Michelle Shero, Nell den Heyer, Caroline Rzucidlo, Greg Breed, Michelle Rivard, Damian Lidgard, Jennifer Burns

Marine mammals have large oxygen (O2) stores that determine how deep and long they can dive, directly influencing foraging patterns and success. However, blood and muscle O2 stores develop slowly in juvenile pinnipeds and limit diving capabilities of pups during their first few months of independent foraging. In all animals, iron is a key micronutrient needed for hemoglobin and myoglobin heme production, which make up the largest components in pinniped total body O2 (TBO2) stores. Low iron intake from their mother’s low-iron milk can result in pups exhibiting a developmental anemia, potentially slowing TBO2 store development and future survival. If iron is a limiting factor, providing an iron supplement to seal pups during the nursing period should lessen developmental anemia and increase TBO2 store development before they begin foraging. To test this hypothesis, we monitored iron stores and TBO2 development in grey seal (Halichoerus grypus) mom-pup pairs from the Sable Island population during the 2022-2024 breeding seasons. Blood and muscle samples were collected during early nursing (3 days postpartum [dpp]), late nursing (12 dpp), and post-weaning (28 dpp) periods of development. Half of the pups received an iron dextran supplement (20 mg/kg) at 3 dpp and 12 dpp, and the remaining received a saline placebo. Iron indices (total iron binding capacity (TIBC) and serum iron) were measured to gauge how iron is being used. Hematology parameters (hemoglobin, hematocrit, blood volume) were measured to gauge the development of TBO2 stores in the blood. Preliminary results indicate that pups that received the iron supplement have significantly higher hemoglobin levels at the post-weaning stage (iron=18.27 g/dL, sham=17.14 g/dL, p=0.0186). This suggests that iron intake limits hematological development in pups and that maternal diet and iron status may have downstream impacts on pup postweaning survival, beyond solely caloric transfer.

Jay P. McEntee

Carolina wrens (Thryothorus ludovicianus) are small songbirds that form long-term social pair bonds and maintain territories year-round. Male and female Carolina wrens appear similar, but use sex-distinctive vocalizations. Female wrens exhibit a sex-specific vocalization known as the “chatter,” often delivered during male-female duets and less frequently as solos. Some hypothesized functions of this vocalization involve the communication of identity to the male partner. However, it is not yet known if these vocalizations are individually distinctive. My research aims to investigate whether individual female Carolina wrens perform acoustically distinct chatters. To answer this question, I have color band-marked birds for individual identification in the field, and am subsequently recording multiple chatters for each female wren across four sites in SW Missouri. Acoustic analyses will involve the measurement of spectrotemporal characteristics (how sounds change in frequency across time) of chatters. Statistical analyses will focus on whether spectrotemporal variation in features including chatter element rate (per second), harmonic series frequencies (Hz), and peak frequency (Hz) is shared among females within the local Ozark population, or is individually unique. Evidence for unique vocal signatures in females would show plausibility for chatter’s hypothesized functions involving individual identity signaling within social pair bonds and among conspecifics.

Dr. John P Masly

There exists great variation in egg morphology among Drosophila species, however, little is known about the mechanism(s) that specify egg shape and size of Drosophila. Some studies suggest that pre-embryonic gene expression might influence egg size variability. Drosophila sechellia is known to produce much larger eggs, and Drosophila sechellia is also known to produce fewer eggs compared to its sister species D. mauritiana, D. melanogaster, and D. simulans. This egg size difference presents an opportunity to leverage the arsenal of genetic tools available among these species to understand the molecular bases of egg size variation. Here, we study a collection of interspecific genetic introgression that have a mostly D. sechellia w genomic background with a small segment of D. mauritiana genomic material. We collected, measured, and analyzed egg length data and discovered that one of these introgression lines, 3Q1(A), produces much smaller eggs compared to D. sechellia pure species. To identify the gene(s) that causes this difference in egg length, we sequenced the genome of 3Q1(A) and compared it to the genomes of D. sechellia and D. mauritiana. We identified the limits of the D. mauritiana genetic material within the 3Q1(A) introgression region and are currently performing functional genetic tests of these candidates using resources available in D. melanogaster. We anticipate that our results will provide direction for future developmental genetic studies of oogenesis among these species.

Lana Daniels, Zachary Emberts

Sexual selection has resulted in some of the most elaborate traits seen in animals, many of which are used as weapons. These weapons can be incredibly diverse, even within species. Such morphological variation has largely been attributed to the environment in which individuals are reared and their genetics. However, variation in weapon form could also be the result of a weapon wearing out from usage. This mechanism has received relatively little attention. In this study, we demonstrate that sexually selected weapons can wear out from repeated use, providing experimental evidence that weapon usage can contribute to the diversity of weapon shapes observed within species. In a second experiment, we demonstrate that having a worn-out weapon decreases an individual’s fighting ability. This finding illustrates that the shape of a weapon can have an important role in determining contest outcomes. Overall, these results suggest that individuals are limited in the number of times they can effectively use their weapons, which may be one factor (among others) influencing how frequently an animal engages in a fight.

Amber Restivo, Georgia Rabaey, and Ronald M. Bonett

All animals rely on sensory systems to collect information about their internal and external environments, yet nervous tissue is expensive to manufacture and maintain. Species can mitigate the energetic costs of nervous tissue by only investing in sensory systems that detect signals with high fidelity. Some signal types may be more reliable than others with respect to different environments. Both survival and reproductive success can be hampered if animals invest in sensory systems that recognize a signal that is nonexistent, weak, or obscured by too much noise. Sensory investment is especially consequential for animals with complex life cycles, which move between habitats through ontogeny and experience dynamic signal fidelity. Salamanders exhibit multiple life cycles (biphasy and paedomorphosis) and ecologies (cave, stream, and pond), making them a particularly well-suited model for observing shifts in sensory investment.
This study aims to determine if transformations in life cycle or ecological transitions lead to different adaptive peaks, i.e., sensory investment, in the number of lateral line receptors (LLR) found in salamanders. To address this, we conducted a comparative phylogenetic analysis, Ornstein-Uhlenbeck (OU), to determine the adaptive evolution of LLR given different selective regimes (that being life cycle or ecology). So far we have determined that the best fitting model is a 3-state ecological OUM model.

Body size is a fundamental organismal trait, and the genetic basis of body size variation remains largely unknown. The nematode Caenorhabditis elegans is a widely studied model organism with a sophisticated experimental genetic toolkit in tandem with a wealth of developmental genetic background knowledge. Caenorhabditis inopinata is a sister species of C. elegans that has evolved a much larger body size.

In C. elegans, a TGF-β signal transduction pathway regulates body size, and many downstream factors and collagens likewise regulate body size. Thus, the genes in this pathway represent prime candidates as substrates for the evolution of large body size in C. inopinata. To understand the evolution of the functions of these genes, we are perturbing them in C. inopinata. We will present findings regarding the body size RNAi phenotypes of dbl-1, lon-1, lon-2, and lon-3 in C. elegans and C. inopinata.

The effect sizes of perturbation will inform hypotheses regarding the evolution of body size in this system. For instance, if the body sizes of dbl-1(RNAi) animals are the same in both species, this suggests that the factors driving body size change in C. inopinata are entirely downstream of this TGF-β signaling pathway. This is just one of many possible alternative outcomes of this work. Regardless, this work represents key steps in establishing an evolutionary developmental biology research program heralded by the existence of a morphologically divergent sister species of a core genetic model system.

Matthew B. Toomey

Northern cardinals (Cardinalis cardinalis) are a common bird throughout North America known for their vivid red plumage. They are sexually dimorphic, males have brilliant red carotenoid-pigmented plumage while females are much drabber in color. Males with a brighter red coloration tend to have better quality territories and produce more offspring. Therefore, coloration may be a signal of male quality, but it is not understood how color encodes this information. My goal is to determine what these colors mean, and in order to do this, I must determine how these colors are made. Recently, two enzymes and a protein that catalyze the conversion of yellow dietary carotenoids to red plumage carotenoids were discovered in domesticated canaries (Serinus canaria). I hypothesize that northern cardinals use this same mechanism to produce the red carotenoid pigments in their plumage. To test this hypothesis, I cloned the northern cardinal homologs of the enzymes (BDH1L and CYP2J19) and the protein (TTC39B), expressed them in cultured cells, and provided them with yellow carotenoids (lutein, zeaxanthin, and beta-carotene), and then measured carotenoid products with high-performance liquid chromatography. Consistent with our hypothesis, in combination, CYP2J19, BDH1L and TTC39B catalyzed the conversion of yellow pigments to red pigments. Our results show that the mechanism of red carotenoid metabolism in northern cardinals is the same mechanism as that of domesticated canaries.

Dr. Ronald Bonett and Dr. Dustin Siegel

Plethodontid salamanders possess numerous courtship glands. Previous studies have shown that the glands are more prominent in male individuals than females, and often experience periods of atrophy and hypertrophy throughout the year that correlate to the non-mating and mating seasons, respectively. We sampled male and female Eurycea bislineata throughout the year to test the hypothesis that external nasal glands are courtship glands. External nasal glands are paired, branched tubular glands that extend from excretory ducts dorsal to the nares to terminal secretory units posterior to the eyes. We found that the glands hypertrophy and stain/react more intensely with histochemical procedures during the mating season. We found no ultrastructural differences between male and female external nasal glands. In all specimens, the glandular tubules were lined by a simple, columnar epithelium that was packed with secretory granules that often obscured other cytoplasmic contents. We have also begun to look at other gland characteristics in other species of Plethodontid salamanders which exhibit patterns possibly influenced by the life history of the salamander. All paedomorphic salamanders exhibit no gland, while most biphasic salamanders have gland extension past the eye and direct developing salamanders have it extending to the anterior portion of the eye.

Kacey Bengel, Lizbeth Gomora, Mary Kate Heatherman, Mataya Woodard, Ronald Bonett, and Cassie Vestal

The oviduct is the passageway for eggs and an important site of their maturation in the female reproductive system. In amphibians, the epithelial component of the oviduct produces secretions and the egg jelly coat, which is crucial in the development, and protection of the embryo. The production of the egg jelly coat involves the secretions of a group of active glands located in three different regions of the oviduct: Pars recta, Pars convoluta, and the Caudal part. In some species glands located in these regions secrete several layers of jelly coat that covers the egg. Several studies show that Pars convoluta may play the most important role in the secretion of egg jelly coat. In our study, we used transcriptome sequencing and histology to evaluate the relationship between microanatomy and the gene expression of secretory cells in three oviduct regions of the polymorphic Oklahoma salamander, Eurycea tynerensis. Our analysis focused on three different reproductive stages: 1) pre-oviposition, 2) post-oviposition, and 3) non-reproductive, as well as in two different life cycle modes. The results show microanatomical changes on the epithelial wall in different regions of the oviduct and the upregulation of mucin genes during reproductive stages.

Charles R. Brown

Numerous factors affect how long animals live and often represent trade-offs in survival and reproduction. Animals that live longer tend to be larger and have lower metabolisms. Birds in some ways are an exception to this rule, as they have high metabolisms but are longer lived than many mammals with similar body sizes. Additionally, models have suggested that birds, like the Cliff Swallow, that are more social and have longer migration are more likely to live longer. We used a 32-year mark-recapture dataset from Cliff Swallows that were captured as nestlings or juveniles to see how long Cliff Swallows lived and examine whether there is evidence of senescence in these birds i.e. a decrease in survival with age. Additionally, we looked to see if there are any correlations between lifespan and average colony size. Individuals in larger colony sizes could have longer lifespans as this allows them to share information as well as provide protection from predators. Alternatively, individuals in smaller colonies may incur survival advantages from having less competition. This work has implications for better understanding the advantages of living in social groups.

J. Hurd, E. McCullagh

Prairie voles (Microtus ochrogaster) are a socially monogamous rodent species native to the Great Plains region of North America and a popular model in neuroendocrine research. This study seeks to investigate potential neural mechanisms that regulate testicular function in response to changes in the social environment. Adult males were categorized into three experimental groups: paired, naive, or olfactory exposure. Naive males were kept in same-sex cages until harvest. Paired males were individually placed with a single female until harvest. Same-sex cages of olfactory exposure males were routinely provided with soiled bedding from a designated same-sex cage of females until harvest. We begin the process by slicing perfused male brains from each experimental group to include target brain regions. Preliminary data demonstrates that exposure to conspecific females or their odors induces significant changes in the reproductive physiology of male prairie voles, as evidenced by larger testes and higher epididymal sperm counts in addition to substantial alterations of testicular cellular composition. To determine the neural mechanism regulating this phenomenon, we will use immunohistochemistry and fluorescence microscopy. We seek to identify changes in the neuronal population/connectivity of oxytocin (OT), gonadotropin-releasing hormone (GnRH), and kisspeptin (Kiss) neurons in key social and olfactory brain regions. OT is involved in regulating social and reproductive behavior, GnRH is a key component of the hormonal network that orchestrates the reproductive system’s functions, and Kiss is a regulator of GnRH neuron activity. We can conclude that there is a difference in testicular function and sperm output that correlates with exposure to female odors. Understanding how these neuron types work together to regulate testicular function will enhance our understanding of social modulation of male reproduction and fertility.

Tamara Woodley, Elizabeth McCullagh

Oxytocin (OT) is a neuropeptide that is partially synthesized in the paraventricular nucleus (PVN) with both endocrine and neural effects. In the endocrine system, OT is secreted into the blood stream and aids in several biological processes (i.e. reproduction). As a neurotransmitter, OT influences many social behaviors. Our work has shown that OT is present in the auditory brainstem – specifically the medial nucleus of the trapezoid body (MNTB), an area of the brain important for sound localization. Prairie voles are often used to study social behavior due to their ability to pair bond and exhibition of biparental behavior, which are partially facilitated by OT. We hypothesize that OT in the auditory brainstem (MNTB) aids in sound localization of important conspecifics (such as opposite-sex mates) and therefore helps establish and maintain pair bonds. We predict that OT in the MNTB originates from the PVN. To determine the connection between where OT is synthesized (the PVN) and the MNTB, we injected two types of neural tracers. First, retro dye beads were injected, in vivo, into the MNTB of anesthetized prairie voles to trace if the origin of OT in the MNTB is the PVN. After 2-3 days of incubation of the retro beads, brains were taken and stained via immunohistochemistry. Next, we will inject an OT-specific virus into the PVN and search for a connection to the MNTB. These objectives will aid in determining where OT in the auditory brainstem originates, providing insight into its function in the auditory brainstem.

William Kirkpatrick, Sarah Heissenberger, Sarah DuRant

Avian development is directly affected by environmental temperature. Understanding how natural temperature impacts avian physiological development is crucial for understanding how climate change will impact birds. Under expected climate change, nesting environments will become warmer on average and more variable. To estimate the impact of shifting thermal conditions, we examined offspring growth and metabolic rate in nestling Eastern Bluebirds that were exposed to either an increased mean temperature nest box or an increased temperature fluctuation nest box relative to unmanipulated boxes. We collected growth measurements from nestlings on days 1, 5, 10, and 12, and resting metabolic rates on days 5 and 10. Preliminary analysis revealed that nestlings exhibited increased mass and skeletal growth in response to higher temperature fluctuations than those in increased mean temperature boxes. Metabolic data is still being analyzed, though initial anecdotal data suggests a positive relationship between metabolic rate and body size. The larger body size of the increased temperature fluctuation nestlings could suggest a higher metabolic rate. While a larger body size for a nestling might provide benefits for overwinter survival, increased temperature fluctuation nests also saw smaller clutch sizes than other treatments, suggesting an overall reduction in nest productivity.

Kent Teague, Ph.D., Salvador Guinjoan, M.D., Ph.D., Jonathan Savitz, Ph.D.

Introduction: Major depressive disorder (MDD) is characterized by immune dysregulation, including inflammation and impaired viral immunity. Cytomegalovirus (CMV) is a common herpesvirus that has a seroprevalence of 50% in the US and establishes life-long latent infections. CMV is reactivated by stress and inflammation, inducing a host immune response, and potentially exacerbating inflammation. In theory, this could worsen symptoms of depression. We therefore hypothesized that treatment of depressed, CMV seropositive (CMV+) individuals with the anti-viral drug, valganciclovir (VGCV), could have antidepressant effects.

Methods: In this double-blind, placebo-controlled, parallel group clinical trial, CMV+ participants with a Quick Inventory of Depressive Symptomatology-Self Report (QIDS-SR) scale score ≥11 were randomized (1:1) to 8 weeks of treatment with VGCV (900mg/day, PO) or placebo as an adjunct to their existing treatment. Each subject completed three in-person visits (baseline, 4 weeks, and 8 weeks) and 6 telephonic interviews (weeks 1-3 and 5-7). Data were analyzed with linear mixed models using SPSS. The primary outcome was changes in QIDS while secondary outcomes included changes in Montgomery-Asberg Depression Rating Scale (MADRS), Snaith-Hamilton Pleasure Scale (SHAPS), Overall Anxiety Severity and Impairment Scale (OASIS), Perceived Stress Scale (PSS), and Cohen-Hoberman Inventory of Physical Symptoms (CHIPS).

Results: There was, on average, a greater numerical decrease in scores over time in group A versus group B for QIDS, despite no statistically significant differences (F=0.745, p=0.652, ηp2=0.057). Similarly, there was a numerically greater decrease in group A versus group B and no statistically significant differences for all other scales, including the secondary outcomes MADRS (F=0.738, p=0.658), SHAPS (F=0.659, p=0.529), OASIS (F=0.019, p=0.981), PSS (F=0.929, p=0.410), and CHIPS (F=0.323, p=0.728).

Conclusion: Although the results were not statistically significant, there is some indication that group A showed a greater decrease in symptoms of depression and anxiety over the 8 weeks compared to group B. The results raise the possibility that VGCV may be helpful for the treatment of depression in some individuals.

Dr. Erin Wiley

Shade is a common stressor that tree seedlings must cope with and the ability to survive shade relies on the maintenance of a positive carbon balance. Because warming temperatures can increase both photosynthesis and respiration rates, it is therefore not known how climate change will impact shade tolerance. In this experiment, we explored the impact of warmer temperatures on the germination, growth and survival of a moderately shade tolerant tree species, Quercus phellos (willow oak). Acorns were germinated under three different light levels (full light, low shade (8.9% of full light) and high shade (1.4%)) and at two different temperature conditions (ambient treatment: 20°/10°C day/night vs warming treatment: +10°C ). The date of emergence was recorded for each individual, and seedlings were harvested 34 days after emergence.

While the number of leaves produced did not differ between treatments, germinating seedlings were significantly taller under high shade at both temperatures. Root length was significantly shorter for germinating seedlings at the warmer temperature. There was also a significant interaction between temperature and light availability: root length decreased with shading at ambient temperatures while it increased with shading under warming. Additionally, tissue dieback under high shade increased with warming; 36% of seedlings exhibited tissue death under the warming treatment compared to 10% at ambient temperatures. The longer stems under shade are a common shade avoidance strategy, consistent with the intermediate shade tolerance classification of Willow Oak. In general, the effects of warming on root length suggest seedlings may be more susceptible to drought stress in the future, though shading may alleviate some of this stress. However, the greater dieback under high shade suggests warming has a negative effect on seedling carbon balance, which will reduce this species’ shade tolerance.

Stacey Herriage, Matteo Minghetti

The impact of metal chemical speciation on the absorption, and toxicity of metal mixture remains poorly understood. In laboratory settings, cells are typically exposed to individual metals, rather than metal mixtures. However, in natural environments, metals often interact with one another and with surrounding inorganic and organic matter. For example, the Tar Creek Superfund site, which spans northeastern Oklahoma, southeastern Kansas, and southwestern Missouri, is contaminated with high levels of zinc, lead cadmium, copper, arsenic, and other heavy metals. To investigate metal mixture toxicity, we used RTgill-W1 fish cell lines derived from rainbow trout. Each metal and metal combination are tested in triplicate to ensure statistical significance. These cells were seeded at a density of 150,000 cells/cm² in 24-well plates, incubated for 48 hours at 19°C, and then exposed to various concentrations of copper, cadmium, zinc, zinc-cadmium, zinc-copper, and copper-cadmium mixtures for 24 hours in a synthetic medium mimicking fresh water but compatible with cell culturing. After exposure, a multiple endpoint viability assay was used to measure metabolic activity, cell membrane integrity, and lysosomal membrane integrity. This approach allowed the determination of dose-response curve and calculation of the effective concentration inhibit cell viability by 50% (EC50]. For cadmium, the EC50 values were determined for three endpoints: metabolic activity (68.75 μM), lysosomal activity (95.05 μM), and cell membrane activity (54.74 μM). In comparison, copper showed EC50 values for metabolic activity (5.33 μM), lysosomal integrity (3.17 μM), and cell membrane integrity (6.32 μM), respectively. Every EC50 concentration is calculated using GraphPad software. These metals are toxic to intracellular mechanisms such as cell metabolic activity and membrane integrity, with copper being particularly harmful at higher concentrations despite its role as an essential element. The next step will be to use the single metal EC50s to determine the mixture toxicity of copper and cadmium using the concentration addition model design.

Nathan Piccoli, Kylie Atkinson, Veronica Nguyen, Brian Greene, and David A. Penning

Environmental temperature is a critical factor influencing the physical activity of ectotherms. Higher body temperatures can often lead to faster movements, while lower temperatures can reduce performance. One strategy that organisms may employ to mitigate the effects of temperature is to use elastic-recoil mechanisms. The potential energy stored in elastic structures is less affected by temperature than the chemical processes used during muscle contractions. Therefore, the use of elastic mechanisms allows for similar performances across a wide range of temperatures. A common method for assessing organismal performance in relation to temperature is the use of temperature coefficients (Q10). A Q10 value of 1 indicates no change in performance between the two temperatures, suggesting the utilization of elastic recoil mechanisms. Prior studies using electromyography have suggested that some snakes use elastic recoil mechanisms for striking. If this is true, strike performance should be relatively independent of body temperature (Q10=1). To test this hypothesis, we quantified defensive strike performance in 18 Agkistrodon piscivorus. Using high-speed cameras and motion capture technology, we measured strike performance at body temperatures of 17 °C, 22 °C, and 27 °C. While strike distance (cm) and venom yield (g) exhibited no temperature dependence, we found that many components of defensive strike performance were significantly affected by temperature. Strike duration (Q10 = 0.86) was notably shorter at higher body temperatures, while average strike velocity (Q10 = 1.82), maximum strike velocity (Q10 = 1.99), average strike acceleration (Q10 = 2.13), and maximum strike acceleration (Q10 = 2.64) were all significantly higher in performance at higher temperatures. Our whole-body results indicate that snake striking is not accomplished via elastic recoil mechanisms.

A Riley, E Cochrane, S Lane, B Bespoyasny, B Heidinger, C Lattin, J Grindstaff

Overcoming neophobia, the fear of novelty, is an important strategy birds use to adapt to changing environments. During breeding season, being less neophobic can be valuable for offspring survival. However, many factors can modulate neophobia including life history strategies. Latitude may play a large role in an individual’s neophobic response as birds can adopt different life history strategies at varying latitudes. Birds at northern latitudes tend to have shorter lifespans than birds at southern latitudes which may alter behavioral strategies. Since birds with shorter lifespans have less time to invest in reproduction, they may alter their behavior to increase their success in foraging and offspring survival. House Sparrows are a geographically widespread invasive species that are often associated with human habitats. Additionally, they are social birds and biparental. The objective of this study is to determine how latitude may influence neophobic behaviors in House Sparrows. To test neophobia, we utilized a latitudinal gradient (ND, OK, TX) and conducted novel object trials at feeders during the non-breeding season and nest boxes during the breeding season. We designed feeders to have zones to quantify the distance to a novel object. Latency to feed was measured when a novel object was present compared to absent. To test parental neophobia, we measured latency to enter the box in the presence of a novel object and compared it to its absence. If latitude influences neophobic behavior, we expect birds at northern latitudes to be less neophobic than birds at southern latitudes due to harsher and more limited conditions. Thus, birds in northern latitudes may be better at adapting to changing environments.

Holly M. Todaro, Courtney J. Duchardt, & Scott R. Loss

Climate change, coupled with alterations in land use, is a primary driver of global changes in biodiversity. Rising temperatures, altered precipitation patterns, and severe weather events pose a significant threat to numerous species. Birds face multiple challenges associated with climate change because their life cycles, including breeding, migration, and non-breeding periods, are intricately linked to specific ecological conditions. Fluctuations in temperature and precipitation can influence reproductive success and population dynamics by shifting the timing of natural events such as spring green-up and insect emergence, consequently impacting food availability and threatening population viability. Birds display a range of life history traits, and their diverse nesting strategies (e.g., ground vs. open-cup vs. cavity-nesters) may moderate impacts of changing weather and climate on reproductive success. Ground-nesting species, for example, may face heightened risks in the future if increased frequency and/or severity of flooding events leads to increased nest failures. To examine how precipitation and flooding events affect nest success of species exhibiting different nesting strategies, we will conduct a global vote-counting meta-analysis of peer-reviewed literature. We hypothesize that higher levels of precipitation, as well as flooding events, will be associated with reduced nest success, and that this effect will be especially strong for ground-nesting species. To test this hypothesis, we will conduct a vote count analysis to evaluate numbers of studies finding positive, negative, neutral, and mixed effects of precipitation on nest success. Understanding how changing weather patterns influence nest success is essential for developing informed conservation and management strategies that benefit declining bird populations.

Genesis Alarcon, Olivia Emerson, Grant Emerson, Dr. Elizabeth McCullagh

Autism spectrum disorder (ASD) is a neurodevelopmental disability, affecting how a person communicates and interacts with each other and their environment. A large part of communicating effectively is being able to accurately and acutely process and localize sounds. The most common monogenic cause of ASD is Fragile X Syndrome (FXS), which is caused by a mutation of the Fmr1 gene that encodes Fragile X Ribonucleoprotein (FMRP). Auditory dysfunction is thought to be caused by an imbalance of excitatory and inhibitory neurological imbalances in the auditory brainstem, where FMRP is highly expressed. We aim to better understand the development of auditory processing in our knock-out (FXS) and wild-type mice at different critical time points: P8, P14, P18, P21, and adulthood (85-90 days old), where P is denoted as postnatal followed by how many days old. To measure auditory development, we will be using acoustic startle response (ASR) and prepulse inhibition (PPI) measurements, where ASRs measure whole-body responses to a startle stimulus and PPI precedes the ASR with a certain cue (prepulse), that inhibits the ASR. This will be done at the developmental timepoints stated above. Therefore, PPI is a measurement of sensorimotor gating, and having improved or diminished responses to startle stimuli will ultimately show if the animal has any disruptions in the auditory pathway. We expect robust startle to develop at P14 and for our KO group to have less of an overall startle response compared to the WT. Additionally, comparisons between KO and WT mice will be analyzed and provide insight into different processing mechanisms.

Kimberly A. Moser, Gavin C. Woodruff

Body size contributes to multiple different biological processes in all forms of life, such as life span, metabolism, development, and reproduction. Diversity in body size within and across different species is not fully understood particularly at the genetic level. A forward mutagenesis screen was performed in C. inopinata to identify genes regulating body size in this species. An autosomal recessive allele causing a dumpy phenotype, nok3, was identified. Here, we will present the current status of the mapping and characterization of this allele. Bulk segregant mapping of recombinant F3 individuals revealed an enrichment of markers associated with the mutagenized genetic background on the left arm of chromosome IV. A number of SNPs predicted to have impacts on protein function were detected in this region. We are currently using CRISPR/Cas9 technology to perturb the genes associated with these candidate mutations, and a successful deletion of at least one candidate gene is currently being characterized. Additionally, NILs and an additional mapping population are also being characterized to further narrow the mapping interval. Taken together, this work is part of an ongoing effort to uncover genes regulating body size in C. inopinata in order to understand the genetic drivers of body size evolution. This work was supported in part by an award from the NSF (2238788).

David A. Penning

Snakes are highly adaptable, ectothermic predators that have complex digestive systems and diverse physiological processes. While snake digestive and feeding behavior have been studied extensively, less work has been done on snake hematology; especially regarding blood glucose levels. Glucocorticoids are steroid hormones that are secreted by the adrenal gland and function to modify glucose utilization by cells. Available data on snakes shows that glucocorticoids do not directly affect blood glucose concentrations. However, it is unknown how blood glucose varies by the feeding habit of the animal. Snakes are known to modify their digestive and overall metabolic processes in response to different prey sizes, and suffer an energy cost when doing so. In theory, this means meals are only favorable when gains are larger than the cost to digest. The goal of the study is to determine the relationship between prey size and blood glucose levels using readily available technology. The use of glucometers has been robustly validated to measure glucose in snakes. To collect blood in repeated measurements, a novel capillary puncture technique was employed at the cloaca, using the effect of gravity on circulation. This method can be used in the field and on any species, maximizing animal welfare while rapidly collecting hematological data. An active foraging snake, Lampropeltis getula, was fed 5%, 10%, 15%, and 20% of their body mass on a randomized bi-weekly schedule (n=10 snakes). Plasma glucose was measured immediately, 8 hours, and 24 hours post-feeding. Results found statistically significant elevations in glucose in the 15% and 20% (high-volume) groups, but no elevation in the 5% and 10% (low-volume) groups. To further elucidate this pattern, we plan to measure glucose-levels hourly, in order to capture more fine-scale changes in metabolism and determine the effect of handling events.

Ghufran Murtuza, James. A. Carr, Breanna N. Harris

One of the most important decisions that an animal must make for survival is when to flee and when to feed. Animals must use sensory and situational information to assess the level of importance between hiding from predation and hunting for prey. In the species Xenopus laevis, the optic tectum is responsible for consolidating visual and lateral line information, and this brain region is also involved in making decisions relating to the feed vs flee tradeoff. Previous research in our lab shows corticotropin-releasing factor (CRF) inhibits feeding on multisensory prey by binding to CRF R1 receptors of the optic tectum. While we do know that CRF reduces feeding behaviors, we do not know which sensory modality CRF impacts, hence leading us to test how CRF affects Xenopus laevis’ response to lateral line cues. Here we will subject Xenopus laevis to tectal CRF injection and measure how CRF affects prey capture. Data collection is currently underway, however, we predict that CRF will reduce feeding-related behaviors in response to lateral line or live prey cues. To test this hypothesis, frogs are injected with one of four doses of CRF, or are in one of four control conditions (unmanipulated, saline, gauged, and antagonist) and one hour later, we expose frogs to lateral line stimuli (air puffs), followed by a live prey (cricket) trial. Our results will help us determine not only how Xenopus laevis responds to multisensory cues when injected with CRF, but will also illustrate whether or not CRF alters the way that Xenopus laevis responds to discrete lateral line cues. NSF Funded (Grant No. 1656734)

Todd Watson, Alicia Mathis

Following exposure to increased predation risk, prey individuals often take measures to decrease their visibility to predators. For territorial species, such measures include decreasing high-visibility behaviors involved in territorial defense. The costs and benefits of contests over territories are typically affected by whether the contestants are territory owners (residents) or intruders into the territory of other individuals. We tested the hypothesis that status as a resident or intruder influences behavior following simulated predator attacks for two species of terrestrial salamanders, Plethodon angusticlavius and P. serratus.
We simulated snake attacks in the laboratory by grasping focal individuals (resident or intruder in each trial) with forceps for a 2-min period and an allowed subsequent 20-min recovery period. Aggressive, submissive, and chemosensory behaviors were recorded for both residents and intruders. The data for residents and intruders were analyzed separately, and statistical comparisons were between stressed and nonstressed individuals. For both species, stress did not affect behaviors of residents, but intruders decreased aggressive posturing after being stressed, which is consistent with different costs and benefits of territorial contests for residents and intruders. For P. angusticlavius, residents had generally high levels of aggression regardless of stress treatments, indicating that residents show strong territorial defense even in the face of high predation risk. In contrast, P. serratus residents had generally low levels of aggression regardless of stress treatment, which is consistent with lower overall activity (in the current study as well as others) for this species.

Maya Greenquist, Jillian Hackney, and Gabe McClain

The mechanisms of constriction involve snakes wrapping or winding their body around prey while contracting muscles to exert high pressures that incapacitate their prey. Our current understanding of how pressure impacts the tissues of prey is growing but remains incomplete, especially considering the diversity of prey consumed by snakes. Here, we provide a historical perspective on our understanding of constriction by summarizing the currently known constriction mechanisms. We discuss how constriction is used, how it works, how it is discussed within the literature, what we may be getting wrong, and what we still don’t know about this evolutionarily significant mechanism. Furthermore, we provide novel data on pressures generated within the thoracic cavity and cranium of endothermic prey and provide new insights into how constriction may function differently with ectothermic prey. Lastly, we performed an extensive literature review to produce an estimate of the total constriction diversity used by snakes to gain a more thorough understanding of the evolutionary origins and diversity of this behavior. We were able to quantify prey-handling behaviors in 3,391 snake species using Genus-level generalizations and species-level accounts. Overall, we found that 28.8% of all snakes are reported to constrict prey (16.16% obligate constrictors, 12.64% facultative constrictors), and the remaining 71.2% of snakes are not reported to constrict prey.

Body size is a fundamental phenotypic trait that correlates with fecundity, metabolic rate, fitness, and evolutionary history. Caenorhabditis inopinata, a close relative of Caenorhabditis elegans, exhibits a significantly larger body size, raising questions about the genetic basis of this divergence. My research focuses on two transcription factors, rnt-1 and zip-10, which are associated with the Transforming Growth Factor-β (TGF-β) pathway, known to regulate body size in C. elegans. I hypothesize that these genes contribute to body size evolution in C. inopinata.

Using CRISPR/Cas9 mediated microinjection, I have successfully generated rnt-1 deletion mutants in C. inopinata and established a homozygous line. I am currently observing the phenotypes of these null mutants to assess potential changes in body size. In parallel, RNA interference (RNAi) experiments have revealed that the knockdown of rnt-1 reduces 8% body size in C. inopinata, indicating a functional role for rnt-1 in regulating this trait.

Next, I will perform transcriptomic analysis on wild-type and mutant strains to identify downstream targets and pathways regulated by rnt-1 and zip-10. This will provide further insight into the genetic networks involved in body size regulation. Additionally, spatial gene expression analysis using reporter constructs will determine where these genes are expressed within C. inopinata and C. elegans, helping to elucidate their tissue-specific functions. This research aims to uncover the genetic mechanisms driving body size evolution in C. inopinata, contributing to a broader understanding of phenotypic diversity across species.

This work was supported in part by an award from the NSF (2238788).

Elisa Casadei

The early development of teleost fishes heavily relies on innate immunity to mediate the host interactions with the aquatic environment, aiming to defeat pathogens while fostering beneficial microbes. Among innate immune molecules, antimicrobial peptides (AMP), particularly beta-defensins, have a prime role in the process of shaping the microbiome. Beta-defensins are a highly conserved family of AMPs in vertebrates and well-known for their broad-spectrum activity against several pathogens. Thus, beta-defensins are crucial for all mucosal tissues, including skin.
Since the expression and modulation of beta-defensins at different developmental stages are still unclear in fish, we decided to investigate it by raising 122 rainbow trout (Oncorhynchus mykiss) fries at 16°C in a recirculating system, feeding daily. Fish were sampled at 312, 421, 530, 639, 748 and 857 degree-days (DD). For each timepoint, the whole fish body was collected in DNA/RNA shield for RT-qPCR (n=8), or buffered PFA 4% for RNAScope analysis (n=5). Our data suggest that beta-defensin genes (omDB) are constitutively expressed throughout trout growth (except omDB-2, undetectable at all timepoints), and each omDB has a distinct expression pattern. While expression of omDB-1a and 1b significantly decreased at 748 DD (≈2-fold), at same late timepoints, omDB-3 (≈2-fold) and 4 (≈7-fold) reached their highest levels. Also, we observed a particular fluctuation of omDB-5 levels among intermediate timepoints. RNAScope analysis revealed that different layers of the trout skin present a co-expression of multiple omDB genes, even at the earliest timepoint (312 DD). For instance, mucus-producing cells seem to be hotspots of omDB-3 transcripts in the epithelium, while omDB-4 expression was predominant in the dermis, especially at the latest timepoint. These findings suggest a dynamic and spatially distinct regulation of beta-defensin genes in trout skin since early stages of development.

David A. Penning

Terrestrial and arboreal environments present animals with considerably different risks and challenges. For example, mistakes in navigating an arboreal environment can result in significant injury from falls. Further, for predators, the size of prey encountered in any ecosystem comes with variable risks depending upon the situation; larger prey often pose larger risks. For constricting snakes, they often use large portions of their body to subdue/disable their prey. However, in arboreal environments, snakes must also use portions of their body to anchor to branches to prevent falling and potentially significant injuries. Using Carpet Pythons (Morelia spilota), we explore the potential changes in predation and ingestion behaviors as a function of ecosystem type (terrestrial vs. arboreal) and prey size (“small” = ~3.5% snake mass; large = ~13% snake mass). Based on preliminary data, M. spilota constrict larger prey in an arboreal environment (mean=758 seconds) significantly longer than smaller prey (mean=264 s). The same pattern for prey size is apparent in a terrestrial environment but both large prey (mean=509 s) and small prey (mean=201 s) were constricted for significantly shorter durations than the same size prey in an arboreal environment. Further, ingestion posture was notably different with arboreally-feeding snakes using more of their body and orienting the long-axis of their prey perpendicular to gravity during ingestion. Terrestrial feeding was accomplished with the long axis of the prey remaining parallel to the terrestrial environment. Ingestion time was only impacted by prey size with larger prey taking 2.7 × times longer than smaller prey. Both prey size and feeding environment show significant impacts on the prey-handling and ingestion behaviors in Carpet Pythons. Future predation work in snakes should continue to consider the effects of both variation in prey size as well as variation in the environment in which predation occurs.

Erin Sauer, Kamiah Turner, Salvador Barraza Del-Barco, Sarah Durant

Chronic stress is related to a decline in immune function in all living organisms and is known to increase the likelihood of developing chronic non-infectious diseases. However, the role of chronic stress in affecting outcomes of infectious diseases important to individual health and endpoints important to epidemic dynamics are not well understood. In this study we exposed canaries to chronic stress or control conditions after which they were inoculated with Mycoplasma Gallisepticum, a bacterium causing respiratory disease in birds.  

Following the chronic stress protocol, the canaries were assessed every day for measures of body condition (body mass and fat score) and disease pathology (eye swelling). Once a week, we also swabbed eye conjunctiva to measure pathogen load and collected blood samples to measure hematocrit. In this system greater eye swelling and higher pathogen loads are associated with greater likelihood of MG transmission.  

Preliminary data demonstrate that birds exposed to chronic stress weighed more and had more fat but also had greater disease pathology than control birds. Soon, we will use qPCR to determine canary pathogen load. So far, our data indicates that chronic stress can prolong recovery and may be more likely to transmit MG given that transmission. These findings indicate that wildlife populations experiencing frequent or chronic stress may be more susceptible to disease and experience greater transmission rates than unstressed populations.

Zachary Emberts

Many animals that directly compete with one another over access to mates and resources have sexually selected weapons. These weapons are used to physically attack their rivals. Thus, weapons can wear out and break. Possessing a damaged weapon can decrease an individual’s fighting ability. Despite this consequence, both the frequency of damaged weaponry observed in the wild and our ability to predict which individuals are more likely to have broken weapons remains understudied. To address this gap in knowledge, first we quantified the frequency of weapon damage observed in a wild population of Acanthocephala femorata. Males of this species use their enlarged, spine-ridden hind legs to squeeze and pierce rival males. As a result, the hind leg spines can wear out and break. After quantifying spine damage, we conducted a few correlations (e.g., with body size and weapon shape) to investigate why only some individuals have broken weapons.

Xuan Zhuang

Comparative evolution provides valuable insights into how natural selection shapes species traits. Comparative genomic analysis of lineages that display convergent traits has the potential to uncover molecular and functional convergence, as well as lineage-specific adaptive mechanisms. One remarkable example of convergent evolution is the independent development of freeze resistance in phylogenetically distant polar fish lineages. While the direct mechanisms underlying freeze resistance, evolution of antifreeze proteins, is relatively well studied, the broader genomic context of adaptation to freezing conditions in these fish lineages remains largely unexplored. Leveraging the whole genome sequences previously assembled in our lab, along with other high-quality genomes available in GenBank, we analyzed the genomes of freeze-resistant species and related non-resistant species across three teleost fish lineages: Cottidae, Labridae, and Notothenioidei. By examining gene family expansion and contraction as well as signatures of positive and relaxed selection, we generated functional profiles of genetic changes in the freeze-adapted species of these lineages. We investigated these functional profiles in the context of existing literature on their phenotypic traits and biogeographic history in order to draw inferences about the adaptions of these freeze-resistant fish.

Maëlle CM Gueguen, Sarah Qundes, Aardron EOC Robinson

When people make a decision, they tend to rely on the subjective values they
attribute to each available option to make a choice. This subjective valuation is heavily reliant on context, i.e. the environment in which the choices are presented, thus facilitating option comparison and optimizing value scale from least to most preferred. Decision-making is also known to be influenced by affective states, but their specific interaction with contextual valuation
remains unclear. The purpose of this study is to test the hypothesis that contextual valuation is state dependent with affective state being able to explain a significant part of the behavioral variability during test-retest experiments. We used an online version of a previously validated contextual reinforcement learning (cRL) task to probe context-dependent subjective valuation. Context is biased experimentally during the learning phase and its effects on valuation were measured during the testing phase of the task by comparing choice rates of cues.
First, we looked at the learning curves and found that while starting at chance level, participants are close to 100% correct choice rate in all trial types by the end of the learning phase. As mentioned earlier, we focused on M1vM2 during the testing phase and found that M1 is significantly chosen over M2 as predicted. This contextual bias of choices is also observed at the subjective value level with a significant value by context interaction. Given the successful contextual valuation effects observed in this pilot, we are ready to launch the full study focusing on mood and its influence on context-dependent valuation. This research will support a larger study on the interaction of affective state and decision making in individuals with Methamphetamine Use Disorder.