Appleton, Miles (Georgia Institute of Technology), Mentor: Charlotte Greene (University of Virginia)
Effects of male population age structure on competitive trait selection in Bolitotherus cornutus
Abstract: Sexual selection varies widely across time and space, driven by intraspecific demographic factors such as density and operational sex ratio (OSR). Population age structure is another demographic variable that may influence competitive environments by altering male–male interactions and female mate choice. We tested whether age structure modulates selection on competitive traits in the Forked Fungus Beetle (Bolitotherus cornutus), predicting that old‑biased populations would exhibit heightened competition and stronger selection on male traits. We established 12 semi‑natural populations differing in male age composition (young‑biased vs. old‑biased) and measured body size, aggression, and reproductive success (via mate guarding behavior) over four weeks. Across both treatments, large male body size was under strong positive selection, while aggression showed no correlation with fitness. Older males had higher fitness than younger males regardless of treatment. Contrary to expectations, selection on body size and aggression did not differ between our population treatments, suggesting that either age structure did not measurably alter the competitive landscape or body size is under consistent selection. We propose that body size may be of great importance across multiple mating contexts (male–male combat, grip strength in mate guarding, and possibly female choice), while aggression may operate under context‑dependent “neighborhood” selection not detectable at the population level. These findings highlight the complexity of sexual selection dynamics and suggest that the influence of age structure on trait evolution may depend on behavioral plasticity and localized social interactions.
Golwala, Oskar (University of California - Berkeley), Mentor: Sandy Kawano (University of Virginia)
Could variation in feeding behaviors impact competition between Plethodon salamanders?
Abstract: The competitive dynamics between native and introduced species can hinge on subtle ecological or behavioral differences, particularly in systems where niche overlap is high and resources are abundant. In this study, we examined variation in prey-capture behavior to determine how utilizing such variation could help explain competitive dynamics between two sympatric salamander species. Using high-speed videography and kinematic analyses, we quantified prey-capture strategies across two prey types (crickets and waxworms) to assess inter- and intraspecific variation in prey-modulation. Our results revealed consistent species-specific differences in approach angle and tongue projection, as well as each species’ own distinct modulation profile. P. cylindraceus exhibited stereotyped, angle-driven strikes with consistent modulation, while P. montanus showed more variable kinematic responses across a broader range of traits. These biomechanical distinctions may enable cryptic niche differentiation, playing a role in apparent competition avoidance.
Hickman, Samantha (University of Pittsburgh), Mentor: Corlett Wood (University of Pennsylvania)
Investigating the Roles of Trichomes in Medicago lupulina
Abstract: Trichomes are a widespread multifunctional trait in plants that is important for resistance to herbivory and abiotic stress. In order to learn more about the functions and limitations of trichomes, I used Medicago lupulina as a model organism. I tested the preference of two different types of insects (aphids and earwigs), and I also observed and analyzed patterns of herbivory in a large field experiment. With these, I found that chomping insects were more strongly deterred by trichomes than sap suckers, though omnivorous chomping insects, such as earwigs, had no preference for or against trichomes. I also used an herbivory manipulation experiment to assess whether trichomes are an inducible defense in M. lupulina, and I found that they likely are not, but that there may be some environment by genotype interaction acting on trichome expression. Furthermore, I assessed the ways that trichomes may help a plant resist abiotic stressors, particularly drought and heat stress. My results for drought stress were contradictory to much of the literature, and so I concluded that our methodology was unsuitable and additional tests must be conducted in order to obtain trustworthy results. My results for heat stress were not statistically significant, but showed a slight pattern, so future tests should be conducted to parse out the existence of that pattern.
Kendrick, Clara (Oberlin College), Mentor: Charlotte Greene (University of Virginia)
An investigation of female harassment in the forked fungus beetle Bolitotherus cornutus
Abstract: Due to differing reproductive strategies between the sexes, males evolve strategies of coercion to gain access to more mates. Female harassment, defined as repeated attempts to copulate, can be costly to females. Intensity of female harassment can be dependent on the social context and therefore create unexpected variation in female fitness that can potentially influence variation in selection on female traits. This study investigated the cost of courtship and male aggression on fecundity in the forked fungus beetle Bolitotherus cornutus in two different population age structures. We found no variation in female fecundity due to courtship, male aggression, or male population age structure. We offer three alternate explanations for this trend: (1) females minimize courtship costs by convenience mating, (2) the cost of courtship is offset by nuptial gifts, and (3) rather than fecundity, females suffer a longevity cost.
Kennedy, Elena Ray (Leigh University), Mentors: Chloé Lahondère and James Moloney (Virginia Tech)
Characterization of the Mosquito Aedes japonicus and its Interaction with Fly Poison (Amianthium muscitoxicum): Pollination and Phytophagy
Abstract: Aedes japonicus is a species of mosquito invasive to the U.S. that carries deadly pathogens such as St. Louis encephalitis, West Nile Virus, and Japanese encephalitis [10]. With no current proposed methods of control, this study investigates the relationship between Aedes japonicus and the fly poison plant (Amianthium muscitoxicum) to inform the potential development of attractive toxic sugar baits (ATSBs). Ae. japonicus phytophagy and pollination of A. muscitoxicum is explored through plant visitation assays, pollinator observations, force feedings, and scent collection. We found that seventy percent of Ae. japonicus consumed fructose from A. muscitoxicum, while 5% were found with pollen–preliminarily indicating Ae. japonicus consumes nectar and are pollinators of this plant. Force-feeding assays demonstrated that the consumption of fly poison nectar decreased Ae. japonicus survival, causing a steep die off within the first 5 days. Mosquito nectar consumption varied as fly poison scent changed throughout the blooming stages, demonstrating the specificity of mosquito floral attraction for phytophagy. The results suggested Ae. japonicus both nectar-feeds and pollinates A. muscitoxicum during peak blooming, and A. muscitoxicum has strong potential to be an effective model for ATSBs for this species.
Lan, Ellen (University of Texas at Austin), Mentor: Clara Stahlmann Roeder (University of Virginia)
Preferences in male pheromone composition in female forked fungus beetles
Abstract: Male sex pheromones are often used as criteria in mate selection by females resulting in the evolution of specific pheromone compositions due to sexual selection. Past research demonstrated that female Bolitotherus cornutus change preferences for male chemical cues based on winner-loser status; however, the identities and preferences for specific chemical compounds in male chemical cues of B. cornutus have not yet been identified. In this experiment, I investigated female preferences for male sex pheromone composition in forked fungus beetles by collecting scent samples from male B. cornutus before and after dyadic male competition trials and analyzing them using gas chromatography mass spectrometry. Prominent compounds identified in male forked fungus beetle pheromones included benzaldehyde, octanal, 1-(2-butoxyethoxy)ethanol, and 2-butoxyethanol. No significant differences were detected in overall pheromone composition before and after dyadic male competition trials or between winning and losing males, possibly due to methodological limitations in Porapak-P absorption ability. However, the amount of benzaldehyde detected in male pheromones was shown to have a marginally significant correlation with body size, suggesting that it may be a potential predictor of male fitness.
Paczkowski, Madeline (University of Virginia), Mentor: Clara Stahlmann Roeder (University of Virginia)
Factors resulting in same-sex sexual behavior in forked fungus beetles (Bolitotherus cornutus)
Abstract: Same Sex Sexual Behavior (SSB) is found across many taxa in the animal kingdom. However, there is no one definitive reason why animals engage in this costly behavior which has no obvious direct benefit. There have been many studies investigating why SSB occurs in different species, but there has been no consensus across these species. In this experiment, we investigated the effect of SSB in male forked fungus beetles (Bolitotherus cornutus) on individual beetle fitness. Forked fungus beetles are promiscuous, sexually dimorphic, and have previously exhibited high rates of SSB, making them ideal for this experiment. I placed two size matched males in dyadic courtship arenas for 2.5 hours and monitored any SSB which occurred there continuously. Then I placed the beetles in beetlearies, semi-natural environments which simulated the beetles’ natural log habitat, and monitored SSB and different sex sexual behavior (DSB) by scan sampling them three times each day for 28 days. I hypothesized that males court each other to gain experience for female courtship and predicted that males which are courted in dyadic arena settings will have more instances of guarding behaviors on females in the beetlearies. This hypothesis was not supported by our data as there was no correlation between initiated or received SSB and DSB frequency or success. However, there was a positive correlation between aggression and SSB initiated, a negative correlation between aggression and SSB received, and a negative correlation between size and courtship received. As such, we concluded that there is no correlation between SSB and fitness, though SSB is tied to aggression.
Schmeder, Iris (University of Texas at Austin), Mentors: David McLeod (Mary Baldwin University) and Chloé Lahondère (Virginia Tech)
Investigating host-seeking behavior and pathogen prevalence in Culex territans and its hosts Rana clamitans and Rana catesbeiana
Abstract: Amphibian populations around the world are increasingly threatened with extinction. Much of this is driven by disease-causing pathogens, including ranaviruses, chytrid fungi, and, to a lesser known extent, trypanosomes. Understanding how pathogens are being moved within and between amphibian populations is imperative to slowing amphibian population declines. Only recently have mosquitoes been explored as possible disease vectors among amphibians. How ectotherm-feeding mosquitoes, such as Culex territans, find their hosts and act as a pathogen vector remains unclear. Here, we explore the olfactory basis of host-seeking behavior in Cx. territans to help elucidate the sensory mechanisms used to locate hosts, namely Rana clamitans and R. catesbeiana. We conclude that olfaction of volatile organic compounds is necessary for Cx. territans to successfully locate hosts; however, olfaction alone is insufficient when vision is removed, suggesting an interactive effect between the two senses. We demonstrate that CO2 sensing does not significantly contribute to Cx. territans ability to host-seek. We also investigate the prevalence of trypanosomes and ranavirus in populations of Cx. territans, R. clamitans, and R. catesbeiana at Mountain Lake Biological Station (MLBS). As part of an ongoing anuran disease surveillance effort at MLBS, our results reveal an outbreak of both trypanosomes and ranavirus among Cx. territans and R. clamitans in 2025.
Schuster, Landon (University of Tennessee at Chattanooga), Mentor: Jen Moss (Virginia Tech)
Interactions Of Macro- and Microclimate and Behavior in Plethodon Cinereus at Mountain Lake Biological Station
Abstract: We are currently in the midst of a biodiversity crisis: species and habitat diversity are decreasing on a global scale. Amphibians are particularly vulnerable, with the IUCN Red List citing climate change as being responsible for over one quarter of classifications listed as threatened or endangered. Most studies on amphibians have focused on understanding broadscale species-level responses to macroclimatic factors, but for many small-bodied amphibians with poor dispersal capabilities, fine-scale variation in microclimate is far more relevant. Compared to macroclimate, knowledge of how populations and individuals respond to changes in microclimate is poorly understood. To investigate this, I conducted a mark-recapture study across four different coverboard sites at Mountain Lake Biological Station in Pembroke, Virginia to examine the responses of red-backed salamanders (Plethodon cinereus) to changes in macroclimate and microclimate and to determine if their response varies based on factors such as sex or age. Each of the four sites contained an array of 50 coverboards, which served as cover objects and were used to assess microclimate (soil temperature and soil saturation) twice weekly across the seven-week study in Summer 2025. We found that the activity of P. cinereus across sites generally decreases as air temperature increases, that the salamanders select relatively cooler and wetter boards within sites, and that juveniles are more likely to be active at higher temperatures than adults. However, trends differed slightly between sites depending on their exposure. Specifically, these trends show that the rate of temperature change is similar across all sites, but less-exposed sites have lower air and board temperatures than more-exposed sites at any given time; the relationships between canopy cover, air humidity, and soil moisture is less clear. The most-exposed (least canopy cover, hottest, driest) site consistently supported the most surface activity, implying an additional unknown variable within the site may be increasing favorability for salamanders. Understanding how amphibians respond to climatic factors at these scales is integral for understanding where/how to protect habitat and mitigate biodiversity declines in anticipation of the looming threat of a changing climate.
Tieman, Anna (University of Indiana – Bloomington), Mentor: Corlett Wood (University of Pennsylvania)
The Curious Case of the Bewildering Black Spots
Abstract: During the first week of the REU program at Mountain Lake Biological Station we found the surrounding population of Medicago lupulina displayed black leaf spots. I investigated this natural history observation using a complementary approach of both lab and field experiments. With this approach I asked three main questions: what impacts host susceptibility to black spot fungus, how harmful are the black spots, and lastly who is the black spot fungus? Both leaf age and trichome density were investigated for their impact on host susceptibility. The most recently developed leaves as well as trichome dense leaves exhibited the lowest probability of infection. I also measured the impact of abiotic and biotic environmental factors on host susceptibility to black spot fungus. I found that the abiotic factor of moisture level had a much larger impact on black spot infection than the biotic factor of M. lupulina’s mutualist microbe. Lastly, the potential agent of the black spot infection was identified as Fusarium.