mountains populations within a clade of Sceloporus consobrinus that includes the Rocky Mountains in Colorado. Given the prevalence of mtDNA introgression in Sceloporus, we also conducted phylogenetic analyses using 4 nuclear loci (RAG-1, R35, BDNF, and PNN) for a subset of samples. Species tree analysis of the nuclear data further verified that the Laramie Mountains population belongs to S. consobrinus. Given the very limited data available on the range, prevalence, and ecology of S. consobrinus in Wyoming, as well its designation as a Species of Greatest Conservation Need in Wyoming, more research must be done to ensure protection of this population.

Body shape varies drastically across vertebrates, making it an effective trait to study when trying to understand macroevolutionary patterns of phenotypic variation. Body shape has been quantified in many ectothermic clades, but rarely in mammals. The goal of our research is to quantify body elongation in the family Sciuridae, as this area has been understudied thus far. Squirrels (Sciuridae) can be sorted into three distinct ecotypes based on life history and locomotion: ground, tree, and gliding. This leads to questions regarding differences in body shape between ecotypes in their respective environmental niches, and how differences in elongation correlate to different types of locomotion. We hypothesize that tree squirrels will be the most elongate, followed by ground squirrels, then gliding squirrels due to ecological and functional adaptations. To determine the potential differences in elongation between ecotypes, we will calculate the head-body elongation ratio (hbER) from skeletons held at natural history museums. We will use phylogenetic comparative methods to compare hbER between the three ecotypes. Thus far, our preliminary data shows both gliding and ground squirrels to have a statistically significant difference in hbER from tree squirrels. Tree squirrels are the most elongate, followed by ground, then gliding squirrels. We hope to further test differences between the hbER of ground and gliding squirrels with an increased sample size. Research on correlations between robustness and bone density in this clade is already underway, which will complement our results on elongation ratios between ecotypes.

In vertebrates, differences in limb morphology are often the result of adaptions to locomotion. While previous researchers have examined the external shape of skeletal elements, there have been relatively fewer studies examining internal bone structure despite its potential significance to locomotor biomechanics. This study aims to help fill this gap by quantifying internal differences in forelimb skeletal morphology of squirrels (Sciuridae) across three locomotor ecologies: ground, tree, and gliding. We test the hypothesis that forelimb internal bone structure reflects adaptations to these ecotypes. To test our hypothesis, we micro-CT scanned the humeri of 61 species of squirrels and conducted bone structure analyses in the open-source software 3D Slicer. We assessed cortical bone composition by measuring material properties including global compactness (bone density), diaphysis (shaft) elongation, and second moment of area (bending ability). Based on biomechanical demands,we predict that A) gliders will have relatively less compact long bones with more elongated diaphyses due to the gravitational/aerodynamic constraints of gliding and B) ground squirrels will exhibit highly compact long bones with more robust diaphyses to gain more force while digging burrows​​. Preliminary results support our prediction that larger ground squirrels exhibit relatively more compact, robust, and bend-resistant humeri in accordance with their digging locomotion. This research furthers the understanding of diversity in forelimb morphology across mammals and the connection between forelimb morphology and locomotion. This study also lays the groundwork for future biomechanical and behavioral work to examine the evolutionary ties between form and function.

Bacteria have the ability to transfer certain small, mobilizable pieces of DNA from one cell to another, nearly regardless of species, through a process called conjugation. During conjugation, a donor cell containing a plasmid donates a copy to a recipient cell lacking a plasmid to form a transconjugant (a recipient cell now containing a plasmid). This has strong implications for the spread of antibiotic resistance among bacterial communities, as plasmids often harbor genes which confer resistance to certain antibiotics. Sharing of these plasmids between bacteria can increase the amount of resistant individuals in a population, which can produce infections that can be difficult to treat clinically. Therefore, having an accurate method to predict the rate at which these transconjugant cells form within a bacterial population can provide key insights to the spread of antibiotic resistance through plasmid-mediated gene transfer. Current models rely heavily on the presumed deterministic nature of transconjugant formation; however, we revealed that experiment estimates with these currently available methods can lead to biased estimates. In need of a more accurate and robust method to estimate the conjugation rate, we developed a novel stochastic model and accompanying lab protocol that effectively provides an accurate estimate of the conjugation rate. Our approach was inspired by the classic experiments of Luria and Delbrück, which revealed that mutation (changing a normal cell into a mutant cell type) was a stochastic process (i.e., random). Similarly, we hypothesized that this stochastic framework could be useful for creating a method for estimating conjugation (changing a recipient cell into a transconjugant cell type). We found using experiments and simulations that our method is accurate and robust under a variety of conditions. In conclusion, we developed a new method for the accurate estimation of plasmid conjugation rate.

Epilepsy is a neurological disorder characterized by the presence of seizures (periods of abnormally synchronized neural hyperactivity) and interictal spikes (transient abnormal neural synchronization that occurs between seizures). Different genetic mutations and backgrounds lead to different forms of epilepsy, which in turn may lead to different manifestations of epileptiform neural activity. I used machine learning (ML) to detect interictal spikes in mouse models of different epilepsies. I used neural activity previously recorded in mice using two electrocorticographic (ECoG) electrodes and one electromyographic (EMG) electrode. I used data from mouse models of Dravet syndrome (DS; Heterozygous Scn1a gene deletion), focal cortical dysplasia (FCD; Pik3ca gene mosaic), Leigh Syndrome (LS; GABAergic Ndufs4 knockout) and, Alzheimer's Disease (AD; Increased beta-amyloid production), as well as wild type (WT) control. I used recordings binned into 10 second interictal spikes. I then used a computer algorithm that extracted 96 features - events that characterize ECoG and EMG electrical signals. These features and the manually identified interictal spikes were used to train several ML models to score unidentified interictal spikes in the remaining recorded data. The best performing ML algorithm had a mean test accuracy between 60% and 80% for each of the different models of epilepsy, but the features it used were different in each epilepsy mouse model. These results suggest that, while our ML-based method may capture epileptic activity with high accuracy, its success relies on features that are characteristic of each type of epilepsy. These results suggest the potential need to utilize different ML models for different forms of epilepsy in order to attain the highest possible accuracy if used for real-time interictal spike detection and potential seizure forecasting.

One of the most striking adaptations in land plant evolution has been the specialization of reproductive structures and strategies. LEAFY (LFY) is a gene well characterized in flowering plants (angiosperms) as a transcription factor that initiates the development of the flower, which contains the reproductive organs. LFY has also been shown to regulate the first cell division of the zygotes in mosses (a type of non-vascular plant). The fern Ceratopteris richardii (CrLFY) is a type of non-flowering plant that is midway phylogenetically between mosses and flowering plants, and belongs to the sister clade to seed plants (angiosperms and gymnosperms). Therefore, C. richardii is an ideal model to study LFY's functional evolution. Previous research has shown, through the suppression of CrLFY expression via RNAi, that it maintains the identity of the apical stem cell in gametophytes, the haploid life cycle stage. To further characterize the function of LFY in ferns, we are now studying the effects of its over expression on gametophyte phenotypes. Given that overexpression of LFY causes early flowering in angiosperms, we might expect to see early development of the sperm and egg producing reproductive structures (antheridia and archegonia) in fern gametophytes. Here, I analyze data on the morphology and developmental timing of antheridia and archegonia of fern gametophytes overexpressing each of the two gene duplicates, CrLFY1 and CrLFY2. Our goal is to address whether CrLFY plays a role in the reproductive development of gametophytes, as it does in the sporophytes of seed plants. Characterizing the function of this gene will help us map how the LFY gene, and other master regulators of development more generally, have adapted through the evolution of land plants to serve vastly different functions in different plant lineages.

Global climate change is likely to have an effect on plants, pollinators, and the interactions between the two ecological groups. Recent studies have suggested that climate change may affect the growth and development of these organisms in the long-term, but variations in temperature could also change the short-term behavior of pollinators when they visit plants. For instance, pollinators with certain physical traits might be better suited to forage in areas with higher or lower temperatures. In this study, I explored this idea with the assumption that the foraging decisions of pollinators are indicative of the temperatures that they are flying at. I addressed the questions of 1) how variation in temperature affects pollinator traits? and 2) are certain pollinator traits correlated with differences in the identities and traits of the plants that they are captured visiting? To answer these questions, I measured the size of bees collected in the Rocky Mountains during the summer of 2021, and I compared these sizes to the temperatures at the sites at which the bees were caught. I predicted that 1) pollinator traits would correlate with temperature, and 2) the interactions in my data analysis would show trait matching between the pollinators and the plants that they were visiting when caught. The results of this study should help illustrate how the impacts of climate change might affect plant-pollinator communities, which could help to identify potentially advantageous traits as well as interactions that may be flexible or persistent during changing climatic conditions.

Hovering flight is one of the most energetically expensive forms of locomotion in hummingbirds. While flying animals already dissipate large amounts of muscle-generated heat to avoid overheating (thermoregulation), hummingbirds' expensive hovering flight and extensive muscle use suggests they may need to lose larger amounts of heat to remain normothermic. It is known that hummingbirds dissipate excess heat through heat dissipation areas (HDA) around the eye, shoulder, and feet. Other birds with larger bills use their bills as a supplemental tool for heat dissipation. Given the length of the hummingbird bill in relation to their body size, it could be possible that their bills have potential for heat dissipation. Using the FLIRT6xx-Series Thermal Imaging camera, we measured the temperature gradient between the environment and the bill surface of Anna’s Hummingbirds during flight in a range of temperatures that occur naturally in their home range (for this study, Seattle, WA). We also quantified bill surface area in high-resolution microCT scans of museum specimens, using open-source software (SlicerMorph). Further, we are developing novel scanning methods (macro photogrammetry) to allow for data collection in the field with free-living hummingbirds in situ. We hypothesize that if the bill is used for heat dissipation during flight, we will see a strong correlation between bill surface area and the thermal gradient of the bill-environment interface. Furthermore, we are considering the time of active hovering as a possible cause of variation in heat dissipation. This analysis could lead to more information about the limits of endurance for flying endothermic animals under the effects of climate change. Moreover, the methods developed to analyze bill surface area could be extended to related subjects, such as observing specimens from a variety of time periods, to quantify potential evolutionary patterns.

Genomic data provide critical information about biodiversity and phylogeography, particularly since genomics has become increasingly used to understand the nature of species boundaries. Species boundaries are difficult to delimit using morphology alone, while genomic data provide direct evidence for understanding the connectivity between populations or species. A recently described horned lizard, Phrynosoma diminutum, inhabits a unique ecological region of Colorado and is miniaturized relative to the surrounding populations of greater short-horned lizards (P. hernandesi). Phrynosoma hernandesi is a wide-ranging species with substantial morphological variation throughout its range, and despite the obvious size difference between P. diminutum and P. hernandesi, a complete lack of gene flow between these populations seems unlikely since there is no clear barrier to dispersal, which would cause speciation. To determine the extent of gene flow between populations and test the genetic support for P. diminutum as a distinct species, we compared P. diminutum genetic samples to surrounding populations of P. hernandesi. Using 3,000+ genetic markers distributed throughout the genome, I found that P. diminutum does not form a distinct evolutionary lineage and is only weakly differentiated from nearby P. hernandesi populations. Comparisons of genetic differentiation among all 17 species of horned lizards using fixation index (FST) values provides further evidence that the low levels of divergence observed in P. diminutum are reflective of population-level and not species-level divergence. Therefore, we propose that P. diminutum be synonymized with P. hernandesi rather than recognized as a distinct species. This conclusion has implications for land management, since it may be necessary to maintain corridors of gene flow between the miniaturized and surrounding populations. Furthermore, we show how genomic data can be used to avoid artificially inflating biodiversity estimates by more accurately testing species boundaries, and this allows managers to make precise decisions for wildlife and whole ecosystem conservation.

Plants recognize insect herbivore attack by detecting molecular patterns in their oral secretions. Steinbrenner et al. have recently identified a host plant receptor for one such pattern, termed the Inceptin Receptor (INR). INR binds herbivore-derived inceptin peptide and confers signaling and defense responses in response to inceptin, including a measurable burst of reactive oxidative species and the gaseous hormone ethylene. INR is present only in species of the legume subtribe Phaseolinae (e.g., common bean, Phaseolus vulgaris). INR was previously studied using heterologous expression in tobacco, but the role of INR in beans themselves has not been studied due to difficulty of genetic transformation and knockout approaches. I have created a backcrossed line of common bean introgressing a naturally occurring inr- mutation into a genome sequenced variety. Inceptin response is compromised in inr- near isogenic lines. I plan to use the inr- near isogenic line to measure the contribution of INR to caterpillar feeding relative to wild type plants. To quantify the feeding habit of caterpillar species when fed these two lines, I optimized a high throughput herbivory assay and imaging pipeline to quantify feeding behavior and tissue consumption. We hypothesize that plants lacking INR will show reduced deterrence, increased tissue consumption, and increased larval weight gain upon caterpillar feeding. Understanding how plants sense attack will help us to develop varieties that are resistant to pests and pathogens.

Corepressors are proteins that do not directly touch DNA but work with other proteins to keep the gene from being transcribed. TPL is a corepressor from the model plant Arabidopsis thaliana. While we understand a lot about how TPL works, there are still many mysteries remaining. The goal of my project is to identify other proteins that work with TPL to form a transcriptional repression complex at a single engineered promoter site. First, we created a synthetic repressor called dCas9-TPL that binds and represses the transcription of the RUBY reporter. The RUBY reporter is a visual marker expressed throughout the entire plant, turning the green plant a bright purple. Our engineered RUBY line also carries two guide RNAs in its promoter with sequences not found anywhere else in the Arabidopsis genome. This allows dCas9-TPL to bind to and repress this particular gene and not affect the transcription of other genes. We then crossed this transgenic plant line with plants expressing the dCas9-TPL repressor and the matching guide RNA. Visual screening of the Repressed RUBY line showed these plants turn faint whitish-pink instead of bright purple, signifying that the repression by TPL is working. I am currently on the next step which is identifying a homozygous line of Repressed RUBY to generate a mutagenesis population using the chemical EMS. Once I have these seeds, I will use visual screening to search for plants that have bright red or purple organs, which means that the repression by TPL is not working as well. By identifying regulators of corepressor function in plant biology, I hope to learn principles that can inform cellular engineering across many organisms and better understand why certain mutations associated with transcriptional repression cause developmental defects or diseases like cancer in humans.

The Miocene Climatic Optimum was a period of rapid warming that occurred from 17 to 14 million years ago where temperatures rose 2-4°C above pre-warming estimates and CO2 concentrations increased to ~400-600 ppm. This event was coeval with the eruption of the Columbia River Basalts (16.6-15.9 Ma), a series of large flood basalts covering much of the Pacific Northwest. The combined forces of these events led to this period being characterized by tumultuous changes to Pacific Northwest plant communities. To quantify these changes, I am reconstructing canopy openness. Ranging from open deserts to closed rainforests, degree of canopy openness describes the amount of sunlight reaching the understory of a plant community. These differences in sunlight exposure affect the size and shape of leaf epidermal cells. Leaves grown in shaded conditions tend to have larger, more undulated epidermal cells when compared to those grown in full sunlight. In the fossil record, silica casts of those cells called phytoliths can be measured to reconstruct the canopy openness of ancient ecosystems. I am using samples from four fossil sites in Central Oregon: Hawk Rim (16.4-16.2 Ma), Mascall (15.1 Ma), Haystack Valley (23-18 Ma), and Picture Gorge Basalts (17.23-16.06 Ma). These sites range from immediately before the Miocene Climatic Optimum (MCO) through the first two million years of warming. They also include samples from sedimentary layers interbedded with basalts. Therefore, they will provide insight on changes that occurred within the plant community both as warming began and because of volcanic eruption. I hypothesize that increased temperature and CO2 concentrations resulted in longer growing seasons and a CO2 fertilization effect. These conditions promoted high vegetation productivity and therefore closed canopies. Additionally, I expect that areas impacted by eruption will exhibit open canopies due to repeated disturbance preventing the re-establishment of forests.

Batillaria attramentaria (hereafter Batillaria) is a highly prolific mud snail in Padilla Bay, WA, with an estimated 8 billion plus in the bay alone. Understanding the ecology of Batillaria is important, as it is an invasive species and its ecological role within the bay is unknown. This study aims to identify Batillaria’s substrate preference when given access to bare sediment, algae, and Zostera detritus in Padilla Bay. Three experiments were developed to test the hypothesis that Batillaria prefers algae detritus over Zostera detritus, over bare sediment with organic content (hereafter mud). First, a field substrate preference experiment was set up at two locations with three plot types: algae, Zostera, and control (mud). Both sites were resampled three times over a 21-day period. A second experiment was designed to obtain a higher resolution of temporal data, for nine days. The second experiment used two plot types at one location: algae and control. A third experiment was conducted in-lab to see if and how snails would move toward specific kinds of detritus, in which Batillaria were placed in tubs and videoed with a timelapse camera for 1.5 hours. In field experiments, Batillaria highly preferred algae detritus over Zostera detritus at one location (IC) as measured by ANOVA (p<0.01), but at the other, Batillaria did not show a preference between Zostera detritus and algae (West-90) (p>0.01). At both sites, detritus was preferred over bare sediment. In the lab experiment, Batillaria oriented toward detritus, consistent with field findings, but reversed their detrital preference. The effects of Batillaria on decomposition and nutrient cycling within the bay are unknown, so understanding their detrital preferences is the first step in unlocking Batillaria’s role in the ecosystem.

Sexual dimorphism is the presence of morphologically distinct characteristics between males and females of the same species. Our project investigates the evolution of sexual dimorphism in the mandible across the family Canidae. We have created a database of 3D scans of specimens from the Burke Museum's mammalogy collection. We used a macroevolutionary approach to understand why sex-based differences exist today. Rensch's rule states that in male-biased species, sexual dimorphism is more evident in larger species. In female-biased species, the opposite effect is observed with smaller species exhibiting a greater degree of sexual dimorphism. Our project tests Renschs rule across a variety of Canids to determine if the degree of sexual dimorphism is greater in larger taxa. Using 3D models and geometric morphometrics, we placed landmarks on digitized mandibles to quantify sexual dimorphism in mandibular traits between males and females across various Canid species. Landmarked differences quantify sexually dimorphic features in the mandible, which we incorporated into evolutionary models to hypothesize how sexual dimorphism arose through evolution. Our project investigates whether Rensch's rule is applicable in Canids of various body sizes. We hypothesized that Canids will conform to Rensch's rule and that in larger Canid species, there will be a larger degree of sexual shape dimorphism for male-biased species. Rensch's rule is often tested with respect to size dimorphism, but limited studies use a multivariate approach to look at interspecific differences in sexual shape dimorphism. Our study will help answer ecological questions such as whether size and shape dimorphism is more significant in larger Canid species and whether sexual selection or niche divergence may be attributed to their evolution.

Arabidopsis thaliana, a long day plant, has important flowering time mechanisms in place to ensure reproductive success. The FLOWERING LOCUS T (FT) gene encodes a florigen molecule that regulates flowering time in Arabidopsis. In long day conditions FT protein is synthesized in phloem companion cells in the leaf and transported from the leaf through the phloem to the shoot apical meristem (SAM) in order to initiate a flowering response. Here we investigate the Myb-related protein ALTERED PHLOEM DEVELOPMENT (APL) which is believed to cause a late flowering phenotype in Arabidopsis by repressing FT transcriptionally. Flowering time experiments with varying results and gene expression analysis with APL overexpressing transgenic lines indicated that two versions of the APL protein exist. We then hypothesized that there is an alternative start site downstream from the original start site of the APL gene which, when synthesized, becomes a shorter version of the APL protein. When the shorter version of the APL protein heterodimerizes with the full length APL protein, the heterodimer complex is not able to bind to the FT transcription domain, allowing activation of FT and an early flowering phenotype. This was hypothesized because early flowering was observed in further flowering time experiments with the shorter version of APL overexpressed. Studying the FT locus, and factors that affect it, uncovers the mechanism by which plants flower at particular times depending on different light conditions. Understanding this molecular reproductive mechanism in plants is useful for enhancing crop yield.

Plants make their first root in the embryo, which is then called the primary root. Roots that emerge from the primary root later in development are called lateral roots (LRs). LRs are important for providing stability to the plant, and assisting in acquisition of nutrients and water. I am using LRs to understand how cell division (the cell cycle) is connected to developmental transitions. Previous studies have shown plant hormones auxin and cytokinin play important roles in cell division and LR organogenesis. Cells that have the capacity to become LRs with the right signal are called founder cells. Founder cells form when a few undifferentiated cells in the primary root respond to a pulsatile auxin signal to become ‘specified’ LR stem cells, retaining potential to proliferate and the ability to differentiate into LR. These specified LR stem cells arrest in the G2 phase of the cell cycle, respond to auxin signaling, and undergo rounds of cell division, marking the onset of LR development. In this study, I investigated whether G2-arrested cells in the specification stage are receptive to auxin and cytokinin. Specifically, I analyzed LR primordia shape, LR developmental progression, and LR density in response to treatment with auxin and cytokinin in plant lines where the cell cycle is disrupted. Preliminary results reveal an increased density of LRs in plants with a long G2/M transition when they are exposed to auxin. This suggests that progression through the cell cycle may reduce auxin sensitivity. The understanding gained from these experiments is helping build a framework for how the cell cycle contributes to LR development, allowing for future genetic modifications to improve root structure in crop plants.

While it is established that plants generate defenses in response to herbivory, little is known about the specific elicitor-receptor interactions that initiate the immune response. The recently discovered inceptin receptor (INR), which is found in certain legume speices, recognizes an 11-amino acid polypeptide named inceptin (In11) commonly found in caterpillar oral secretions. INR is a receptor-like protein and consequently does not have a kinase domain, which is essential for initiating the signaling pathway that results in an effective plant immune response. However, we hypothesize that INR forms a receptor complex with coreceptors that transmit the initiating signal intracellularly. These coreceptors may also enable INR to recognize and respond to In10, a truncated version of In11 that is only recognized by Phaseolus vulgaris (common bean). To determine the specific function of these coreceptors, a genome-wide association study was performed to identify potential candidate genes; this analysis pointed us to the somatic embryogenesis receptor kinases (SERKs), which are known to play a role in many signaling pathways for plant immunity and have been found to associate with INR in response to peptide treatment. I cloned and coexpressed five common bean SERK proteins along with INR in N. benthamiana via agrobacterium mediated transformation and measured production of ethylene and reactive oxygen species as assays for inceptin perception and immune response. We found that most SERK homologs did not appear to modify INR function, although some homologs showed elevated immune outputs in the absence of inceptin. Further experiments involving these candidate genes, such as a western blot to verify interaction between INR and the SERK homologs, are needed to establish the function of these coreceptor candidates. By understanding cell surface signaling networks involved in INR signaling, we can implement more specified pest management systems that enhance crop resistance, making more sustainable agricultural practices.

Cyclic population tendencies, found in small mammals like voles, lemmings, and snowshoe hares, have fascinated ecologists for over a century. More recently, it has been suggested that large mammals like ungulates may have cyclic patterns as well. For example, Indigenous history and palaeoecological records show that caribou or reindeer (Rangifer tarandus) can have population cycles that last from 50-100 years. Though caribou are well-studied globally, few studies have examined the underlying conditions prompting these dynamics, and so little is known about what causes them. It is hypothesized that factors such as climate, vegetation growth, predation, density-dependence, and subsistence harvest are all influential. I aimed to identify which of these factors contribute to population cycling, and better understand how to manage caribou for subsistence and recreational harvest. To do so, I built a tri-trophic mathematical model based on ordinary differential equations representing wolf-caribou-vegetation dynamics under various parameter scenarios. Based on available data, I chose to focus on North American barren-ground caribou herds located in Alaska and Canada. I extracted parameter values from existing literature on caribou and moose to parameterize my tri-trophic model. I ran my model in R, manipulating parameter values to see which factors influenced cycle period and amplitude most significantly. The results from these model simulations can better inform future management strategies and policy implementation surrounding sustainable harvest. Caribou are immensely important to Indigenous communities for cultural and subsistence purposes. With a shift in global climate, sensitive biomes such as the tundra are increasingly at risk of experiencing lasting negative impacts which will severely impact wildlife and other biotic systems. Adaptive caribou management is crucial to ensure survival for this globally declining species.