The effective detection of environmental vibrations such as sound waves depends on the transmission of tympanic membrane motion through the middle ear to the inner ear hair cells. In birds, the bony element of the middle ear is the columella; its distal end joins the cartilaginous extracolumella and tympanic membrane, while its basal expansion (the footplate) interfaces with inner ear fluid at the oval window, where it is held in place by the stapedial (columellar) annular ligament. Variation in footplate and oval window geometry can alter the annular ligament's size and shape, thereby influencing middle ear mechanics. Previous studies have noted relatively small footplates in aquatic birds as compared to their terrestrial relatives, and suggested that the adaptive significance of these may relate to their influence on the relative size of the annular ligament. Here, I examine a taxonomically and ecologically broad sample of bird species to test the hypothesis that aquatic lineages have convergently evolved proportionally larger annular ligaments. Results show larger ligaments are characteristic of aquatic, and particularly diving species, while narrower ligaments occur in high-frequency specialists. These patterns are polyphyletic and, alongside their strong ecological associations, indicate repeated functional adaptation of the middle ear. Larger ligaments are consistent with reduced system stiffness and enhanced low-frequency transmission, a hypothesis which is plausible for pelagic seabirds. In contrast, the extreme ligament enlargement in diving taxa is unlikely to be related to hearing, and instead may play a role in protection from barotrauma.

The genus Nitrospira, which includes canonical nitrite-oxidizing bacteria (NOB) and species capable of complete ammonia oxidation (comammox), plays an important role in the global biogeochemical nitrogen cycle. Typically, lineage IV Nitrospira predominate in marine environments, and other lineages are thought to be less abundant and remain poorly characterized in oceanic systems. Here, we recovered five novel metagenome-assembled genomes (MAGs) affiliated with Nitrospira lineage II–IV from deep-sea sediments. Notably, two of these MAGs represent members of lineage III and comammox Nitrospira, respectively, suggesting the presence of previously uncharacterized lineages in the deep sea. Phylogenetic and gene locus analyses indicated that deep-sea lineage III and comammox Nitrospira form distinct evolutionary clades that diverge from their terrestrial and coastal relatives, and we therefore designate these two marine-derived groups as “lineage III clade B” and “comammox clade A4”, respectively. Comparative read recruitment analyses revealed that these lineages exhibit potential pan-oceanic distribution in deep-sea sediments and waters, albeit at very low abundances. Furthermore, the identification of genes encoding amtB-type ammonium transporters (amtB), the ABC-type glycerol-3-phosphate transport system (ugpABCE), a multi-subunit Na+/H+ antiporter (mnh), and betaine transporters (BetT, opuABC) suggests that these newly discovered Nitrospira species possess adaptive capabilities to thrive in oligotrophic and saline marine environments. These findings provide novel insights into the occurrence, metabolic features, and adaptation strategies of lineage III and comammox Nitrospira, expand our understanding of Nitrospira diversity in the deep sea, and offer valuable perspectives on the evolutionary history of various Nitrospira lineages.

ABSTRACT Aim Species richness is generally lower in marine than in terrestrial ecosystems, but the reasons behind this disparity remain unclear. This study examines whether marine mammals diversify at a slower pace than their non‐marine counterparts, aiming to shed light on the factors explaining potential diversification differences among them. Location Global. Time Period Contemporary. Major Taxa Studied Mammals. Methods We combined time‐calibrated phylogenies, species distribution data, and life‐history traits to compare DR variation among marine and non‐marine mammals, and to assess DR correlation with ecological realm and species traits. Results Contrary to previous findings at higher taxonomic scales, our results show that marine mammals do not exhibit lower DR than non‐marine mammals, but even higher depending on the phylogenetic framework. Our regression analyses indicate that taxonomy (particularly family) is the dominant predictor of DR variation among mammals rather than the ecological realm. Still, DR appears negatively correlated with body mass in marine mammals and with range size in non‐marine mammals. Besides, the geographic distribution of DR points to a more uniform pattern in marine than in non‐marine artiodactyls, for which high DR values concentrate in the Northern Hemisphere. Conversely, high DR values for marine carnivores are clustered around the poles, while a more homogeneous distribution is observed across continents for their terrestrial relatives. Main Conclusions These findings challenge the conventional view that marine ecosystems inherently constrain species diversification. Instead, they suggest that taxonomy and species‐specific traits, rather than the ecological realm alone, are the primary drivers of mammalian diversification. Our study emphasizes the complexity of mammalian evolutionary patterns and the importance of integrating taxonomic, ecological, and biogeographic factors in macroevolutionary analyses.

The convergent genomic dynamism for aquatic adaptation in vascular plants.

Abstract Oxidative stress, triggered by hypoxia during repetitive diving, represents a notable environmental adaptation of marine mammals. Glutathione (GSH) is a widely acknowledged antioxidant that protects crucial cellular elements from damage by reactive oxygen species (ROS). Nevertheless, the role of the glutathione metabolism pathway in shaping the adaptation to oxidative stress in marine mammals is not fully elucidated. In this study, we conducted evolutionary analyses on 37 genes related to the GSH metabolism pathway in marine and terrestrial mammals. We found that in comparison with their terrestrial relatives, marine mammals showed convergently accelerated evolution on the core modules of GSH metabolism. Specifically, we identified a total of 16 genes with significant evolution signals unique to marine mammals, and several genes (e.g., accelerated evolution genes: RRM1 and SMS , positively selected genes: ANPEP and GCLC ) were shared in marine mammal lineages. Eight genes were discovered to possess specific amino acid modifications that are common among all marine mammals. Functional assays of marine mammal GCLC showed a downregulation of HIF‐1α and enhanced GSH levels under hypoxic conditions, suggesting heightened protection of marine mammals against oxidative stress induced by hypoxia. Our study identified key genes with significant evolutionary signals in marine mammals, providing genomic and functional support for convergent hypoxia adaptation mechanisms within this taxon.

To cope with thermal challenges of aquatic environments, marine mammals, including cetaceans, sirenians, and pinnipeds, independently evolved a substantially thickened subcutaneous blubber layer compared to terrestrial relatives. The blubber is a specialized adipose tissue layer under the skin of marine mammals and is vital for heat insulation, energy storage, buoyancy control and enhancement of locomotion. However, the molecular evolutionary mechanism underlying blubber thickening remains largely unexplored. An evolutionary analysis of the mammalian GPR12 gene was conducted to identify a cetacean-specific amino acid substitution that is absent in any other mammals. In vitro cellular experiments suggested that this amino acid substitution could reduce the expression of adipose triglyceride lipase (ATGL) and thereby decrease lipolytic activity. This study uncovered critical genetic signals which could influence lipolysis capacity in cetaceans and might have been the evolutionary mechanism underlying the blubber thickening in cetaceans during secondary aquatic adaptation.

SummarySkin pigmentation contributes to thermoregulation in ectothermic vertebrates, while homeotherms rely on insulation such as feathers, fur, or blubber. Heat-sensing in vertebrates largely depends on transient receptor potential (TRP) channels, with TRPA1 showing evolutionary shifts in sensitivity. The exploration of a role for TRP channels in skin physiology has largely focused on human pigmentation and overlooked the evolution of different thermoregulatory structures in the integument of distinct vertebrates. We investigated heat-induced skin darkening in the ectotherm Xenopus laevis and found TRPA1 mediates melanosome dispersion. Conversely, TRPA1 mediates cold sensation in rodents and UV-induced tanning in humans. In Euarchontoglires, a switch to TRPA1 cold thermal sensitivity correlates with a change in an essential amino acid (V→G878). Aquatic mammals (manatees, whales) that rely on blubber for insulation show reduced TRPA1 selection pressure as compared to their terrestrial relatives. Our findings highlight TRPA1’s adaptive evolution across vertebrates, linking thermal sensing to integumentary specialization.

The paleohistology of Permo-Triassic anomodonts has been extensively studied and, independent of phylogeny, body size and lifestyle, reflects a pattern of rapid growth indicated by a woven-parallel complex. Moreover, anomodonts uniformly show a relative bone cortical thickness (RBT) exceeding 30% and a medullary cavity generally filled by trabeculae. Here, we investigate the paleohistology of the basal anomodont Suminia getmanovi from the Permian of Russia, which has been hypothesized as one of the earliest arboreal tetrapods. Osteohistology and skeletal proportions reveal that our sample comprises at least two late juvenile to early subadult individuals, exhibiting well-vascularized and mostly uninterrupted woven-parallel complex or parallel-fibered tissues, suggesting relatively high growth rates, consistent with other anomodonts. However, all elements of Suminia present an open medullary cavity virtually free of bony trabeculae and a RBT lower than 18%. The microanatomy of Suminia thus differs from all other anomodonts studied so far, including its closest relative Galeops, as well as more basal synapsids that also tend to show higher RBT values and/or a medullary territory obstructed by trabeculae. Compared to extant climbers, which possess thinner bone walls and lower compactness than their terrestrial and aquatic relatives, the bone architecture of Suminia further supports its arboreal lifestyle.

Terrestrial vertebrates from at least 30 distinct lineages in both extinct and extant clades have returned to aquatic environments. With these transitions came numerous morphological adaptations to accommodate life in water. Relatively little attention has been paid to the cervical region when tracking this transition. In fully aquatic cetaceans, the cervical vertebrae are compressed, largely because a loss of neck mobility reduces drag. We ask whether this pattern of cervical evolution is present in the more recently evolved semiaquatic pinnipeds. Here, we compare neck morphology and function in three families of pinnipeds, the Otariidae, Phocidae, and Odobenidae as well as between pinnipeds and their terrestrial arctoid relatives (ursids and mustelids). Using cranial CT scans, we quantified the occipital surface area for neck muscle attachment as well as vertebral size and shape using linear measurements. Results show that pinnipeds have a relatively larger occipital surface area than ursids and terrestrial mustelids, suggesting that marine carnivorans have enlarged their neck muscles to assist with head stabilization during swimming. Within pinnipeds, we found quantitative differences in cervical morphology between otariids and phocids that coincide with their locomotor style. Phocids are hindlimb‐dominated swimmers that propel themselves with pelvic oscillations. Their necks are relatively stiff and their cervical vertebrae are compressed anteroposteriorly with reduced muscular attachment areas. By contrast, otariids are forelimb‐dominated swimmers that locomote in water and on land using their pectoral limbs, often recruiting their neck to initiate turns underwater as well as assisting in “walking” on land. Consequently, otariids have stronger, more flexible necks than phocids, which is reflected in more elongate cervical vertebral centra with larger muscle attachments. The walrus (Odobenidae) has a cervical vertebrae morphology intermediate to that of phocids and otariids, consistent with a phocid swimming mode combined with a more muscular neck that likely functions in intraspecific conflict and haul‐out behavior.

The photopigment-encoding visual opsin genes that mediate color perception show great variation in copy number and adaptive function across vertebrates. An open question is how this variation has been shaped by the interaction of lineage-specific structural genomic architecture and ecological selection pressures. We contribute to this issue by investigating the expansion dynamics and expression of the duplicated Short-Wavelength-Sensitive-1 opsin (SWS1) in sea snakes (Elapidae). We generated one new genome, 45 resequencing datasets, 10 retinal transcriptomes, and 81 SWS1 exon sequences for sea snakes, and analyzed these alongside 16 existing genomes for sea snakes and their terrestrial relatives. Our analyses revealed multiple independent transitions in SWS1 copy number in the marine Hydrophis clade, with at least three lineages having multiple intact SWS1 genes: the previously studied Hydrophis cyanocinctus and at least two close relatives of this species; Hydrophis atriceps and Hydrophis fasciatus; and an individual Hydrophis curtus. In each lineage, gene copy divergence at a key spectral tuning site resulted in distinct UV and Violet/Blue-sensitive SWS1 subtypes. Both spectral variants were simultaneously expressed in the retinae of H. cyanocinctus and H. atriceps, providing the first evidence that these SWS1 expansions confer novel phenotypes. Finally, chromosome annotation for nine species revealed shared structural features in proximity to SWS1 regardless of copy number. If these features are associated with SWS1 duplication, expanded opsin complements could be more common in snakes than is currently recognized. Alternatively, selection pressures specific to aquatic environments could favor improved chromatic distinction in just some lineages.

BackgroundThe deep (> 200 m) ocean floor is often considered to be a refugium of biodiversity; many benthic marine animals appear to share ancient common ancestry with nearshore and terrestrial relatives. Whether this pattern holds for vertebrates is obscured by a poor understanding of the evolutionary history of the oldest marine vertebrate clades. Hagfishes are jawless vertebrates that are either the living sister to all vertebrates or form a clade with lampreys, the only other surviving jawless fishes.ResultsWe use the hagfish fossil record and molecular data for all recognized genera to construct a novel hypothesis for hagfish relationships and diversification. We find that crown hagfishes persisted through three mass extinctions after appearing in the Permian ~ 275 Ma, making them one of the oldest living vertebrate lineages. In contrast to most other deep marine vertebrates, we consistently infer a deep origin of continental slope occupation by hagfishes that dates to the Paleozoic.ConclusionOur results establish hagfishes as ancient members of demersal continental slope faunas and suggest a prolonged accumulation of deep sea jawless vertebrate biodiversity.

Chelicerae, distinctive feeding appendages in chelicerates, such as spiders, scorpions, or horseshoe crabs, can be classified based on their orientation relative to the body axis simplified as either orthognathous (parallel) or labidognathous (inclined), exhibiting considerable diversity across various taxa. Among extinct chelicerates, sea scorpions belonging to the Pterygotidae represent the only chelicerates possessing markedly elongated chelicerae relative to body length. Despite various hypotheses regarding the potential ecological functions and feeding movements of these structures, no comprehensive 3D kinematic investigation has been conducted yet to test these ideas. In this study, we generated a comprehensive 3D model of the pterygotid Acutiramus, making the elongated right chelicera movable by equipping it with virtual joint axes for conducting Range of Motion analyses. Due to the absence in the fossil record of a clear indication of the chelicerae orientation and their potential lateral or ventral movements (vertical or horizontal insertion of joint axis 1), we explored the Range of Motion analyses under four distinct kinematic settings with two orientation modes (euthygnathous, klinogathous) analogous to the terminology of the terrestrial relatives. The most plausible kinematic setting involved euthygnathous chelicerae being folded ventrally over a horizontal joint axis. This configuration positioned the chelicera closest to the oral opening. Concerning the maximum excursion angle, our analysis revealed that the chela could open up to 70°, while it could be retracted against the basal element to a maximum of 145°. The maximum excursion in the proximal joint varied between 55° and 120° based on the insertion and orientation. Our findings underscore the utility of applying 3D kinematics to fossilized arthropods for addressing inquiries on functional ecology such as prey capture and handling, enabling insights into their possible behavioral patterns. Pterygotidae likely captured and processed their prey using the chelicerae, subsequently transporting it to the oral opening with the assistance of other prosomal appendages.

Functional ecology and evolution of terrestrial and epiphytic species of Rhododendron section Schistanthe (Ericaceae)

Odontocetes primarily rely on fish, cephalopods, and crustaceans as their main source of nutrition. In the digestive system, their polygastric complex exhibits similarities to that of their closest terrestrial relatives such as cows, sheep, and giraffes, while the entero‐colic tract shares similarities with terrestrial carnivores. The morphology, caliber, and structure of the odontocete intestine are relatively constant, and, since there is no caecum, a distinction between the small and large intestine and their respective subdivisions is difficult. To address this issue, we used the intestinal vascularization pattern, specifically the course and branching of the celiac artery (CA) and the cranial and caudal mesenteric arteries (CrMA and CdMA). A series of pictures and dissections of 10 bottlenose dolphins (Tursiops truncatus) were analyzed. Additionally, we performed a cast by injecting colored polyurethane foam in both arteries and veins to measure the caliber of the arteries and clarify their monopodial or dichotomous branching. Our results showed the presence of multiple duodenal arteries (DAs) detaching from the CA. The CrMA gave origin to multiple jejunal arteries, an ileocolic artery (ICA), and, in six cases, a CdMA. In four specimens, the CdMA directly originated from the abdominal aorta. The ICA gave rise to the mesenteric ileal branches (MIB) and mesenteric anti‐ileal branches and the right colic arteries (RCA) and the middle colic arteries. From the CdMA originated the left colic and cranial rectal arteries (LCA and CrRA). The measurements revealed a mixed monopodial and dichotomous branching scheme. The analysis of the arteries and their branching gave us an instrument, based on comparative anatomy, to distinguish between the different intestinal compartments. We used the midpoint of anastomoses between MIB and RCA to indicate the border between the small and the large intestine, and the midpoint of anastomoses between LCA and CrRA, to tell the colon from the rectum. This pattern suggested an elongation of the duodenum and a shortening of the colic tract that is still present in this species. These findings might be related to the crucial need to possess a long duodenal tract to digest prey ingested whole without chewing. A short aboral part is also functional to avoid gas‐producing colic fermentation. The rare origin of the CdMA on the CrMA might instead be a consequence of the cranial thrust of the abdominopelvic organs related to the loss of the pelvic girdle that occurred during the evolution of cetaceans.

BackgroundSea snakes underwent a complete transition from land to sea within the last ~ 15 million years, yet they remain a conspicuous gap in molecular studies of marine adaptation in vertebrates.ResultsHere, we generate four new annotated sea snake genomes, three of these at chromosome-scale (Hydrophis major, H. ornatus and H. curtus), and perform detailed comparative genomic analyses of sea snakes and their closest terrestrial relatives. Phylogenomic analyses highlight the possibility of near-simultaneous speciation at the root of Hydrophis, and synteny maps show intra-chromosomal variations that will be important targets for future adaptation and speciation genomic studies of this system. We then used a strict screen for positive selection in sea snakes (against a background of seven terrestrial snake genomes) to identify genes over-represented in hypoxia adaptation, sensory perception, immune response and morphological development.ConclusionsWe provide the best reference genomes currently available for the prolific and medically important elapid snake radiation. Our analyses highlight the phylogenetic complexity and conserved genome structure within Hydrophis. Positively selected marine-associated genes provide promising candidates for future, functional studies linking genetic signatures to the marine phenotypes of sea snakes and other vertebrates.

Phylum Tardigrada is represented by microscopic eight-legged panarthropods that inhabit terrestrial and marine environments. Although tardigrades are emerging model animals for areas of research including physiology, evolutionary biology, and astrobiology, knowledge of their external morphology remains insufficient. For instance, homologies between marine and terrestrial relatives largely remain unexplored. In the present study we provide detailed pictures of the head sensory organs in a new tardigrade, Ramazzottius groenlandensis sp. nov. Specimens were collected from a mixed moss and lichen sample on Ella Island, East Greenland. The new species differs from congeneric species in the presence of polygonal sculpturing on the dorsal cuticle, which is accentuated in the posterior region of the body, a lateral papilla on leg IV, and distinctive egg morphology. A Bayesian phylogenetic analysis (18S rRNA + 28S rRNA + COI) places the new species within the genus Ramazzottius with high confidence. Interestingly, the new species shows a full set of well-developed cephalic organs, which correspond to all sensory fields found in eutardigrades. Details on the full set of head organs were present only for heterotardigrades. The surface of these organs is covered with small pores, which presumably play a sensory role. This discovery suggests the homology of head sensory structures between heterotardigrades and eutardigrades, implying that the distinctive arrangement and positioning of sensory organs on the head is a plesiomorphic feature of tardigrades. Moreover, we find that the Ramazzottius oberhaeuseri morphotype forms a morphogroup, not a monophyletic species complex.

In this study, we investigate how the terrestrial-aquatic transition influenced patterns of axial integration and modularity in response to the secondary adaptation to a marine lifestyle. We use 3D geometric morphometrics to quantify shape covariation among presacral vertebrae in pinnipeds (Carnivora; Pinnipedia) and to compare with patterns of axial integration and modularity in their close terrestrial relatives. Our results indicate that the vertebral column of pinnipeds has experienced a decrease in the strength of integration among all presacral vertebrae when compared to terrestrial carnivores (=fissipeds). However, separate integration analyses among the speciose Otariidae (i.e., sea lions and fur seals) and Phocidae (i.e., true seals) also suggests the presence of different axial organizations in these two groups of crown pinnipeds. While phocids present a set of integrated “thoracic” vertebrae, the presacral vertebrae of otariids are characterized by the absence of any set of vertebrae with high integration. We hypothesize that these differences could be linked to their specific modes of aquatic locomotion –i.e., pelvic vs pectoral oscillation. Our results provide evidence that the vertebral column of pinnipeds has been reorganized from the pattern observed in fissipeds but is more complex than a simple “homogenization” of the modular pattern of their close terrestrial relatives.

Across vertebrate diversity, limb bone morphology is typically expected to reflect differences in the habitats and functional tasks that species utilize. Arboreal vertebrates are often recognized to have longer limbs than terrestrial relatives, a feature thought to help extend the reach of limbs across gaps between branches. Among terrestrial vertebrates, longer limbs can experience greater bending moments that might expose bones to a greater risk of failure. However, changes in habitat or behavior can impose changes in the forces that bones experience. If locomotion imposed lower loads in trees than on the ground, such a release from loading demands might have produced conditions under which potential constraints on the evolution of long limbs were removed, making it easier for them to evolve in arboreal species. We tested for such environmental differences in limb bone loading using the green iguana (Iguana iguana), a species that readily walks over ground and climbs trees. We implanted strain gauges on the humerus and femur, and then compared loads between treatments modeling substrate conditions of arboreal habitats. For hindlimbs, inclined substrate angles were most correlated with strain increases, whereas the forelimbs had a similar pattern but of lesser magnitude. Unlike some other habitat transitions, these results do not support biomechanical release as a mechanism likely to have facilitated limb elongation. Instead, limb bone adaptations in arboreal habitats were likely driven by selective pressures other than responses to skeletal loading.

_ Accommodation cabin is a living place for operators, and it should play a role in alleviating the fatigue and stress. This paper focuses on the problem of monotony and lack of emotional care in the design of accommodation, and develops a design system to meet the emotional needs of operators based on Kansei Engineering. First, the key design elements affecting emotional comfort are extracted and the virtual reality experimental platform is established. Second, the affective factors are extracted, constituting the semantic space. Third, the mapping relationship between affective factors and design elements is established. Finally, the design system of accommodation cabin based on the emotional needs is developed. The system can output and evaluate the design scheme through virtual reality technology, so it makes the design process more intuitive and efficient. It has a certain reference value for improving the comfort experience of operators and the design level of accommodation cabin. Introduction Offshore platform is an important guarantee for territorial development and utilization of marine resources. As offshore platform is relatively special, it has particular structure that is different from buildings on land. It is made of steel and equipped with a lot of large equipment, so it is relatively closed. During offshore operation, operators need to work and life on offshore platforms for a long time. Monotonous working condition and long-term alienation from terrestrial landscape and relatives will have impact on their physical and mental health (Xu et al. 2013). According to the survey, about 13% of the workers who have worked on the platform for more than 10 years will have psychologic or behavioral abnormalities (Wu 2015). It has affected their normal life, and even increased the safety risk.

Abstract Southeast Asia supports the greatest diversity of felids globally, but this diversity is threatened by the severe forest loss and degradation occurring in the region. The response of felids to disturbances appears to differ depending on their ecology. For example, the largely terrestrial and nocturnal leopard cat (Prionailurus bengalensis) thrives near forest edges and in oil palm plantations where it hunts rodents (Muridae) at night, thereby avoiding human activity peaks. Conversely, we hypothesized that the sympatric and similar‐sized marbled cat (Pardofelis marmorata) would respond negatively to edges and relatively open oil palm plantations as they are more arboreal than leopard cats, rely on tree connectivity for hunting, and are diurnal so have less potential to temporally avoid humans. We used camera trapping from Southeast Asia to test habitat associations at multiple spatial scales using zero‐inflated Poisson generalized linear mixed models and hierarchical occupancy modeling. We found that marbled cats were positively associated with large intact forests and, in contrast to leopard cats, negatively associated with oil palm plantations. Furthermore, we found preliminary evidence suggesting marbled cats may adapt their diel activity to become more crepuscular in degraded forests, likely shifting their activity to avoid humans. These findings suggest that the marbled cat's International Union for Conservation of Nature (IUCN) Red List conservation status should potentially be upgraded from Near Threatened to Vulnerable, matching other forest‐dependent felids in the region. We posit our findings may be generalizable such that semi‐arboreal and diurnal felids could face greater threats from habitat degradation than their terrestrial and nocturnal relatives.