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The costs of foraging can be high while also carrying significant risks, especially for consumers feeding at the top of the food chain. To mitigate these risks, many predators supplement active hunting with scavenging and kleptoparasitic behaviours, in some cases specializing in these alternative modes of predation. The factors that drive differential utilization of these tactics from species to species are not well understood. Here, we use an energetics approach to investigate the survival advantages of hunting, scavenging and kleptoparasitism as a function of predator, prey and potential competitor body sizes for terrestrial mammalian carnivores. The results of our framework reveal that predator tactics become more diverse closer to starvation, while the deployment of scavenging and kleptoparasitism is strongly constrained by the ratio of predator to prey body size. Our model accurately predicts a behavioural transition away from hunting towards alternative modes of predation with increasing prey size for predators spanning an order of magnitude in body size, closely matching observational data across a range of species. We then show that this behavioural boundary follows an allometric power-law scaling relationship where the predator size scales with an exponent nearing 3/4 with prey size, meaning that this behavioural switch occurs at relatively larger threshold prey body size for larger carnivores. We suggest that our approach may provide a holistic framework for guiding future observational efforts exploring the diverse array of predator foraging behaviours.

This poster was presented at the UCSB EEMB research symposium in 2024.Seed predation by granivores limits plant survival and recruitment of new germinates, especially of rare species limited by small populations and increasing pressure from nonnative invasives. The relationship between granivores and native flora at the Dune Protected Area in Callandar, CA is currently shifting away from historic patterns; Nipomo  mesa lupine (L. nipomensis) and other dune stabilizing plant species have been impacted by the habitat-wide colonization by the invasive perennial veldt grass (Ehrharta calycina). Current veldt management practices prevent the use of herbicide to control the grass within a 15-foot buffer of extant lupine populations. Understanding how dense stands of veldt grass may support increased populations of L. nipomensis seed predators can inform the management of veldt grass and the recovery of the endangered lupine. This study assessed seed predation through low profile boxes baited with L. nipomensis seeds and camera traps capturing both video and still images to compare seed predation rates relative to dense stands of veldt grass. Conservation implications were further assessed by considering the role of cages (fencing) in reducing seed predation.  We found that increased proximity to veldt grass modestly increased seed predation, and that uncaged bait stations lost the most seeds (~70% loss rates compared to ~15% in caged plots). The most common seed predators captured on camera were Heermann’s kangaroo rats, Dipodomys heermanni (found outside of cages and away from veldt grass), Deer mice, Peromyscus maniculatus (found outside of cages and adjacent to veldt grass), and California towhees (found within cages and away from veldt grass). Our results establish patterns of seed predation consistent with predicted results and emphasize potential vulnerability to seed predation in areas near veldt or areas unprotected by caging.

Macroecologists traditionally emphasized the role of environmental variables for predicting species distribution and abundance at large scale. While biotic factors have been increasingly recognized as important at macroecological scales, producing valuable biotic variables remains challenging and rarely tested. Capitalizing on the wealth of population density estimates available for African savannah ungulates, here we modeled species average population density at 100 × 100 km as a function of both environmental variables and proxies of biotic interactions (competition and predation) and estimated their relative contribution. We fitted a linear mixed effect model on 1043 population density estimates for 63 species of ungulates using Bayesian inference and estimated the percentage of total variance explained by environmental, anthropogenic, and biotic interactions variables. Environmental and anthropogenic variables were the main drivers of ungulate population density, with NDVI, Distance to permanent water bodies and Human population density showing the highest contribution to the variance. Nonetheless, biotic interactions altogether contributed to a quarter of the variance explained, with predation and competition having a negative effect on species density. Despite the limitations of modelling biotic interactions in macroecological studies, proxies of biotic interactions can enhance our understanding of biological patterns at broad spatial scales, uncovering novel predictors as well as enhancing the predictive power of large-scale models. [ABSTRACT FROM AUTHOR]

We experimentally tested whether the presence of a free benthic predator (Odonata naiads) alters the displacement time, the position occupied in the water column, and the proportion of food consumed by benthic and nektonic tadpoles. The presence of predators did not influence the displacement time or the proportion of food consumed by any of the two species. In the presence of predators, benthic tadpoles avoided the benthic microhabitat, increasing their time in the middle of the water column. This behavior was unexpected since the previous studies indicate that the morphology of benthic tadpoles restricts them to the bottom of water bodies. We, thus, hypothesize that such a drastic behavior change was a consequence of the real risk of predation to which the tadpoles were exposed. Our results are in accordance with the threat-sensitivity hypothesis, in which prey behave flexibly when exposed to different degrees of predation threats. Nektonic tadpoles, however, slightly increased their permanence in the water column in the presence of the same benthic predators. Therefore, we provide support for the hypothesis that predators induce greater behavioral changes in prey that exhibit patterns of microhabitat use similar to theirs. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a specialist predator-prey model within a closed patchy network of streams. Specifically, we focus on the dynamics and asymptotic profiles of positive steady states. Our findings reveal that specialist predators can successfully invade when the mortality rate remains sufficiently low. Additionally, we explore the effects of diffusion and advection on these steady states and the overall species concentration. [ABSTRACT FROM AUTHOR]

This paper is concerned with existence, non-existence and uniqueness of positive (coexistence) steady states to a predator-prey system with prey-dependent dispersal. To overcome the analytical obstacle caused by the cross-diffusion structure embedded in the prey-dependent dispersal, we use a variable transformation to convert the problem into an elliptic system without cross-diffusion structure. The transformed system and pre-transformed system are equivalent in terms of the existence or non-existence of positive solutions. Then we employ the index theory alongside the method of the principle eigenvalue to give a nearly complete classification for the existence and non-existence of positive solutions. Furthermore we show the uniqueness of positive solutions and characterize the asymptotic profile of solutions for small or large diffusion rates of species. Our results pinpoint the positive role of prey-dependent dispersal on the population dynamics for the first time by showing that the prey-dependent dispersal in the predator-prey system is a beneficial strategy increasing the chance of predator's survival and hence promoting the coexistence of species. [ABSTRACT FROM AUTHOR]

This paper deals with a predator-prey system with density-dependent diffusion and indirect pursuit-evasion interaction under homogeneous Neumann boundary conditions. By providing appropriate conditions, the asymptotic stability of solution is investigated. [ABSTRACT FROM AUTHOR]

Large carnivore species frequently predate and consume wild or domestic prey, which is referred to as food-related predation. Large carnivores can also hunt and kill prey exceeding their immediate needs (i.e., they do not consume prey), which is referred to as surplus predation. We used 173 records of livestock predations by gray wolves (Canis lupus; n = 133) and Persian leopards (Panthera pardus tulliana; n = 40) reported by governmental organizations of Iran during 2009–2019 to investigate food-related and surplus predation incidents of livestock. We found that for wolves, the number of reported surplus predation incidents was greater than that of food-related predation incidents during all 4 seasons (spring through winter), whereas for leopards, the number of food-related and surplus predation incidents were similar in all seasons. The number of livestock killed per surplus predation incident was greater for wolves than for leopards and that surplus predations by both species occurred more frequently within corrals than on free-range pastures. As corrals in most villages across Iran are poorly constructed and largely accessible to predators, we recommend that livestock owners enhance corral construction, use well-trained dogs during day and particularly at night, employ people to watch livestock at night, and use fire (e.g., torches) during night to scare carnivores. These strategies can mitigate predation incidents and corresponding economic losses, resulting in fewer losses of livestock, wolves, and leopards, as these two carnivore species are mainly killed by humans due to livestock predations across Iran. [ABSTRACT FROM AUTHOR]

Predation reduces the population density of prey, affecting its fitness and population dynamics. Few studies have connected trait changes with fitness consequences in prey and the molecular basis and metabolic mechanisms of such changes in bat-insect systems. This study focuses on the responses of Helicoverpa armigera to different predation risks, focusing on echolocating bats and their calls. Substantial modifications were observed in the nocturnal and diurnal activities of H. armigera under predation risk, with enhanced evasion behaviors. Accelerated development and decreased fitness were observed under predation risks. Transcriptomic and metabolomic analyses indicated that exposure to bats induced the upregulation of amino acid metabolism- and antioxidant pathway-related genes, reflecting shifts in resource utilization in response to oxidative stress. Exposure to bat predation risks enhanced the activity of DNA damage repair pathways and suppressed energy metabolism, contributing to the observed trait changes and fitness decreases. The current results underscore the complex adaptive strategies that prey species evolve in response to predation risk, enhancing our understanding of the predator–prey dynamic and offering valuable insights for innovative and ecologically informed pest management strategies. Helicoverpa armigera shows adaptive trait changes under bat predation risk, with increased evasion, accelerated development, and fitness decreases. Molecular analyses reveal shifts in metabolism and stress response pathways linked to these changes. [ABSTRACT FROM AUTHOR]

Predators can alter the movement of nutrients through ecosystems by depositing waste products following predation. Whilst the benefits of predator waste for large predators (e.g. bears) or dense accumulations of predators (e.g. seabirds on islands) seem clear, less is known about whether smaller, solitary predators can have measurable effects on local ecosystem processes. In separate experiments with web‐building and wandering spiders, we tested if the presence of predators affected soil nutrient content, soil respiration, soil microbial communities, and plant growth. In the first experiment with black widow spiders, total nitrogen and nitrate were not affected by spider presence, but ammonia and phosphorus were higher from soil under the edge of the spider web than soil away from the spider. Soil respiration and plant growth were both higher in soil collected from under the spider retreat compared with soil collected away from the spider web. In a second experiment with wolf spiders, we tested for interactions between spiders and soil microbial communities. There were positive effects of wolf spider presence on all soil nutrients and there were interactions between spiders and soil type (i.e. field‐collected versus autoclaved) for total carbon, total nitrogen, nitrate, and pH. Spider presence and soil type also affected soil respiration and spider presence had a large effect on the composition of the microbial community of the soil. There were also positive effects of wolf spider presence on plant biomass and plant height, with a significant interaction between spiders and soil type for plant height. Overall, our results show that two spiders with different life histories (i.e. web‐building and wandering) both have significant positive effects on plant growth through the deposition of their waste products. These effects may occur through the direct deposition of nutrients and changes in soil microbial communities. Although, further work is needed to resolve these interactions. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Secondary metabolites often function as antipredator defenses, but when bioactive at low concentrations, their off-target effects on other organisms may be overlooked. Candidate "keystone molecules" are proposed to affect community structure and ecosystem functions, generally originating as defenses of primary producers; the broader effects of animal chemistry remain largely unexplored, however. Here, we characterize five previously unreported polyketides (alderenes A to E) biosynthesized by sea slugs reaching exceptional densities (up to 9000 slugs per square meter) in Northern Hemisphere estuaries. Alderenes comprise only 0.1% of slug wet weight, yet rendered live slugs or dead flesh unpalatable to three co-occurring consumers, making a potential food resource unavailable and redirecting energy flow in critical nursery habitat. Alderenes also displaced infauna from the upper sediment of the mudflat but attracted ovipositing snails. By altering communities, such compounds may have unexpected cascading effects on processes ranging from bioturbation to reproduction of species not obviously connected to the producing organisms, warranting greater attention by ecologists. [ABSTRACT FROM AUTHOR]

Predator and prey traits are important determinants of the outcomes of trophic interactions. In turn, the outcomes of trophic interactions shape predator and prey trait evolution. How species' traits respond to selection from trophic interactions depends crucially on whether and how heritable species' traits are and their genetic correlations. Of the many traits influencing the outcomes of trophic interactions, body size and movement traits have emerged as key traits. Yet, how these traits shape and are shaped by trophic interactions is unclear, as few studies have simultaneously measured the impacts of these traits on the outcomes of trophic interactions, their heritability, and their correlations within the same system.We used outcrossed lines of the ciliate protist Paramecium caudatum from natural populations to examine variation in morphology and movement behaviour, the heritability of that variation, and its effects on Paramecium susceptibility to predation by the copepod Macrocyclops albidus.We found that the Paramecium lines exhibited heritable variation in body size and movement traits. In contrast to expectations from allometric relationships, body size and movement speed showed little covariance among clonal lines. The proportion of Paramecium consumed by copepods was positively associated with Paramecium body size and velocity but with an interaction such that greater velocities led to greater predation risk for large body‐sized paramecia but did not alter predation risk for smaller paramecia. The proportion of paramecia consumed was not related to copepod body size. These patterns of predation risk and heritable trait variation in paramecia suggest that copepod predation may act as a selective force operating independently on movement and body size and generating the strongest selection against large, high‐velocity paramecia.Our results illustrate how ecology and genetics can shape potential natural selection on prey traits through the outcomes of trophic interactions. Further simultaneous measures of predation outcomes, traits, and their quantitative genetics will provide insights into the evolutionary ecology of species interactions and their eco‐evolutionary consequences. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

This study provides a comprehensive analysis of the dynamics of a three-level vertical food chain model, specifically focusing on the interactions between vegetation, herbivores, and predators in a Snowshoe hare-Canadian lynx system. By simplifying the model through dimensional analysis, we determine conditions for equilibrium existence and identify various types of bifurcations, including Saddle-Node and Hopf bifurcations. Additionally, the study explores codimension-two bifurcations such as Bogdanov–Takens (BT) and zero-Hopf bifurcations. Coefficient formulas of normal forms are derived through the use of center manifold reduction and normal form theory. The study also presents an approximation of homoclinic orbits near a BT bifurcation of the system by computing explicit asymptotics based on regular perturbation methods. Utilizing the MATLAB package MATCONT, a family of limit cycles and their associated bifurcations are computed, including limit point cycles, period-doubling bifurcations, cusp points of cycles, fold-flip bifurcations, and various resonance bifurcations (R1, R2, R3, and R4). The biological implications of the findings are discussed in detail, highlighting how the identified bifurcations and dynamics can impact the population dynamics of vegetation, herbivores, and predators in real-world ecosystems. Numerical experiments validate the theoretical results and provide further support for the conclusions. [ABSTRACT FROM AUTHOR]

The idea that species interactions are more ecologically and evolutionarily important toward lower latitudes underpins seminal theories in ecology and evolution. Recent global studies have found the predicted latitudinal gradients in interactions, particularly predation. However, latitudinal patterns alone do not reveal why interactions vary geographically and so do not provide strong predictions in space (e.g., for specific ecosystems) or time (e.g., forecasting responses to global change). Here, I review theory to identify a clearer, mechanistic, and testable framework for predicting geographic variation in the importance of species interactions. I review competing metrics of importance, proximate mechanisms that can increase interaction importance, and environmental gradients that could generate predictable geographic patterns (climate extremes and stability, warmer temperatures, productivity, and biodiversity). Strong empirical tests are accumulating thanks to the rise of global experiments and datasets; renewed focus on testing why interactions vary spatially will help move the field from identifying latitudinal patterns to understanding broader mechanisms. [ABSTRACT FROM AUTHOR]

Recent tracking technology has shown that some birds migrate at extreme altitudes, potentially to avoid predators. Predation risk during migration is a significant factor contributing to high mortality rates among birds. A study tracking Grey Plovers revealed that one bird was killed by a Peregrine Falcon at 3000m above ground, challenging the idea that flying at extreme altitudes can always protect against predators. The research was funded by the Dutch Research Council and conducted by a team of scientists. [Extracted from the article]

The article explores the role of ephemeral river islands in the Meta River in eastern Colombia as habitats for migratory songbirds from the northern and southern hemispheres during migration and the nonbreeding period. The islands emerge during the dry season, providing roosting and foraging sites for thousands of migratory birds. The study highlights the importance of understanding the habitat use and quality of nonbreeding areas for long-distance migrants and raises questions about the ecological associations, spatial-temporal dynamics, and conservation priorities of these ephemeral islands. [Extracted from the article]

The article explores the seasonal piscivory behavior of pumpkinseed sunfish in pond ecosystems in Southern Ontario, Canada. The study reveals that pumpkinseed sunfish exhibit extensive seasonal fish consumption in ponds, even in the absence of large predators. The findings suggest that mesopredator fish like pumpkinseed may fill the top predator niche in pond ecosystems, highlighting the importance of considering ponds in ecological research and understanding the impacts of expanding mesopredator species on aquatic food webs. The study emphasizes the need for further research to test the mesopredator release hypothesis and quantify the consequences of meso- and top predator expansion in pond ecosystems. [Extracted from the article]

Defensive traits are hypothesized to benefit prey by reducing predation risk from a focal predator but come at a cost to the fitness of the prey. Variation in the expression of defensive traits is seen among individuals within the same population, and in the same individual in response to changes in the environment (i.e., phenotypically plastic responses). It is the relative magnitude of the cost and benefit of the defensive trait that underlies the defensive trait expression and its consequences to the community. However, whereas the cost has received much attention in ecological research, the benefit is seldom examined. Even in a defensive trait as extensively studied as vigilance, there are few studies of the purported benefit of the behavior, namely that vigilance enhances survival. We examined whether prey vigilance increased survival and quantified that benefit in a natural system, with white‐tailed deer (Odocoileus virginianus) experiencing unmanipulated levels of predation risk from Florida panther (Puma concolor coryi). Deer that spent more time vigilant (as measured by head position using camera trap data) had a higher probability of survival. Indeed, an individual deer that was vigilant 75% of the time was more than three times as likely to be killed by panthers over the course of a year than a deer that was vigilant 95% of the time. Our results therefore show that within‐population variation in the expression of a defensive trait has profound consequences for the benefit it confers. Our results provide empirical evidence supporting a long‐held but seldom‐tested hypothesis, that vigilance is a behavior that reduces the probability of predation and quantifies the benefit of this defensive trait. Our work furthers an understanding of the net effects of a trait on prey fitness and predator–prey interactions, within‐population variation in traits, and predation risk effects. [ABSTRACT FROM AUTHOR]

Aim: Long‐standing theory predicts that the intensity of biotic interactions increases from high to low latitudes. Studies addressing geographic variation in predation on insect prey have often relied on prey models, which lack many characteristics of live prey. Our goals were to explore global latitudinal patterns of predator attack rates on standardised live insect prey and to compare the patterns in predation on live insects with those on plasticine prey models. Location: Global forested areas. Time Period: 2021–2023. Major Taxa: Arthropods, birds. Methods: We measured predation rates in 43 forested locations distributed across five continents from 34.1° S to 69.5° N latitude. At each location, we exposed 20 sets of three bait types, one set per tree. Each set included three live fly larvae (maggots), three live fly puparia and three plasticine models of the puparia. We used glue rings to isolate half of the sets from non‐flying predators. Results: Arthropod attack rates on plasticine prey decreased linearly from low to high latitudes, whereas attack rates on maggots had a U shaped distribution, with the lowest predation rates at temperate latitudes and the highest rates at tropical and boreal latitudes. This difference emerged from intensive predator attacks on live maggots, but not on plasticine models, in boreal sites. Site‐specific attack rates of arthropod predators on live and plasticine prey were not correlated. In contrast, bird attack rates on live maggots and plasticine models were positively correlated, but did not show significant latitudinal changes. Main Conclusions: Latitudinal patterns in predation differ between major groups of predators and between types of prey. Poleward decreases in both arthropod and combined arthropod and bird predation on plasticine models do not mirror patterns of predation on our live prey, the latter likely reflecting real patterns of predation risk better than do patterns of attack on artificial prey. [ABSTRACT FROM AUTHOR]

The survival of animals is impacted by landscapes of spatially varying mortality factors including habitat type, predation risk or harvest risk, among others. Characterization of these spatial mortality processes is important for managing animal populations and their habitats, yet this information has proved challenging to capture. Advances in telemetry now make it possible to monitor tagged individuals' locations through time for a wide range of taxa, providing opportunity to assess movement and mortality simultaneously through spatial time‐to‐event data. Existing time‐to‐event modelling frameworks have largely ignored spatially varying mortality processes or have treated an animal's location as fixed at a regional level.Here we present a general spatial survival model for analysing time‐to‐event data arising from animal telemetry. Our model has a flexible Cox regression form and can estimate the effects of conventional non‐spatial risk factors (size, seasonality, etc.), spatial covariates (e.g. habitat type) and spatial variation in risk not explained by covariates on mortality. We show how to fit our model using Bayesian methods and demonstrate applications of our model with several simulated examples and two animal telemetry case studies.Our model produced consistent and unbiased parameter estimates throughout simulations with a variety of spatial and non‐spatial hazards. In the first case study, data from 147 tagged caribou in British Columbia, Canada, revealed a spatially heterogeneous mortality landscape with caribou survival varying by elevation, likely in response to space use by predators. Our second case study involved a dataset of 390 acoustically tagged Atlantic cod in a southern Norwegian fjord where a marine protected area (MPA) was established during the study. We found that the MPA led to a shift from mostly fishing mortality to mostly natural mortality within the fjord and that these risks had markedly different spatial hazard patterns.Our spatial time‐to‐event model can make use of data from a variety of widely used telemetry technologies to characterize landscapes of mortality risks for different taxa. Our work provides new opportunities to inform the spatial ecology and management of fish and wildlife populations. [ABSTRACT FROM AUTHOR]

The article "Unveiling the enigmatic cone snails along the coastal environments of the South Andaman Islands: diversity, distribution and their habitat preference" published in Frontiers in Marine Science explores the diversity, distribution, and habitat preferences of cone snails in the South Andaman Islands. The study reveals that Conus ebraeus is the predominant species among the nine study sites, with Conus litteratus and Conus leopardus found exclusively in specific locations with soft, muddy substrates. The research highlights the importance of substrate type, waterline zones, and habitat characteristics in shaping the distribution patterns of cone snails, emphasizing the need for responsible management and conservation practices. [Extracted from the article]

Globally, key predators such as lobsters are thought to control urchins. In southeastern Australia, the role of Sagmariasus verreauxi (eastern rock lobster) as a key predator of the native urchin Centrostephanus rodgersii (long-spined urchin) has been questioned while the sympatric Heliocidaris erythrogramma (short-spined urchin) may be eaten more frequently. To test this, we tethered and filmed 100 urchins (50 C. rodgersii and 50 H. erythrogramma) outside of a lobster den over 25 nights to identify predators and quantify predation rates, time to feeding onset and handling time. Sagmariasus verreauxi exhibited very low predation rates (4%), despite being filmed walking past urchins repeatedly whereas Heterodontus galeatus (crested horn shark) was the main predator (45%). Predation rates by all predators (lobsters and sharks) were influenced primarily by tethering night but not urchin size or species. Predation increased throughout the study and while H. erythrogramma and C. rodgersii were eaten at similar rates, there was a trend for lobsters to eat H. erythrogramma and sharks to eat C. rodgersii. Feeding onset had no significant predictors though large C. rodgersii took longer to handle during feeding for both predators. Importantly, sharks readily consumed 25 C. rodgersii up to 121 mm Test Diameter (TD) while lobsters only ate one C. rodgersii (58 mm TD). These findings, although from only one test location, provide important insights into the species eating urchins and highlight the potential significance of overlooked predators such as H. galeatus. [ABSTRACT FROM AUTHOR]

Sensing limitations have impeded knowledge about how individual predator-prey interactions build to organized multi-species group behaviour across an ecosystem. Population densities of overlapping interacting oceanic fish predator and prey species, however, can be instantaneously distinguished and quantified from roughly the elemental individual to spatial scales spanning thousands of square kilometres by wide-area multispectral underwater-acoustic sensing, as shown here. This enables fundamental mechanisms behind large-scale ordered predator-prey interactions to be investigated. Critical population densities that transition random individual behaviour to ordered group behaviour are found to rapidly propagate to form vast adversarial prey and predator shoals of capelin and surrounding cod in the Barents Sea Arctic ecosystem for these keystone species. This leads to a sudden major shift in predator-prey balance. Only a small change in local behaviour triggers the shift due to an unstable equilibrium. Such unstable equilibria and associated balance shifts at predation hotspots are often overlooked as blind spots in present ocean ecosystem monitoring and assessment due to use of highly undersampled spatio-temporal sampling methods. This study utilises OAWRS to demonstrate mass shoaling behaviour of predatory cod and their capelin prey in the Barents Sea. The result is a mass consumption event, skewing the predator-prey ratio with implications for ecosystem stability. [ABSTRACT FROM AUTHOR]

Predators regulate communities through top‐down control in many ecosystems. Because most studies of top‐down control last less than a year and focus on only a subset of the community, they may miss predator effects that manifest at longer timescales or across whole food webs. In southeastern US salt marshes, short‐term and small‐scale experiments indicate that nektonic predators (e.g., blue crab, fish, terrapins) facilitate the foundational grass, Spartina alterniflora, by consuming herbivorous snails and crabs. To test both how nekton affect marsh processes when the entire animal community is present, and how prior results scale over time, we conducted a 3‐year nekton exclusion experiment in a Georgia salt marsh using replicated 19.6 m2 plots. Our nekton exclusions increased densities of plant‐grazing snails and juvenile deposit‐feeding fiddler crab and, in Year 2, reduced predation on tethered juvenile snails, indicating that nektonic predators control these key macroinvertebrates. However, in Year 3, densities of mesopredatory benthic mud crabs increased threefold in nekton exclusions, erasing the tethered snails' predation refuge. Nekton exclusion had no effect on Spartina biomass, likely because the observed mesopredator release suppressed grazing snail densities and elevated densities of fiddler crabs, whose burrowing alleviates soil stresses. Structural equation modeling supported the hypotheses that nektonic predators and mesopredators control invertebrate communities, with nektonic predators having stronger total effects on Spartina than mud crabs by controlling densities of species that both suppress (grazers) and facilitate (fiddler crabs) plant growth. These findings highlight that salt marshes can be resilient to multiyear reductions in nektonic predators if mesopredators are present and that multiple pathways of trophic control manifest in different ways over time to mediate community dynamics. These results highlight that larger scale and longer‐term experiments can illuminate community dynamics not previously understood, even in well‐studied ecosystems such as salt marshes. [ABSTRACT FROM AUTHOR]

Predator–prey interactions are crucial components of populations and communities. Their dynamics depend on the covariation of traits of the interacting organisms, and there is increasing evidence that intraspecific trade‐off relationships between defense and competitive traits are important drivers of trophic interactions. However, quantifying the relevant traits forming defense–competitiveness trade‐offs and how these traits determine prey and predator fitness remains a major challenge. Here, we conducted feeding and growth experiments to assess multiple traits related to defense and competitiveness in six different strains of the green alga Chlamydomonas reinhardtii exposed to predation by the rotifer Brachionus calyciflorus. We found large differences in defense and competitive traits among prey strains and negative relationships between these traits for multiple trait combinations. Because we compared trait differences among strains whose ancestors evolved previously in controlled environments where selection favored either defense or competitiveness, these negative correlations suggest the presence of a trade‐off between defense and competitiveness. These differences in traits and trade‐offs translated into differences in prey and predator fitness, demonstrating the importance of intraspecific trade‐offs in predicting the outcome of predator–prey interactions. [ABSTRACT FROM AUTHOR]

Rapid adaptation is thought to be critical for the survival of species under global change, but our understanding of human-induced evolution in the wild remains limited. We show that widespread deforestation has underpinned repeated color shifts in wild insect populations. Specifically, loss of forest has led to color changes across lineages that mimic the warning coloration of a toxic forest stonefly. Predation experiments suggest that the relative fitness of color phenotypes varies between forested and deforested habitats. Genomic and coloration analyses of 1200 specimens show repeated selection at the ebony locus controlling color polymorphism across lineages. These findings represent an example of human-driven evolution linked to altered species interactions, highlighting the possibility for populations to adapt rapidly in the wake of sudden environmental change. [ABSTRACT FROM AUTHOR]

In this article, a stochastic predator-prey system with regime switching and Lévy jumps is formulated. First, the extinction and persistence in mean of each species are investigated by use of the stochastic differential comparison theorem and some stochastic inequalities. Second, the sufficient criteria for the stochastic permanence are established by constructing some Lyapunov functionals. In the end, simulation examples are given to illustrate the theoretical results and reveal the impacts of regime switching, distributed time delays and Lévy jumps on the dynamics, respectively. [ABSTRACT FROM AUTHOR]

The removal or addition of a predator in an ecosystem can trigger a trophic cascade, whereby the predator indirectly influences plants and/or abiotic processes via direct effects on its herbivore prey. A trophic cascade can operate through a density‐mediated indirect effect (DMIE), where the predator reduces herbivore density via predation, and/or through a trait‐mediated indirect effect (TMIE), where the predator induces an herbivore trait response that modifies the herbivore's effect on plants. Manipulative experiments suggest that TMIEs are an equivalent or more important driver of trophic cascades than are DMIEs. Whether this applies generally in nature is uncertain because few studies have directly compared the magnitudes of TMIEs and DMIEs on natural unmanipulated field patterns. A TMIE is often invoked to explain the textbook trophic cascade involving wolves (Canis lupus), elk (Cervus canadensis), and aspen (Populus tremuloides) in northern Yellowstone National Park. This hypothesis posits that wolves indirectly increase recruitment of young aspen into the overstory primarily through reduced elk browsing in response to spatial variation in wolf predation risk rather than through reduced elk population density. To test this hypothesis, we compared the effects of spatiotemporal variation in wolf predation risk and temporal variation in elk population density on unmanipulated patterns of browsing and recruitment of young aspen across 113 aspen stands over a 21‐year period (1999–2019) in northern Yellowstone National Park. Only 2 of 10 indices of wolf predation risk had statistically meaningful effects on browsing and recruitment of young aspen, and these effects were 8–28 times weaker than the effect of elk density. To the extent that temporal variation in elk density was attributable to wolf predation, our results suggest that the wolf–elk–aspen trophic cascade was primarily density‐mediated rather than trait‐mediated. This aligns with the alternative hypothesis that wolves and other actively hunting predators with broad habitat domains cause DMIEs to dominate whenever prey, such as elk, also have a broad habitat domain. For at least this type of predator–prey community, our study suggests that risk‐induced trait responses can be abstracted or ignored while still achieving an accurate understanding of trophic cascades. [ABSTRACT FROM AUTHOR]

For prey, movement synchrony represents a potent antipredator strategy. Prey, however, must balance the costs and benefits of using conspecifics to mediate risk. Thus, the emergent patterns of risk-driven sociality depend on variation in space and in the predators and prey themselves. We applied the concept of predator–prey habitat domain, the space in which animals acquire food resources, to test the conditions under which individuals synchronize their movements relative to predator and prey habitat domains. We tested the response of movement synchrony of prey to predator–prey domains in two populations of ungulates that vary in their gregariousness and predator community: (i) elk, which are preyed on by wolves; and (ii) caribou, which are preyed on by coyotes and black bears. Prey in both communities responded to cursorial predators by increasing synchrony during seasons of greater predation pressure. Elk moved more synchronously in the wolf habitat domain during winter and caribou moved more synchronously in the coyote habitat domains during spring. In the winter, caribou increased movement synchrony when coyote and caribou domains overlapped. By integrating habitat domains with movement ecology, we provide a compelling argument for social behaviours and collective movement as an antipredator response. This article is part of the theme issue 'The spatial–social interface: A theoretical and empirical integration'. [ABSTRACT FROM AUTHOR]

Ocean deoxygenation and standing levels of hypoxia are shrinking fundamental niches, particularly in coastal areas, yet documented repercussions on species development and behaviour are limited. Here, we tackled the impacts of deoxygenation (7 mg O2 l−1), mild hypoxia (nocturnal 5 mg O2 l−1) and severe hypoxia (nocturnal 2 mg O2 l−1) on cuttlefish (Sepia officinalis) development (hatching success, development time, mantle length), cognition (ability to learn individually and socially) and behaviour (ability to camouflage and to explore its surroundings spatially). We found that hypoxia yielded lower survival rates, smaller body sizes and inhibited predatory (increased latency to attack the prey) and anti-predator (camouflage) behaviours. Acute and chronic exposure to low oxygen produced similar effects on cognition (inability to socially learn, increased open-field activity levels, no changes in thigmotaxis). It is thus expected that, although cuttlefish can withstand oxygen limitation to a certain degree, expanding hypoxic zones will diminish current habitat suitability. [ABSTRACT FROM AUTHOR]

Background: Cryptolaemus montrouzieri (Coccinellidae) is widely utilized as biological control agents in modern agriculture. A comprehensive understanding of its food preference can help guide mass rearing and safety management during field application of pest control. Although some studies have paid attentions to the impacts of prey shift on C. montrouzieri, little is known regarding the role of post-transcriptional regulations in its acclimation to unnatural preys. Results: We performed a genome-wide investigation on alternative splicing dynamics in C. montrouzieri in response to the predation transition from natural prey to unnatural ones. When feeding on undesired diets, 402–764 genes were differentially alternative spliced in C. montrouzieri. It is noteworthy that the majority of these genes (> 87%) were not differentially expressed, and these differentially spliced genes regulated distinct biological processes from differentially expressed genes, such as organ development and morphogenesis, locomotory behavior, and homeostasis processes. These suggested the functionally nonredendant role of alternative splicing in modulating physiological and metabolic responses of C. montrouzieri to the shift to undesired preys. In addition, the individuals feeding on aphids were subject to a lower level of changes in splicing than other alternative diets, which might be because of the similar chemical and microbial compositions. Our study further suggested a putative coupling of alternative splicing and nonsense-mediated decay (AS-NMD), which may play an important role in fine-tuning the protein repertoire of C. montrouzieri, and promoting its acclimation to predation changes. Conclusion: These findings highlight the key role of alternative splicing in modulating the acclimation of ladybirds to prey shift and provide new genetic clues for the future application of ladybirds in biocontrol. [ABSTRACT FROM AUTHOR]

The long-term decline of the black grouse population throughout Europe is influenced by many factors that affect populations differently depending on the distribution range, from Central Europe to the Scandinavian countries. Therefore, we analyzed available literature sources to describe the main reasons for the population decline of this species and to suggest conservation measures. In total, 228 pieces of literature from 1955 to 2024 were analyzed for this study. Based on the literature analysis, it is clear that the drivers of population decline differ across the distributional range. In Central Europe, where the population is declining rapidly, habitat loss and forest fragmentation are crucial factors, as is the negative impact of tourism. In Scandinavia, where the population is gradually declining, decreasing breeding success and increasing chick mortality rates are generally considered the main negative factors. However, these factors also affect black grouse populations in Central Europe. It is crucial to acknowledge that a significant proportion of the contributing factors, such as predation and habitat loss, can be attributed to human activities. Therefore, it is necessary to emphasize that environmental protection should work hand in hand with wildlife managers to improve the situation. [ABSTRACT FROM AUTHOR]

For most rodent species, there is a lack of detailed studies of their diet to understand their predatory impact on other vertebrate taxa. For this reason, rodent predation on bird nests remains a largely unexplored field. Here we provide the first direct evidence, with the use of time-lapse video surveillance, that edible dormouse Glis glis depredated or attempted to depredate eggs and nestlings of two open-nesting passerine species, the Eurasian blackcap Sylvia atricapilla, and the common blackbird Turdus merula in a central European woodland. In the blackcap, we detected three predation events. In the first two cases, edible dormouse drove away incubating/brooding females and preyed upon either the eggs or the nestlings. The third case documents egg predation on an abandoned nest. In the blackbird, we document a single case of dormouse attacking a brooding female. The female and nestlings managed to escape. The fifth case documents an attempt to forage on eggs in an abandoned song thrush Turdus philomelos nest. Our observations provide evidence for dormice predation on passerine birds and highlight the value of direct nest surveillance for documenting rodent predation on birds. [ABSTRACT FROM AUTHOR]

Antagonistic co-evolution can be asymmetric, where one species lags behind another. Asymmetry in a predator–prey context is expressed by the 'life–dinner principle', a classic informal model predicting that prey should be in some sense ahead in this arms race, since prey are running for their lives, while predators lag as they only run for their dinner. The model has undergone surprisingly little theoretical scrutiny. We derive analytical models that show coevolutionary outcomes do not always align with the life–dinner principle. Our results show that other important asymmetries can easily reverse the outcome, especially the rare-enemy principle: predators are usually outnumbered by their prey, sometimes substantially (trophic asymmetry), which can make selection on prey relatively weak. We additionally show that the antagonists typically exhibit different evolutionary responses to a situation where both predator and prey start out as equally fast runners. Although predators sometimes become so efficient that attacks always succeed, attack success often reaches a stable intermediate value. We conclude that the life–dinner principle has some validity as a metaphor, but its effect is of an 'all else being equal' type, which is surprisingly easily overridden by other features of the evolutionary dynamics. [ABSTRACT FROM AUTHOR]

Large mammalian herbivores (LMH) are important functional components and drivers of biodiversity and ecosystem functioning in grasslands. Yet their role in regulating food-web dynamics and trophic cascades remains poorly understood. In the temperate grasslands of northern China, we explored whether and how grazing domestic cattle (Bos taurus) alter the predator–prey interactions between a dominant grasshopper (Euchorthippus unicolor) and its avian predator the barn swallow (Hirundo rustica). Using two large manipulative field experiments, we found that in the presence of cattle, grasshoppers increased their jumping frequency threefold, swallows increased foraging visits to these fields sixfold, and grasshopper density was reduced by about 50%. By manipulatively controlling the grasshoppers' ability to jump, we showed that jumping enables grasshoppers to avoid being incidentally consumed or trampled by cattle. However, jumping behaviour increased their consumption rates by swallows 37-fold compared with grasshoppers that were unable to jump. Our findings illustrate how LMH can indirectly alter predator–prey interactions by affecting behaviour of avian predators and herbivorous insects. These non-plant-mediated effects of LMH may influence trophic interactions in other grazing ecosystems and shape community structure and dynamics. We highlight that convoluted multispecies interactions may better explain how LMH control food-web dynamics in grasslands. [ABSTRACT FROM AUTHOR]

Anti-predator behaviours in response to predator cues can be innate, or they can be learned through prior experience and remembered over time. The duration and strength of continued anti-predator behaviour after predator cues are no longer present, and the potential for an enhanced response when re-exposed to predator cues later is less known but could account for the observed variation in anti-predator responses. We measured the carryover effects of past predation exposure and the potential for anti-predator learning and memory in the marine snail Nucella canaliculata from six populations distributed over 1000 km of coastline. We exposed lab-reared snails to cues associated with a common crab predator or seawater control in two serial experiments separated by over seven months. Responses were population- and sex-dependent, with some populations retaining anti-predator behaviours while others showed a capacity for learning and memory. Male snails showed a strong carryover of risk aversion, while females were able to return to normal feeding rates and grow more quickly. These behavioural differences culminated in strong impacts on feeding and growth rates, demonstrating that this variation has implications for the strength of trait-mediated indirect interactions, which can impact entire ecosystems. [ABSTRACT FROM AUTHOR]

Background and Research Aims: Human-wildlife conflict is a significant issue worldwide mainly in developing countries where livestock husbandry and crop production are important aspects of rural people's livelihoods and income. This study on human-wildlife conflict was conducted in and around Chebera-Churchura National Park from September 2019 to August 2021. The main aim of the study was to investigate the extent of human-wildlife conflict in the study area. Methods: Data were collected using semi structured questionnaire and direct observation on crop damage. Descriptive statistics was used to analyze the collected data and responses were compared by using chi-square test (χ2) and one-way ANOVA. Results: The result indicated that problems encountered by the local people due to wildlife species were crop damage (99.2%), livestock predation (67.8%), disease transmission (28.8%) and human attack (11.9%). According to the report of those who are affected, the average number of livestock predated by wild animals in and around Chebera Churchura National Park was 2.69±0.17 per household per year. Maize was the most highly affected crop type by different raiders in the study area, for instance the average maize loss by olive baboon (Papio anubis) was 303 ETB (Ethiopian Birr) (6USD) per household per year. Generally, the loss of the total estimated cost of all crop types during the study period due to crop raiders was 320,515.00 ETB (Ethiopian Birr) (6410 USD). Conclusion: Conflict has occurred in the study area for many years and the rate of conflict is increasing from time to time. Implication for Conservation: Integrated conflict mitigation measures should be implemented by the park administration and stakeholders to alleviate the problem and ensure sustainable coexistence of wildlife and human in the area. [ABSTRACT FROM AUTHOR]

Identifying the processes underlying community assembly and dynamics remains a central goal in ecology. Although much research has been devoted to analyzing how environments affect species diversity, fewer studies have resolved the link between the fundamental process of ecological selection and species diversity. It has been suggested that identifying ecological selection by estimating changes in community‐weighted variance (CWV) and mean (CWM) of functional traits may help to identify more general rules of community assembly. Here, we asked whether and how selection by predation and competition affect species diversity, and how this is determined by the initial CWV and CWM for traits governing species interactions, as in our case: Competitiveness and defense against a predator. We tracked experimental five‐species phytoplankton communities in the presence and absence of a rotifer predator over time. We manipulated the initial community composition so that communities shared at least three of the five species but differed in CWV and CWM for defense against predation. We found that species diversity was highest with higher initial trait distributions and that temporal changes in diversity correlated with trait selection. The initial distributions determined the form of selection over time, with directional selection for defense and competitiveness, followed by reduced selection and an increase in niche availability when the initial trait distribution was low or high. For intermediate initial trait distributions, we observed directional selection in only one trait, followed by stabilizing selection. Differences and changes in selection for defense, competitiveness, and species diversity correlated with the changes in predator density over time. This suggests that the initial trait distribution determined species diversity through a feedback loop with changes in selection on traits and predator density. Overall, our study shows that identifying ecological selection on functional traits can provide a mechanistic understanding of community assembly. [ABSTRACT FROM AUTHOR]

Prey depletion threatens many carnivore species across the world and can especially threaten low‐density subordinate competitors, particularly if subordinates are limited to low densities by their dominant competitors. Understanding the mechanisms that drive responses of carnivore density to prey depletion is not only crucial for conservation but also elucidates the balance between top‐down and bottom‐up limitations within the large carnivore guild. To avoid predation, competitively subordinate African wild dogs typically avoid their dominant competitors (lions) and the prey rich areas they are associated with, but no prior research has tested whether this pattern persists in ecosystems with anthropogenically‐reduced prey density, and reduced lion density as a result. We used spatial data from wild dogs and lions in the prey‐depleted Greater Kafue Ecosystem to test if wild dogs continue to avoid lions (despite their low density), and consequently avoid habitats with higher densities of their dominant prey species. We found that although lion density is 3X lower than comparable ecosystems, wild dogs continue to strongly avoid lions, and consequently avoid habitats associated with their two most important prey species. Although the density of lions in the GKE is low due to prey depletion, their competitive effects on wild dogs remain strong. These effects are likely compounded by prey‐base homogenization, as lions in the GKE now rely heavily on the same prey preferred by wild dogs. These results suggest that a reduction in lion density does not necessarily reduce competition, and helps explain why wild dogs decline in parallel with their dominant competitors in ecosystems suffering from anthropogenic prey depletion. Protecting prey populations within the few remaining strongholds for wild dogs is vitally important to avoid substantial population declines. Globally, understanding the impacts of prey depletion on carnivore guild dynamics should be an increasingly important area of focus for conservation. [ABSTRACT FROM AUTHOR]

Optimal foraging theory (OFT) and the energy maximization hypothesis (EMH) have long been essential when examining wildlife habitat selection. At high latitudes and altitudes, animals in winter face greater limitations in availability and accessibility of forage. Here we explore the foraging behavior of wood bison (Bison bison athabascae) during winter within the Ronald Lake bison herd in northeastern Alberta, Canada, and examine the trade‐offs they face due to limitations in forage abundance and availability (snow conditions), as well as the need to minimize predation risk. We used Global Positioning System (GPS) location data collected from 70 female wood bison to identify winter foraging sites and craters selected by bison to access forage beneath the snow. Within wetlands used by bison we selected 190 pairs of used (foraged) and random (available) sites to test eight a priori hypotheses explaining how bison traded‐off between forage availability, accessibility, and minimizing predation risk. We found with matched‐paired logistic regression that Carex atherodes was 1.21‐times more likely to be selected per unit increase in ground cover, compared to 1.17‐times per unit ground cover for C. aquatilis and C. utriculata. However, all Carex species showed an increase in selection when cover was > 50% cover within individual craters. While the importance of Carex was clear, forage site selection was still inversely related to snow depth. There is also a neutralizing combined effect of snow depth and Carex species ground cover which suggests that bison maximized their energy return by avoiding areas with deep snow (> 30 cm) that demanded intensive cratering, even when highly selected forage was accessible beneath. Avoidance of forage areas with deep snow demonstrates that wood bison employed a foraging strategy that considers both forage availability and environmental conditions, with snow depth being a limiting factor. We highlight the relationship between optimal foraging based on food availability and the trade‐offs within an energy restrictive winter season, furthering the understanding of how large herbivores forage strategically to maximize energy intake in northern environments. [ABSTRACT FROM AUTHOR]

The global decline in insect biomass has far‐reaching implications for terrestrial and freshwater food webs, impacting species reliant on insects as a crucial component of their diet. This issue extends to species traditionally considered agricultural pests, such as the common cockchafer Melolontha melolontha. In the race to combat cockchafers through collection, insecticide use, and other control methods, the repercussions of their numerical fluctuations on predators, including species of high conservation importance like bats, have been largely overlooked. Drawing on 31‐years of monitoring data for a greater horseshoe bat Rhinolophus ferrumequinum population in the Aosta Valley (Western Italian Alps), we investigated whether annual fluctuations in bat counts are influenced by cockchafer availability and weather conditions. Despite an overall positive trend in bat abundance, we observed pronounced annual fluctuations, mostly driven by cockchafer availability rather than variations in temperature and precipitation. Furthermore, we found a significant association between cockchafer availability and the median date of birth and birth rate of bats. Births occurred approximately 5 days earlier in cockchafer flight years, with earlier births also linked to warmer spring temperatures and higher numbers of warm days in April. Moreover, the ratio pups/older bats was 0.56 in cockchafer flight years, compared to 0.47 in other years. Our results underscore the importance of considering predator–prey dynamics when examining the long‐term population trends of species of conservation concern. We recommend implementing restrictions on the use of chemicals and other potentially harmful practices that may diminish prey abundance or quality, including that of species considered as agricultural pests. In designing conservation strategies, a delicate balance should be struck between the current interests of farmers and the overarching goal of preserving biodiversity against potential future threats. [ABSTRACT FROM AUTHOR]

Management decisions often focus on the habitat selection of marked individuals without considering the contribution to demographic performance in selected habitats. Because habitat selection is not always adaptive, understanding the spatial relationship between habitat selection and demographic performance is critical to management decisions. Mapping both habitat selection and demographic performance for species of conservation concern can help guide population‐scale conservation efforts. We demonstrate a quantitative approach to differentiate areas supporting selection and survival at large spatial extents. As a case study, we applied this approach to greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse), an indicator species for sagebrush ecosystems. We evaluated both habitat selection and survival across multiple reproductive life stages (nesting, brood‐rearing) in the Bi‐State Distinct Population Segment, a genetically distinct and geographically isolated population of sage‐grouse on the southwestern edge of the species' range. Our approach allowed us to identify both mismatches between selection and survival and trade‐offs between reproductive life stages. These findings suggest resource demands vary across time, with predation risk being a dominant driver of habitat selection during nesting and early brood‐rearing periods when chicks are smaller and flightless, whereas access to forage resources becomes more important during late brood rearing when resources become increasingly limited. Moving beyond identifying and managing habitat solely based on species occupancy or use by incorporating demographic measures allows managers to tailor actions to their specific goals; for example, protections of areas that support high selection and high survival and restoration actions focused on increasing survival in areas of high selection and low survival. [ABSTRACT FROM AUTHOR]

To investigate the effects of predation by the paddle crab Charybdis japonica on the culture and survival of scallops (Mizuhopecten yessoensis) during bottom culture, we investigated the behavioral characteristics of three sizes (small, medium, and large) of scallops in response to exposure to crabs. We found that scallops escaped from crab predation by continuous shell closure or movement. Shell closure force increased with scallop size, and scallops of the same size that were stimulated by the presence of crabs closed their shell more frequently than control scallops. We also measured the activities of superoxide dismutase, catalase, arginine kinase, and octopine dehydrogenase in the gill, adductor muscle, and mantle of scallops before and after exposure to predation. Tissues that showed significant differences between control and test specimens were selected for deep sequencing of the transcriptome to identify and validate the key genes that were sensitive to predation. We found that when M. yessoensis is stimulated by the presence of predators, its behavioral characteristics and related physiological and ecological indexes undergo significant changes. The results are relevant for developing specifications for M. yessoensis seedling casting during bottom culture. [ABSTRACT FROM AUTHOR]

This paper studies the transient dynamics in a fast–slow ecological model with a Monod–Haldane functional response. Geometric singular perturbation theory is utilized to examine the transient dynamics generated by intrinsic multiple time scales. An asymptotic series solution is derived for the normally hyperbolic sub-manifold in the slow flow. The paper proves the existence of relaxation oscillations near fold points and the existence of a smooth family of canard cycles arising from folded singularities. Furthermore, it investigates the resulting canard explosion and transient dynamics numerically. By incorporating the Monod–Haldane functional response, which represents the inhibitory effect on predation at high prey population levels, this study illustrates the occurrence of transient dynamics under this mechanism. [ABSTRACT FROM AUTHOR]

Biological invasions have caused the loss of freshwater biodiversity worldwide. The interplay between adaptive responses and demographic characteristics of populations impacted by invasions is expected to be important for their resilience, but the interaction between these factors is poorly understood. The freshwater gastropod Amnicola limosus is native to the Upper St. Lawrence River and distributed along a water calcium concentration gradient within which high‐calcium habitats are impacted by an invasive predator fish (Neogobius melanostomus, round goby), whereas low‐calcium habitats provide refuges for the gastropods from the invasive predator. Our objectives were to (1) test for adaptation of A. limosus to the invasive predator and the low‐calcium habitats, and (2) investigate if migrant gastropods could move from refuge populations to declining invaded populations (i.e., demographic rescue), which could also help maintain genetic diversity through gene flow (i.e., genetic rescue). We conducted a laboratory reciprocal transplant of wild F0A. limosus sourced from the two habitat types (high calcium/invaded and low calcium/refuge) to measure adult survival and fecundity in home and transplant treatments of water calcium concentration (low/high) and round goby cue (present/absent). We then applied pooled whole‐genome sequencing of 12 gastropod populations from across the calcium/invasion gradient. We identified patterns of life‐history traits and genetic differentiation across the habitats that are consistent with local adaptation to low‐calcium concentrations in refuge populations and to round goby predation in invaded populations. We also detected restricted gene flow from the low‐calcium refugia towards high‐calcium invaded populations, implying that the potential for demographic and genetic rescue is limited by natural dispersal. Our study highlights the importance of considering the potentially conflicting effects of local adaptation and gene flow for the resilience of populations coping with invasive predators. [ABSTRACT FROM AUTHOR]

A Leslie–Gower predator–prey model with nonlinear harvesting and a generalist predator is considered in this paper. It is shown that the degenerate positive equilibrium of the system is a cusp of codimension up to 4, and the system admits the cusp-type degenerate Bogdanov–Takens bifurcation of codimension 4. Moreover, the system has a weak focus of at least order 3 and can undergo degenerate Hopf bifurcation of codimension 3. We verify, through numerical simulations, that the system admits three different stable states, such as a stable fixed point and three limit cycles (the middle one is unstable), or two stable fixed points and two limit cycles. Our results reveal that nonlinear harvesting and a generalist predator can lead to richer dynamics and bifurcations (such as three limit cycles or tristability); specifically, harvesting can cause the extinction of prey, but a generalist predator provides some protection for the predator in the absence of prey. [ABSTRACT FROM AUTHOR]

Alleged practices of magical assault and vampirism are a recurrent feature of popular explanations of misfortune in Tuva, South Siberia. Based on a field study of healing practices in an "Association of Shamans", this article analyses rituals of redressing curse afflictions in the context of Russian political domination. A central purpose of this discussion is to foreground the centrality of kinds of parasitical worship and occult threat to structures of political power in—and beyond—the territory of Tuva. Focusing on a "cursescape", which develops from the combative practices of shamans, occult specialists, and office-holders, the article probes a repertoire of shamanic healing symbols. It is argued that healing efficacy is constructed in the process of engaging with hunting symbols and animal spirits, which appear in Indigenous Siberian cosmologies. The analysis shows that ideas of ritual risk underpin the process of symbolic resolution. Whereas shamanic practices provide refuge to spirits evicted from their natural landscapes, Tibetan Buddhism—the unifying religion of Tuva—offers an alternative path of healing the effects of the shamans' propagation of spirits. The article highlights indigenous perceptions of a "cursed" landscape as a space where the agencies of "darkness" and their political sponsors are confronted with an emancipating religious modality emerging from local Buddhist rituals. The analysis displays the unsolved drama of itinerant spirits and shamanic ancestral souls, whose agency is revealed through successive—yet inauspicious—forms of reincarnation. [ABSTRACT FROM AUTHOR]

Grasslands are recognized as important reservoirs of soil biodiversity. Livestock grazing is implemented as a grassland management strategy to improve soil quality and enhance plant diversity. Soil microbial communities play a pivotal role in grassland ecosystems, so it is important to examine whether grazing practices affect the soil microbiome. Previous studies on grazing have primarily focused on bacteria and fungi, overlooking an important group--protists. Protists are vital in soil microbiomes as they drive nutrient availability and trophic interactions. Determining the impact of grazing on protists and their relationships with bacterial and fungal communities is important for understanding soil microbiome dynamics in grazed ecosystems. In this study, we investigated soil bacterial, fungal, and protist communities under four grazing levels: no grazing, moderate-use grazing, full-use grazing, and heavy-use grazing. Our results showed that heavy grazing led to a greater diversity of protists with specific groups, such as Discoba and Conosa, increasing in abundance. We also found strong associations between protist and bacterial/fungal members, indicating their intricate relationships within the soil microbiome. For example, the abundance of predatory protists increased under grazing while arbuscular mycorrhizal fungi decreased. Notably, arbuscular mycorrhizae were negatively associated with predatory groups. Furthermore, we observed that microbial network complexity increased with grazing intensity, with fungal members playing an important role in the network. Overall, our study reports the impact of temporal grazing intensity on soil microbial dynamics and highlights the importance of considering protist ecology when evaluating the effects of grazing on belowground communities in grassland ecosystems. IMPORTANCE The significance of this study lies in its exploration of the effects of temporal grazing intensity on the dynamics of the soil microbiome, specifically focusing on the often-neglected role of protists. Our findings provide insights into the complex relationships between protists, bacteria, and fungi, emphasizing their impact on trophic interactions in the soil. Gaining a better understanding of these dynamics is essential for developing effective strategies for grassland management and conservation, underscoring the importance of incorporating protist ecology into microbiome studies in grasslands. [ABSTRACT FROM AUTHOR]

Zooplankton exhibit diverse swimming behaviors to reposition themselves in the water column, feed, find mates, and avoid predation. Environmental stressors that modify behavior can have cascading effects on population distributions and predator–prey interactions. Understanding zooplankton population dynamics is challenging, largely because traditional methods for quantifying zooplankton distributions are costly, limited in scope, and require extended analysis by trained analysts. We developed a novel methodology that combined remotely deployed camera systems, machine learning‐based identification of zooplankton, and video‐based tracking technology to quantify copepod and amphipod in situ swimming behavior in Hood Canal, WA, USA, a seasonally hypoxic and acidified fjord. Behavioral analysis showed copepods of all sizes swam on average 24% slower in stressful (hypoxic and acidified) waters relative to non‐stressful waters. Copepods exhibited less frequent escape responses in stressful waters, with a 68% decrease in the amount of time spent "jumping" for copepods 1–2 mm in length. Interestingly, abundances of small copepods increased in stressful waters, with 56% more 1–2 mm long copepods in stressful vs. non‐stressful conditions. In contrast, amphipods' average "darting" speeds did not differ between environmental conditions, but the abundance of amphipods significantly decreased in stressful waters relative to non‐stressful waters, suggesting avoidance of stressful conditions. Changes in swimming behavior are informative metrics in understanding ecosystem impacts of environmental stress because swimming speed has individual, population, and community‐level implications. Our results suggest that, among copepods, in situ behaviors may be useful proxies in monitoring the impacts of climate change on coastal ecosystems. [ABSTRACT FROM AUTHOR]

Exploited forage fishes serve a dual role in marine ecosystems by supporting directed fisheries and predator productivity, and thus both harvest and predatory removals should be accounted for when developing stock assessments and evaluating management trade-offs. Predator catch and stomach content data collected on the Northeast US Shelf from 1978 to 2019 by two fisheries-independent surveys were combined within multivariate spatiotemporal models to estimate time-series of consumptive removals during spring and fall for four commercially exploited prey; Atlantic herring (Clupea harengus), silver hake (Merluccius bilinearis), butterfish (Peprilus triacanthus), and longfin squid (Doryteuthis pealeii). Seasonal consumption trends were mostly synchronous for Atlantic herring and silver hake, asynchronous for butterfish and longfin squid, and predatory removals were generally greater during fall. Consumption has increased since the 1990s for all prey except Atlantic herring and butterfish during fall, which coincides with the widespread implementation of harvest constraints meant to rebuild predator and prey populations. These time-series were linked to hypothesized drivers using state-space regression models; prey availability (bottom-up; positive relationships) and commercial catch (top-down; primarily negative relationships) were the strongest predictors of consumption. Although the mechanisms underlying these relationships remain unresolved, these linkages highlight connections among the systemic drivers of productivity on the Northeast Shelf. [ABSTRACT FROM AUTHOR]