Royal Society Open Science最新文献

The Barremian-aged Wessex Formation of the Isle of Wight, UK, offers a globally significant glimpse into the sauropod dinosaur faunas of the early Cretaceous. These deposits have yielded specimens of several neosauropod lineages, such as rebbachisaurids, titanosauriforms (including some of the earliest titanosaur remains), and possible flagellicaudatans. Here, we report an undescribed sauropod partial hindlimb from the Wessex Formation (NHMUK PV R16500) and analyse its phylogenetic affinities. This hindlimb preserves the left tibia, astragalus and pes, lacking only a few phalanges. NHMUK PV R16500 can be diagnosed based on two autapomorphies: an unusually high distal end to midshaft transverse width ratio in metatarsals III and IV, and the presence of small bump-like projections located in the centre of the proximal articular surfaces of the unguals of pedal digits I and II. The phylogenetic affinities of NHMUK PV R16500 are uncertain: although our analyses recover it as an early-branching somphospondylan, a single character change moves it to close to Flagellicaudata when extended implied weighting is applied. The possibility of flagellicaudatan affinities for NHMUK PV R16500 implies a potential ghost lineage that survived the Jurassic/Cretaceous boundary; however, we present evidence that the somphospondylan position is more probable and should be preferred.

The Photorhabdus virulence cassette (PVC) is an extracellular contractile injection system. In the producing bacterium, N-terminal signal peptides enable effector 'payloads' to be loaded into the PVC's hollow tube-facilitated by the 'ATPases associated with diverse cellular activities' (AAA) ATPase, Pvc15-ready for injection of the toxin or virulence factor into eukaryotic cytosols. Pvc15's function and its interaction with the signal peptide were unclear. This study describes the signal peptide diversity in extracellular contractile injection system clades and interrogates the Pvc15-signal peptide interaction using ATPase assays, cell respiratory assays and western blot quantification of Escherichia coli lysates and co-purifications of PVCs with their payloads. This study found that extracellular contractile injection system signal peptides can be grouped according to sequence alignment, owing to potentially homologous loading mechanisms. Pvc15 contains three domains, including tandem AAA domains D1 and D2. By constructing Pvc15 mutants, we found that while each domain is necessary for PVC-payload loading, domain D2 is the sole bioactive ATPase domain and rescues unstable payloads via the signal peptide. Finally, truncating the signal peptide abolishes Pvc15-dependent PVC loading and has varying effects on payload stability. This study provides crucial insights into extracellular contractile injection system effector loading mechanisms and their ATPase chaperones, and suggests that these devices could be bioengineered for injection of therapeutic proteins into human cells.

Understanding sexual communication requires assessing the behaviour of both the sender and the receiver. Receiver responses to sexual displays carry relevant information, but such signals or cues may be subtle and therefore technically challenging to investigate. Here, we focus on receiver body movements in response to high-intensity courtship in spotted bowerbirds (Ptilonorhynchus maculatus). Male bowerbirds perform a vigorous courtship choreography on dedicated display structures-bowers. Bower owners tolerate other non-territorial males at their bowers, yet the courtship displays of these so-called 'subordinate' males rarely result in successful copulations. Males that display at high intensity are preferred by females in this species, yet excessively aggressive displays may be threatening, hence scaring prospective mates away. In this study, we hypothesized that bower owners are better able to exhibit high-intensity movements without startling their audience compared with subordinate males. To address this question, we used a combination of behavioural coding and AI-based tracking of body movements, which allows precise spatial and temporal resolution for the study of subtle behavioural responses. Contrary to our predictions, we found that bower owners evoked stronger startle responses than subordinate males. We discuss these unexpected results and suggest further experimental approaches for future investigations.

[This corrects the article DOI: 10.1098/rsos.221353.].

Despite strong interest in how noise affects marine mammals, little is known for the most abundant and commonly exposed taxa. Social delphinids occur in groups of hundreds of individuals that travel quickly, change behaviour ephemerally and are not amenable to conventional tagging methods, posing challenges in quantifying noise impacts. We integrated drone-based photogrammetry, strategically placed acoustic recorders and broad-scale visual observations to provide complementary measurements of different aspects of behaviour for short- and long-beaked common dolphins. We measured behavioural responses during controlled exposure experiments (CEEs) of military mid-frequency (3-4 kHz) active sonar (MFAS) using simulated and actual Navy sonar sources. We used latent-state Bayesian models to evaluate response probability and persistence in exposure and post-exposure phases. Changes in subgroup movement and aggregation parameters were commonly detected during different phases of MFAS CEEs but not control CEEs. Responses were more evident in short-beaked common dolphins (n = 14 CEEs), and a direct relationship between response probability and received level was observed. Long-beaked common dolphins (n = 20) showed less consistent responses, although contextual differences may have limited which movement responses could be detected. These are the first experimental behavioural response data for these abundant dolphins to directly inform impact assessments for military sonars.

This study incorporates environmental feedback into the optional prisoner's dilemma and rock-paper-scissors games to examine the mutual influence of eco-evolutionary outcomes and strategy dynamics. A novel game-theoretic model is developed that integrates the optional prisoner's dilemma and rock-paper-scissors games by incorporating an environmental state variable. By adjusting feedback parameters, chaos, oscillations and coexistence are observed that surpass the usual outcomes of social dilemmas when the environment transitions between depleted and replenished states. Defection is no longer advantageous in evolution; cooperation, abstention and cyclic dominance arise. The observed transitions align with natural economics, ecology and sociology phenomena. The inclusion of abstention options and environmental feedback has a significant impact on collective outcomes when compared with conventional games. This has important implications for studying adaptation and decision-making in situations with ecological constraints.

The invention of the wheel is widely credited as a pivotal moment in human history, yet the details surrounding its discovery are shrouded in mystery. There remains no scholarly consensus on key questions such as where, how and by whom this technology was originally invented. In this study, we employ state-of-the-art techniques from computational structural mechanics to shed light on this long-standing puzzle. Based on this analysis, we propose a probable path along which the wheel evolved via a sequence of three major innovations. We also introduce an original computational design algorithm that autonomously generates a wheel-and-axle system using an evolutionary process that offers insight into the way in which the first wheels likely evolved nearly 6000 years ago. Our analysis provides new supporting evidence for the recently advanced theory that the wheel was invented by Neolithic miners harvesting copper ore from the Carpathian Mountains as early as 3900 BC. Moreover, we show how the discovery of the wheel was made possible by the unique physical features of the mine environment, whose impact was analogous to the selective environmental pressures that drive biological evolution.

Madagascar is one of the world's foremost biodiversity hotspots with more than 90% of its species endemic to the island. Malagasy carnivorans are one of only four extant terrestrial mammalian clades endemic to Madagascar. Although there are only eight extant species, these carnivorans exhibit remarkable phenotypic and ecological diversity that is often hypothesized to have diversified through an adaptive radiation. Here, we investigated the evolution of skull diversity in Malagasy carnivorans and tested if they exhibited characteristics of convergence and an adaptive radiation. We found that their skull disparity exceeds that of any other feliform family, as their skulls vary widely and strikingly capture a large amount of the morphological variation found across all feliforms. We also found evidence of shared adaptive zones in cranial shape between euplerid subclades and felids, herpestids and viverrids. Lastly, contrary to predictions of adaptive radiation, we found that Malagasy carnivorans do not exhibit rapid lineage diversification and only marginally faster rates of mandibular shape evolution and to a lesser extent cranial shape evolution, compared to other feliforms. These results reveal that exceptional diversification rates are not necessary to generate the striking phenotypic diversity that evolved in carnivorans after their dispersal to and isolation on Madagascar.

Himatiichnus mangano igen. et isp. nov., a new trace fossil from the late Ediacaran Huns Member of the Urusis Formation, southern Namibia, comprises intertwining tubes exhibiting dual lineation patterns and reminiscent of both modern and early Cambrian examples of priapulid worm burrows. These similarities support the interpretation of a total-group scalidophoran tracemaker for H. mangano, thus providing direct evidence for the first appearance date of Scalidophora in the late Ediacaran ca 539 Ma. This new material is thus indicative of the presence of total-group scalidophorans below the Cambrian boundary and supports inference of a lengthy Precambrian fuse for the Cambrian explosion.

Like many mammals, grasshoppers (infraorder Acrididea) chew using molariform structures. Despite decades of research on mammals, little is known about grasshopper molar form and how it relates to grasshopper feeding biomechanics, diet, dietary ecology and evolution. Here, we develop a method for quantifying molar form and apply it to two species of distantly related grasshoppers with different diets (Phymateus saxosus, seven females; Valanga nigricornis, seven females, 11 males). We show that there are quantifiable differences in molar form, potentially related to diet. There are some differences in molar shape between left and right molars in both species and sexes, and significant differences in molar size, potentially due to scaling. Like in mammals, molar wear can cause large differences in molar shape. Species differences in molar shape did not match what was expected based on mammalian molar functional morphology. Dental topographic analysis is a promising new avenue for quantifying molar form in grasshoppers and a distinct advantage over traditional two-dimensional microscopy methods, and promises to reveal much about the biology, biomechanics and evolution of Acrididea.