Silver, A., Portman, R., Koch, R. and Toomey, M. B.

Haematococcus is a unicellular, biflagellate green alga that serves as a key source for astaxanthin, a red carotenoid pigment with commercial value as antioxidant and food additive. While the myriad of studies of Haematococcus have focused efforts on maximizing astaxanthin yield in a single isolate, we have concentrated our efforts on first assessing natural diversity among multiple isolates of Haematococcus. In addition to evaluating astaxanthin yield, we have also assessed morphological, anatomical, ultrastructural, developmental and molecular phylogenetic variability among Haematococcus isolates from proprietary and international culture collections. Our investigations and those of a handful of other researchers have revealed multiple, phylogenetically-distinct lineages, most of which have been further characterized as taxonomically distinct. These investigations have also indicated that molecular diversity is not generally reflected in variation of morphological, anatomical or ultrastructural features. On the other hand, our analyses revealed significant variation in astaxanthin yield among a set of 21 isolates. Interestingly, molecular phylogenetic diversity does not appear to be a good predictor of astaxanthin yield. Although textbooks indicate that Haematococcus development progresses from green motile, to green non-motile (palmella) and finally to red non-motile (astaxanthin-rich akinete) cells, our studies support the hypothesis that some Haematococcus isolates follow a different pattern. The textbook developmental pattern may be the most common, but our studies revealed Haematococcus isolates that progress from green motile to red motile (astaxanthin-rich) and eventually to red nonmotile (astaxanthin-rich akinete) cells. The bulk of studies focused on maximizing astaxanthin yield also concentrated their efforts on the akinete stage whose thick cell wall—acquired during development—serves as a significant challenge for pigment extraction. In contrast, the motile stage bears a thin cell wall that is easily breached for pigment extraction. Thus, the red motile cell may be a better target for commercial production and harvesting of astaxanthin in Haematococcus.

Claudia Solís-Lemus, Ricardo Betancur-R

Hybridization and gene flow, where species combine genetic material, are more complex than what can be depicted in a bifurcating phylogenetic tree and are instead represented as network diagrams, formally called phylogenetic networks. However, the fastest algorithm for inferring these networks, known as SNAQ, can process a maximum of only 50 species. This limitation arises because, for these 50 species, SNAQ continuously evaluates a large table known as the concordance factor table, which summarizes the genetic information of all possible combinations of four-species taxa, formally known as quartets. This process involves assessing 230300 rows of the table for each iteration to evaluate the overall phylogenetic network pseudolikelihood. To expedite this process for a given dataset, we train two sparse machine learning models—Elastic Net and Ensemble Learning + Elastic Net—that can subsample the minimum number of rows necessary to accurately predict the overall phylogenetic network pseudolikelihood. Both methods account for the inherent correlation among rows, which arises because rows can overlap species quartet information. For a simulated dataset with 6 species, which involves 15 rows in the concordance factor table, Elastic Net selects 6 rows (~40% of rows) on average to infer the correct phylogenetic network. For a simulated dataset with 15 species, involving 1365 rows in the concordance factor table, Ensemble Learning + Elastic Net selects 428 rows (~31% of rows) on average to infer the correct phylogenetic network. In both datasets, random selection of rows of the same sizes did not produce the correct phylogenetic network. The average time reduction for inferring the phylogenetic network using the subsampled datasets via sparse machine learning models was 32% for 6 species and 70% for 15 species. These results demonstrate a high degree of redundancy in the input data for inferring a phylogenetic network, indicating that accurate phylogenetic networks can be inferred using only a subsample of the input data.

Buzz pollination, a type of interaction between bees that can vibrate flowers to collect pollen and flowers that conceal pollen within tube-like (poricidal) morphology, involves more than half of all bee species and 10 percent of all angiosperm species. In fact, the evolution and diversification of both buzzing bees and buzz pollinated plant species is thought to be strongly affected by this ancient behavior and interaction. Yet despite 120 years of research on buzz pollination, much work remains to understand the broad ecological and evolutionary consequences. We discuss our work on the evolution of buzzing behavior, its adaptive significance, and drivers of the global distribution of buzzing taxa. We also discuss our research on patterns and evolution of buzz pollinated floral morphology. Overall, we find that buzzing is a key behavior enabling flexible pollen collection from buzz and non-buzz pollinated plant taxa alike. Furthermore, we find that drivers of buzzing bee biogeography differ from those of non-buzzing taxa and are closely associated with buzz pollinated plant biogeography. Finally, we find that buzzing evolved before the earliest buzz pollinated plant species, and that buzz pollination occurs across 87 plant families and more than 635 genera, with on average 200 independent gains and 150 independent losses and is strongly associated with increased plant diversification. Finally, we present alternative hypotheses for the functional significance of floral poricidal morphology.

Leonardo Maurici Borges; Fabio Andrade Machado

Changes in floral morphology are one of the key factors behind the evolutionary success of flowering plants. Increased diversification rates in several plant lineages are closely linked to floral disparification and may be due to the influence of flower morphology on mating precision. However, many species-rich and ecologically diverse plant groups show low variation in floral morphology. We investigated the evolution of floral morphology in Mimosa, a megadiverse genus with relatively low floral morphological variation. Given that different floral organs may be subject to distinct functional and developmental constraints, we addressed two main questions: (1) Is floral disparity distributed unevenly among floral organs? If so, (2) do these differences arise from changes in evolutionary modes and rates? To explore this, we applied a multivariate approach and phylogenetic comparative methods to understand trait evolution in a geographically and phylogenetically representative set of Mimosa species. We found that Mimosa floral morphology lacks clear phylogenetic structure, with different clades converging in similar regions of the floral morphospace. Furthermore, the evolution of all floral organs fit better to an adaptive Ornstein-Uhlenbeck model than to a neutral Brownian Motion one. Floral organs not only differ in their levels of disparity but also evolve at different rates. However, the most variable floral organs are not necessarily those that change the fastest. These results suggest that while morphological variation tends to be concentrated in certain floral organs, less disparate organs also undergo fast morphological changes, albeit within a constrained area of the floral morphospace.

Dylan J. Klewer

Tardigrades are a group of invertebrates that have increasingly been the focus of studies because of their unique ability to withstand extreme environmental stresses. There is limited literature published on the diversity and ecology of this group, despite popular interest in them. We collected foliose and fruticose lichens from fallen branches in four distinct areas of Southwest Missouri. Tardigrades living within each lichen sample were identified to genus, and when possible, to species. A total of 177 tardigrades were collected and identified from 61 lichen specimens. Foliose lichens had a much greater tardigrade diversity living on them as compared to the fruticose lichens. We found a strong correlation between the tardigrade Ramazzottius sp. and the fruticose lichen, Teloschistes chrysopthalamus. Of the 80 tardigrades collected and identified from T. chrysophthalamus, 78 of them were of the genus Ramazzottius. Additionally, we have the first documented record for the tardigrade Barbaria bigranulata in the state of Missouri.

Samuel R. Wilson, & Guinevere O.U. Wogan

When introduced species are brought into novel environments, they are often exposed to dramatically different climates than those in their native environments. With the increasing threat of climate change, introduced species can act as a model for understanding how species can respond to dramatic environmental shifts. Broadened temperature tolerances may be conferred by adaptive response or phenotypic plasticity. Temperature tolerance is encoded at the genetic level and can be selected as a heritable trait, but a single genotype can produce multiple alternative forms when subjected to environmental differences. Hemidactylus turcicus, the Mediterranean House Gecko, is native to the Arabian Peninsula but is found throughout the Southern United States, ranging as far north as Illinois and Pennsylvania. While present across a broad climatic range, little work has been done to characterize the genetic basis of temperature tolerance. To distinguish between genetic adaptation and phenotypic plasticity, we will conduct physiological trials to test both critical minimum and critical maximum temperatures across their range in the United States. We have conducted trials on 45 individuals from 11 cities from Carbondale, IL to Brownsville, TX, encompassing the latitudinal gradient of this species in its introduced distribution. We hypothesize that geckos from higher latitudes have a lower critical minimum temperature to allow them to survive colder winters via genetic adaptation. By differentiating between genetic adaptation and phenotypic plasticity in this species, we can better understand the mechanisms introduced squamates use to invade areas perceived to be climatically unsuitable. The results uncovered herein have broader application to myriad invasive species and to the management of native species in the face of changing climates.

As the landscape of a region changes, so do the ranges of the species that inhabit it. In the U.S., following colonization and agricultural expansion, giant river cane (Arundinaria gigantea) has been reduced to only 1-2% of its original extent, causing shifts in species populations and distributions for over 50 animal species (Brantley & Platt 2001). Among those species are the Bachman’s warbler (Vermivora bachmanii), which is now considered extinct due to the decline in canebrakes, and the Swainson’s warbler (Limnothlypis swainsonii), which has been known to prefer canebrakes as habitat during the breeding season (Anich et al. 2010). Though there is little known about the historical range of the Swainson’s warbler and its current population status, some have speculated that due to its preferred habitat being reduced, its population may have declined (Somershow et al. 2003, Thomas et al. 1996). Given that this species of bird is rare and often evasive, creative forms of tracking must be considered when attempting to observe its current reliance on canebrakes in Southwest Missouri. Autonomous recording units (ARUs) offer a minimal-effort and highly efficient way to monitor species. With ARUs, we can gain more knowledge on which bird species are inhabiting the current established canebrakes in SW Missouri. More specifically, we may learn if the uncommon Swainson’s warbler is using them as breeding grounds after migration.

Adam Siepielski

Adult sex ratio (ASR) is a fundamental demographic trait underpinning the evolution of mating systems. Theory predicts that a balanced OSR needs to be maintained but deviations from a 1:1 sex ratio are common. But ASR can vary across time or space resulting in differing levels of sexual conflict. A bias in male sex ratio predicts more intense sexual conflict and leads to lower female fecundity and greater male competition. Despite high fitness costs, biased sex ratios are common in nature suggesting that both sexes can adapt to such conditions. I studied natural sex ratio variation in two damselfly species: Enallagma exsulans and E. traviatum. My results indicate that sex ratio is more male biased in E. exsulans. Further, I conducted experiments by manipulating sex ratio and measuring female fecundity. These experiments involve keeping a single female with either one male or four males for 24 hours, after which the females were allowed to lay eggs on wet filter paper. I predicted that Enallagma exsulans females would show a lower decrease in fitness in male-biased cage treatments as the females are adapted to a male-biased sex ratio in nature. After analyzing the number of eggs and larvae hatched for each female, E. exsulans females showed no reduction in fitness with the experimental increase in sex ratio. But E. traviatum females which face a more balanced sex ratio showed a reduction in fertility (ratio of eggs/ hatched larvae) when number of males was increased to four. Our results indicate that females might be able to develop tolerance to male-mating harassment due to highly male-biased sex ratios in nature. Although previous research indicates that male-harassment is known to reduce female fitness when sex ratios become more male-biased, our results indicate that this reduction in fitness can be highly species-dependent.

Derek Bateman, Kevin Babbitt, Alexander Edmond, Day B. Ligon

Alligator Snapping Turtles (Macrochelys temminckii) are of acute conservation concern following decades of declines, chiefly fueled by hunting and a proliferation of dams fragmenting most of the rivers within its range. To assess the species’ status, Oklahoma has conducted several population surveys. Here, we report results from the first two seasons of a survey focused in southeastern Oklahoma. In May–June 2023, we conducted surveys of the aquatic turtle communities at nine sites, including subsites at Lake Eufaula and the Verdigris, Neosho, Arkansas, Little, and Illinois rivers. Subsequently, in August–October 2023 we conducted surveys at Hugo Lake and the associated Kiamichi River, the Blue River, and resampled a subset of sites at Lake Eufaula and Neosho River. In May–June 2024, we conducted surveys in several tributaries of the Red River, an additional subsite within the Verdigris River system, and follow-up surveys at Lake Eufaula. Using 0.9-m diameter hoop nets baited with fish, we captured a total of 3,131 turtles 3,208 times. We captured 0, 0, 1, 2, 3, 3, 5, 20, 29, and 111 M. temminckii (total = 174 captures of 148 unique individuals) across the ten sites we surveyed, indicating that the species is likely thriving in some water bodies but rare or have been extirpated from others. Because M. temminckii were deemed rare in the Neosho River based on previous survey efforts, 100 captive-bred and head-started individuals were released in 2021; of the 29 M. temminckii we captured at that site, only 20 were introduced head-starts and the remaining nine were of wild animals. Across all captures, the majority of M. temminckii were immature or young adults, suggesting that populations may be in recovery from past harvest pressures and highlights the persistent impacts harvesting adults of long-living species with delayed maturity can have on a population.

Luke Frishkoff

Ecologists understand that where species occur in their habitat (structural niche position and breadth) is governed by a broad suite of biotic and abiotic factors. Competition is among those forces limiting a species’ ability to fully occupy its “fundamental” structural niche. The ecological theory of adaptive radiation posits that available niche space drives diversification, with new species evolving to occupy unfilled gaps. Thus, theory suggests that older or species-rich faunas will tend to “fill out” community-wide niche space more than younger or species-depauperate faunas. However, it is also possible that young, species-depauperate faunas can fill available niche space to a similar extent, with each component species occupying a larger breadth in the absence of competitors. Therefore, it remains unclear whether the filling of community niche space is primarily driven by faunal age and diversity, or whether idiosyncrasies related to geography or taxon are more important. Here we investigate the importance of island size, climate, evolutionary history, and competition in shaping the structural niche space occupied by both species and whole communities of lizards and frogs across the vertical profile of forest habitats. Our study includes community data from well-known replicate adaptive radiations (Anolis lizards, Eleutherodactylus frogs) on the islands of Puerto Rico, Hispaniola, and Jamaica, as well as Madagascar, a known hotspot for adaptive radiation of various taxa. On each island we collected data from three distinct landscape types (warm dry, warm wet, and cool wet forest) for a total of 37 unique vertical tree-climbing transects. By using vertical tree-climbing transects, we are able to uniquely assess the full range of structural niche space available to entire communities in each locality. Our study design incorporates differences in island size, regional species pool size, and focuses on two different focal taxa, which therefore allows us to test multiple hypotheses about the drivers of community niche space occupancy.

Thomas Zapletal, Denise Thompson, Donald McKnight, Day B. Ligon

The Northern Giant Musk turtle (Staurotypus triporcatus), is a highly aquatic freshwater turtle species native to southern Mexico as well as the majority of Guatemala and Belize. Classified as a near-threatened species by the IUCN, the greatest threat to this species arises from hunting pressure for both personal consumption and the meat market. Results from past studies have suggested that S. triporcatus tends toward being a bottom crawling species. However, no previous work as been conducted on the activity or movement patterns for the species. Therefore, my research objectives aimed to fill in these gaps to help inform us about other aspects of S. triporcatus’ biology. To quantify both daily and seasonal activity patterns of S. triporcatus in a small lagoon with limited seasonal connectivity, I equipped 10 females with accelerometers to record acceleration (activity), temperature, and water depth. Each study animal was also equipped with a sonic transmitter and Holohil radio transmitter to ensure recapture success both in water and on land. This combination of technology also allowed me to collect frequent movement data. Data was collected over a one-year period from June 2023 to June 2024, with available continuous activity data per turtle ranging from 2–13 months. In accordance with anecdotal observations, my results indicate that this species exhibits a nocturnal activity pattern, with the lowest rates of activity occurring during the diurnal period. We saw higher levels of activity during the wet season. Within the wet season, S. triporcatus was more active during periods of flooding than periods without. Concerning movement data, we saw variation in maximum distances moved across individuals. However, data suggests that turtles moved an average of two times the distance during flood conditions when compared to pre-flood conditions.

Y. Watanabe, G. Tobin, C. Miller, A. Ford, D. Kelley, Z. Donaldson, and E. McCullagh

Mammalian testicular function exhibits plasticity in response to alterations of the social environment, with cause-and-effect being species dependent. However, this concept has been primarily examined in promiscuous species. Differences in mating strategy and paternal care investment correlate to differences in male neuroendocrine profiles and reproductive physiology between species. Special consideration should therefore be given to mating and parental structures when investigating the role of neural networks in regulating reproduction. We investigated the impacts of novel female exposure on testis form and function in three rodent species: the socially monogamous and biparental prairie vole (Microtus ochrogaster), and the promiscuous and nonpaternal meadow vole (Microtus pennsylvanicus) and laboratory mouse (Mus musculus). Naïve and female-paired individuals of each species were compared. Long-term female pairing significantly increased testis size and sperm production in prairie voles, but not meadow voles or lab mice. These changes are accompanied by alterations in testicular composition. A third experimental group of prairie voles demonstrated that female pheromone exposure alone – in the absence of direct female encounters – was able to increase testis size and sperm production and alter testicular composition. These data demonstrate that prairie voles exhibit remarkable neuronally-regulated testicular plasticity in response to female exposure and pair bonding, whereas meadow voles and lab mice do not. While prairie voles are socially monogamous, they exhibit extra-pair sexual promiscuity. This observed version of socially mediated testicular plasticity may provide specific advantages to prairie vole males depending on their active reproductive environment (i.e. alloparental, non-pair-bonded breeder, or pair-bonded breeder). This discovery proposes an innovating perspective by which male reproduction and fertility may be investigated with respect to species-level social structure.

Cora Dyslin, Denise M. Thompson, Donald T. McKnight, Sean P Maher

The Central American River Turtle (Dermatemys mawii), native to southern Mexico, eastern Guatemala, and Belize, is critically endangered primarily due to hunting for consumption and market meat. Traditionally considered nocturnal based on netting and visual surveys, recent evidence suggests the species may be active during both day and night. This raises questions about the true extent of their nocturnality, which may have been biased by the timing of surveys. Understanding the daily and seasonal activity patterns of D. mawii is vital for informing biological knowledge and improving hunting regulations. To address this, we studied 24 turtles (8 males, 8 females, 8 juveniles) in a natural river system in Belize from June 2021 to July 2022. We equipped them with archival dataloggers to record movement, temperature, and water depth, and sonic transmitters for relocation. Data were successfully retrieved from 18 turtles, with tracking periods ranging from 1 to 13 months. Contrary to previous beliefs, our results reveal that D. mawii displays a crepuscular activity pattern, with the lowest activity rates occurring at night. Males were more active than juveniles, who were more active than females. A seasonal pattern was also observed: nocturnal activity increased during the rainy season, while diurnal activity was higher in the dry season. These findings challenge existing perceptions and have significant implications for conservation strategies.

Antarctic notothenioid fishes represent a fascinating system for studying adaptive evolution, particularly in response to extreme environmental conditions. The evolutionary radiation of these fishes began with the opening of the Drake Passage between South America and Antarctica, approximately 25–22 million years ago, leading to the formation of the Antarctic Circumpolar Current and Polar Front. These geological events effectively isolated the Southern Ocean, creating a unique environment characterized by extreme cold, high oxygen levels, and geographical seclusion. In response, Antarctic notothenioids have evolved distinct adaptations, including antifreeze glycoproteins (AFGPs), cold-stable cytoplasmic microtubules, giant muscle fibers with reduced fiber numbers, increased mitochondrial densities, and higher concentrations of polyunsaturated lipids. These traits enable their survival in sub-zero waters.

While adaptive gains, such as AFGPs, have been extensively studied, the molecular mechanism of trait loss in Antarctic notothenioids remains underexplored. A prominent example is the loss of hemoglobin in the Channichthyidae family, commonly known as icefish. Loss-of-function mutations, though often associated with genetic disorders, can also drive phenotypic diversity and play a key role in evolutionary processes. In this study, we investigate the molecular signatures of trait loss in Antarctic notothenioids, aiming to understand how these fishes have adapted by shedding genetic traits that may have become dominant group in Southrn Ocean under cold stress. By systematically examining the genomic architecture, we aim to identify the precise nucleotide changes associated with trait loss and explore how these genetic alterations have contributed to the resilience and survival of notothenioids in one of the harshest environments on Earth. This research sheds light on the adaptive mechanisms of polar fishes and provides new insights into evolutionary processes driven by both genetic gain and loss.

Population genetic studies of the hematophagous Cimicidae indicate that the dispersal of the parasite is closely tied to host movement. Swallow bugs (Cimex vicarius) parasitize cliff swallow colonies and rely on their avian hosts for passive dispersal, but the frequency of this movement remains uncertain. In this study, we used single nucleotide polymorphisms (SNPs) generated through double digest restriction-associated sequencing (ddRAD-seq) to assess the population structure and genetic diversity of swallow bugs across a population in Nebraska. Swallow bugs were collected from 23 cliff swallow colonies in 2014 and 14 colonies in 2021. Genetic analyses revealed low population differentiation among colonies and greater genetic variation within individuals than within colonies, suggesting panmixia. These results indicate that passive dispersal may occur more frequently than previously estimated. Colonies unoccupied by cliff swallows exhibited reduced genetic diversity, highlighting the importance of cliff swallows in facilitating long-distance passive dispersal of swallow bugs. Overall, the weak population structure observed in swallow bug populations across southwestern Nebraska suggests high levels of admixture and limited genetic isolation.

Amanda W. Carter, Fabio A. Machado, Erika Hingst-Zaher, Mikayla S. Struble, Ashlyn H. Trujillo, Colton Roberts

Body sizes in many taxonomical groups are reportedly decreasing, and these shifts are often linked to climate change through Bergmann’s Rule. Bergmann’s Rule posits that body size is related to environmental temperature, and can be applied across spatial (e.g., latitude) and temporal (e.g., climate change) temperature gradients. While there is an active discussion in recent literature suggesting decreasing body sizes may be a universal response to climate change in endotherms, it is unclear if ectotherms should be similarly affected. Additionally, little is known about whether these size changes result from phenotypic plasticity or natural selection, which is critical for understanding species’ adaptation to climate change. Using museum collections of a widely distributed butterfly, Vanessa cardui, we tested Bergmann’s clines across western North America over the past century. We found that wing and thorax sizes are decreasing over time and across latitude. To explore contributions of plasticity versus selection, we collected climate data at varying temporal and geographic scales to estimate the developmental temperatures of each specimen and the temperatures across the population’s range in multi-generation intervals. Preliminary findings suggest that selection may drive decreasing body sizes more so than plasticity, which is surprising in a species known for temperature-driven plasticity. Our study highlights the importance of understanding the mechanisms driving biogeographic trends to improve predictions of climate change impacts.

Jay McEntee

Bewick’s wren (Thryomanes bewickii) is a small songbird that shows notable geographic variation in song. Two of these variants, referred to here as the Eastern and Mexican lineages, sing strikingly different songs. There appear to be considerable disparities between these two dialects in song complexity and other acoustic parameters. I aim to quantify the differences and determine where the ranges of these two song forms come into contact. The ultimate purpose of this research is to better understand phenotypic diversity within Bewick’s wren, with the goal of flagging possible cryptic species-level diversity for future research.
I made recordings of Bewick’s wrens and collected geographic data in Arizona and New Mexico to determine the range boundaries of two song variants. Using these recordings, I will compare two different methods for quantifying differences between songs of the two dialects. I will train a machine learning model to distinguish between the two song forms and apply explainable AI (XAI) tools to the model. XAI, which provides explanations about what influenced a classification model’s prediction, has yet to be utilized in the field of bioacoustics. I will also conduct a discriminant function analysis to determine which acoustic variables contribute most to the distinction between groups. By comparing the results from these two methods, I can glean insight about the key differences between dialects and determine whether XAI will be a valuable bioacoustics tool in the future.
My results show that the ranges of the Eastern and Mexican song variants come into contact in west-central Arizona. In this region, I made recordings of two birds who sang songs typical of both forms. These mixed singers are evidence of cultural interaction between these variants. This study enhances our understanding of the nature of geographic song variation in Bewick’s wrens and introduces a novel method for quantifying said variation.

Thomas C. Buckman, Angelica R. Harper, Erica M. Nadolski, John P. Masly

Morphological structures that are shared among closely related species can differ significantly in size and shape. The molecular mechanisms that give rise to this morphological divergence are not well understood. Among the four sister species of the Drosophila melanogaster complex (D. mauritiana (mau), D. melanogaster (mel), D. simulans (sim), and D. sechellia (sech)), males have evolved novel reproductive structures called the epandrial posterior lobes (ePL), a rapidly diverging trait that aids in copulation and is necessary for successful reproduction. Using an inter-species genetic mapping approach, we identified a novel gene, Goldilocks (Glds), that negatively regulates the size of the ePLs in Drosophila. The sequence features of Glds include a 51 base pair region that encodes a putative Signal Peptide (SP) at the 5’ end. We tested the function of this region in directing secretion of the Glds protein and found that Glds is secreted in all four species and that the SP sequence is both necessary and sufficient for secretion. Interestingly, the SP sequences in sim/sech and in mau differ from mel by two individual unique amino acids (AA). A secretion assay for Glds showed that the AA substitution in mau directs significantly greater Glds secretion amount compared to the other species. However, our results also show that additional species-specific AA substitutions in Glds outside of the SP sequence also contribute to secretion rates. CRISPR-Cas9 genome editing experiments are underway to test the phenotypic effects of species-specific AA substitutions in Glds along with cross-linking mass spectrometry experiments to identify candidates for Glds protein interactors.

In many animal species, individuals engage in fights with conspecifics over access to limited resources (e.g. mates, food, or shelter). Most theoretical fighting models assume that damage has an important role in determining the contest winner. Thus, defensive structures that reduce the amount of damage an individual accrues during intraspecific competition should provide a fighting advantage. Examples of such damage-reducing structures include the dermal shields of goats, the dorsal osteoderms of crocodiles, and the armored telsons of mantis shrimps. Although numerous studies have identified these defensive structures, no study has investigated whether they influence the outcomes of intraspecific fights. Here I investigated whether inhibiting damage by enhancing an individual’s armor influenced fighting behavior and success in the giant mesquite bug, Pachylis neocalifornicus (Insecta: Hemiptera: Coreidae). I found that experimentally manipulated individuals (i.e. those provided with additional armor) were 1.6 times more likely to win a fight when compared to the control. These results demonstrate that damage, and damage-reducing structures, can influence fighting success. The implications of these results are twofold. First, these results experimentally support a fundamental assumption of most theoretical fighting models: that damage is a fighting cost that can influence contest outcomes. Second, these results highlight the importance of an individual’s defensive capacity, and why defense should not be ignored.

Xuan Zhuang

Many ectotherms living in subzero environments have evolved remarkable survival strategies to cope with freezing conditions. A notable example is the independent evolution of diverse antifreeze proteins (AFPs) in various cold-water marine fish lineages, such as a subset of right-eye flounder. While we have elucidated the evolution of AFP in this fish lineage, a comprehensive understanding of cold and freezing resistance adaptation at the genome level across different species is lacking. Phylogeny of right-eye flounders displays an interesting pattern of cold adaptation from warm water dwelling species. Further, within cold water species members, deep-water AFP-lacking (AFP-) species form a sister clade to the AFP-bearing (AFP+) clade. Therefore, we hypothesized that the two clades of flounders employ two distinct strategies to avoid freezing in cold waters, with deep-water species relying on undercooling/supercooling, while shallow-water species synthesize AFP. To explore how members within this family, adapting to the equivalent subzero waters, employ different strategies to avoid freezing, we aim to identify genomic signatures of freezing-resistant adaptation using comparative genomics Here, we used 14,430 protein-coding gene alignments from 9 Pleuronectidae species to identify positively and relaxed selected genes. We found 1493 genes (10.35% of alignments tested) with statistically significant evidence for positive selection and 2351 genes (16.29% of alignments tested) that likely evolved under relaxed selection. Positively and selected relaxed genes are statistically enriched in gene ontology terms and biological processes related to plasma membrane, membrane receptors, cytoskeleton structures and cellular component organization. ECM receptor interaction and other glycan degradation are two main pathways enriched in positive selection. Relaxed selected genes implicated in ABC transporter, ECM receptor interaction and focal adhesion pathways. All these pathways are plausibly related to the evolution of cold and freezing resistance adaptation in right eye flounders. By identifying candidate genes and functional pathways, including the evolution of molecular and cellular characteristics, this study will shed light on two distinct freezing avoidance strategies employed by right-eye flounders to survive in harsh environmental conditions.

Anindita Basu, Neil Shubin, and Katie Mika

Across the phylogeny, the pectoral fins of fish have incredibly diverse morphologies. The mechanisms of gene and gene pathways in the evolution and development of this variation are still unknown. We can now investigate how gene expression changes in individual cell types can shift across development and influence the variation in morphology by using single cell sequencing. We collected single cell sequencing data from wildtype zebrafish and two known pectoral fin morphological mutants – hoxa13a and hoxa13b knockout zebrafish. By comparing these data, we have identified rdh1 as a gene involved in fin development. Rdh1, also known as retinol dehydrogenase, is a part of the retinoic acid pathway. This pathway is known to help establish hox gene expression boundaries, but little is known about its role downstream of hox genes. In our data, the removal of hoxa13a or hoxa13b directly results in the loss of expression of most copies of rdh1 within the pectoral fins. To investigate this further and the possible connection between these genes, we plan to perform a retinoic acid rescue experiment, as well as generating a knockout of rdh1 itself using CRISPR/CAS9. We hypothesize that the pectoral fin will be lost when rdh1 is not present, indicating rdh1 and the retinoic acid pathway play significant roles in zebrafish pectoral fin development.

Ciaran Shaughnessy

Heat shock proteins (HSPs) are a conserved group of molecular chaperones that have played a pivotal role in vertebrate evolution by facilitating cellular acclimation and adaptation to environmental stress. HSPs assist in the proper folding, stabilization, and degradation of proteins, maintaining proteostasis across different physiological conditions. Throughout vertebrate evolution, the ability to cope with diverse environmental challenges, like temperature fluctuations, oxidative stress, or variable salinity, has been critical for survival. HSPs are central to this adaptive flexibility, as they help mitigate the harmful effects of stress on proteins, thereby enabling organisms to thrive in varying habitats. One basal vertebrate, the sea lamprey (Petromyzon marinus), has a life cycle uniquely poised for these types of extreme environmental challenges. Sea lamprey are an anadromous fish that experience both osmotic stress as well as temperature stress during migration events. Although HSPs are a common biomarker of thermal stress responses, there has been limited work completed on their corresponding gene-specific expression. In this study, we examine gene expression of two stress-induced members of the HSP family, hsp70 and hsp90; as well as hsc70, a commonly assessed constitutively expressed gene within fishes. We found that both hsp70 and hsp90 were both induced by exposure to different thermal stressors, with gill hsp90 being more sensitive to all temperature increases above 20℃. This study, in combination with previous work, suggests that rising springtime temperatures may determine the end of the window of opportunity for saltwater entry in late-season out-migrating juvenile lamprey. This work can help inform management practices of this evolutionary significant anadromous fish.

Kameron C. Voves, Brian S. Edmond, and Day B. Ligon

Seasonal and diel activity cycles play an important role in meeting the biological needs of organisms. Defining these patterns provides useful insights into the physiology, behavior, and ecology of animals. Photoperiod (daylength) is a key factor regulating the activity cycles of most animals while temperature plays a critical role in the activity regulation of ectotherms. We used automated radiotelemetry and the signal change method to study the effects of temperature and light intensity phases (daytime, nighttime, twilight) on the seasonal and diel activity patterns of a captive population of Alligator Snapping Turtles maintained under semi-natural conditions in southeastern Oklahoma over a one-year period. Females were seasonally more active within a warmer average temperature range (17.1–31.8°C) than males (12.7–27.6 °C). Temperature also explained a greater portion of seasonal variation in female activity (49%) than male activity (31%). Both sexes maintained some level of activity throughout the year suggesting they do not enter complete dormancy. Activity was detected during all hours of the day across most months and changed in proportion with light availability. Diel activity patterns changed seasonally such that turtles exhibited modest nocturnal tendencies during the warmer months of the year, pronounced diurnal rhythms during the cooler months of the year and an arrhythmic diel cycle during the hottest month of the year. Changes in diel activity patterns were influenced by changes in light intensity and temperature.

Ivan de la Hera, Maria Moiron

Understanding the evolution of traits subject to trade-offs is challenging because phenotypes can (co)vary at both the among- and within-­ individual levels. Among-individual covariation indicates consistent, possibly genetic, differences in how individuals resolve the trade-off, while within-individual covariation indicates trait plasticity. There is also the potential for consistent among-individual differences in behavioral plasticity, although this has rarely been investigated. We studied the sources of (co)variance in two characteristics of an acoustic advertisement signal that trade-off with one another and are under sexual selection in the gray treefrog, Hyla chrysoscelis: call duration and call rate. We recorded males on multiple nights calling spontaneously and in response to playbacks simulating different competition levels. Call duration, call rate, and their product, call effort, were all repeatable both within and across social contexts. Call duration and call rate covaried negatively, and the largest covariance was at the among-individual level. There was extensive plasticity in calling with changes in social competition, and we found some evidence for among-individual variance in call rate plasticity. The significant negative among-individual covariance in trait values is perpendicular to the primary direction of sexual selection in this species, indicating potential limits on the response to selection.

Elizabeth A. McCullagh

Hearing is critical for the survival and fitness of all taxa. Previous studies determined that sex, ear shape, body size, habitat type, and environmental factors are important in influencing mammalian hearing. However, few studies have explored whether social grouping strategies influence mammalian hearing as well. In this study, we compared the threshold, amplitude, and latency of auditory brainstem responses (ABRs) recorded from 90 wild rodents of 9 species, grouping into three broad social classifications (solitary, monogamous, social). The ABR thresholds across frequencies of these wild rodent species ranged from 25 to 40 dB SPL with maximal sensitivity around 8kHz. Social species have slightly better low-frequency hearing thresholds than other groups measured. The amplitude of wave I and IV increased with click stimulus intensity and differed considerably among different species at each intensity. Peak latency of wave I and IV decreased with click increase intensity in each species. No significant difference was detected for wave I and IV latency with increased intensity for each species. Significant differences were detected in the latency shift of the DN1 component of the BIC in relation to ITD normalized for ITD at zero across species and social groups while no significant differences were detected in relative DN1 amplitude across ITD normalized to zero ITD. This data is valuable for understanding the various factors that influence hearing across species.

Jonathan Savitz

Inflammation, a risk factor for depression, alters the metabolism of kynurenine producing more neurotoxic kynurenine metabolites such as 3-hydroxykynurenine (3-HK) and quinolinic acid (QA) at the expense of kynurenic acid (KynA), which is thought to be neuroprotective. Here we investigated the association between kynurenine pathway (KP) metabolites and depressive symptoms/functional ability in 220 individuals with a DSM-V diagnosis of major depressive disorder (MDD). Depression-related symptoms were measured with the Patient-Reported Outcomes Measurement Information System (PROMIS) and Temporal Experience of Pleasure Scale (TEPS) self-report scales. KP metabolites were measured in serum using high-performance liquid chromatography and tandem mass spectrometry. Associations between kynurenine metabolites and depressive symptoms as well as self-reported functioning were tested using linear regression. Age, sex, race/ethnicity, years of education, body mass index, and psychotropic medication status were controlled for based on Bayesian Information Criteria. QA was inversely associated with the PROMIS Depression scale (β = -1.971, p < 0.01) while KynA/3-HK (β = 1.611, p < 0.05) and KynA/QA (β = 1.863, p < 0.01) were positively associated with depression scores. Moreover, KynA/3-HK was significantly negatively associated with scores on the PROMIS Positive Affect (β = -1.584, p < 0.001), PROMIS Applied Cognition (β = -1.667, p < 0.01), and TEPS Consummatory Pleasure (β = -1.351, p < 0.01). Counter to the extant literature, the results suggest that higher concentrations of neuroprotective relative to neurotoxic metabolites are associated with reduced self-reported emotional well-being and cognitive functioning. Although the KP appears to be dysregulated in MDD, the results highlight the need for further investigation into complex effects of the KP on mood and function.

Nagayasu Nakanishi, PhD.

Mechanosensory neurons are crucial for detecting physical stimuli. Mechanosensory neurons are found across various metazoan lineages. In bilaterians, a core gene regulatory network (coGRN) governs mechanosensory development, with factors like Notch, SoxB, Atonal, Gfi1b, and POU4 playing key roles in mechanosensory specification and differentiation.

In the non-bilaterian Nematostella vectensis, orthologs of these factors are involved in neurogenesis, including SoxB2, Notch, and POU4. Additionally, POU4 is involved in maintenance of mechanosensory neuron structure and function, mechanosensory neuron development is initiated in the developing larva and restricted to the circumoral ectoderm that gives rise to mature mechanosensory neurons like Hair cells. The function of upstream regulators of the gene regulatory network is less defined. Hence, it is difficult to assess homology of mechanosensory coGRNs between bilaterians and non-bilaterians.

This research aims to identify the upstream regulators of the coGRN for mechanosensory development in non-bilaterians using Nematostella vectensis. Our results show that SoxB2 is not involved in the initial specification of hair cells, but Notch signalling restricts hair cell number. Additionally, ATACseq analysis revealed a Gfi1b motif in the POU4 promoter region. These findings suggest some level of conservation between the upstream regulators of bilaterian and non-bilaterian coGRNs. Further research is necessary to fully understand the evolutionary implications of these findings like exploring if aspects of these coGRNs between bilaterian and non-bilaterians are conserved ,or if these coGRNs have diverged.

Elizabeth McCullagh

Fragile X Syndrome (FXS) and autism are neurodevelopmental and communication disorders. FXS is a monogenic form of autism. Hypersensitivity to sound and altered binaural hearing are two common symptoms in these disorders. Binaural hearing and spatial acuity are important for localizing a sound source and separating sounds of interest from noisy backgrounds. Sound information computation starts with the auditory brainstem which compares interaural timing differences (ITD) and interaural level differences (IID) from both ears. Highly myelinated axons in the auditory brainstem encode ITD and IID sound information quickly and precisely. Whether there are changes to myelination that underly auditory sensitivity and dysfunction at the level of the auditory brainstem in FXS is unknown and important for understanding auditory symptomology and treatment.
The study of myelination during critical developmental timepoints will help to establish when during development auditory dysfunction arises using amouse model of FXS, Fmr1 knockout (KO) mice (male and female C57BL/6J wildtype, Fmr1 KO and heterozygote female mice). We analyzed anatomical markers of myelin including diameter and thickness of myelination, spacing and size of sodium channels (nodes/paranodes), in Fmr1 KO mice and controls at several critical developmental timepoints, P9, P12-14, and P21-23 and P60-90 using immunohistochemistry and electron microscopy. We are measuring Auditory Brainstem Responses (ABRs) to show brainstem specific auditory function across the same developmental timepoints. The ABR is a non-invasive electrophysiological measure that records a pattern of waveforms that is directly related to auditory brainstem function.
Preliminary data suggests that similar to adult phenotypes, FXS mice have altered auditory brainstem development as measured by ABR that may be related to myelination. These findings are important for understanding mechanisms underlying FXS related to myelination and when during development they arise.

Bierbaum EL, Herrboldt MA, Eckhardt CW, Hess AJ, McGouran CN, Jones LR, McGlone RH, and SN Sowell

The evolution of developmental mechanisms can impact the diversification of traits and species. However, there are inherent challenges to connecting such processes to macroevolutionary patterns. In this presentation I will discuss endocrine mechanisms of development, and the results of comparative hormone experiments on larval salamanders. Such experiments show how shifts to the timing of tissue transformation can reflect phenotypic variation across clades. I will put these results in a broader framework for understanding how developmental mechanisms affect trait diversification.

Ronald M. Bonett

A commonly observed pattern in visual ecology is the tuning of the sensory system to available light in the environment. This is accomplished by the duplication, diversification, and differential expression of visual system genes. Proteins involved in the visual system can reside in the lens, which is composed of crystallins. In the lens of the eye, crystallin genes have undergone extensive duplications and deletions, but it remains unknown how they have diversified with respect to changes in lens morphology and function across diverse environments. Within amphibians, salamanders are an excellent model to study visual systems because of their diverse life cycle modes and extreme transitions in habitat across ontogeny. The life cycles of salamanders not only include the typical metamorphic life cycle of a frog (aquatic juvenile, terrestrial adult), but also permanently aquatic and terrestrial lineages. Representatives occupy a plethora of habitats ranging from ponds, streams, lakes, swamps, and caves that vary in light environment and media type. As a consequence, their visual systems have undergone repeated transitions in visual media, often across development. Amphibian lenses also appear to change shape from round as larvae to flattened as adults, which allows them to accommodate differently between water to land. To understand the diversity of crystallin genes I deep transcriptome sequenced whole eyes.

PATEL Dhvani, Eryn WAGONER, Aadhya SUBHASH, Shelby KUHNERT, Mary KILMER, and Alla BARRY

The process of cardiac remodeling (CR), triggered by heightened sympathetic outflow, involves changes in heart geometry and accumulation of connective tissue (CT) within the myocardium. These alterations lead to impaired ventricular functions and the progression of heart failure. Simultaneously, parasympathetic outflow, through cardiac branches of the Vagus Nerve (VN), exerts cardioprotective effects, reducing the risk of CR. Recent studies revealed the presence of catecholaminergic fibers (CF) in the cervical VN. These newly discovered CF, likely postganglionic sympathetic, challenge the current understanding. The aim of our study was to explore the correlation between the quantity of CF within the cervical VN and indicators of CR. Cervical VN samples were obtained from 10 formalin-preserved adult human cadavers (male n=5, female n=5). All sections were prepared using Luxol fast blue and anti-Tyrosine Hydroxylase (TH) antibody. Superior Cervical Ganglia were examined for TH-reactivity to confirm the quality of TH detection. Myocardium was stained with trichrome. TH+ areas and CT were measured using ImageJ and analyzed using PAST 4.11. Analysis revealed the presence of TH+ fibers bilaterally or unilaterally in 9 of 10 examined donors, with varying prevalence ranging from 0% to 15%. Upon conducting linear regression analysis, no statistically significant correlation was observed between the quantity of vagal CF and indicators of CR. However, a trend towards significance emerged in the relationship between the quantity of CF and abnormal thickness observed in the left ventricular wall and interventricular septum (p=0.056). Our study reinforced the understanding of the persistent presence of CF within the cervical VN. The findings indicated a lack of correlation between the quantity of TH+ fibers and extent of CR. However, several trends for statistical significance were detected. Further investigations with an expanded sample size are warranted to enhance the robustness of our conclusions.

McGraw SA, Hellmers JM, O’Connell TA, Heimovics SA.

Pair bonding has evolved in socially monogamous species; it improves reproductive success and offspring survival. Although the neuroendocrine regulation of pair bond formation has been researched extensively, the neural mechanisms influencing maintenance of social monogamy in the face of challenges remain largely unexplored. Social behavior is largely coordinated through neuronal regions of the social decision-making network (SDMN), and dopamine (DA) is a critical neurotransmitter for behavioral regulation like with pair bond formation. Therefore, in the current study, we sought to characterize the social and neuroendocrine factors impacting pair bond maintenance in zebra finches, using phosphorylated tyrosine hydroxylase (pTH), the rate limiting step of DA synthesis, in the SDMN. First, adult male and female zebra finches were paired together randomly, and the pair bond strength was quantified by observing spontaneously occurring, home-cage affiliative behavior over three weeks. The pairs were separated overnight; then, each pair faced a social challenge—the jealousy test—where the pair-mate male observed the pair-mate female partner in close proximity to a bachelor male. Upon completion of the jealousy test the pair-mate males were sacrificed, and immunohistochemistry (IHC) was performed to detect immunoreactivity (-ir) of pTH in the SDMN of pair-mate males to investigate pair bond maintenance during a social challenge. Levels of pTH-ir, were visualized through IHC and quantified. Then structural equation modeling (SEM) examined relations in pTH-ir to pair bond strength and response to the jealousy test. SEM revealed behaviors prior to and during the jealousy test are significantly related to pTH-ir in specific brain regions of the SDMN, including in the ventral tegmental area (VTA) and caudal medial preoptic area (cPOM). These regions have bidirectional communication, via DA, and are critical to pair bonds as the cPOM plays an important role in male sexual behavior and the VTA is crucial to reward mediation.

Erin Wiley

Stomata regulate gas exchange in plants; therefore, their properties are important determinants of rates of photosynthesis and water loss. While many environmental conditions can affect stomatal properties during leaf development, there is little known of the effects of defoliation. In response to reduced carbon availability, plants may increase stomatal size and/or density of re-flush leaves to increase leaf-level photosynthesis. However, since re-flush leaves are often smaller, a higher density could also passively result from reduced cellular expansion. Stomatal changes could also result from the warmer temperatures that occur during re-flush, later in the growing season.
To determine how and why defoliation affects stomatal properties, leaves from two defoliation experiments were collected. The first study investigated defoliation effects on stomatal traits of mature Green Ash (Fraxinus pennsylvanica), while the second study examined the impacts of a heatwave (+10°C) on defoliation recovery in potted Pin Oak (Quercus palustris) saplings. Stomatal impressions were made, and stomal area (i.e. size) and stomatal density were measured. Additionally, correlations between stomatal properties and root and stem carbohydrate storage, leaf size, and gas exchange measurements were explored.

Defoliation varied in effect, increasing stomatal density in ash but size in oak. In oak, both defoliation and warmer temperatures increased stomal size independently. In both species, the stomatal property increased by defoliation—either size or density—was related more to root or stem carbohydrate concentrations than leaf size, suggesting that plants make re-flush leaves capable of greater gas exchange as a direct response to reduced carbon availability. Finally, both photosynthetic rate and minimum leaf conductance correlated with stomal size in oak. Together, these results suggest that recovery after defoliation involves changes in stomatal properties that increase leaf-level C assimilation, compensating for reduced leaf area and remobilized reserves. However, these alterations may come at the expense of reduced drought tolerance.

Robert Sheaff

There is a strong body of literature establishing the bioactivity of compounds extracted from matcha green tea, but only a few responsible compounds have been identified, especially in green teas. This project aimed to determine whether matcha, roasted coffee, or espresso samples contained compounds capable of inhibiting cellular metabolism in transformed (cancerous) cell lines, and if so, what compounds were responsible for the inhibition. Techniques included organic extraction and purification, CTG assays for cellular activity, and GC-MS (gas chromatography-mass spectrometry) for charactarization of compounds. Several compounds of interest were determined. This presentation will discuss the characteristics of the compounds identified in each of these experiments, and the likelihood of their responsibility.

Elizabeth McCullagh

Fragile X Syndrome (FXS) is the leading genetic cause of autism, resulting from a mutation in the Fmr1 gene. Along with, the well-known cognitive and behavioral abnormalities, FXS patients often experience gastrointestinal dysfunction with poorly understood mechanisms. Gut microbial dysbiosis impairs metabolism and absorption of bioelements, thus altering the elemental bioavailability and gut barrier integrity in the host. This raises a key question whether the gastrointestinal dysfunction in FXS patients is mediated through gut dysbiosis. Here, we tested the hypothesis that FXS alters the intestinal microbiota profile and bioelemental composition resulting in impaired intestinal barrier integrity. We used a Fmr1 knockout mouse model that recapitulates FXS disease phenotypes and wildtype littermate controls. To test whether FXS causes alteration in the gut microbiota profile, we performed 16S ribosomal RNA sequencing in gut samples of both wildtype and knockout mice, where we found the knockout mice had a distinct gut flora compared to wildtype mice. Now, to see the effect of gut dysbiosis, we next assessed gene expression on the intestinal samples using RT-qPCR. We found that the expression of gut-barrier-maintaining genes (Occludin-1, Claudin-2, MUC-2, ALPi, PLVAP, REG3G, and TJP1) were significantly downregulated in knockout mice compared to wildtype, suggesting impaired gut barrier integrity in FXS. Finally, we measured the elemental distribution of gut and brain tissues using ICP-MS (mass spectrometry). We found elemental compositional shifts (Ca, Cu, Li, Mn, Mg, Na, P, S, Zn) in knockout as compared to wildtype mice. Further correlational analysis of the elemental compositional network with intestinal microorganisms may help link elemental and microbial data as indicators of gut pathogenesis in FXS. Collectively, the results of this study show that FXS is related to altered gut microbiota and bioelemental profile and disrupted gut barrier function. Future research could help establish potential probiotic treatments to ameliorate gastrointestinal disturbances in FXS. Thus, the results from this study hold promise for establishing potential biomarkers and novel treatments to tackle gastrointestinal illnesses in FXS patients.

Grace Phelps, Ciaran Shaughnessy

The present study investigated osmoregulatory and molecular mechanims of sea water acclimation in the Atlantic Sturgeon, Acipenser oxyrinchus oxyrinchus, an ancient bony fish. Atlantic Sturgeon exist along the east coast of the United States up into Canada, existing in rivers, estuaries, and costal shores. Atlantic Sturgeon are unique in the sense that they migrate between fresh water and the sea. Adults often can move in and out of seawater and typically enter rivers every year for spawning then re-enter seawater when spawning is complete. Because of this active movement between environmental salinities, the Atlantic Sturgeon presents an excellent opportunity for investigations into the osmoregulatory and molecular mechanisms underlying acclimation between freshwater and saltwater environments. Here, Sturgeon where acclimated to freshwater or saline environments and a profile of tissues were collected. Additionally, posterior intestine was collected from sturgeon at different time points of seawater acclimation, to investigate mechanisms associated with osmoregulation and seawater desalination in the intestine. Plasma osmolarity, glucose, hematocrit, and triglycerides were taken from fish sampled over the 10-day time-course of seawater acclimation. Molecular mechanisms of osmoregulation were assessed by gene expression using quantitative polymerase chain reaction and protein expression Western blot analysis. By investigating the molecular mechanisms of intestinal function during seawater acclimation in the Atlantic Sturgeon, we hope to better understand how these mechanisms evolved during the radiation of fishes.

Dr. Gavin Woodruff

Animals live in a microbe-rich world, and host-microbe interactions influence fitness and organismal health in both beneficial and detrimental manners. Caenorhabditis nematodes have been a model system for half a century. Laboratory cultures of these animals are reared on Escherichia coli. As rotting plant bacterivores, this is an ecologically artificial environment for the nematodes implemented for experimental convenience. Only recently has the natural microbial context of these organisms been considered. How can natural microbial associates inform the biology of longstanding experimental systems? To understand the evolution of host-microbe interactions, we have isolated approximately one hundred strains of wild microbes associated with the nematode C. inopinata in nature. C. inopinata is the closest known relative of C. elegans and inhabits a divergent ecological niche while having distinct, divergent morphology. Here, we have reared C. inopinata on a subgroup of our bacterial isolates and have measured fecundity, developmental rate, and other life history traits. We also performed similar experiments with C. elegans to see whether the associated host-microbe phenotypes have diverged or been conserved. We have found that one isolate, from the genus Klebsiella, resulted in a one hundred three percent mean increase in population growth for C. inopinata compared to Escherichia coli; however, at the individual level, mean fecundity was not significantly different. Upon further investigation, we determined that C. inopinata’s developmental rate increases when reared on Klebsiella sp. nov. compared to Escherichia coli, allowing it to reach reproductive maturity faster. We will perform RNA-sequencing on C. inopinata and C. elegans reared on our Klebsiella isolate and Escherichia coli to identify candidate genes that may produce the phenotypes observed within our life history trait experiments. In this way, these experiments have given us a framework to disentangle the molecular and genetic bases of host-microbe interaction evolution using a divergent nematode species.

Anand B. Karki, and Mohamed K. Fakhr

Aerotolerance is one of contributing factors in the survival of Campylobacter jejuni in the food supply, but the genetic mechanisms underlying aerotolerance remain unclear. This study compares the differential gene expression of two strains of C. jejuni – one aerotolerant and one aerosensitive – under aerobic and microaerobic conditions using RNA-Seq technology. The results show that the aerotolerant strain differentially regulates a greater number of genes compared to the aerosensitive strain when exposed to aerobic conditions. Both strains upregulated multiple heat shock genes in response to oxygen exposure. Several genes involved in iron acquisition or transport were found to be significantly upregulated in the aerosensitive strain, potentially leading to the formation of reactive oxygen radicals due to increased iron levels. A spike in gene expression after 12 hours of oxygen exposure was frequently noted. Our data suggests that the aerotolerant strain may be more effective at conserving resources than the aerosensitive one, which could enhance its survival. This study identifies numerous candidate genes that may be involved in aerotolerance and should be subjected to future investigation.

Alexandra C N Kingston

Snapping shrimp are marine crustaceans in which some species engage in mutualisms. One such species is the tiger snapping shrimp, Alpheus bellulus, which engages in heterospecific partnerships with the yellow watchman goby, Cryptocentrus cinctus. In these partnerships, A. bellulus constructs and maintains a burrow that provides both partners with shelter, while C. cinctus warns of nearby predators and competitors. Once a partnership is formed, it is imperative that the partners identify each other or potentially face lethal consequences. We asked if snapping shrimp can identify their goby partner and what sensory modalities they use during identification. We hypothesize that A. bellulus identifies partner C. cinctus using vision and olfaction. To test this, we used a choice test where a snapping shrimp was allowed to freely choose between two gobies: its partner and a stranger. Next, we temporarily altered the sensory capabilities of A. bellulus by visually blinding, olfactory blinding, or both, and repeated the partner choice test. Unaltered snapping shrimp spend more time with their goby partner compared to strangers. We found that altered shrimp in all groups spend equal amounts of time with their partner and the stranger goby, indicating that both vision and olfaction are important in partner identification. We suggest that A. bellulus uses vision to identify a goby from a distance and olfaction to distinguish between their partner and stranger goby.

Charles Brown, Matthew Toomey

The cliff swallow (Petrochelidon pyrrhonota) is a colonial bird known to live within a highly variable social environment– colony sizes range from 2 to 6000 nests. Adult cliff swallows feature a prominent white forehead patch, which we hypothesize is a signal of nest occupancy, useful in mitigating costly nest intrusion interactions within dense social environments. We predicted that more extensive patches (i.e. brighter, larger) should enhance this function and be associated with birds that nest in larger colonies, or that spend more time in the nest. Additionally, given the general ecological trend towards higher frequencies of large colonies, and the known heritable propensity for colony size in this species, we predicted that the signal should be selected for and inherited over time. To test these predictions, I measured both the brightness and size of the forehead patch in 234 preserved specimens in relation to the sex, colony size, and year of collection of the birds. I used reflectance spectroscopy to quantify the brightness of the forehead patch and discern the contrast between adjacent plumage pigments, and imaging software to quantify the size and shape of the patch. ​Our findings place signal evolution in the context of a variably social colonial species, revealing an interesting facet of social evolution in birds.

Nathan Piccoli, Kylie Atkinson, Grace Chang, Veronica Nguyen, and Brian Greene

Body size plays a major role in all aspects of an organism’s life history. Smaller individuals are often at a disadvantage compared to their larger counterparts when competing for food or when confronted with potential threats. Body size also plays a significant role in an organism’s ability to acquire food and defend against potential predators. Therefore, size-dependent changes in behavior and performance are common. Some organisms change behaviors entirely or display disproportionately high levels of performance for their size. Here, using high-speed cameras, we investigate the impacts of body size on the strike performance and venom yield in the semi-aquatic pitviper, Agkistrodon piscivorus (n=40). Further, we explore the proximate determinates of venom delivery by measuring venom yield in combination with strike biomechanics. A. piscovorus are able to strike very quickly (0.058 ± 0.01 sec.) over variable distances (range=4.8–18.6 cm). Larger snakes strike over greater absolute distances than smaller snakes, but use less of their body, resulting in lower relative strike distances in larger snakes compared to smaller individuals. Snakes struck with high velocities (max = 2.96 ± 0.43 m/s) and accelerations (max = 231.6 ± 92.3 m/s2), independent of body mass. Bite durations (0.18 ± 0.15 sec.) were not related to body mass but were a significant predictor of venom yield (range = 0.002–0.28 g). Our data show that venom yield is positively and significantly related three primary factors; body mass, bite duration, and average strike acceleration.

Larissa Saarel, David A. Penning, Donald T. McKnight, Day B. Ligon

Belize is home to nine species of freshwater and terrestrial turtles, many of which are listed as Critically Endangered, Vulnerable, or Near Threatened, chiefly due to overharvesting for consumption. The Northern Giant Musk Turtle (Staurotypus triporcatus) is an unusually charismatic species that has nonetheless received scant recent study. In comparison to the more widely recognized Central American River Turtle, this species is primarily carnivorous, inhabits a wider range of wetland types, and resides in terrestrial habitats for part of the year. Strike kinematics analysis of this species is lacking with only one study involving a small number of captive individuals. To better understand this species ecological role and trophic position, we elected to conduct parallel studies of diet and strike kinematics. To investigate variation in these traits we intend to work in six populations – three that inhabit systems with typically turbid water and three occupying systems with relatively better water clarity. Turtles were captured via active pursuit with dip nets, free diving, and passively using baited hoop traps. After capture, turtles were transported back to the Savanna Field Station where they underwent at least a 12-hour acclimation period. Following this, individuals underwent three strike kinematic trials where bite force, strike acceleration, and maximum gape angle were measured. Force scaled positively with head height and straight carapace length but also varied among water bodies.

Calvin Schaefer, Erin Westeen, Guin Wogan

Colubriform (fanged) snake skulls are highly diversified due to multiple evolutionary events. Initially, constriction in snakes allowed multiple skull structures, such as the maxilla, to become highly kinetic due to consuming larger prey. As environmental conditions changed to favor smaller and quicker snakes, smaller colubriform snakes began to dominate over large constrictors, eventually leading to the development of fanged teeth, mobile skull elements, and venom glands to aid in prey capture. With these developments, colubriform skull morphology diversified quickly. Many studies have examined the potential effects of ecological factors on modern diversification within singular families, but a wide-scale study across colubriform families has not been achieved. Our goal is to examine the effects of diet, foraging mode, and habitat use on variation in colubriform snake skull morphology. We sampled 171 species across 5 families (Colubridae, Elapidae, Homalopsidae, Lamprophiidae, Viperidae) and obtained 3D skull data using landmarks placed on microCT scanned museum specimens and scans from Morphosource©. We used Squambase, the R package “Squamatabase” and previous literature to assign foraging mode, habitat use, and diet categories. We used geometric morphometrics with phylogenetic comparative approaches to determine the effect of diet, foraging mode, habitat use, and size on skull morphology. We observed significant effects of the ecological factors on the palatine, quadrate, maxilla, mandible, ectopterygoid, supratemporal, and non-trophic skull elements, but habitat had no significant effect.

Dr. Luke Frishkoff

The division of prey resources is thought to promote coexistence of species by mitigating interspecific competition. Similarly, individuals within a population of a single species must divide resources among themselves, often resulting in individual specialization on a given resource. In the context of food resources, this may result in individuals of the same population having very different diets from one another. According to the niche variation hypothesis, populations should experience an increase in total niche width as individuals become more specialized, since this increases variation in the population. This in turn has implications for that population regarding resilience to anthropogenic change, as well as the outcomes of species interactions. While research has generally supported this relationship, the drivers of individual specialization are less clear. Under what circumstances do individuals become more specialized? Theory suggests that both ecological opportunity, as well as local community abundance can both play a role. If more resources (i.e prey availability) are available for individuals to specialize on, this can facilitate separation between those individuals in their diets. In addition, an increase in local abundance may also promote dietary specialization, by increasing competition between individuals. While these two scenarios are possibilities, they are not mutually exclusive, which highlights that the drivers of specialization can be quite complex. While patterns of individual specialization have been well documented, the forces behind these patterns are less clear. Here, we quantify individual specialization by comparing the diets of anole lizards from nine sites in Ecuador and the Caribbean island of Puerto Rico using DNA barcoding of fecal samples. We pair this with estimates of local anole community abundance and insect availability to link diet variation among individuals to properties of their communities.