Royal Society Open Science最新文献

Many studies have shown that prey can optimize their defence mechanisms based on cues indicating predator presence and pressure. However, little is known about whether prey can assess the actual threat by considering both predator density and the motivational state of cannibalistic predators, which can be influenced by threats from higher order predators. We conducted laboratory experiments to test the hypothesis that high predator density, combined with chemical cues indicating predator stress (e.g. alarm and disturbance cues), may inhibit prey defences. Using Daphnia and Zygoptera/Anisoptera larvae, we observed that Daphnia's strong response to low-density predator kairomones was suppressed when exposed to high-density predator kairomones and disturbance cues. Surprisingly, we found no evidence of a suppressive response to alarm cues. Our study is to our knowledge, the first to show that prey uses predator stress cues to avoid unnecessary defences, suggesting a 'cascade of fear' in which fear at one trophic level reduces fear at a lower level. Furthermore, it is to our knowledge the first to demonstrate that prey can reduce their anti-predator response in the presence of high densities of cannibalistic predators.

Individuals can strongly vary in their ability to process face identity. Understanding the mechanisms driving these differences is important for theoretical development, and in clinical and applied contexts. Here we investigate the role of face-space properties in relation to individual face identity processing skills. We consider two fundamental properties of face-space: expansion (how distant from each other similar faces are located in such space) and adaptability (the degree to which these distances change over time). Fifty-two participants performed a face detection task, with faces systematically varying in their location in face-space, and a comprehensive face identity processing test battery. We replicate previous results indicating a detection advantage for typical, as compared with distinctive faces. Critically, we find that neither our measure of face-space expansion nor that of face-space adaptability are related to individual face processing abilities. While future studies might benefit from the use of more sensitive measures of face-space properties, these results suggest that the two examined here do not contribute to individual differences in face processing abilities as previous studies suggest.

Seed germination is a crucial stage in plant development, intricately regulated by various environmental stimuli. Understanding these interactions is essential for optimizing planting and seedling management but remains challenging due to the trade-off effects of environmental factors on the germination process. We proposed a new conceptual model by viewing seed germination as a dynamic process in a physiological dimension, with the influence of environmental factors and seed heterogeneity characterized by a germination speed and a dispersion coefficient. To validate the model, we conducted field experiments by drilling wheat seeds at different dates to establish a temperature gradient and in different plots to create a soil water content gradient. Comparisons with our experimental data and literature results show the model accurately reproduces all germination patterns and the subsequent seedling tillering, with R ² > 0.95. Our results reveal that within suboptimal temperature range, the seed germination increases asymptotically with temperature, and that as soil water content increases, the germination speed increases initially before decreasing, illustrating the trade-off effect of soil water on bioavailability of water and oxygen. Introducing a physiological dimension enables seed germination and the subsequent tillering process to be modelled as a continuous physiological process, providing deeper insight into plant growth dynamics.

Corals have been used as geochemical proxies since the 1970s, playing a prominent role in paleoceanography. However, it has not been well elucidated how aqueous ions sourced from seawater are transported and precipitated in coral skeletons. There are limited foundational methods to differentiate and quantify biogenic and abiogenic effects during skeletal formation. Especially, Mg in coral skeletons show individual variations suggesting large biogenic effects. Here, we evaluated biological complexity by investigating how coral genes evolved over geologic time scales. We focused on Mg transporter and analysed five species from genus Acropora and three species from genus Porites. Mg transporter of Acropora digitifera, Acropora hyacinthus, Acropora millepora and Porites australiensis showed higher similarity to Mg transporter of vertebrates and were reported to appear on Earth during the Pleistocene. On the other hand, Acropora palmata, Acropora tenuis and Porites astreoides showed lower or no similarity to vertebrates, and they were reported to appear on Earth before the Pleistocene. We suggest such evolutional records can be evidence to demonstrate biological complexity of Mg transport from seawater. This might explain that Mg transport is subject to evolution and why Mg incorporated in coral skeletons tends to show strong biogenic effects compared with other elements.

The flow network model is an established approach to approximate pressure-flow relationships in a bifurcating network, and has been widely used in many contexts. Existing models typically assume unidirectional flow and exploit Poiseuille's law, and thus neglect the impact of bifurcation geometry and finite-sized objects on the flow. We determine the impact of bifurcation geometry and objects by computing Stokes flows in a two-dimensional (2D) bifurcation using the Lightning-AAA Rational Stokes algorithm, a novel mesh-free algorithm for solving 2D Stokes flow problems utilizing an applied complex analysis approach based on rational approximation of the Goursat functions. We compute the flow conductances of bifurcations with different channel widths, bifurcation angles, curved boundary geometries and fixed circular objects. We quantify the difference between the computed conductances and their Poiseuille law approximations to demonstrate the importance of incorporating detailed bifurcation geometry into existing flow network models. We parametrize the flow conductances of 2D bifurcation as functions of the dimensionless parameters of bifurcation geometry and a fixed object using a machine learning approach, which is simple to use and provides more accurate approximations than Poiseuille's law. Finally, the details of the 2D Stokes flows in bifurcations are presented.

The 2019 emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid spread created a public health emergency of international concern. However, the impact of the pandemic in Sub-Saharan Africa, as documented in cases, hospitalizations and deaths, appears far lower than in the Americas, Europe and Asia. Characterization of the transmission dynamics is critical for understanding how SARS-CoV-2 spreads and the true scale of the pandemic. Here, to better understand SARS-CoV-2 transmission dynamics in two southern African countries, Mozambique and Zimbabwe, we developed a dynamic model-Bayesian inference system to estimate key epidemiological parameters, namely the transmission and ascertainment rates. Total infection burdens (reported and unreported) during the first 3 years of the pandemic were reconstructed using a model-inference approach. Transmission rates rose with each successive wave, which aligns with observations in other continents. Ascertainment rates were found to be low and consistent with other African countries. Overall, the estimated disease burden was higher than the documented cases, indicating a need for improved reporting and surveillance. These findings aid understanding of COVID-19 disease and respiratory virus transmission dynamics in two African countries little investigated to date and can help guide future public health planning and control strategies.

Tsunamis are massive waves generated by sudden water displacement on the ocean surface, causing devastation as they sweep across the coastlines, posing a global threat. The aftermath of the 2004 Indian Ocean tsunami led to the establishment of the Indian Tsunami Early Warning System (ITEWS). Predicting real-time tsunami heights and the resulting coastal inundation is crucial in ITEWS to safeguard the coastal communities. Global tsunamis other than those in the Indian Ocean might weaken at Indian coasts due to distance yet still cause significant damage due to local coastal morphological amplification. The current study focuses on tsunami simulations over global oceans. A finite element (FE)-based ADvanced CIRCulation (ADCIRC) model is configured to the global domain to model global tsunamis accurately and efficiently. The model mesh has a spatial resolution of 2 km in the shallow waters and relaxed to 20 km in the deeper waters. Model simulations are performed for significant historical events, assessing their effect on near and far field regions. Computed results are compared with the observations, and it is found that the model's predictions align well with the observations. The simulation results demonstrate that ADCIRC can be applied to real-time tsunami predictions due to its computational efficiency and accuracy.

Across mammals, fertility and offspring survival are often lowest at the beginning and end of females' reproductive careers. However, extrinsic drivers of reproductive success-including infanticide by males-could stochastically obscure these expected age-related trends. Here, we modelled reproductive ageing trajectories in two cercopithecine primates that experience high rates of male infanticide: the chacma baboon (Papio ursinus) and the gelada (Theropithecus gelada). We found that middle-aged mothers generally achieved the shortest interbirth intervals in chacma baboons. By contrast, old gelada females often showed shorter interbirth intervals than their younger group-mates with one exception: the oldest females typically failed to produce additional offspring before their deaths. Infant survival peaked in middle-aged mothers in chacma baboons but in young mothers in geladas. While infant mortality linked with maternal death increased as mothers aged in both species, infanticide risk did not predictably shift with maternal age. Thus, infanticide patterns cannot explain the surprising young mother advantage observed in geladas. Instead, we argue that this could be a product of their graminivorous diets, which might remove some energetic constraints on early reproduction. In sum, our data suggest that reproductive ageing is widespread but may be differentially shaped by ecological pressures.

During the COVID-19 pandemic, both government-mandated lockdowns and discretionary changes in behaviour combined to produce dramatic and abrupt changes to human mobility patterns. To understand the socioeconomic determinants of intervention compliance and discretionary behavioural responses to epidemic threats, we investigate whether changes in human mobility showed a systematic variation by socioeconomic status during two distinct periods of the COVID-19 pandemic in Australia. We analyse mobility data from two major urban centres and compare the trends during mandated stay-at-home policies and after the full relaxation of nonpharmaceutical interventions, which coincided with a large surge of COVID-19 cases. We analyse data aggregated from de-identified global positioning system trajectories, collated from providers of mobile phone applications and aggregated to small spatial regions. Our results demonstrate systematic decreases in mobility relative to the pre-pandemic baseline with the index of education and occupation, for both pandemic periods. On the other hand, the index of economic resources was not correlated with mobility changes. This result contrasts with observations from other national contexts, where reductions in mobility typically increased strongly with indicators of wealth. Our analysis suggests that economic support policies in place during the initial period of stay-at-home orders in Australia facilitated broad reductions in mobility across the economic spectrum.

The mechanical properties of dietary items are known to influence skull morphology, either through evolution or by phenotypic plasticity. Here, we investigated the impact of supplementary feeding of peanuts on the morphology of red squirrels (Sciurus vulgaris) from five populations in Britain (North Scotland, Borders, Jersey and two temporally distinct populations from Formby (Merseyside)). Stable isotope analysis confirmed dietary ecology in 58 specimens. Geometric morphometrics were used to analyse three-dimensional and two-dimensional shape variation across 113 crania and 388 mandibles, respectively. Nitrogen isotope ratios (δ¹⁵N) were lower in the 1990s and 2010s Formby squirrels (suggesting a diet with an increased proportion of peanuts), and higher in other populations. Significant differences in cranio-mandibular shape were found between all populations, with 1990s Formby red squirrels exhibiting a morphology associated with reduced masticatory efficiency. This effect was partially reversed following a reduction in supplementary feeding of peanuts. We propose that these morphological changes are related to the reduced mechanical effort needed to process peanuts relative to naturally occurring food items. This could be an example of diet-induced plastic changes to the skeleton in non-muroid wild mammals, although further research is needed to exclude other driving factors such as genetics.