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.

Perchlorate is an endocrine-disrupting compound (EDC) used for its oxidative properties and has been detected in many industrialized countries in drinking water, soil, foods, and breast milk. Perchlorate competitively inhibits the uptake of iodide into the thyroid, thus reducing thyroid hormone synthesis. Perchlorate causes steatosis in the liver, alters gonadal development, and increases tubule size in kidneys in some fish models but not others. Much less is known of perchlorate's effects on mammals with respect to these organs. We examined the morphological effects of environmentally relevant concentrations (0 ppm, 10 ppm, and 100 ppm) of sodium perchlorate on the thyroid, liver, kidneys, testes, and ovaries on mice exposed from conception. Sexually mature female mice were randomly divided into the three treatment groups, bred, and exposed to perchlorate via water until offspring were weaned at postnatal day 36 (P36). Offspring continued exposure for 49 days at the same concentration as their mother, euthanized at P85, whole body perfused with 4% paraformaldehyde, and target organs were dissected, sectioned, and stained using hematoxylin and eosin. Perchlorate-exposed mice displayed a significant decrease in colloid area and a significant increase in follicle density, angiogenesis, and lipid accumulation within the thyroid. The liver showed a significant increase in the presence of ballooned hepatocytes and lipid accumulation. Within the kidney, we found perchlorate significantly altered nephron tubule thickness. In the testes, perchlorate exposure caused an increase in disorganized seminiferous tubules, an increase in Leydig cell nuclei area. and an increase in the size of blood vessels. There were no effects observed in the ovaries of perchlorate-exposed mice compared to the control. These results indicate many commonalities among fishes and other mammalian models but also the need for understanding disparate results between model species.

Sexual selection is often invoked to explain the evolution of extravagant morphologies, such as antlers and horns. While the focus is typically on the process of exaggeration of these traits, the functional impact of exaggeration remains a topic of debate. One aspect that has been largely overlooked is how exaggerated structures might impact thermal biology. For example, as a hollow (i.e., non-vascularized or non-perfused) structure increases in size, its surface area and volume change, potentially impacting its ability to obtain and dissipate heat passively. However, if the exaggerated structure is vascularized, or in the case of arthropods, has hemolymph perfusion, then it may be actively used as a thermal radiator to avoid overheating in instances of thermal stress. Based on these and additional examples, we propose that morphological exaggeration may influence how arthropods manage heat exchange with the environment. Ultimately, individuals that bear exaggerated structures may develop ecological innovations that, due to selection or as a corollary effect, maximize effectiveness of thermoregulation. Our essay is divided into four sections. First, we delve on how exaggerated structures, particularly animal weapons, may impact how organisms exchange heat with the environment, and the implications for whole-organism thermoregulation. Second, we use beetles and fiddler crabs to provide experimental evidence of how structural exaggeration may influence thermal biology. Third, we examine macroecological data from arthropods to explore how the size of sexually selected morphologies varies with changes in environmental temperature. Finally, we synthesize these pieces of evidence to identify significant ecological implications and gaps in knowledge. Through this essay, we aim to ignite discussion on how morphological changes driven by sexual selection can lead to innovations not only in the functional role of morphologies but also in the thermal biology of individuals.

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.

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.

SynopsisThe ability to regenerate can greatly vary between animal groups and cell types. Some of the outstanding questions in the field of regeneration include: (1) How has regeneration evolved? and (2) What features underlie differences in regeneration potential between animals? Whether regeneration evolved once and diversified or if it evolved multiple times independently by co-opting similar pathways remains unknown. Current research seeks to identify conserved cellular and molecular features that allow for regeneration. However, comparisons between distantly related regenerating animals have revealed a large amount of diversity. In this perspective, I review discussions on the mechanisms, cell types, and genes underlying regeneration. I propose using Cnidaria as a group in which to investigate the evolution of regeneration. As the sister group to Bilateria with notable regenerative capacity, studies in Cnidaria offer insights into the evolutionary history and conservation of regenerative mechanisms. I then highlight how genome-wide studies, single-cell genomics, multi-omics, and gene editing can be used to identify cell types and unknown features of regeneration. Applying these approaches across organisms will give insight into the cell and molecular features that allow for regeneration competency and may be used to alter an organism’s regeneration potential.

The field of phylogenetics employs a variety of methods and techniques to study the evolution of life across the planet. Understanding evolutionary relationships is crucial to enriching our understanding of how genes and organisms have evolved throughout time and how they could possibly evolve in the future. Eucopia sculpticauda Faxon, 1893 is a deep-water peracarid in the order Lophogastrida Boas, 1883, which can often be found in high abundances in pelagic trawls. The species can be found along the Mariana Trench, in the Mid-Atlantic Ridge, west Atlantic and east Pacific Oceans, and in the Gulf of Mexico and as deep as 7526 m. Recent collections of E. sculpticauda in the Gulf of Mexico have revealed putative cryptic diversity within the species based on both molecular and morphological evidence. Previous studies have documented two different morphotypes of the telson: the terminal part of the pleon (abdomen) and part of the tail fan. In adults, the morphotypes can be distinguished by lateral constrictions in the telson. This evidence, combined with a previous barcoding study, led to the speculation that telson morphology may be a distinguishing character useful to define cryptic diversity within E. sculpticauda. This study presents additional molecular data from the mitochondrial genes cytochrome c oxidase subunit I, and the large ribosomal subunit (16S), and the nuclear histone 3 gene (H3) to investigate telson morphotypes in relation to evolutionary history within this species. Molecular data identified two strongly supported clades, lending support for potential cryptic diversification within the Gulf of Mexico. Investigations into telson morphology suggest that this character may be informative, but the morphotypes were sometimes ambiguous and additional characters could not be found that discriminate clades. At present, our data suggest early evidence for cryptic diversification within Gulf of Mexico populations, but additional morphological characters and geographic sampling are needed before a new species can be described.

Birds exhibit a variety of migration strategies. Because sustained flapping flight requires the production of elevated levels of energy compared to typical daily activities, migratory birds are well-documented to have several physiological adaptations to support the energy demands of migration. However, even though mitochondria are the source of ATP that powers flight, the respiratory performance of the mitochondria is almost unstudied in the context of migration. We hypothesized that migratory species would have higher mitochondrial respiratory performance during migration compared to species that do not migrate. To test this hypothesis, we compared variables related to mitochondrial respiratory function between two confamilial bird species-the migratory Gray Catbird (Dumetella carolinensis) and the non-migratory Northern Mockingbird (Mimus polyglottos). Birds were captured at the same location along the Alabama Gulf Coast, where we assumed that Gray Catbirds were migrants and where resident Northern Mockingbirds live year-round. We found a trend in citrate synthase activity, which suggests that Gray Catbirds have a greater mitochondrial volume in their pectoralis muscle, but we observed no other differences in mitochondrial respiration or complex enzymatic activities between individuals from the migrant vs. the non-migrant species. However, when we assessed the catbirds included in our study using well-established indicators of migratory physiology, birds fell into two groups: a group with physiological parameters indicating a physiology of birds engaged in migration and a group with the physiology of birds not migrating. Thus, our comparison included catbirds that appeared to be outside of migratory condition. When we compared the mitochondrial performance of these three groups, we found that the mitochondrial respiratory capacity of migrating catbirds was very similar to that of Northern Mockingbirds, while the catbirds judged to be not migrating were lowest. One explanation for these observations is these species display very different daily flight behaviors. While the mockingbirds we sampled were not breeding nor migrating, they are highly active birds, living in the open and engaging in flapping flights throughout each day. In contrast, Gray Catbirds live in shrubs and fly infrequently when not migrating. Such differences in baseline energy needs likely confounded our attempt to study adaptations to migration.

Investigating Trophic Specialization of the Antarctic Apex Predator, the Leopard Seal, Across Two Chilean