Integrative and Comparative Biology最新文献

Hydrostatic skeletal support is widespread among animals. If modeled as an isovolumetric cylinder that is longer than it is wide, a hydrostatic structure should undergo large changes in length for relatively small changes in diameter. This presents an underappreciated consequence for the muscle fibers controlling hydrostatic skeletal shape: longitudinally oriented muscle fibers may experience remarkably long operating ranges. Superelongation, or the ability to produce relatively high forces over an extreme range of muscle lengths, may thus be necessary for longitudinally oriented fibers. We discovered superelongation and an interesting morphological specialization in an obliquely striated muscle of the polychaete worm Glycera dibranchiata. These worms have an eversible proboscis that is used for burrowing and prey capture. The proboscis retractor muscles extend from the body wall to the gut and likely undergo a large stretch during proboscis eversion. Like two other previously described superelongating muscles in squid and leeches, the proboscis retractor muscles had a broad length-force relationship (LFR). At a given muscle length, however, some muscle fibers were folded while others were not (i.e., the folded fibers were longer than the whole muscle, at least when the muscle was partially contracted). The number of folded fibers and extent of folding were higher at shorter muscle lengths. We hypothesize that the short muscle fibers experience tension at all muscle lengths, while the folded fibers only experience tension at long whole muscle lengths. Thus, each retractor muscle contains populations of fibers of different lengths that may contribute differentially to the broad LFR. Superelongation with varying fiber folding may represent a previously unrecognized strategy in obliquely striated muscle for permitting high force production over a broad range of muscle lengths needed for hydrostatic skeletal support.

Artificial flowers have long been used in pollinator research to understand and manipulate key floral features such as rewards and display. Increased access to 3D printing and Internet of Things (IoT) technologies has expanded the capabilities of artificial flowers, enabling more precise control and real-time data collection. These IoT-enabled artificial flowers, referred to as robotic flowers or robo-flowers, integrate single-board computers, such as the Raspberry Pi series or similar embedded system devices, as well as affordable camera and sensor modules. However, despite their flexibility and modularity, the majority of robotic flowers are designed to investigate how pollinators make foraging decisions based on visual cues linked to floral rewards, with less attention paid to the broader information landscape that pollinators use to decide which flowers to visit. We have developed a robotic flower system that extends this approach to incorporate multimodal signaling capabilities as well as aversive floral stimuli. These stimuli were designed to allow for investigation into the more nuanced information tradeoffs that feature in pollinators foraging decisions, but the designs could be broadly useful for researchers interested in understanding insect nociception, decision-making, and apparent predation in the context of plant-pollinator interactions.

When terrestrial organisms locomote in natural settings, they must navigate complex surfaces that vary in incline angles and substrate roughness. Variable surface structures are common in arboreal environments and can be challenging to traverse. This study examines the walking gait of katydids (Tettigoniidae) as they traverse a custom-built platform with varying incline angles ($30^circ$, $45^circ$, $60^circ$, $75^circ$, $90^circ$) and substrate roughness (40, 120, and 320 grit sandpaper). Our results show that katydids walk more slowly as the incline angle increases and as katydid mass increases, with a decrease of around 0.3 body lengths per second for every 1$^circ$ increase in incline. At steeper inclines and larger sizes, katydids are also less likely to use an alternating tripod gait, opting instead to maintain more limbs in contact with the substrate during walking. Katydids also increased average duty factor when climbing steeper inclines and with increasing body mass. However, substrate roughness did not affect walking speed or gait preference in our trials. These findings provide insights into how environmental factors influence locomotor strategies in katydids and enhance our understanding of effective locomotor strategies in hexapods.

Reptiles are increasingly faced with conservation challenges and ecoimmunological techniques would be a beneficial tool in monitoring and evaluating populations that are at-risk. However, the reptilian immune system is poorly understood, and few studies have made intraspecies comparisons, making generalizations difficult. To help address this gap, innate immune function across three conspecific freshwater turtle species was evaluated. Red-eared sliders (Trachemys scripta elegans), Mississippi mud (Kinosternon subrubrum hippocrepis), and musk turtles (Sternotherus odoratus), are found throughout the Southeastern USA and represent different ecological microhabitats and life histories. In spring 2024, male aquatic turtles were caught using hoop nets, and blood samples were taken to assess immune characteristics. Microbial killing assays were conducted using multiple blood serum and buffy layer (hereafter referred as "serum + BL") manipulations (fresh, frozen, and frozen + heat manipulated serum + BL) as well as three microbes that activate specific immunological responses: Gram-positive bacterium (Staphylococcus aureus), Gram-negative bacterium (Escherichia coli), and a fungus (Candida albicans). By using this suite of microbial assays, differences in immune prioritization can be observed across species. This study revealed that there are differences in immunocompetence in each species of freshwater turtle that varied by microbe and serum + BL manipulation. We determined that because of the contribution of complement proteins when challenged against Gram-negative bacteria, frozen manipulated serum + BL appears to be a reliable way to assess immunocompetence in individuals across turtle species. Conducting intraspecies comparisons in immune function using integrative approaches can provide valuable insight into the underlying patterns of physiological variability within wild organisms, especially those that are of conservation concern.

Dermal denticles (scales) are important in influencing the movement of water around a shark's body. To date, most of the research on denticle morphology and their impacts on hydrodynamics has focused on the lateral flank of fast-swimming species. One understudied region where these interactions may be important is the nares of sharks. The constant flow of water through the nares is critical to olfaction and therefore a shark's survival. We imaged dermal denticles all around the incurrent and excurrent nares of the Pacific spiny dogfish (Squalus suckleyi), a benthopelagic species inhabiting eastern Pacific waters. At the incurrent naris, we quantified denticle morphological traits such as length, width, aspect ratio, ridge number, and angle of rotation off the anterior-posterior axis. We found that denticles at the incurrent naris display two primary morphologies: elongated with ridged crowns and rounded with smooth crowns. Moreover, we show denticles rotated to nearly 180 degrees off the anterior-posterior axis as denticles enter the incurrent naris at the cranial region. Using particle image velocimetry over a 3D printed model of a micro-computed tomography scan of the incurrent naris, we visualized the effects of this rotation on flow and found preliminary data for a reverse circulating vortex in addition to laminar flow into the olfactory chamber. Finally, we propose two hypotheses on the importance of this phenomenon. This work highlights the diversity of shark denticle morphology, particularly with respect to their role in fluid mechanics. Our findings challenge our current understanding of dermal denticle orientation and function, further supporting the need to investigate areas of interest across shark bodies that have not yet been studied in the literature.

Vertebral deformities such as abnormal curvatures and shapes may influence kinematics of fishes during swimming. Our study examines the vertebral deformities of hatchery-reared lumpfish (Cyclopterus lumpus) to better understand the effects of vertebral deformity on swimming kinematics. We recorded and analyzed videos of 50 juvenile lumpfish that were being raised as cleaner fish for salmonid farms. Each lumpfish was observed in 10-s video intervals and then euthanized for X-ray visualization of the skeleton. We used midline tracking to calculate speed, tailbeat amplitude, stride length, tailbeat frequency, and tail curvature during volitional swimming. Body shape analysis using 2D landmarking and principal component analysis showed that there was a significant relationship between the number of deformities and body shape from a dorsal view. We also found that body shape from a lateral view was a significant predictor of speed and stride length. We expected that an increase in deformity would cause a change in tail curvature and a decrease in speed, stride length, tailbeat frequency, and tail amplitude. Instead, we found that the lumpfish swimming was mostly unaffected by the deformity. There was only a significant relationship between tailbeat amplitude and number of early compressed vertebrae. Since vertebral deformities had a significant relationship with body shape, there was also an indirect effect of deformity on swimming speed.

Increasingly sophisticated taxonomic tools have enhanced our understanding of species diversity and phylogenetic relationships in elasmobranchs. Nevertheless, ichthyologists continue to face challenges in resolving the taxonomic placement and authentication of some taxa, particularly those originally described based on morphology. The recently described genus Fontitrygon comprises several Atlantic dasyatid stingrays whose phylogenetic positions have remained unresolved due to the lack of molecular data. In this study, we employed an integrative taxonomic approach to identify and determine the phylogenetic position of the understudied Fontitrygon garouaensis from Nigeria. Specimens were collected from freshwater ecosystems along the Jebba and Lokoja stretches of the River Niger in Nigeria. Comparative morphological analysis distinguished F. garouaensis from other Fontitrygon species by the presence of a depressed central-spine shaft with flanges extending along either side, a flattened oval disc, an obtuse snout, a whip-like tail bearing a sting, a broad and elongated snout, small pelvic fins, and radially arranged pectoral fins. Additionally, morphological measurements of the newly collected F. garouaensis were consistent with those of the syntype and holotype, confirming species identification. Phylogenetic analyses based on mitochondrial cytochrome c oxidase subunit I gene sequences recovered Fontitrygon as a monophyletic lineage and identified F. garouaensis as the sister taxon to F. margarita and F. margaritella. This study provides an integrative taxonomic assessment of F. garouaensis, clarifying its species identity and confirming the presence of F. garouaensis from the upstream of the Jebba stretch of the River Niger. We, therefore, propose an update to its IUCN geographic range.

Wildlife face a number of extrinsic stressors, such as habitat loss, pathogen infections, and contaminant exposure, which can increase the energy needed to maintain optimal health and survival. These multiple extrinsic stressors can also occur simultaneously during intrinsically stressful life stages such as reproduction, migration, or hibernation. To fully understand how to support healthy wildlife populations, we must quantify physiological and immunological phenotypes across a variety of stressors. We pose a framework for conducting field studies to collect individual-level samples that can be used for measuring physiological and immunological phenotypes as well as the potentially stressful intrinsic and extrinsic drivers of those phenotypes. We suggest that collaborative efforts should then be made to create broader, spatially coordinated hypotheses for determining patterns of wildlife health under intrinsically stressful time periods and across extrinsically stressful landscapes. We provide an example and preliminary findings for this multi-stressor, collaborative, and spatially coordinated approach with an ongoing study of North American bat health. Quantifying direct and critical measures of wildlife health and identifying key intrinsic and extrinsic stressors that drive physiological and immunological phenotypes will provide broad targets for conservation strategies and where and when those strategies should be prioritized in the future.

The increasing emergence of virulent pathogens necessitates novel approaches to predict and manage infectious disease risks. The importance of integrating observational and experimental approaches to studying host-pathogen interactions has long been recognized, as captive studies can mechanistically test hypotheses derived from field studies and identify causal factors shaping host susceptibility or tolerance of infection. However, captive experiments can also determine biomarkers of infection outcomes that could improve later interpretation of field data and identify at-risk hosts in wild populations. Such work could be especially useful in preempting or managing risks of pathogen spillover or spillback. SARS-CoV-2 emerged in humans in late 2019 and was rapidly followed by spillback into naïve wildlife, leading to both mortality events and novel enzootic cycles. Of special concern is whether SARS-CoV-2 could establish in bats in the Americas, given that sarbecoviruses coevolved with rhinolophid bats in the Eastern Hemisphere, and as coronavirus infection may exacerbate effects of white-nose syndrome. Here, we leverage residual plasma samples from a previous SARS-CoV-2 challenge study of Mexican free-tailed bats (Tadarida brasiliensis) to identify candidate protein biomarkers of susceptibility and test whether these can predict coronavirus risks in wild bats. We generated plasma proteomes from captive (n = 20; four resistant, five susceptible, 11 unchallenged) and wild (n = 15) bats using the S-Trap method and LC-MS/MS, identifying 475 proteins using data-independent acquisition and a species-specific genome annotation generated by the Bat1K Project. Receiver operator characteristic curves identified 27 potential biomarkers of SARS-CoV-2 susceptibility (AUC ≥ 0.8), and subsequent enrichment analyses of these proteins suggested downregulation of blood clotting and upregulation of complement activation and humoral immunity in susceptible bats. We then mined plasma proteomes from wild bats (sampled in 2022 from Bracken Cave Preserve, the largest known Mexican free-tailed bat population) to show that all candidate biomarkers were present in this population, with coefficients of variation ranging from 16 to 150% per protein. We detected coronaviruses in 20% of wild bats, with two cases of potential SARS-CoV-2 spillback. We demonstrate that at least four of these candidate susceptibility biomarkers classified bats with and without coronavirus infection in the wild. Our results inform the possible immune strategies underlying SARS-CoV-2 susceptibility in bats and give a preliminary example of how captive challenge studies can be coupled with field studies to inform zoonotic and conservation risks.

Comparative biomechanics describes investigating animal models to inform, understand, and improve health and locomotor understanding in humans and across biological organisms and species. In recent years, there has been an increased understanding of comparative biomaterials, which utilizes intincredibly diverse, yet can primarilyerdisciplinary techniques spanning physics, materials science, engineering, and biology to mimic and model the complex morphology and mechanics of biological structures. This perspective piece highlights some recent innovations in biological material characterization of mechanics, morphology, and composition, highlighting specific innovations that help address classical challenges in biomaterials analysis. It concludes with a review of highlights in material fabrication techniques that have expanded the scope of biomaterials through bio-inspired multi-material 3-dimensional printing, textiles, and bio-hybrids. This perspective serves as a starting guide for researchers to broaden their understanding of the innovations that different disciplines have made in characterizing biological materials across various length scales, which could be applied to bio-inspired design.