Scholarly Works, Biological Sciences

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Drivers of population dynamics of at-risk populations change with pathogen arrival
Grimaudo, Alexander T.; Hoyt, Joseph R.; King, R. Andrew; Toomey, Rickard S.; Simpson, Chris; Holliday, Cory; Silvis, Alexander; Doyle, Rick T.; Kath, Joseph A.; Armstrong, Mike P.; Brack Jr, Virgil; Reynolds, Richard J.; Williamson, Ryan H.; Turner, Gregory G.; Kuczynska, Vona; Meyer, Jordan J.; Jansky, Kyle; Herzog, Carl J.; Hopkins, Skylar R.; Langwig, Kate E. (Elsevier, 2024-08-01)
Successful wildlife conservation in an era of global change requires understanding determinants of species population growth. However, when populations are faced with novel stressors, factors associated with healthy populations can change, necessitating shifting conservation strategies. For example, emerging infectious diseases can cause conditions previously beneficial to host populations to increase disease impacts. Here, we paired a population dataset of 265 colonies of the federally endangered Indiana bat (Myotis sodalis) with 50.7 logger-years of environmental data to explore factors that affected colony response to white-nose syndrome (WNS), an emerging fungal disease. We found variation in colony responses to WNS, ranging from extirpation to stabilization. The severity of WNS impacts was associated with hibernaculum temperature, as colonies of cold hibernacula declined more severely than those in relatively warm hibernacula, an association that arose following pathogen emergence. Interestingly, this association was opposite that of a sympatric bat species, the little brown bat (Myotis lucifugus), illustrating that environmental dependence of disease can vary by species in a multi-host community. Simulating future colony dynamics suggests that most extirpations have already occurred, as the pathogen has been present for several years in most colonies, and that relatively small colonies are more susceptible to extirpation. Overall, this study illustrates that emerging infectious diseases can change the factors associated with host population growth, including through novel environmental associations that vary by host species. Consideration of these shifting associations and differences between impacted species will be essential to the conservation of host communities challenged by emerging infectious disease.
Variability in Ice Cover Does Not Affect Annual Metabolism Estimates in a Small Eutrophic Reservoir
Howard, Dexter W.; Brentrup, Jennifer A.; Richardson, David C.; Lewis, Abigail S. L.; Olsson, Freya E.; Carey, Cayelan C. (American Geophysical Union, 2024-07-01)
Temperate reservoirs and lakes worldwide are experiencing decreases in ice cover, which will likely alter the net balance of gross primary production (GPP) and respiration (R) in these ecosystems. However, most metabolism studies to date have focused on summer dynamics, thereby excluding winter dynamics from annual metabolism budgets. To address this gap, we analyzed 6 years of year-round high-frequency dissolved oxygen data to estimate daily rates of net ecosystem production (NEP), GPP, and R in a eutrophic, dimictic reservoir that has intermittent ice cover. Over 6 years, the reservoir exhibited slight heterotrophy during both summer and winter. We found winter and summer metabolism rates to be similar: summer NEP had a median rate of -0.06 mg O2 L-1 day-1 (range: -15.86 to 3.20 mg O2 L-1 day-1), while median winter NEP was -0.02 mg O2 L-1 day-1 (range: -8.19 to 0.53 mg O2 L-1 day-1). Despite large differences in the duration of ice cover among years, there were minimal differences in NEP among winters. Overall, the inclusion of winter data had a limited effect on annual metabolism estimates in a eutrophic reservoir, likely due to short winter periods in this reservoir (ice durations 0-35 days), relative to higher-latitude lakes. Our work reveals a smaller difference between winter and summer NEP than in lakes with continuous ice cover. Ultimately, our work underscores the importance of studying full-year metabolism dynamics in a range of aquatic ecosystems to help anticipate the effects of declining ice cover across lakes worldwide. Lakes and reservoirs around the world are experiencing decreases in ice cover duration, with many waterbodies starting to experience non-continuous ice cover throughout the winter. These changes in ice duration have the potential to influence carbon cycling, but to date few long-term studies have included winter data. We analyzed 6 years of minute-resolution oxygen data from a small reservoir that experiences non-continuous ice cover to estimate whether the surface water was a source or sink of carbon at daily, seasonal, and annual scales. We found that the reservoir was often a source of carbon to the atmosphere, regardless of whether data from winter were included. Our results differed from previous studies conducted in higher-latitude lakes that experience continuous ice cover throughout the winter, potentially due to the already-short duration of ice cover in this reservoir. As the duration of ice cover continues to decrease across lakes and reservoirs worldwide, our work highlights the need for studying how changing winter conditions-especially non-continuous ice cover-affects year-round carbon cycling. Winter data have rarely been included in lake metabolism studies, limiting our understanding of how ice affects metabolism estimates Annual metabolism estimates were similar across 6 years with widely varying ice cover Water chemistry explained variability in daily gross primary production, but not respiration or net ecosystem production, over 6 years
Microplastic burden in native (Cambarus appalachiensis) and non-native (Faxonius cristavarius) crayfish along semi-rural and urban streams in southwest Virginia, USA
Gray, Austin; Mayer, Kathleen; Gore, Beija; Gaesser, Megan; Ferguson, Nathan (Academic Press – Elsevier, 2024-10-01)
Our comparative assessment is the first study to investigate microplastic body burden in native (Cambarus appalachiensis) and non-native (Faxonius cristavarius) crayfish along a semi-rural and urban stream across different seasons. Crayfish, sediment, and surface water were collected, processed, and characterized using mu Raman spectroscopy to compare microplastic polymer types and shapes across compartments. Average surface water concentrations were significantly higher in our urban stream compared to our semi-rural stream (17.3 +/- 2.4 particles/L and 9.9 +/- 1.3 particles/L, respectively; P = 0.015). Average sediment concentrations were similar between urban and semi-rural streams (140 +/- 14.5 particles/kg and 139 +/- 22.5 particles/kg, respectively; P = 0.957). Our findings showed a significant interactive effect of season, site, and nativity (i.e., species) regarding microplastic body burden in crayfish (P = 0.004). The smaller, non-native crayfish amassed more microplastic particles than the native crayfish (0.4-2.0 particles/g versus 0.4-0.8 particles/g, respectively). Fibers and fragments were the most common polymer shapes across compartments, with white and black being the dominant particle colors. Our study identified 13 plastic polymer types in crayfish and three in surface water and sediment; polypropylene was the most common polymer across compartments. This study provides evidence that crayfish body burden of microplastics can differ across species, seasons, and locations, highlighting the need for future studies to consider that sublethal impacts associated with microplastic body burden may vary by region and species.
Effects of climate change on seed germination may contribute to habitat homogenization in freshwater forested wetlands
Carr, Kori; Ozowara, Xavier; Sloey, Taylor M. (Springer, 2024-10-01)
Climate changes in temperate regions are expected to result in warmer, shorter winters in temperate latitudes. These changes may have consequences for germination of plant species that require a period of physiological dormancy. The effect of cold duration on seed germination has been investigated in a number of plant taxa, but has not been well studied in wetland and bottomland forest tree species, an ecosystem that is threatened by habitat homogenization. Our work sought to test the role of changing winter temperatures on seed germination in specialist (Nyssa aquatica and Taxodium distichum) and generalist (Acer rubrum and Liquidambar styraciflua) tree species within forested wetlands throughout the eastern U.S. The experiment was conducted in an environmental chamber in Norfolk, VA, USA. Seeds of T. distichum, N. aquatica, A. rubrum, and L. styraciflua were exposed to each of seven pre-germination cold exposure durations (0, 15, 30, 45, 60, 75, and 90 days) and observed for germination for 30 days. Cold stratification duration positively impacted total percent germination in N. aquatica (p < 0.0001) as well as A. rubrum (p = 0.0008) and T. distichum (p = 0.05). Liquidambar styraciflua seeds exhibited more rapid rates of germination with increasing cold exposure duration and greater percent germination compared to the others regardless of cold stratification duration. Our results provide insight into how community dynamics and biodiversity of wetland and bottomland trees may shift with a changing climate. Further, this work emphasizes the importance of understanding the role of plant functional traits in early life stages in community dynamics and has implications for management practices.
Individual-based modelling of adaptive physiological traits of cyanobacteria: Responses to light history
Ranjbar, Mohammad Hassan; Hamilton, David P.; Pace, Michael L.; Etemad-Shahidi, Amir; Carey, Cayelan C.; Helfer, Fernanda (Elsevier, 2024-09-01)
Adaptive physiological traits of cyanobacteria allow plasticity of responses to environmental change at multiple time scales. Most conventional phytoplankton models only simulate responses to current conditions without incorporating antecedent environmental history and adaptive physiological traits, thereby potentially missing mechanisms that influence dynamics. We developed an individual-based model (IBM) that incorporates information on light exposure history and cell physiology coupled with a hydrodynamic model that simulates mixing and transport. The combined model successfully simulated cyanobacterial growth and respiration in a whole-lake nutrient enrichment experiment in a temperate lake (Peter Lake, Michigan, USA). The model also incorporates non-photochemical quenching (NPQ) to improve simulations of cyanobacteria biomass based on validation against cyanobacteria cell counts and chlorophyll concentration. The IBM demonstrated that physical processes (stratification and mixing) significantly affect the dynamics of NPQ in cyanobacteria. Cyanobacteria had high fluorescence quenching and long photo-physiological relaxation periods during stratification, and low quenching and rapid relaxation in response to low light exposure history as the mixing layer deepened. This work demonstrates that coupling adaptive physiological trait with physical mixing into models can improve our understanding and enhance predictions of bloom occurrences in response to environmental changes.
Impacts of invasion on a freshwater cleaning symbiosis
Bell, Spencer S.; McElmurray, Philip; Creed, Robert P.; Brown, Bryan L. (Springer, 2024-08-01)
Organismal invasions have repeatedly been cited as a driving force behind the loss of biodiversity. Unlike many other impacts of invasion, the effect of invasion on native symbiont communities has received less attention. The introduction of invasive hosts presents a potential opportunity to native symbionts; invasive hosts could benefit native symbionts through providing a novel host environment that improves symbiont fitness relative to their fitness on native hosts. Alternatively, invasive hosts could noncompetent hosts for native symbionts, resulting in negative impacts on native symbiont abundance and diversity. Crayfish in the northern hemisphere host diverse assemblages of obligate annelid symbionts (P: Anellida, O: Branchiobdellida). Two invasive crayfish hosts in the genus Faxonius have been introduced and are interacting with the native crayfish hosts and their symbionts in three watersheds in western Virginia, USA. Previous studies suggest that the invasive host F. cristavarius is a less competent host for symbionts compared to native hosts in the genus Cambarus. We carried out an extensive survey in these watersheds to determine impacts of varying degrees of invasion on branchiobdellidan abundance and diversity. We also conducted a complementary host replacement experiment to investigate how increases in the relative abundance of invasive hosts contributes to observed patterns of symbiont abundance and diversity in the field. In our survey, as the proportion of invasive hosts at a site increased, branchiobdellidan abundance and diversity declined significantly. In the experiment, the worms dispersed onto both native and invasive hosts. As the percentage of noncompetent F. cristavarius hosts increased, the survival of branchiobdellidans declined. Both symbiont survival and opportunities for successful dispersal are reduced as this noncompetent invasive host progressively displaces native hosts, which imperils the integrity of native host-symbiont systems. Given that many native hosts accrue significant fitness benefits from their relationships with native symbionts, including hosts in our study system, losses of beneficial symbionts may produce a positive feedback loop that decreases invasion resistance of native species, exacerbates the effects of invasions, and presents a major conservation issue in invaded systems.
Membrane Composition Modulates Vp54 Binding: A Combined Experimental and Computational Study
Guo, Wenhan; Dong, Rui; Okedigba, Ayoyinka O.; Sanchez, Jason E.; Agarkova, Irina V.; Abisamra, Elea-Maria; Jelinsky, Andrew; Riekhof, Wayne; Noor, Laila; Dunigan, David D.; Van Etten, James L.; Capelluto, Daniel G. S.; Xiao, Chuan; Li, Lin (MDPI, 2025-10-03)
The recruitment of peripheral membrane proteins is tightly regulated by membrane lipid composition and local electrostatic microenvironments. Our experimental observations revealed that Vp54, a viral matrix protein, exhibited preferential binding to lipid bilayers enriched in anionic lipids such as phosphatidylglycerol (PG) and phosphatidylserine (PS), compared to neutral phosphatidylcholine/phosphatidylethanolamine liposomes, and this occurred in a curvature-dependent manner. To elucidate the molecular basis of this selective interaction, we performed a series of computational analyses including helical wheel projection, electrostatic potential calculations, electric field lines simulations, and electrostatic force analysis. Our results showed that the membrane-proximal region of Vp54 adopted an amphipathic α-helical structure with a positively charged interface. In membranes containing PG or PS, electrostatic potentials at the interface were significantly more negative, enhancing attraction with Vp54. Field line and force analyses further confirmed that both the presence and spatial clustering of anionic lipids intensify membrane–Vp54 electrostatic interactions. These computational findings align with experimental binding data, jointly demonstrating that membrane lipid composition and organization critically modulate Vp54 recruitment. Together, our findings highlight the importance of electrostatic complementarity and membrane heterogeneity in peripheral protein targeting and provide a framework applicable to broader classes of membrane-binding proteins.
Integrating Data Science Into Undergraduate Science and Engineering Courses: Lessons Learned by Instructors in a Multiuniversity Research-Practice Partnership
Naseri, Md. Yunus; Snyder, Caitlin; Perez-Rivera, Katherine X.; Bhandari, Sambridhi; Workneh, Habtamu Alemu; Aryal, Niroj; Biswas, Gautam; Henrick, Erin C.; Hotchkiss, Erin R.; Jha, Manoj K.; Jiang, Steven; Kern, Emily C.; Lohani, Vinod K.; Marston, Landon T.; Vanags, Christopher P.; Xia, Kang (IEEE, 2025-02-01)
Contribution: This article discusses a research-practice partnership (RPP) where instructors from six undergraduate courses in three universities developed data science modules tailored to the needs of their respective disciplines, academic levels, and pedagogies. Background: STEM disciplines at universities are incorporating data science topics to meet employer demands for data science-savvy graduates. Integrating these topics into regular course materials can benefit students and instructors. However, instructors encounter challenges in integrating data science instruction into their course schedules. Research Questions: How did instructors from multiple engineering and science disciplines working in an RPP integrate data science into their undergraduate courses? Methodology: A multiple case study approach, with each course as a unit of analysis, was used to identify data science topics and integration approaches. Findings: Instructors designed their modules to meet specific course needs, utilizing them as primary or supplementary learning tools based on their course structure and pedagogy. They selected a subset of discipline-agnostic data science topics, such as generating and interpreting visualizations and conducting basic statistical analyses. Although instructors faced challenges due to varying data science skills of their students, they valued the control they had in integrating data science content into their courses. They were uncertain about whether the modules could be adopted for use by other instructors, specifically by those outside of their discipline, but they all believed the approach for developing and integrating data science could be adapted to student needs in different situations.
Newton's cradle: Cell cycle regulation by two mutually inhibitory oscillators
Dragoi, Calin-Mihai; Tyson, John J.; Novak, Bela (Elsevier, 2024-11-01)
The cell division cycle is a fundamental physiological process displaying a great degree of plasticity during the course of multicellular development. This plasticity is evident in the transition from rapid and stringently-timed divisions of the early embryo to subsequent size-controlled mitotic cycles. Later in development, cells may pause and restart proliferation in response to myriads of internal or external signals, or permanently exit the cell cycle following terminal differentiation or senescence. Beyond this, cells can undergo modified cell division variants, such as endoreplication, which increases their ploidy, or meiosis, which reduces their ploidy. This wealth of behaviours has led to numerous conceptual analogies intended as frameworks for understanding the proliferative program. Here, we aim to unify these mechanisms under one dynamical paradigm. To this end, we take a control theoretical approach to frame the cell cycle as a pair of arrestable and mutually-inhibiting, doubly amplified, negative feedback oscillators controlling chromosome replication and segregation events, respectively. Under appropriate conditions, this framework can reproduce fixed-period oscillations, checkpoint arrests of variable duration, and endocycles. Subsequently, we use phase plane and bifurcation analysis to explain the dynamical basis of these properties. Then, using a physiologically realistic, biochemical model, we show that the very same regulatory structure underpins the diverse functions of the cell cycle control network. We conclude that Newton's cradle may be a suitable mechanical analogy of how the cell cycle is regulated.
Julian Hirniak, an early proponent of periodic chemical reactions
Manz, Niklas; Holovatch, Yurij; Tyson, John J. (Springer, 2024-10-01)
In this article we present and discuss the work and scientific legacy of Julian Hirniak, the Ukrainian chemist and physicist who published two articles in 1908 and 1911 about periodic chemical reactions. Over the last 110+ years, his theoretical work has often been cited favorably in connection with Alfred Lotka's theoretical model of an oscillating reaction system. Other authors have pointed out thermodynamic problems in Hirniak's reaction scheme. Based on English translations of his 1908 Ukrainian and 1911 German articles, we show that Hirniak's claim (that a cycle of inter-conversions of three chemical isomers in a closed reaction vessel can show damped periodic behavior) violates the Principle of Detailed Balance (i.e., the Second Law of Thermodynamics), and that Hirniak was aware of this Principle. We also discuss his results in relation to Lotka's first model of damped oscillations in an open system of chemical reactions involving an auto-catalytic reaction operating far from equilibrium. Taking hints from both Hirniak and Lotka, we show that the mundane case of a kinase enzyme catalyzing the phosphorylation of a sugar can satisfy Hirniak's conditions for damped oscillations to its steady state flux (i.e., the Michaelis-Menten rate law), but that the oscillations are so highly damped as to be unobservable. Finally, we examine historical and factual misunderstandings related to Julian Hirniak and his publications.
CO2 and CH4 Concentrations in Headwater Wetlands Influenced by Morphology and Changing Hydro-Biogeochemical Conditions
Lloreda, Carla Lopez; Maze, James; Wardinski, Katherine; Corline, Nicholas; Mclaughlin, Daniel; Jones, C. Nathan; Scott, Durelle; Palmer, Margaret; Hotchkiss, Erin R. (Springer, 2024-11-01)
Headwater wetlands are important sites for carbon storage and emissions. While local- and landscape-scale factors are known to influence wetland carbon biogeochemistry, the spatial and temporal heterogeneity of these factors limits our predictive understanding of wetland carbon dynamics. To address this issue, we examined relationships between carbon dioxide (CO2) and methane (CH4) concentrations with wetland hydrogeomorphology, water level, and biogeochemical conditions. We sampled water chemistry and dissolved gases (CO2 and CH4) and monitored continuous water level at 20 wetlands and co-located upland wells in the Delmarva Peninsula, Maryland, every 1-3 months for 2 years. We also obtained wetland hydrogeomorphologic metrics at maximum inundation (area, perimeter, and volume). Wetlands in our study were supersaturated with CO2 (mean = 315 mu M) and CH4 (mean = 15 mu M), highlighting their potential role as carbon sources to the atmosphere. Spatial and temporal variability in CO2 and CH4 concentrations was high, particularly for CH4, and both gases were more spatially variable than temporally. We found that groundwater is a potential source of CO2 in wetlands and CO2 decreases with increased water level. In contrast, CH4 concentrations appear to be related to substrate and nutrient availability and to drying patterns over a longer temporal scale. At the landscape scale, wetlands with higher perimeter:area ratios and wetlands with higher height above the nearest drainage had higher CO2 and CH4 concentrations. Understanding the variability of CO2 and CH4 in wetlands, and how these might change with changing environmental conditions and across different wetland types, is critical to understanding the current and future role of wetlands in the global carbon cycle.
Monocytes Reprogrammed by 4-PBA Potently Contribute to the Resolution of Inflammation and Atherosclerosis
Geng, Shuo; Lu, Ran; Zhang, Yao; Wu, Yajun; Xie, Ling; Caldwell, Blake A.; Pradhan, Kisha; Yi, Ziyue; Hou, Jacqueline; Xu, Feng; Chen, Xian; Li, Liwu (Lippincott Williams & Wilkins, 2024-09-27)
BACKGROUND:Chronic inflammation initiated by inflammatory monocytes underlies the pathogenesis of atherosclerosis. However, approaches that can effectively resolve chronic low-grade inflammation targeting monocytes are not readily available. The small chemical compound 4-phenylbutyric acid (4-PBA) exhibits broad anti-inflammatory effects in reducing atherosclerosis. Selective delivery of 4-PBA reprogrammed monocytes may hold novel potential in providing targeted and precision therapeutics for the treatment of atherosclerosis.METHODS:Systems analyses integrating single-cell RNA sequencing and complementary immunologic approaches characterized key resolving characteristics as well as defining markers of reprogrammed monocytes trained by 4-PBA. Molecular mechanisms responsible for monocyte reprogramming were assessed by integrated biochemical and genetic approaches. The intercellular propagation of homeostasis resolution was evaluated by coculture assays with donor monocytes trained by 4-PBA and recipient naive monocytes. The in vivo effects of monocyte resolution and atherosclerosis prevention by 4-PBA were assessed with the high-fat diet-fed ApoE-/- mouse model with IP 4-PBA administration. Furthermore, the selective efficacy of 4-PBA-trained monocytes was examined by IV transfusion of ex vivo trained monocytes by 4-PBA into recipient high-fat diet-fed ApoE-/- mice.RESULTS:In this study, we found that monocytes can be potently reprogrammed by 4-PBA into an immune-resolving state characterized by reduced adhesion and enhanced expression of anti-inflammatory mediator CD24. Mechanistically, 4-PBA reduced the expression of ICAM-1 (intercellular adhesion molecule 1) via reducing peroxisome stress and attenuating SYK (spleen tyrosine kinase)-mTOR (mammalian target of rapamycin) signaling. Concurrently, 4-PBA enhanced the expression of resolving mediator CD24 through promoting PPAR gamma (peroxisome proliferator-activated receptor gamma) neddylation mediated by TOLLIP (toll-interacting protein). 4-PBA-trained monocytes can effectively propagate anti-inflammation activity to neighboring monocytes through CD24. Our data further demonstrated that 4-PBA-trained monocytes effectively reduce atherosclerosis pathogenesis when administered in vivo.CONCLUSIONS:Our study describes a robust and effective approach to generate resolving monocytes, characterizes novel mechanisms for targeted monocyte reprogramming, and offers a precision therapeutics for atherosclerosis based on delivering reprogrammed resolving monocytes.
An unusually large genome from an unusually large stonefly: A chromosome-length genome assembly for the giant salmonfly, Pteronarcys californica (Plecoptera: Pteronarcyidae)
Eichert, Anna; Sproul, John; Tolman, Ethan R.; Birrell, Jackson; Meek, Jared; Heckenhauer, Jacqueline; Nelson, Charles Riley; Dudchenko, Olga; Jeong, Jiyun; Weisz, David; Aiden, Erez Lieberman; Hotaling, Scott; Ware, Jessica L.; Frandsen, Paul B. (Oxford University Press, 2025-05-01)
Pteronarcys californica () is commonly referred to as the giant salmonfly and is the largest species of stonefly (Insecta: Plecoptera) in the western United States. Historically, it was widespread and abundant in western rivers, but populations have experienced a substantial decline in the past few decades, becoming locally extirpated in numerous rivers in Utah, Colorado, and Montana. Although previous research has explored the ecological variables conducive to the survivability of populations of the giant salmonfly, a lack of genomic resources hampers exploration of how genetic variation is spread across extant populations. To accelerate research on this imperiled species, we present a de novo chromosomal-length genome assembly of P. californica generated from PacBio HiFi sequencing and Hi-C chromosome conformation capture. Our assembly includes 14 predicted pseudo chromosomes and 98.8% of Insecta universal core orthologs. At 2.40 gigabases, the P. californica assembly is the largest of available stonefly assemblies, highlighting at least a 9.5-fold variation in assembly size across the order. Repetitive elements account for much of the genome size increase in P. californica relative to other stonefly species, with the content of Class I retroelements alone exceeding the entire assembly size of all but two other species studied. We also observed preliminary suborder-specific trends in genome size that merit testing with more robust taxon sampling.
Population genomics of a specialized insect, Tetraopes texanus (Coleoptera: Cerambycidae), across a fragmented grassland system
Franzem, Thomas P.; Bucholz, Jamie R.; Lozier, Jeffrey D.; Ferguson, Paige F. B. (Springer, 2025-02-01)
Specialist insects are especially susceptible to loss of genetic diversity in the face of habitat destruction and fragmentation. Implementing effective conservation practices for specialist insects will benefit from knowledge of population structure and genetic diversity. Because insects are hyper-diverse, characterizing the population structure of all species within the insect community is untenable, even if focused within a particular habitat type. Thus, concentrating on a single species specialized to a particular habitat type is needed to infer general trends. Here, we investigate the range-wide population genetics of Tetraopes texanus Horn 1878 (Coleoptera: Cerambycidae), which provides a useful model of grassland insects due to its' habitat specificity and unique biology. Tetraopes texanus occurs primarily in Texas and Oklahoma, into Northern Mexico, and possibly into eastern New Mexico but also occurs in Black Belt prairies of Mississippi and Alabama. Mitochondrial and nuclear DNA (RAD-seq) analysis identified two distinct population clusters of T. texanus corresponding to the Texas and Oklahoma population and the Mississippi and Alabama population. Demographic models indicate ongoing, though incomplete, isolation of the two populations, with estimated dates of divergence in the mid-Pleistocene, coinciding with the end of a glacial period and a shift in glacial interval. These results can inform conservation of grassland adapted insects and offers insight to the biogeography of the Gulf Coastal Plain.
Combining graph theory and spatially-explicit, individual-based models to improve invasive species control strategies at a regional scale
Drake, Joseph; O'Malley, Grace; Kraft, John; Mims, Meryl C. (Springer, 2024-10-25)
Context: Invasive species cause widespread species extinction and economic loss. There is an increasing need to identify ways to efficiently target control efforts from local to regional scales. Objectives: Our goal was to test whether prioritizing managed habitat using different treatments based on spatial measures of connectivity, including graph-theoretic measures, can improve management of invasive species and whether the level of control effort affects treatment performance. We also explored how uncertainty in biological variables, such as dispersal ability, affects measures performance. Methods: We used a spatially-explicit, individual-based model (sIBM) based on the American bullfrog (Lithobates catesbeianus), a globally pervasive invasive species. Simulations were informed by geographic data from part of the American bullfrog's non-native range in southeastern Arizona, USA where they are known to pose a threat to native species. Results: We found that total bullfrog populations and occupancy declined in response to all treatments regardless of effort level or patch prioritization methods. The most effective spatial prioritization was effort-dependent and varied depending on spatial context, but frequently a buffer strategy was most effective. Treatments were also sensitive to dispersal ability. Performance of treatments prioritizing habitat patches using betweenness centrality improved with increasing dispersal ability, while performance of eigenvalue centrality improved as dispersal ability decreased. Conclusions: With the careful application of connectivity measures to prioritize control efforts, similar reductions in invasive species population size and occupancy could be achieved with less than half the effort of sub-optimal connectivity measures at higher effort rates. More work is needed to determine if trait-based generalities may define appropriate connectivity measures for specific suites of dispersal abilities, demographic traits, and population dynamics.
Unleash the power of values: how to conduct better science and cultivate thriving research groups
Schoenle, Laura A.; O'Brien, Caleb; Brousseau, Jennifer; Wendler, Amber (Springer, 2025-06-01)
It is undesirable - and perhaps impossible - for scientific research to be value-free. In fact, scientists can enhance their research and build more engaged, motivated, and well-functioning research groups by reflecting on their values and intentionally embedding values into all aspects of their research (e.g., choice of research question, funding sources, methodology). Here, we posit that values shape the scientific process and interpersonal dynamics within research groups. We then provide concrete steps to embed values into research by using tools such as values statements, mentoring expectations agreements, and lab handbooks. Finally, we provide a framework for culture-building activities that can encourage productive and fulfilling interactions among all research group members.
Assessment of the McMurdo Dry Valley Ecosystem: Environmental Stewardship in a Time of Accelerating Change
(Virginia Tech, 2025-10-16)
River Sediments Downstream of Villages in a Karstic Watershed Exhibited Increased Numbers and Higher Diversity of Nontuberculous Mycobacteria
Modra, Helena; Ulmann, Vit; Gersl, Milan; Babak, Vladimir; Konecny, Ondrej; Hubelova, Dana; Caha, Jan; Kudelka, Jan; Falkinham, Joseph O. III; Pavlik, Ivo (Springer, 2024-12-01)
The impact of residential villages on the nontuberculous mycobacteria (NTM) in streams flowing through them has not been studied in detail. Water and sediments of streams are highly susceptible to anthropogenic inputs such as surface water flows. This study investigated the impact of seven residential villages in a karst watershed on the prevalence and species spectrum of NTM in water and sediments. Higher NTM species diversity (i.e., 19 out of 28 detected) was recorded downstream of the villages and wastewater treatment plants (WWTPs) compared to sampling sites upstream (i.e., 5). Significantly, higher Zn and lower silicon concentrations were detected in sediments inside the village and downstream of the WWTP's effluents. Higher phosphorus concentration in sediment was downstream of WWTPs compared to other sampling sites. The effluent from the WWTPs had a substantial impact on water quality parameters with significant increases in total phosphorus, anions (Cl(-)and N-NH3-), and cations (Na+ and K+). The results provide insights into NTM numbers and species diversity distribution in a karst watershed and the impact of urban areas. Although in this report the focus is on the NTM, it is likely that other water and sediment microbes will be influenced as well.
Ectosymbionts improve host gill function in a freshwater cleaning symbiosis
Creed, Robert P.; Thomas, Michael J.; Meeks, April L.; Brown, Bryan L. (Springer, 2024-12-01)
Mutualisms are common interactions that involve a diverse array of taxa. An important aspect in the study of mutualisms is determining the mechanisms that underlie benefits in survival, growth and reproduction of the partner species involved. Crayfish are engaged in mutualisms with ectosymbiotic worms called branchiobdellidans. These worms benefit by using their crayfish hosts as safe habitat and sites for feeding and reproduction. Some of these worm species can improve crayfish survival and growth. We hypothesized that the worms influenced crayfish survival and growth by cleaning their gills of debris and fouling biota and that this cleaning would increase rates of host gas exchange and ammonia excretion. Using surveys and experiments, we examined the effect of the worms on crayfish ammonia excretion and oxygen consumption. There were positive effects of increasing worm density on ammonia excretion by crayfish hosts in both our survey and experiment. No effect of worm density was observed on oxygen consumption in either our survey or experiment. However, molt status of the surveyed crayfish (intermolt/premolt vs. recently molted) did affect oxygen uptake. Recently molted crayfish, which should have gill epithelia largely free of fouling organisms and debris, had higher levels of dissolved oxygen uptake than intermolt/premolt crayfish which should have had higher levels of gill fouling. Increased ammonia excretion at moderate worm densities likely underlies the increased survival and growth responses observed at these densities in previous experiments. Increased growth of crayfish hosting worms probably influences the impacts of these crustaceans on the benthic communities they occupy.
Poison Ivy (Toxicodendron radicans) Leaf Shape Variability: Why Plant Avoidance-By-Identification Recommendations Likely Do Not Substantially Reduce Poison Ivy Rash Incidence
Jelesko, John G.; Thompson, Kyla; Magerkorth, Noah; Verteramo, Elizabeth; Becker, Hannah; Flowers, Joy G.; Sachs, Jonathan; Datta, Jyotishka; Metzgar, Jordan (Wiley, 2023-09-28)
Avoidance of poison ivy plants is currently the primary approach to prevent the estimated 30–50 million annual poison ivy skin rash cases. The “leaves of three let it be” mnemonic device lacks specificity to differentiate poison ivy from other three-leaflet native plants. This report demonstrated that poison ivy leaves show marked total leaf shape variability that likely confounds accurate poison ivy plant identification, and significantly undermines a poison ivy avoidance strategy for mitigating poison ivy rash cases. Therefore, there is an ongoing need to develop prophylactic medical procedures to prevent poison ivy rash that do not depend on human poison ivy plant identification. Summary: Urushiol is the natural product produced by poison ivy (Toxicodendron radicans) that is responsible for millions of cases of delayed contact allergenic dermatitis in North America each year. Avoidance of poison ivy plant material is the clinically recommended strategy for preventing urushiol-induced dermatitis symptoms. However, poison ivy leaf shape is anecdotally notoriously variable, thereby confounding accurate poison ivy identification. This study focused on quantitative analyses of poison ivy and a common poison ivy look-alike (American hog peanut) leaf shape variability in North America to empirically validate the high degree of poison ivy leaf shape plasticity. Poison ivy and American hog peanut iNaturalist.org records were scored for seven attributes of compound leaf shape that were combined to produce a total leaf complexity score. Both the mean and the distribution of poison ivy total leaf complexity scores were significantly greater than that of American hog peanut. Non-metric multidimensional scaling analyses corroborated a high degree of poison ivy leaf shape variability relative to American hog peanut. A poison ivy accession producing frequent palmate penta-leaflet compound leaves was evaluated using linear regression modeling. Poison ivy total leaf complexity was exceedingly variable across a given latitude or longitude. With that said, there was a small but significant trend of poison ivy total leaf complexity increasing from east to west. Palmate penta-leaflet formation was significantly correlated with a stochastic leaflet deep-lobing developmental process in one unusual poison ivy accession. The empirically-validated poison ivy leaf shape hypervariability described in this report likely confounds accurate poison ivy identification, thereby likely resulting in many accidental urushiol-induced clinical allergenic dermatitis cases each year.

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