Integrative and Comparative Biology最新文献

Shark skin is covered superficially by the crowns of dermal denticles, tooth-shaped scales, whose bases are embedded into the dermis. Denticles provide sharks with functional benefits, including protection during mating and enhanced drag reduction during high-speed swimming. In a few species, research showed that denticle morphology changes as a shark matures and differs between sexes, especially in regions where males bite females during mating. We quantified the denticle morphometrics of bonnethead sharks to investigate potential ontogenetic and body region differences as well as sexual dimorphisms. We examined abdominal skin from 24 bonnethead sharks (12 male and 12 female) between the first and second dorsal fins using scanning electron microscopy. Denticle morphometrics-including denticle shape (pointedness), crown width, crown length, % of overlap, ridge width, ridge angle, and the number of ridges-were measured using ImageJ. We hypothesized that embryonic sharks would have denticles shorter in length and width when compared to juvenile and mature sharks to follow a natural growth pattern, and that female sharks would have a higher % overlap and longer denticle crowns, to provide greater protection during mating. Denticle morphology varied significantly across maturity levels, with differences observed in the denticle shape, crown width, and % overlap. These data support our hypothesis that denticle morphology changes with development, potentially to optimize swimming performance. However, sex was only a significant factor for ridge angle and body region was not a significant effect for any variable measured here. These findings suggest that ontogeny drives denticle morphology variation more than sex or body region does for abdominal skin between the two dorsal fins. These results suggest that denticle shape remains consistent in the male and female adults but varies across maturity levels, possibly due to the hydrodynamic constraints of water flow during swimming or to provide a shark with greater protection as it matures. Understanding the developmental and functional adaptations of shark denticles provides insights into their evolutionary role in facilitating survival, locomotion, and reproductive methods.

Marine predators often function as sentinel species, the first organisms to be impacted when a habitat is disturbed, and directly contribute to ecosystem health by maintaining physical connections between distal habitats. Elasmobranch fishes (sharks and rays) are common predators in most aquatic systems, but over the past 50 years, elasmobranch abundance has dropped >70% from overfishing and climate change. Further, many populations throughout the world are known to be Data Deficient, confounding management decisions. To remedy this, we investigated patterns of genetic structure and diversity in two elasmobranchs from Sri Lanka, the tiger shark Galeocerdo cuvier, and the whipray Brevitrygon sp., using the mitochondrial genes ND2 and CO1. Our results showed low diversity and high connectivity in G. cuvier, with several haplotypes shared between sharks in Sri Lanka and other ocean basins. For Brevitrygon sp., our analyses confirmed this species to be Brevitrygon imbricata, a species previously found to have low genetic diversity. Taken together, these results indicate that elasmobranchs sampled from the fish markets of Sri Lanka are connected by gene flow to populations in other regions, suggesting that they may resist depletion better than more-isolated groups.

Non-invasive video tracking offers a scalable, cost-effective alternative to invasive tagging for studying marine megafauna movement. However, its potential with brief footage remains underexplored. This pilot study presents a preliminary application of the method using a 24-s video of a whale shark (Rhincodon typus) near Abu Musa Island in the Persian Gulf on October 10, 2023. Due to the short duration and single-individual observation, findings are exploratory and intended to demonstrate feasibility rather than establish generalizable conclusions. Using VideoTracker software and Python tools (OpenCV, NumPy), we tracked a 4-m-long shark swimming at 5 m depth, covering 19.25 m over 24 s with speeds ranging from 0.51 to 1.16 m/s (mean 0.78 ± 0.19 m/s) and an energy expenditure of 0.66 units. The near-linear trajectory (sinuosity 1.07) suggests steady cruising, consistent with efficient locomotion and prior speed-based movement analyses. This proof-of-concept highlights the potential of video-based tracking in resource-limited contexts and encourages its further refinement for broader ecological applications.

Sri Lankan fisheries have substantial elasmobranch catches, but the local ecology of individual species is not well characterized. We examine the tiger shark (Galeocerdo cuvier) and Bengal whipray (Brevitrygon imbricata), two elasmobranch species with variable life history and feeding ecology that represent differing trophic guilds. Tiger sharks have a global distribution and are well-studied in some regions, but there is a lack of ecological information specific to the Indian Ocean. In contrast, Bengal whiprays are often misidentified at the species level and are thought to largely feed on benthic flatworms. Here, we investigate the trophic ecology of these two species with stable isotope analysis, which tracks the nutrient flow through food webs. Morphometric measurements and samples were obtained from tiger sharks [muscle (n = 24), teeth (n = 17)] and Bengal whiprays [muscle (n = 44)] after boats were onshore; tissues were sampled and dried before transport for stable isotope preparation. Both tiger sharks and Bengal whiprays have a wide range of δ13C values spanning from -17.8 to -14.8‰, indicating diverse feeding habitats. In general, tiger sharks have higher δ15N values (13.3 ± 0.6‰) than Bengal whiprays (12.1 ± 0.7‰), although five Bengal whiprays had similar δ15N values to tiger sharks. There were also δ15N differences by sex among Bengal whiprays, which suggests some foraging or baseline differences within the population. The isotopic differences among market locations were subtle and difficult to discern given differences in sample size. These insights into the ecology of tiger sharks and Bengal whiprays in Sri Lanka, along with other studies, including tagging and stomach content analysis, are critical in developing ecosystem-based management strategies. For example, the identification of essential habitats for the Marine Protected Area designation would restrict fishing and help mitigate impacts on population structure and dynamics, two critical considerations for these two species, which are listed as Near Threatened and Vulnerable, respectively, on the International Union for Conservation of Nature Red List.

The lack of gender, ethnic, and racial diversity in shark and ray research remains a significant concern. Additionally, "parachute" or "helicopter" science, where researchers from wealthier nations conduct studies in developing countries without engaging local scientists, remains widespread. In response, researchers from three Global South countries partnered with Global North peers to establish ICONIC Oceans, an international collaboration guided by Integrated, Coordinated, Open, Networked (ICON) principles. Alongside artisanal fishers, researchers combined biometric and biological data from fishing landings with fisher interviews, citizen science, and direct participation in fishing operations-both at sea and on the beach-in Brazil, India, and Sri Lanka. Each represented country had its own Field Research Lead. Despite sociocultural differences across Asia and South America, researchers faced similar challenges, including sexism, hazardous working conditions, permitting difficulties, and limited or nonexistent infrastructure. Furthermore, some foreign and financially dominant local scientists engage in unethical research practices, exploiting early career researchers and students while fostering unfair competition. Such practices undermine trust and disrupt established collaborations. They can also disrupt the trust and space conquered. Addressing these systemic issues is essential to fostering ethical, equitable, and collaborative marine science. Some of the proposed solutions identified through the first cohort of ICONIC Oceans were clear protocols adapted to resources available to local researchers, shipping/customs guidelines, mentorship, letters of support/collaboration from research partners and contingency timelines for delays.

There is a lack of understanding of how fishing regulations are made as well as a lack of local community trust in policy makers. Communities, particularly communities of color, often feel their interests and challenges are not taken into consideration when potentially disruptive environmental changes are made like dredging and beach renourishment, and they feel they bear a disproportionate amount of the burden of environmental regulations. Overall, the socioeconomic pressures, fishing regulations, and continued systemic oppression these communities face have led to a severe decline in the ability of the cultural practice of fishing to be maintained, and many fear this practice will not be passed on to the next generation. This is of particular concern for communities with a high rate of poverty. We surveyed five fishers in a Black fishing community in Myrtle Beach, SC. The purpose of this study was to understand fishers' attitudes toward conservation, local ecological knowledge, and values related to preservation of fish stocks. This project was co-led by a longstanding member of the fishing community, which allowed us valuable access to unbridled and uncensored discussions with community members. One of the biggest takeaways from the study is that the fish that the community relies on are becoming increasingly scarce.

The persistent underrepresentation of Black, Indigenous, and People of Color (BIPOC) in marine science highlights the need for targeted interventions that address systemic barriers to inclusion, retention, and advancement. Minorities in Shark Sciences, a nonprofit organization dedicated to promoting equity in marine science through shark and ocean conservation, has developed a suite of programs aimed at fostering a sense of belonging, enhancing self-efficacy, strengthening science identity, and improving career retention among BIPOC scientists. This study evaluates the effectiveness of these programs using mixed-methods data collected from participants between 2020 and 2025. Quantitative surveys measured changes in participants' sense of belonging, science identity, and self-efficacy before and after program engagement, while qualitative interviews provided deeper insights into perceived barriers, support systems, and professional development trajectories. Thematic analysis revealed that culturally affirming mentorship, community-building, and access to fieldwork experiences were key drivers of positive outcomes. These findings underscore the importance of identity-affirming, community-rooted programming in diversifying STEM fields and offer a scalable model for improving retention and success of BIPOC professionals in marine and environmental sciences.

The next generation of pollination researchers faces unprecedented environmental change during the Anthropocene and must develop cross-disciplinary research skill sets. Course-based Undergraduate Research Experience (CURE) pedagogy is one instructional approach that can expose students to integrative biology research while introducing them to technologies that will become increasingly important in pollination system studies. CUREs offer additional advantages, including the potential of crowdsourcing research and strategies that can increase retention of underrepresented minorities in science, technology, engineering, and mathematics (STEM). In this perspective, we present CUREs that utilize pollinator research as exemplars of how undergraduates can gain experience with integrative research approaches while providing valuable data on the effects of human activity on pollination systems. At the University of Detroit Mercy, a metabarcoding CURE was developed that utilized nanopore sequencing technology to evaluate pollen profiles in urban apiaries. Another CURE involving the solitary leafcutter bee, Megachile rotundata, is being used to evaluate pollinator habitat restoration efforts in an urban park. The instructional approach involved students integrating classical field biology research techniques with DNA barcoding to determine the success of the restoration efforts. Another example is Bee the CURE, a curriculum at Pima Community College, where students conduct barcoding experiments by uploading bee DNA sequences to a barcoding database. This CURE uses a place-based pedagogy, which has been shown to have a positive impact on Hispanic students' perceptions of STEM. These examples demonstrate that pollinator-centered CUREs can integrate multiple approaches and technologies, contribute to scientific knowledge, and can be successfully implemented in diverse institutions. To expand its impact, the pollinator research community should collaborate to develop scalable programs that train future integrative biologists in emerging technologies, such as high-throughput DNA sequencing, DNA barcoding, and advanced computational methods.

Co-flowering plant species frequently share pollinators, flower-inhabiting bacteria, and fungi, but whether pollen-associated viruses are shared is unknown. Given that pollen-associated viruses are sexually transmitted diseases, their diversity is expected to increase with pollinator sharing. We conducted a metagenomic study to identify pollen-associated viruses from 18 co-flowering plant species to determine whether (1) life history, floral traits, or pollination generalism were associated with viral richness, and (2) plants shared pollen-associated viruses. We demonstrated that pollination generalism influences pollen-associated virus richness and the extent of pollen virus sharing between plant species. We also revealed that perenniality, multiple flowers, and bilateral floral symmetry were associated with high pollen viral richness locally, confirming and extending patterns observed previously at a continental scale. Our results highlight the importance of plant-pollinator interactions as drivers of plant-viral interaction diversity.

As climate change progresses, it is important to be able to predict how the effects of elevated temperatures are affected by the ability of ectotherms to seek shelter. Many studies on ectotherms have suggested that mobility is a vital characteristic to understand how species will react to warming. Highly mobile ectotherms are not often exposed to thermally stressful conditions because they can actively select temperatures that are thermally beneficial or benign. Slow-moving or sessile ectotherms, however, are not able to change habitats quickly enough to escape from thermal stress or even death. In order to measure how mobility affected how organisms cope with temperature, we quantified the body temperatures, environmental temperatures (using biomimetic models), and thermal limits using respirometry of eight intertidal ectotherms in four mobility classes: fast, intermediate, slow, and sessile. In addition, we also calculated thermal safety margins (TSMs) for each of our species. While we predicted that fast and intermediately mobile species would have lower thermal limits and narrower TSMs than slow and sessile animals, we found that faster organisms had lower thermal limits and narrower thermal safety margins than the other three mobility classes. Our findings indicate that there is an effect of mobility on how organisms cope with temperatures and lay the groundwork for understanding how communities may respond to climate change.