The three-dimensional (3D) learning model for science teaching and learning introduced in A Framework for K-12 Science Education and the Next-Generation Science Standards (NGSS) provide guidance towards including science practices in biology coursework. Science practices incorporate both content knowledge and skills and describe activities that scientists routinely engage in. The 3D-Learning Assessment Protocol (3D-LAP) provides criteria required for each science practice. We used the 3D-LAP to evaluate the extent to which three linked introductory biology laboratory courses have the potential to engage students in science practices. In the three courses, we found that 24/25 of the lab sessions had the potential to engage students in at least one science practice, with a total of 152 instances over the three courses. There was strong emphasis on four practices: Analyzing and Interpreting Data, Developing and Using Models, and Constructing Explanations and Engaging in Argumentation from Evidence. However, three practices-Planning Investigations, Communicating Information, and Defining Problems/Designing Solutions-were not identified in any of the biology laboratory sessions. In the courses we investigated, we also found that the potential for students to engage in science practices would increase by 89% if activities that met all but one criterion from the 3D-LAP ("near misses") were modified so that all criteria were met. Based on our assessment, if near misses were available in these courses, students would have the opportunity to engage in two science practices that are otherwise absent from the laboratory curriculum. We propose that instructors can align introductory-level, course-based laboratory work with the criteria in the 3D-LAP. A practice-focused curricula can help students gain technical facility and participate in science practices in ways that also support the Core Competencies described in Vision and Change.
Abstract Plasticity—the ability of a genotype to produce different phenotypes in response to environmental input—can provide insight into the mechanical forces experienced by biological structures. Bones are particularly plastic, remodeling in response to sustained and repetitive mechanical stress. In many mammals, males possess a bone in their penis called a baculum. Across species, its extreme morphological divergence suggests it undergoes recurrent adaptive evolution, and several studies have explicitly linked baculum size and shape to reproductive fitness. However, the precise functions of this bone remain largely unknown. Here we test whether copulation imposes mechanical loading sufficient to induce remodeling in the baculum. We compared bacula of mated vs. unmated males across five rodent species with divergent baculum morphologies and mating ecologies, using high-resolution morphometric analyses of size and shape, and synchrotron-enabled quantification of bone microstructure. We found no consistent effect of mating on size, shape, or microstructure of the baculum. These results suggest that copulation does not impose mechanical loads sufficient to induce remodeling in the baculum. More broadly, our findings indicate that the rapid evolutionary divergence of the baculum is unlikely to be enabled by plasticity associated with copulation.
Developing data literacy is a core goal of biology education, yet many students struggle to engage with scientific research and data. DataVersify is a resource designed to support data literacy while simultaneously humanizing science. These activities integrate two established programs, Data Nuggets and Project Biodiversify, to engage students in the work of scientists and introduce them to the people behind the research. Within each activity, students encounter a scientist profile, read about a study, explore and visualize a dataset, construct evidence-based explanations, and ask questions of their own. Here, we synthesize over a decade of resource development and large-scale, coordinated research efforts to share the effective features of DataVersify activities. We found that pairing data literacy activities with humanizing details about a scientist's life in and out of science increases students' ability to relate to scientists and engage with course materials. We present six evidence-based recommendations for using DataVersify, including emphasize authenticity, pair data with scientist stories, and highlight a variety of contemporary scientist role models. Together, our work demonstrates how integrating authentic data experiences with scientist stories can support student outcomes in data literacy and biology education.
Synopsis Low temperature is a major environmental constraint for animals inhabiting cold plateau regions because it increases thermoregulatory energy demand and can disrupt oxidative balance. We examined physiological responses of two sympatric plateau rodents, Eothenomys miletus and Apodemus chevrieri, during 28 days of cold exposure (5°C ± 1°C) relative to control conditions (25°C ± 1°C). Both species increased resting metabolic rate (RMR) and food intake and showed lower body mass under cold conditions. Cold exposure also increased liver mass and induced digestive-tract remodeling, with more extensive changes in E. miletus than A. chevrieri. Activities of the antioxidant enzyme superoxide dismutase (SOD) and catalase (CAT), together with the oxidative stress markers malondialdehyde (MDA) and hydrogen peroxide (H2O2), changed in a tissue- and species-specific manner. Correlation and principal component analyses further indicated different patterns of oxidative regulation in the two species. Eothenomys miletus showed a comparatively dense inter-organ correlation structure centered on CAT, whereas A. chevrieri showed fewer significant inter-organ associations. Thus, the two rodents share a broad metabolic response to sustained cold exposure but differ in the organ-level organization of oxidative balance.
Geometric morphometrics (GM) is a well-established and cost-effective approach for quantifying shape variation and has been widely applied over the past few decades to resolve morphological differentiation and to discriminate among closely related taxa. A key analytical advantage of GM lies in its structured workflow, which transforms complex morphological features into multivariate shape data while inherently managing dimensionality. Consequently, GM outputs serve as powerful, optimized feature sets for training machine learning classifiers in taxonomic and ecological studies. We present an integrative framework combining GM, traditional machine learning (ML) algorithms, and convolutional neural networks (CNNs) for species discrimination. This study focused on the classification of digital wing images of Aedes vittatus and Aedes aegypti using a small binary dataset as a case study, and proposes a hybrid methodology integrating these approaches within a GM-based workflow. We evaluated multiple ML classifiers trained on principal component (PCA)-reduced features derived from GM. Furthermore, Procrustes-aligned and raw landmark coordinates were converted into rasterized grayscale images, enabling the application of CNNs to landmark-based shape data derived from GM. All approaches successfully discriminated the two Aedes species. During model development, traditional ML classifiers based on selected principal components achieved high internal performance, with the support vector machine (SVM) producing the strongest results among them. In contrast, CNN performance varied depending on network architecture and input representation. Among the evaluated models, the Baseline CNN exhibited the greatest stability, demonstrating consistent performance across input types and better generalization on independent data. Based on bootstrapped external validation, it achieved the highest overall classification performance, exceeding that of the best-performing ML model (SVM). The Deep CNN showed strong dependence on input representation, achieving acceptable performance only when trained on raw coordinate images that retained original size, orientation, and scale information. This highlights the sensitivity of deeper architectures to feature representation, particularly after Procrustes normalization. Notably, transfer learning using the pre-trained MobileNetV2 model performed poorly across all data formats, likely due to substantial domain mismatch between ImageNet natural images and the sparse, abstract representations of landmark-based GM data. Overall, this study establishes a proof-of-concept framework that integrates GM, ML, and CNN approaches, demonstrating their complementary strengths for species discrimination under data-limited conditions.
Specialized ecological niches can represent evolutionary traps that increase extinction risk when environments change. The consumption of coral tissue, mucus, and skeleton is a rare feeding niche despite the abundance of coral on reefs, which raises questions about the evolutionary consequences of this dietary specialization. In this study, we used phylogenetic comparative methods, micro-CT scanning, and scanning electron microscopy to explore the evolutionary history of corallivory across reef fishes and compare feeding morphology across species within a major clade of corallivorous species (Chaetodontidae) that vary in their coral consumption. We show that obligate corallivory has evolved independently at least 17 times but is an evolutionary "dead end" for most reef fish species. Early origination of facultative corallivory may have contributed to the success of butterflyfishes, the predominant clade of coral-feeding fishes, as they diversified in competitive reef environments. Obligate and facultative butterflyfish species differ primarily in dental morphology while overall cranial traits are largely similar between groups. Coral feeding requires continuous foraging with narrow energetic margins, and climate-driven disturbances occur markedly faster than evolutionary transitions away from corallivory. This temporal mismatch between change at ecological and evolutionary timescales subjects corallivorous fishes to heightened vulnerability as climate-driven disturbances increase in frequency and severity.
Chimaeras-a group of cartilaginous fishes-swim using a distinctive locomotory mode, termed flapping flight. Dorsoventral oscillation of the flexible pectoral fins is driven by muscles at the base of the fin. This motion induces an undulatory wave which travels from the leading edge to the trailing edge of the fin. It is thought that this undulatory wave is passively induced, and hence, the kinematic waveform is largely influenced by the fin's structure. Recent work focusing on bony fishes and models of their fins has shown that fin models with internal structure (fin rays) show different kinematic waveforms than models made of a single material, but our understanding of which structural parameters of fin rays are most influential on kinematics is still developing. Our goal was to understand the significance of internal structure for the swimming kinematics of chimaeras. We designed a physical modeling system based on the kinematic patterns of real chimaeras and examined artificial fins of varying fin ray diameter and packing density to investigate how internal anatomy influences pectoral fin tip amplitude, leading-edge curvature, and undulatory waves. As diameter and packing density increased, fin tip amplitude and leading-edge curvature decreased. Diameter had a much larger effect on fin tip amplitude than packing density over the tested ranges. Surprisingly, undulatory wave speed was greatest in the most flexible fin models rather than the stiffest. Empirical evidence and the mathematical equations stating that wave speed increases with stiffness run counter to this last result, suggesting our findings align with a more nuanced relationship between fin stiffness and wave kinematics described by a mathematical fluid flow model. Our work provides new insights into the anatomical parameters that could influence the evolution of chimaera flapping flight and pectoral fin locomotion more broadly and provides direction for possible biomimetic applications.
The three bird species within the family Anhimidae (screamers) are of great interest to the big picture of avian evolution due to both their phylogenetic position and their unusual combination of features. As screamers are early diverging members of Anseriformes (waterfowl), which itself is an early diverging clade within the extant bird radiation, their anatomy may help shed light on that of the common ancestor of both Anseriformes and crown-group birds as a whole. To reveal new information about the wing anatomy of anhimids, we generated a three-dimensional musculoskeletal model of the flight apparatus of the extant Southern Screamer (Chauna torquata) using diffusible iodine-based contrast-enhanced computed tomography (diceCT). We found that the wing muscle anatomy of Chauna reflects the soaring flight style employed by anhimids, as opposed to the rapid continuous wingbeats used by most other anseriforms. In Chauna, this manifests as a more distal insertion of the pectoralis muscle on the humerus to facilitate slower, stronger wingbeats, and a reduction in the length of antebrachial muscle origins and insertions that serves to reduce the distal inertia of the wing. Our three-dimensional dataset represents a typical musculoskeletal system of a bird with strong flight capabilities. This, combined with our observation that most flight-related muscles in Chauna leave recognizable osteological correlates associated with their attachments to the skeleton, means that this work can help form a basis for future comparative studies of the avian musculoskeletal system, with implications for reconstructing the flight apparatus of fossil birds.
Recent innovations in a species may expand opportunities to obtain new resources or previously inaccessible habitats. Over time, the novel behavior may diversify in response to an adaptive landscape or become canalized by convergent selective pressures into a narrowed performance window. Selective pressures also change across life stages, which may further enhance diversification or constrain performance. To test these alternative hypotheses, we compared ontogenetic changes in the performance of a novel locomotor behavior-waterfall-climbing-across five amphidromous species of gobiid fishes from the Pacific, Caribbean, and Indian Oceans. Two species climb waterfalls using an inching motion, a derived functional innovation that alternates movements of pelvic and oral suckers. The remaining species climb waterfalls using short "powerbursts" of swimming, followed by long rest periods in which the pelvic sucker is attached to the waterfall substrate. Among adults, net climbing speed (including rest) was similar across the three powerburst species and one inching species, but a derived, faster speed was observed in one inching taxon, suggesting greater functional diversity in the younger innovation. However, kinematic data indicate that similar performance levels can be achieved through multiple functional pathways. Moreover, patterns of functional diversity across species observed in juveniles do not track neatly into adulthood, highlighting the range of potential influences that can shape the trajectory of ontogenetic change in function.
Maternal effects play a key role in shaping offspring phenotype variation in birds, particularly through the allocation of different substances into the egg yolk. Among these, androgens and antioxidants are essential for early development. These compounds may exert sex-specific effects, as male and female offspring often differ in their development even from very early phases of their ontogeny. It has been therefore hypothesized that females might strategically allocate different amounts of these yolk compounds depending on the sex of the embryo. To test this hypothesis, we conducted an observational study in a wild population of spotless starlings (Sturnus unicolor), measured yolk concentrations of androgens (testosterone and androstenedione) and antioxidants (vitamin E, vitamin A, and carotenoids) in freshly laid eggs, and molecularly sexed the embryos from those eggs. We found no evidence that embryo sex influenced the concentration of any yolk compound. These results suggest that sex-specific allocation is constrained, possibly due to mechanistic limitations, such as the tight temporal overlap between oocyte meiosis (when embryonic sex is determined) and yolk formation. We also conducted a systematic literature review of studies that tested the association between embryo sex and yolk androgens and/or antioxidants in birds. Most studies (73%) did not report any significant effect. Among those that did, effects were often context-dependent or potentially biased by the effect of embryonic metabolism due to late sampling after laying. Overall, we found no robust evidence supporting differential maternal allocation of these yolk compounds based on embryo sex.
Abstract This teaching innovations article explains how to develop a course-based undergraduate research experience built upon data from the Paleobiology Database with the principles of relational culture theory. This approach integrates psychosocial skills associated with research, like persistence through frustration, with scientific skills, such as observation, statistical analysis, locating and reading primary literature, and writing a scientific paper. Specifically, this course was designed to align with The Five Good Things in relational culture theory: to develop positive learning ethos, to create knowledge, development of self-worth, action or movement toward deeper learning, and a desire for continued learning. To achieve these aspects of relational culture theory, the course uses a survey—issued on the first day of class and revisited throughout the term—to establish a connection between the instructor and students; weekly observations of photos of fossils to make data from the Paleobiology Database less abstract; and an alternative grading scheme that emphasizes spiral feedback. This course meets once a week, with extra homework in lieu of additional class time. The first part of the course teaches paleobiology content through interactive lectures, carefully selected readings, and short videos. Students use collaborative note-taking software to discuss readings and videos that inspire research topics. The second part of the course is about analyzing paleobiological data, and students learn different statistical tests they can apply; simultaneously, they formulate their research hypotheses and download their data. This section of the course concludes with students analyzing their own data. In the third part of the course, students use primary literature to both justify the study and interpret the results they obtained. The final project is a scientific paper, which some students choose to submit to the campus research journal. Relational culture theory adds value to the research experience, and the strategies that build it into this course can be adopted to other contexts. In the future, focus group interviews with undergraduates who have taken the course could offer a nuanced analysis of the simultaneous effects of the approaches.
Abstract Garter snakes are semi-aquatic obligate carnivores with diverse diets and behavioral adaptations for foraging at the water’s edge. In this study, we tested the persistence of innate chemosensory prey preference and aquatic prey capture ability in two garter snake species, the Lake Chapala garter snake (Thamnophis eques obscurus) and checkered garter snake (T. marcianus) that were captive bred and naïve to aquatic prey and aquatic prey capture contexts. Using number of tongue flicks, number of attacks, and attack latency as proxy for interest in terrestrial and aquatic prey extracts, we corroborated dietary preferences reported in the literature that described T. e. obscurus as an obligate forager and T. marcianus as a facultative aquatic forager in their native habitat. We then categorized strike mode and quantified several metrics describing prey capture efficiency at two treatment depths – shallow (2 cm; wading depth) and deep (10 cm; submerged depth). At shallow depths, T. e. obscurus used mostly forward strikes, had a greater gape angle, was more accurate at striking live mosquito fish, was faster at capturing fish prey, and had better visual acuity as indicated by pupil constriction. In shallow water, T marcianus used lateral strikes to capture prey. Foraging at increased depth resulted in forward strikes, larger gape angles, longer prey capture latency, longer foraging times, and greater pupil constriction in both species. Moreover, in deeper water, both snake species tended to stay underwater to transport (swallow) prey rather than resurface. We also compared head shape to help explain strike mode and found that T. e. obscurus had narrower and shorter heads compared to T. marcianus who had wider and taller heads. Our work provides insight into the innate prey preference of naïve snakes and their adaptability to aquatic prey capture contexts. Specifically, we show how an aquatic specialist is more efficient at capturing aquatic prey but that a terrestrial-aquatic generalist is flexible and exhibits behavioral variation across aquatic contexts. Finally, we show how the deep-water context requires behavioral convergence in strike mode, pupil constriction to respond to refractive changes in the water, and tests the ability of semi-aquatic snakes to stay underwater for longer periods of time.
Notable characteristics of bonnethead sharks (Sphyrna tiburo) include an omnivorous diet and sexual dimorphism in cephalofoil morphology, with males exhibiting a more prominent tip at the anterior of their snout, which one study hypothesized develops with sexual maturity. However, it is not known if this characteristic is prevalent in all bonnethead subpopulations, nor whether it is consistent across their range. The potential ecological or physiological function (mating, feeding, swimming energetics) of this difference is also unknown. In this study, cephalofoil morphology was assessed by sex and maturity for bonnethead sharks in Biscayne Bay and Tampa Bay, Florida. Additionally, muscle biopsies were analyzed for stable isotope composition to explore potential associations with diet. Sharks were caught between May 2022 and May 2023 via longline (Biscayne) and gillnet (Tampa). Body measurements and dorsal and ventral photographs of the head were taken as part of a scientific workup and sharks were promptly released. Images were analyzed in ImageJ to determine a best-fit parabolic curve; comparisons of cephalofoil curvature were based on the absolute "a" coefficient from the parabolic curve equation y = ax2 + bx + c via ANOVA and PERMANOVA. Shape coordinates were also analyzed with a Procrustes ANCOVA to test for differences among groups while controlling for covariates. In both Biscayne Bay and Tampa Bay, males and females had significantly different head shapes, but, contrary to previous hypotheses, the cephalofoils of both sexes became rounder at maturity. There was greater rounding in female cephalofoils than male, and females experienced greater changes in cephalofoil shape as they matured. Diet, as examined through δ13C and δ15N values of muscle biopsies, showed isotopically distinct food webs with differing ontogenetic dietary patterns between Biscayne Bay and Tampa Bay following ANOVA and ANCOVA tests, but was not correlated to bonnetheads' cephalic sexual dimorphism. From this result, we hypothesize that younger and smaller bonnethead sharks of both sexes may benefit from the pointed cephalofoil for enhanced swimming performance, and that larger adult females may outgrow these benefits through development of physical characteristics, including larger body sizes necessary for reproduction.
Global warming increasingly exposes ectotherms to temperatures near or beyond their physiological limits, threatening survival and persistence. Vulnerability of species to rising temperatures is shaped by multiple factors, including the thermal environments they experience, their physiological tolerances, and the temperature dependence of key performance traits. Here, we investigated the thermal ecology and climate vulnerability of two co-occurring tropical agamid lizards from semi-arid Southern India: the arboreal generalist Calotes versicolor and the saxicolous specialist Psammophilus dorsalis. For both species, we measured microenvironmental temperatures using physical copper models in open and shaded microhabitats, quantified field-active body temperatures (Tb), measured preferred temperature range (Tpref), critical thermal limits (CTmin and CTmax) and determined thermal performance curves for sprint speed and bite force. Thermal vulnerability indices (thermoregulatory accuracy, habitat thermal quality based on physical models, effectiveness of thermoregulation, warming tolerance, and thermal safety margin) were calculated and we projected future performance declines under IPCC Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP5-8.5). Although both species experienced similar microhabitat temperatures, they differed in thermoregulatory strategies and vulnerability. The widely distributed C. versicolor had a wider Tpref range, higher CTmax, lower CTmin, broader thermal tolerance range, greater thermoregulatory effectiveness in open microhabitats, lower deviations from preferred temperatures, and more favorable habitat thermal quality. In contrast, P. dorsalis displayed narrower Tpref range, lower CTmax, higher CTmin, narrower thermal tolerance and reduced thermoregulatory accuracy and effectiveness, operating closer to its upper thermal limits and experiencing narrower safety margins. Sprint speed had higher thermal optima and narrower performance breadths than bite force in both species, rendering locomotion more sensitive to warming. Projections indicated minimal impacts on both sprint speed and bite force, even under high-emission scenarios. Nevertheless, narrow warming tolerances, thermal safety margins, and the saxicolous specialization of P. dorsalis suggest potential vulnerability through other ecological and physiological axes. Our findings reveal that closely related co-occurring lizards can occupy different thermal niches and face unequal climate risks despite shared ambient conditions. Species differences in microhabitat specialization, rather than exposure alone, emerges as a key driver of thermal vulnerability, underscoring its critical role in shaping resilience to ongoing climate warming.
Research in science education highlights the value of sensemaking-the process of identifying gaps in understanding and constructing explanations to fill them-for student learning and engagement. Yet college students often perceive undergraduate biology classrooms as prioritizing correct answers over their own questions and ideas. In this paper, we argue that eliciting students' questions about what they find confusing can create opportunities for them to engage in creative and critical thinking to make sense of biological phenomena. We illustrate this conceptual argument with examples drawn from three interviews with college students about evolutionary biology. We show how framing interviews around students' questions led to productive biological sensemaking and conclude by discussing implications for how biology instructors might foster a sensemaking approach in their classrooms.
The Linnaean family of monkeys that includes baboons, macaques, and mandrills (among others) is notably characterized by large, extended muzzles that vary in lateral nasal dorsum profile. In paleontological studies, this variation is referred to as the anteorbital drop (AOD). Here, we first devise a method to quantify this phylogenetic character. We then employ quantitative genetic analyses using a MCMCglmm model of facial variation in a captive, pedigreed baboon colony (n = 934), including admixed individuals derived from at least two Papio species, from the Southwest National Primate Research Center to assess the quantitative variation of the AOD, its genetic integration relative to other aspects of facial variation, and its relative evolvability. Specifically, we test two hypotheses to assess the appropriateness of the AOD as a way to characterize lateral nasal dorsum profile variation for paleontological studies. We find that the first hypothesis of limited variation within the population is rejected, as this admixed population demonstrates a remarkable degree of AOD variation spanning what is observed across papionin genera. The second hypothesis proposes that variation in the AOD is highly heritable and highly evolvable. Our results indicate that the AOD is highly heritable, but simultaneously less evolvable than other aspects of facial variation. Additionally, sex has little influence on AOD variation, in contrast to other facial measurements. These results challenge the use of AOD as a phylogenetic character, as it likely results from a broad range of non-sexually dimorphic processes that contribute to facial length. We caution against using AOD as a discrete character in phylogenetic analyses and invite further investigation of its biological significance. This study aims to illustrate how quantitative genetic approaches can probe the evolutionary relevance of traditional traits used in paleontology.
Outreach events are an excellent way to expose science disciplines to the public beyond the ivory tower of academics. In this paper, we describe how a zoo-academia collaborative team designed and hosted an interdisciplinary outreach event exposing thousands to the wonders of bio-inspired design and biomechanics. Over the past 4 years, we have run such a collaborative outreach event which has attracted 26,750 people, allowing children and adults to be exposed to diverse research fields through our annual Zoo Biomechanics Day. In partnering with labs, companies, and student organizations, we have hosted 17 unique booths highlighting human, plant, and animal biomechanics and bio-inspiration to showcase engaging demonstrations of science, technology, engineering, arts, and medicine principles. This event is low-cost ([Formula: see text] annually) while increasing attendance at the zoo by over 65% compared to similar non-event days. Furthermore, participating researchers get connected to the zoo, allowing discussions of new collaborative research between the zoo and universities. This paper will serve as a framework for others to host events which highlight the zoo-university collaborations that enhance the dual objectives of outreach and research at modern zoos.
Cheek teeth are filled to the cusp with information about mammalian evolution. Studying the evolution of mammalian cheek tooth crown complexity has benefited our understanding of mammalian evolution in developmental, morphological, and ecological contexts. Most work is focused on individual cheek tooth loci as opposed to considering the premolars and molars as serial homologues. This focus on individual tooth loci has left the exploration of inter-regional phenomena understudied. One such phenomenon is the molarization of premolars across hoofed mammals; some have simple unicuspid premolars while others have premolar crowns that are equal in complexity to their molars. Many developmental models have been proposed to understand cheek tooth evolution, but minimal work has been done to synthesize these models into a holistic understanding of cheek tooth crown complexity evolution. We investigated if applying a synergized theoretical framework of the inhibitory and patterning cascade model to artiodactyl and perissodactyl taxa could be used to study the evolution of molarization in hoofed mammals. We applied an existing 2D landmarking scheme for the upper and lower premolar molar boundaries of hoofed mammals to capture the morphology across this important identity boundary. Shape data were analyzed through phylogenetically informed modularity analyses to capture the covariation structure at the upper and lower premolar-molar boundaries. A-priori modularity hypotheses were proposed based on developmental models including the patterning cascade model and the inhibitory cascade model. Both artiodactyl and perissodactyl results showed support for modularity across the upper and lower premolar molar boundary but showed more variation in the upper premolar molar boundary. Artiodactyls show consistency in support for modularity hypotheses between upper and lower premolar molar boundaries where perissodactyls show significant differences in support for modularity hypotheses between upper and lower premolar molar boundaries. Our results illustrate that the covariation structure at the premolar molar boundary has convergent and divergent elements that both have consequences for our understanding of the evolution of molarization within and between artiodactyls and perissodactyls.
The nature of speciation within subterranean ecosystems following invasions from the surface remains poorly understood. Most proposed examples of in situ subterranean speciation instead appear to reflect multiple independent surface invasions, supporting the classic hypothesis that subterranean ecosystems are evolutionary dead ends. Here, we examine the species diversity within the most widespread subterranean vertebrate species, the Southern Cavefish Typhlichthys subterraneus. Phylogenomic analyses reveal that T. subterraneus as currently recognized is paraphyletic with respect to the Missouri Cavefish T. eigenmanni, as a distinct set of populations is resolved as the sister lineage of a clade formed by T. eigenmanni and T. subterraneus sensu stricto. High-resolution computed tomography (CT) scanning reveals skeletal autapomorphies of this lineage, supporting its recognition as a new species: Typhlichthys styx sp. nov. Ancestral biogeographic reconstructions reveal that speciation in Typhlichthys has occurred along aquifer boundaries, with lineages dispersing through widespread karstic aquifer systems across southeastern and central North America. This dispersal facilitated secondary sympatry among cavefish species that last shared common ancestry approximately eight million years ago. Together, these results reveal aquifer geology as a driver of allopatric speciation in obligate cave-dwelling vertebrates, with implications for understanding biodiversity in subterranean ecosystems worldwide.
Engaging students in integrative and organismal biology often requires instructional approaches that balance disciplinary rigor with accessibility and curiosity. Extraordinary traits in real organisms, such as regeneration in axolotls, echolocation in bats, or cryptobiosis in tardigrades, offer compelling entry points for exploring adaptation, evolutionary trade-offs, and the diversity of life. This article describes a curriculum activity, Biology of Superpowers, designed to leverage these traits to promote engagement, reinforce evolutionary concepts, and develop science communication skills in courses spanning introductory and upper-level biology. In this activity, students select a biological "superpower," investigate its functional mechanisms and adaptive significance, and communicate their findings in a creative, public-facing format. An optional extension invites students to connect their chosen trait to superheroes or fictional characters, prompting critical evaluation of scientific accuracy and common misconceptions in popular media. The activity has been implemented in two distinct settings: an introductory non-majors Diversity of Life course and an upper-level Evolution course for biology majors. These dual contexts illustrate the adaptability of the assignment across levels. In the non-majors course, students emphasized accessible explanations and broad connections to survival and reproduction for general audiences, whereas majors more often incorporated mechanistic detail, comparative thinking, and consideration of constraints and trade-offs. Assessment is guided by revised rubrics that emphasize biological explanation, evolutionary reasoning appropriate to course level, clarity of communication, and use of evidence. Student artifacts are presented as illustrative examples of engagement with the activity rather than as formal evidence of learning gains. To strengthen implementation, the revised instructor and student materials include explicit prompts related to source evaluation, image attribution, appropriate AI use, and avoidance of common evolutionary misconceptions such as teleological reasoning or framing evolution as only about survival. Blank organizer templates are also provided to support scaffolding across course contexts. Together, these materials position Biology of Superpowers as a flexible curriculum model for teaching integrative and organismal biology by pairing curiosity-driven content with evolutionary thinking, evidence use, and science communication.
