Royal Society Open Science最新文献

Humans typically walk at low speeds and run at higher speeds. Previous studies of transitions between walking and running were mostly on treadmills, but real-world locomotion allows more flexibility. Here, we study overground locomotion over long distances (800 or 2400 m) under time constraints, simulating everyday scenarios like traveling to an appointment. Unlike on treadmills, participants can vary both speed and gait during this task. Gait transition in this overground task occurs over a broad 'gait transition regime' spanning average speeds from 1.9 to 3.0 m s^-1. In this regime, people use mixtures of walking and running on each travel bout: mostly walking at low average speeds (around 1.9 m s^-1) and mostly running at high average speeds (3.0 m s^-1). The walk-run fraction changes gradually between these speed limits and is 50% at about 2.5 m s^-1. Within each walk-run mixture, walking is slower than running, with an unused gap between the two gait speeds. These gait mixtures and their speed dependence are predicted by energy optimality. These findings extend earlier results for shorter distances, showing that similar energetic principles govern longer, more physically and cognitively demanding tasks. Our results highlight the role of whole-task energy minimization including transients in shaping human locomotion and gait choice.

How the intricate mammalian cochlea evolved, and its functional implications, remain only partly understood. Here, we explore cochlear morphology across 101 extant and fossil species of the mammalian grand order Euarchonta using micro-computed tomography, three-dimensional geometric morphometrics and phylogenetic comparative analyses. We find substantial shape variation across taxa, likely driven by an interplay between evolutionary history, morphological constraints and potentially functional demands, although these remain difficult to interpret. Evolutionary models suggest the rate of cochlear shape evolution was heterogeneous, with some lineages showing particularly high rates, likely linked with adaptive selection pressures (e.g. tarsiers, Cercopithecus). Ancestral state reconstructions reveal lemuriforms retain the ancestral strepsirrhine cochlear shape-conical with around 2½ turns-while lorisiforms exhibit a derived cylindrical cochlea with increased coiling. The highly coiled cochlea of tarsiers reflects cranial constraints and functional demands, particularly for high-frequency hearing. In anthropoids, platyrrhines nest within catarrhine variation. Among the latter, cercopithecins trend towards increased coiling, whereas colobines and hominoids retain less coiled shapes. Finally, while body size has little effect on cochlear shape, its interaction with cochlear length predicts the number of turns, supporting the theory that cochlear coiling enabled the development of a longer basilar membrane within a small petrous space.

Palaeoloxodon is the largest known terrestrial mammal in the history of Taiwan. However, little is known about the palaeoecology and palaeoenvironment of these extinct proboscideans. In this study, we investigate the stable carbon and oxygen isotopic ratios of sequential enamel samples taken along the growth direction of molars from three Palaeoloxodon specimens of different ontogenetic ages from the Pleistocene of Taiwan. Our results suggest that these proboscideans relied extensively on a C₄ diet, a dietary niche distinct from the Eurasian Palaeoloxodon antiquus but similar to the predominantly C₄-grazing species Palaeoloxodon namadicus. The specimens show depleted δ ¹⁸O values, indicating obligate drinking and reliance on running water sources, such as monsoon-fed rivers, which exhibit more depleted δ ¹⁸O values. Additionally, the juvenile specimen shows an isotopic shift in both δ ¹³C and δ ¹⁸O values, aligning with the known signals of weaning in proboscideans. This could provide a novel insight into the life history and weaning age of Palaeoloxodon. Our results highlight, to our knowledge, the first evidence of a unique palaeohabitat of Palaeoloxodon from the Pleistocene of Taiwan, represented by C₄ vegetation and the presence of a palaeo-river system that supported these giant proboscideans.

The evolution of skull diversity in Crocodylia is rather well documented, but the developmental foundation of their cranial architecture remains poorly understood. Here, we present the first three-dimensional reconstruction of the embryonic cartilaginous skull of Caiman crocodilus based on histological sections. We provide a comprehensive anatomical description and morphometric analysis of the chondrocranium of this species, integrating linear measurements and comparative anatomical data to assess interspecific variation and evaluate whether closely related taxa exhibit greater similarity in chondrocranial morphology. We identified both qualitative and quantitative differences between major crocodilian clades, which may reflect diverse ecological demands. Within Crocodylidae, orbitotemporal proportions strongly influence chondrocranial morphology, likely reflecting adaptations related to bite force and visual acuity, linked to prey type and diverse aquatic habits. Within Alligatoridae, by contrast, the emphasis on nasal capsule proportions suggests a reliance on olfactory and respiratory functions, consistent with their occupation of densely vegetated environments and more restricted geographic ranges. Additionally, we identified a set of embryonic diagnostic features located in the splanchnocranium of Caiman and in the neurocranium of Alligatoridae. These findings shed new light on the developmental basis of cranial diversity in Crocodylia and emphasize the evolutionary significance of chondrocranial traits in shaping macroevolutionary patterns.

Sound production is widespread across the animal kingdom and can take many forms and serve various functions. A hissing sound is a non-vocal acoustic signal produced by forced air ventilation and is hypothesized to be a behavioural symplesiomorphy in Amniota. Yet, hissing sounds are typically associated with reptiles and have received comparably little research attention in birds. Here, we identified at least 86 families within 34 avian orders in which members produced hissing sounds. Despite being widespread, almost nothing is currently known about the mechanism(s) of avian hissing sound production. Functions of hissing signals were divided into broad categories based on the social/behavioural context in which they are typically expressed and most evidence pointed towards a main role in threat/defence displays towards predators. Yet, interesting examples exist where avian hissing signals are involved in agonistic interactions, parent-offspring communication, sibling competition, mating displays, pair communication and heterospecific eavesdropping. Our review also emphasizes that research on hissing sounds regarding individual variation, acoustic individuality, geographic variation and fitness consequences is still in its infancy. Overall, hissing sounds are widespread and can be involved in communication in many crucial aspects of avian life, thereby spanning various contemporary disciplines in behavioural and evolutionary ecology.

Sometimes, when a golfer attempts to putt a golf ball, it appears to enter the hole, only to re-emerge almost immediately, having undergone an angle of turn around the hole rim that can exceed ${180}^{\circ }$ . We consider the problem from the point of view of mechanics. We show analytically that there are at least two distinct types of lip out: the rim lip out, where the centre of mass of the golf ball does not fall below the level of the green, and the hole lip out where it does. At the heart of both lip outs is a family of degenerate saddle equilibria of the dynamics on the rim (the golf balls of death). When perturbed one way, the golf ball executes a rim lip out. When perturbed another way, the golf ball enters the hole, only to re-emerge (provided it does not touch the base of the hole) if it is spinning about an axis perpendicular to the wall of the hole.

Electrostatic fog collection offers a low energy cost and highly efficient method for fog collection; however, the correlation between efficiency and collector surface wettability has not yet been fully explored. This study examines the effectiveness of polytetrafluoroethylene (PTFE)-coated carbon papers in electrostatic fog collection and reveals that their performance is comparable to that of hydrophilic carbon papers. These findings suggest that PTFE coating on the carbon paper surface has a minimal influence on the electrostatic fog collection efficiency. On hydrophilic carbon paper, deposited fog droplets coalesce into a continuous water film that subsequently drains, whereas on hydrophobic carbon paper, the droplets aggregate into discrete spherical forms. This variation in wetting behaviour exerts nearly no influence on the overall fog collection efficiency. Furthermore, the efficiency of electrostatic fog collection is unaffected by charge polarity, with both negative and positive high voltages yielding comparable fog collection efficiencies. Collection efficiency is directly correlated with electrostatic current and shows an exponential relationship: collection efficiency rises sharply with increasing current before reaching a near-plateau. In addition, a thermal camera was utilized to map the zone where the fog stream is collected on the carbon paper, and it was shown that a strong electric field could cause segregation of the charged fog stream.

Global biodiversity is in rapid decline, with invasive alien species playing a major role. Predicting which is most damaging and under what conditions is key to proactive management. We investigated whether behavioural traits, specifically boldness and exploration, predict ecological impact in the invasive red lionfish (Pterois volitans). Despite the modest sample size of adults (n = 8) and juvenile (n = 8) lionfish, using repeated behavioural assays, we found strong personality consistency: 93% of juveniles and 56% of adults used shelter, with traits like latency to interact with novel objects showing high repeatability. Bold individuals spent less time in shelter and interacted more with novel stimuli. However, in groups of eight, personality expression shifted, with only 7% of juveniles and 44% of adults using shelter, indicating that social context alters behaviour. Functional response experiments revealed Type II feeding curves across three prey species, reflecting a saturating, hyperbolic relationship in which predators rapidly consume prey at low densities but are increasingly constrained by handling time as prey density rises. Neither adult nor juvenile lionfish reduced feeding effort when prey became scarce, allowing them to exert strong predation pressure even at low prey densities. Adults displayed significantly higher attack rates and shorter handling times on Artemia salina, whereas juveniles showed these patterns towards Gammarus oceanicus, underscoring the greater per capita feeding impact of adults. Contrary to expectations, boldness did not correlate with feeding impact but was linked to slower reaction times in shy individuals. These findings highlight the complex, context-dependent relationship between personality and ecological impact during invasions.

Understanding the past, current and future dynamics of dengue epidemics is challenging yet increasingly important for global public health. Using data from northern Peru across 2010-2021, we introduce a multi-model approach that integrates new and existing techniques for understanding and predicting dengue epidemics. Using wavelet analyses, we unveil spatio-temporal patterns and estimate space-varying epidemic drivers across shorter and longer dengue cycles, while our Bayesian hierarchical model allows us to quantify the timing, structure and intensity of such climatic influences. For forecasting, as a single model is generally suboptimal, we introduce trained and untrained probabilistic ensembles. In settings that mirror real-world implementations, we develop climate-informed and covariate-free deep learning forecasting models involving foundational time series, temporal convolutional networks and conformal inference. We complement modern techniques with statistically principled training, assessment and benchmarking of ensembles, alongside interpretable metrics for outbreak detection to disseminate outputs with communities and public health authorities. Our ensembles generally outperformed individual models across space and time. Looking forward, whether the public health objective is to learn from the past and/or to predict future dengue epidemic dynamics, our multi-model approach can be used to inform the decision-making and planning of public health authorities.

Bioluminescence is a common phenomenon found in many marine environments and has evolved independently dozens of times across the Tree of Life. In Anthozoa, a single origin of bioluminescence in Octocorallia has been proposed, while the evolution of bioluminescence in Hexacorallia remains unclear due to incomplete taxon sampling. This study, based on recent deep-sea surveys in southern Japan, describes a new bioluminescent Corallizoanthus species that is epibiotic on Coralliidae octocoral species and also provides observations of bioluminescence activity and spectral data for the new species and another parazoanthid species. As bioluminescence in Hexacorallia has been primarily found in order Zoantharia, integrating bioluminescence data into zoantharian taxonomy would allow not only a new understanding of the evolution of Hexacorallia, but also insights into the ecological aspects of bioluminescence in deep-sea environments.