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Consumers are thought to select food resources based on their nutritional content. While laboratory experiments have explored this, the nutritional dynamics of invertebrate predators have been scarcely studied in the field given various methodological constraints. The intersection of these nutritional dynamics with predator traits is also poorly characterised, leading to many gaps in our understanding of how different predators forage and feed in natural systems. Here, we integrate dietary metabarcoding with prey macronutrient (protein, lipid and carbohydrate) content and abundance to assess how nutrients and predator traits (sex, life stage and taxonomy) interactively drive prey preferences in the field, using spider–prey interactions as a model system. Different spider genera, sexes and life stages had nutritionally distinct diets. Our analyses demonstrated disproportionate foraging (selection and avoidance) for prey rich in different macronutrients, with the nature of these relationships differing between spider taxa, life stages and sexes. This may be explained by niche differentiation among spider groups, driven by biases toward prey rich in different nutrients, or nutrient‐specific foraging in which individual spiders vary their nutritional preferences to redress deficits, although further evidence is required to confirm this. This insight into the nutritional dynamics of generalist invertebrate predators extends our understanding beyond lab‐based behavioural assays and provides a novel framework for other complex real‐world systems. [ABSTRACT FROM AUTHOR]

Dietary decisions by predators can affect prey abundance and overall food web dynamics. Many predators do not forage on the same prey at the same frequency throughout their lives. Ontogenetic shifts in prey preference are not, however, often accounted for when modeling food web relationships, despite growing literature that suggests that stage specific dietary relationships may be an important consideration when modeling trophic interactions. We investigated the importance of considering size-structure of a predator population with ontogenetic diet shifts in evaluating relationships with prey response using a manipulative experiment with the brown treesnake (Boiga irregularis) in Guam. After removing ~ 40% of the snake population via toxic mammal carrion, we measured the strength of the relationship between snake density and the response of two types of prey (lizards and mammals). We evaluated these relationships based on total population size or division of the population into stage specific size categories based on diet preference predictions. We hypothesized that the density of juvenile snakes would correlate more strongly with lizard detections, while adult snakes would better correlate to rodent detections. We also measured reproductive output following changes in rates of prey detection. As expected by known ontogenetic shifts in dietary preference, explicit stage-based models better predicted shifts in rates of observed prey items than did total predator density for both lizards and mammals. Additionally, rodent detections were predictive of one reproductive pulse from snakes, while lizard detections were not predictive or correlated. Our findings support that consideration of predatory species stage-based dietary preference can be meaningful for understanding food web dynamics, particularly when a predator has a broad diet or one that changes through time. [ABSTRACT FROM AUTHOR]

In this paper, we propose a food chain model in which the primary predator moves directly toward areas of high prey density. Simultaneously, the primary predator, which serves as the prey for the secondary predator, indirectly influences the directional movements of the secondary predator through cues such as chemical signals, scents, or excretions. We investigate whether the distinct influences of direct taxis and indirect taxis, as observed in prey–predator dynamics, are also manifested in the proposed food chain model. Our study demonstrates that the model, which incorporates both direct and indirect prey‐taxis, possesses bounded and global solutions up to three‐dimensional space. [ABSTRACT FROM AUTHOR]

Understanding the drivers of food web community structure is a fundamental goal in ecology. While studies indicate that many coral reef predators depend on pelagic subsidies, the mechanism through which this occurs remains elusive. As many of these species are important fishery targets, a better understanding of their trophodynamics is needed. To address these gaps, we employed a comprehensive structural equation modelling approach using extensive surveys of the reef community to explore relationships between groupers and snappers, their prey, and the surrounding habitat in an oceanic coral reef system. There were significant positive relationships between site-attached and transient planktivores and grouper and snapper biomass, respectively, indicating that pelagic subsidies are transferred to upper trophic levels through planktivores. Contrary to previous studies, habitat complexity and depth were not important for predators or prey. Instead, corallivores and site-attached and transient planktivores were primarily associated with live habitat and coral cover. This indicates that a decline in coral cover could have severe direct and indirect impacts on the structure and functioning of multiple levels of the reef food web. While pelagic reliance may suggest that predators are resilient to bleaching-related habitat loss, the associations of their planktivorous prey with live coral suggest that both benthic and pelagic pathways should be preserved for continued resilience of these food webs and their fisheries. By considering direct and indirect relationships, our study generated insights not only on the complex dynamics of coral reef ecosystems, but also on how they may respond to environmental change. [ABSTRACT FROM AUTHOR]

Trophic interaction modifications (TIM) are widespread in natural systems and occur when a third species indirectly alters the strength of a trophic interaction. Past studies have focused on documenting the existence and magnitude of TIMs; however, the underlying processes and long‐term consequences remain elusive. To address this gap, we experimentally quantified the density‐dependent effect of a third species on a predator's functional response. We conducted short‐term experiments with ciliate communities composed of a predator, prey and non‐consumable 'modifier' species. In both communities, increasing modifier density weakened the trophic interaction strength, due to a negative effect on the predator's space clearance rate. Simulated long‐term dynamics indicate quantitative differences between models that account for TIMs or include only pairwise interactions. Our study demonstrates that TIMs are important to understand and predict community dynamics and highlights the need to move beyond focal species pairs to understand the consequences of species interactions in communities. [ABSTRACT FROM AUTHOR]

In this paper, a fractional food chain system consisting of a Holling type II functional response was studied in view of a fractional derivative operator. The considered fractional derivative operator provided nonsingular as well as a nonlocal kernel which was significantly better than other derivative operators. Fractional order modeling of a model was also useful to model the behavior of real systems and in the investigation of dynamical systems. This model depicted the relationship among four types of species: prey, susceptible intermediate predators (IP), infected intermediate predators, and apex predators. One of the significant aspects of this model was the inclusion of Michaelis-Menten type or Holling type II functional response to represent the predator-prey link. A functional response depicted the rate at which the normal predator consumed the prey. The qualitative property and assumptions of the model were discussed in detail. The present work discussed the dynamics and analytical behavior of the food chain model in the context of fractional modeling. This study also examined the existence and uniqueness related analysis of solutions to the food chain system. In addition, the Ulam-Hyers stability approach was also discussed for the model. Moreover, the present work examined the numerical approach for the solution and simulation for the model with the help of graphical presentations. [ABSTRACT FROM AUTHOR]

Among-individual variation in predator traits is ubiquitous in nature. However, variation among populations in this trait variation has been seldom considered in trophic dynamics. This has left unexplored (a) to what degree does among-individual variation in predator traits regulate prey populations and (b) to what degree do these effects vary spatially. We address these questions by examining how predator among-individual variation in functional traits shapes communities across habitats of varying structural complexity, in field conditions. We manipulated Chinese mantis (Tenodera sinensis) density (six or twelve individuals) and behavioral trait variability (activity level by movement on an open field) in experimental patches of old fields with varying habitat complexity (density of plant material). Then, we quantified their impacts on lower trophic levels, specifically prey (arthropods > 4 mm) and plant biomass. Predator behavioral variability only altered prey biomass in structurally complex plots, and this effect depended on mantis density. In the plots with the highest habitat complexity and mantis density, behaviorally variable groups decreased prey biomass by 40.3%. In complex plots with low mantis densities, low levels of behavioral variability decreased prey biomass by 32.2%. Behavioral variability and low habitat complexity also changed prey community composition, namely by increasing ant biomass by 881%. Our results demonstrate that among-individual trait variation can shape species-rich prey communities. Moreover, these effects depend on both predator density and habitat complexity. Incorporating this important facet of ecological diversity revealed normally unnoticed effects of functional traits on the structure and function of food webs. [ABSTRACT FROM AUTHOR]

Variability in phenological shifts (seasonal changes in biological events) has become more common with climate change. As phenological variability increases due to climatic factors, species interactions within diverse communities can be affected. Shifts in hatching phenology can lead to body size variability that can alter species interactions, especially within and across trophic levels in complex food webs. To understand the effects of hatching phenology and food web complexity on prey communities, we conducted an experiment with ectotherms from ponds by manipulating hatching synchrony of a prey species across three dates and food web complexity. We hypothesized that predation on prey would be highest in the lowest synchrony treatment due to predator satiation effects in high synchrony additions. Food webs with top predators present had the lowest survival rates for prey compared to other food webs. Prey size at metamorphosis was also highest in the top predator food webs, suggesting a thinning effect. Hatching synchrony treatments did not have a significant impact on prey survival or size at metamorphosis except in treatments where intermediate and top predators were absent. Overall, our results show that top-down effects of predators may be enough to suppress the influence of phenological shifts in prey. [ABSTRACT FROM AUTHOR]

The arrival of invasive species in native communities impacts the structure and functioning of ecosystems, and is considered a critical indicator of loss of biodiversity. Exploring the effects of new species in communities presents challenges addressable through theoretical ecology. Species body size not only shapes trophic relationships, but may also impact predator success and facilitate species coexistence. However, little attention has been paid to the effects of differences in species body size on interactions between native and invasive primary consumers, which could be relevant to their coexistence with higher-level predators. Our aim is to investigate demographic patterns using a dynamic, mechanistic model of two age-structured primary consumers (one invasive and one native) sharing a plant resource and preyed upon by a common predator. In our model, we highlight three crucial phenomena: the structuring of primary consumers into adults and juveniles, reproduction occurring in discrete pulses, and the seasonal addition of new individuals to the population. Hence, the success of one species over the other relies on its reproductive capacity to incorporate individuals in each reproductive cycle. Our simulations reveal that abundance patterns are influenced by body size, suggesting that changes in predator body size could serve as key indicators of shifts in community structure. [ABSTRACT FROM AUTHOR]

In an environment, the food chains are balanced by the prey–predator interactions. When a predator species is provided with more than one prey population, it avails the option of prey switching between prey species according to their availability. So, prey switching of predators mainly helps to increase the overall growth rate of a predator species. In this work, we have proposed a two prey–one predator system where the predator population adopts switching behavior between two prey species at the time of consumption. Both the prey population exhibit a strong Allee effect and the predator population is considered to be a generalist one. The proposed system is biologically well-defined as the system variables are positive and do not increase abruptly with time. The local stability analysis reveals that all the predator-free equilibria are saddle points whereas the prey-free equilibrium is always stable. The intrinsic growth rates of prey, the strong Allee parameters, and the prey refuge parameters are chosen to be the controlling parameters here. The numerical simulation reveals that in absence of one prey, the other prey refuge parameter can change the system dynamics by forming a stable or unstable limit cycle. Moreover, a situation of bi-stability, tri-stability, or even multi-stability of equilibrium points occurs in this system. As in presence of the switching effect, the predator chooses prey according to their abundance, so, increasing refuge in one prey population decreases the count of the second prey population. It is also observed that the count of predator population reaches a comparatively higher value even if they get one prey population at its fullest quantity and only a portion of other prey species. So, in the scarcity of one prey species, switching to the other prey is beneficial for the growth of the predator population. [ABSTRACT FROM AUTHOR]

Plants can detect neighbouring plants through a reduction in the ratio between red and far‐red light (R:FR). This provides a signal of plant–plant competition and induces rapid plant growth while inhibiting defence against biotic stress, two interlinked responses designated as the shade avoidance syndrome (SAS). Consequently, the SAS can influence plant–herbivore interactions that could cascade to higher trophic levels. However, little is known about how the expression of the SAS can influence tritrophic interactions. We investigated whether changes in R:FR affect the emission of herbivore‐induced plant volatiles (HIPVs), and whether these changes influence the attraction of the zoophytophagous predator Macrolophus pygmaeus. We also studied how the expression of the SAS and subsequent inhibition of plant defences affects the reproduction of M. pygmaeus in both the presence and absence of the greenhouse whitefly (WF) (Trialeurodes vaporariorum) as arthropod prey. The results show that changes in R:FR have little effect on HIPV emissions and predator attraction. However, a reduction in R:FR leads to increased reproduction of both the predator and the WFs. We discuss that shade avoidance responses can increase the population development of M. pygmaeus through a combination of reduced plant defences and increased herbivore densities. Summary statement: Changes in red and far‐red light (FR) have little influence on the emission of volatiles by tomatoes and also do not influence the attraction of the predatory bug Macrolophus pygmaeus. However, FR light does increase M. pygmaeus reproduction on tomatoes, both in the absence and presence of whiteflies (WFs) as arthropod prey. This is related to reduced plant defences in FR light and increased WF densities. [ABSTRACT FROM AUTHOR]

The purpose of this work is to present a three-species harvesting food web model that takes into account the interactions of susceptible prey, infected prey, and predator species. Prey species are assumed to expand logistically in the absence of predator species. The Crowley–Martin and Beddington–DeAngelis functional responses are used by predators to consume both susceptible and infected prey. Additionally, susceptible prey is consumed by infected prey in the formation of a Holling type II response. Both prey species are considered when prey harvesting is taken into account. Boundedness, positivity, and positive invariance are considered in this study. The investigation covers all the equilibrium points that are biologically feasible. Local stability is evaluated by analyzing the distribution of eigen values, while global stability is evaluated using suitable Lyapunov functions. Also, Hopf bifurcation is analyzed at the harvesting rate H 1 . At the end, we evaluate the numerical solutions based on our findings. [ABSTRACT FROM AUTHOR]

A domination of generalist predators in soil communities suggests a wide overlap in their prey spectra, resulting in a probability of tense trophic relationships within the predator complex, in particular during the periods of prey scarcity caused by natural community reorganisations or anthropogenic disturbance. It has been argued that soil physical structure (e.g. pore size and connectivity) can limit interactions between the potential trophic competitors facilitating their coexistence (Erktan et al., 2020). Another possible mechanism of coexistence of generalist predators would be a variation in their life history traits resulting in a certain partitioning of their trophic niches. On an example of a field experiment studying soil mesofauna succession in decomposing plant remains, we compared potential trophic spectra of the abundant predators (firstly, gamasid mites), outlined by significant correlations of their densities with densities of other members of the community. A wide variation of potential prey objects was revealed for the major predators which thus should be treated as generalist feeders with activities spanning over several trophic levels. At the same time, the predators were characterised by individual spectra of the potential prey taxa and a low interspecific similarity between these spectra. The results suggest a certain differentiation of trophic niches in the mesofauna predatory complex. In addition, the prey spectra underwent temporal changes in the course of mesofauna succession, indicating possible switching of predators between the prey objects in response to environmental changes during the decay process. [ABSTRACT FROM AUTHOR]

Predators are widely recognized for their irreplaceable roles in influencing the abundance and traits of lower trophic levels. Predators also have irreplaceable roles in shaping community interactions and ecological processes via highly localized pathways (i.e. effects with well‐defined and measurable spatio–temporal boundaries), irrespective of their influence on prey density or behavior. We synthesized empirical and theoretical research describing how predators – particularly medium‐ and large‐sized carnivores – have indirect ecological effects confined to discrete landscape patches, processes we have termed 'patchy indirect effects (PIEs) of predation'. Predators generate PIEs via three main localized pathways: generating and distributing prey carcasses, creating ecological hotspots by concentrating nutrients derived from prey, and killing ecosystem engineers that create patches. In each pathway, the indirect effects are limited to discrete areas with measurable spatial and temporal boundaries (i.e. patches). Our synthesis reveals the diverse and complex ways that predators indirectly affect other species via patches, ranging from mediating scavenger interactions to influencing parasite/disease transmission risk, and from altering ecosystem biogeochemistry to facilitating local biodiversity. We provide basic guidelines on how these effects can be quantified at the patch and landscape scales, and discuss how predator‐mediated patches ultimately contribute to landscape heterogeneity and ecosystem functioning. Whereas density‐ and trait‐mediated indirect effects of predation generally occur through population‐scale changes, PIEs of predation occur through individual‐ and patch‐level pathways. Our synthesis provides a more holistic view of the functional role of predation in ecosystems by addressing how predators create patchy landscapes via localized pathways, in addition to influencing the abundance and behavior of lower trophic levels. [ABSTRACT FROM AUTHOR]

Lures and other adaptations for prey attraction are particularly interesting from an evolutionary viewpoint because they are characterized by correlational selection, involve multicomponent signals, and likely reflect a compromise between maximizing conspicuousness to prey while avoiding drawing attention of enemies and predators. Therefore, investigating the evolution of lure and prey-attraction adaptations can help us understand a larger set of traits governing interactions among organisms. We review the literature focusing on spiders (Araneae), which is the most diverse animal group using prey attraction and show that the evolution of prey-attraction strategies must be driven by a trade-off between foraging and predator avoidance. This is because increasing detectability by potential prey often also results in increased detectability by predators higher in the food chain. Thus increasing prey attraction must come at a cost of increased risk of predation. Given this trade-off, we should expect lures and other prey-attraction traits to remain suboptimal despite a potential to reach an optimal level of attractiveness. We argue that the presence of this trade-off and the multivariate nature of prey-attraction traits are two important mechanisms that might maintain the diversity of prey-attraction strategies within and between species. Overall, we aim to stimulate research on this topic and progress in our general understanding of the diversity of predator and prey interactions. [ABSTRACT FROM AUTHOR]

The study of marine food web models has increased during the last years, but input data of important groups such as cephalopods are missing sometimes which restricts the quality of the model results. Cephalopods feed on a variety of preys, ranging from small crustaceans to large commercially important fish species. In turn, they are taken by larger invertebrates, fish, cephalopods, marine mammals and seabirds, which emphasizes their important role in various marine food webs. Our study presents stomach content analyses of various cephalopod species from the North Sea and describes their general feeding trends. The results further support the inclusion of cephalopods as predators into food web models to increase our knowledge of the North Sea ecosystem and to improve its management. Our data in combination with observed increasing biomasses of North Sea cephalopods suggest that the impact of cephalopods in the North Sea food web has increased and that large-sized cephalopods have become more important as predators for commercially exploited fish species during recent years. [ABSTRACT FROM AUTHOR]

Antagonistic coevolution between natural enemies can produce highly exaggerated traits, such as prey toxins and predator resistance. This reciprocal process of adaptation and counter‐adaptation may also open doors to other evolutionary novelties not directly involved in the phenotypic interface of coevolution. We tested the hypothesis that predator–prey coevolution coincided with the evolution of conspicuous coloration on resistant predators that retain prey toxins. In western North America, common garter snakes (Thamnophis sirtalis) have evolved extreme resistance to tetrodotoxin (TTX) in the coevolutionary arms race with their deadly prey, Pacific newts (Taricha spp.). TTX‐resistant snakes can retain large amounts of ingested TTX, which could serve as a deterrent against the snakes' own predators if TTX toxicity and resistance are coupled with a conspicuous warning signal. We evaluated whether arms race escalation covaries with bright red coloration in snake populations across the geographic mosaic of coevolution. Snake colour variation departs from the neutral expectations of population genetic structure and covaries with escalating clines of newt TTX and snake resistance at two coevolutionary hotspots. In the Pacific Northwest, bright red coloration fits an expected pattern of an aposematic warning to avian predators: TTX‐resistant snakes that consume highly toxic newts also have relatively large, reddish‐orange dorsal blotches. Snake coloration also seems to have evolved with the arms race in California, but overall patterns are less intuitively consistent with aposematism. These results suggest that interactions with additional trophic levels can generate novel traits as a cascading consequence of arms race coevolution across the geographic mosaic. see also the Perspective by John N. Thompson [ABSTRACT FROM AUTHOR]

The idea that changing environmental conditions drive adaptive evolution is a pillar of evolutionary ecology. But, the opposite--that adaptive evolution alters ecological processes--has received far less attention yet is critical for eco-evolutionary dynamics. We assessed the ecological impact of divergent values in a key adaptive trait using 16 populations of the brown anole lizard (Anolis sagrei). Mirroring natural variation, we established islands with short-or long-limbed lizards at both low and high densities. We then monitored changes in lower trophic levels, finding that on islands with a high density of short-limbed lizards, web-spider densities decreased and plants grew more via an indirect positive effect, likely through an herbivore-mediated trophic cascade. Our experiment provides strong support for evolution-to-ecology connections in nature, likely closing an otherwise well-characterized eco-evolutionary feedback loop. [ABSTRACT FROM AUTHOR]

The capacity of an apex predator to produce nonconsumptive effects (NCEs) in multiple prey trophic levels can create considerable complexity in nonconsumptive cascading interactions, but these effects are poorly studied. We examined such effects in a model food web where the apex predator (blue crabs) releases chemical cues in urine that affect both the intermediate consumer (mud crabs seek shelter) and the basal prey (oysters are induced to grow stronger shells). Shelter availability and predator presence were manipulated in a laboratory experiment to identify patterns in species interactions. Then, experimentally induced and uninduced oysters were planted across high‐quality and low‐quality habitats with varying levels of shelter availability and habitat heterogeneity to determine the consistency of these patterns in the field. Oyster shell thickening in response to blue crab chemical cues generally protected oysters from mud crab predation in both the laboratory and in field environments that differed in predation intensity, structural complexity, habitat heterogeneity, and predator composition. However, NCEs on the intermediate predator (greater use of refugia) opposed the NCEs on oyster prey in the interior of oyster reefs while still providing survival advantages to basal prey on reef edges and bare substrates. Thus, the combined effects of changing movement patterns of intermediate predators and morphological defenses of basal prey create complex, but predictable, patterns of NCEs across landscapes and ecotones that vary in structural complexity. Generalist predators that feed on multiple trophic levels are ubiquitous, and their potential effects on NCEs propagating simultaneously to different trophic levels must be quantified to understand the role of NCEs in food webs. [ABSTRACT FROM AUTHOR]

The transient dynamics capture the time history in the behavior of a system before reaching an attractor. This paper deals with the statistics of transient dynamics in a classic tri-trophic food chain with bistability. The species of the food chain model either coexist or undergo a partial extinction with predator death after a transient time depending upon the initial population density. The distribution of transient time to predator extinction shows interesting patterns of inhomogeneity and anisotropy in the basin of the predator-free state. More precisely, the distribution shows a multimodal character when the initial points are located near a basin boundary and a unimodal character when chosen from a location far away from the boundary. The distribution is also anisotropic because the number of modes depends on the direction of the local of initial points. We define two new metrics, viz., homogeneity index and local isotropic index, to characterize the distinctive features of the distribution. We explain the origin of such multimodal distributions and try to present their ecological implications. [ABSTRACT FROM AUTHOR]

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Simultaneously defending against predators, stymieing competitors, and generating immune responses can impose conflicting demands for host species caught in the entanglement of a food web. Host immunity is not only shaped by direct interactions among species, but also many indirect cascading effects. By reducing competition, predators in particular can affect resource acquisition necessary for hosts to mount energetically costly immune responses. However, identifying the links between predators and host immune responses determined by resource acquisition is a complex affair, because predators can (1) reduce host density and thus competition among hosts, (2) exert non-consumptive trait-mediated effects on host resource acquisition behavior, and (3) generate natural selection on host resource acquisition behavior. To examine the relative contributions of these potential predator driven density- and trait-mediated effects on a key aspect of immune function (total phenoloxidase activity, total PO), we conducted mesocosm and field experiments with larval damselflies (Enallagma signatum) and their dominant fish predator (Lepomis macrochirus). Although we expected to observe declines in total PO activity with increases in damselfly density, we found no relationship between density and total PO activity. We also found no support for the prediction that total PO activity would vary as a result of either non-consumptive trait-mediated effects or selection on damselfly foraging activity underlying resource acquisition. Despite the lack of trait- or density-mediated effects, we did find that total PO activity increased with damselfly prey density among lakes, implying resource limitation for this aspect of immune function. These unexpected results point to the need to better understand the ecological conditions whereby predators and competitors constrain immune functions necessary for species to defend themselves in complex food webs. [ABSTRACT FROM AUTHOR]

In this study, we analyze a tri-trophic food chain model with disease circulating in an intermediate predator. Firstly, we observe the dynamics of the disease-free system by varying halfsaturation constant. Then we pay our attention to control the original system's chaotic dynamics by varying the nutritional value and infection rate in the intermediate predator population. We obtain criteria for local stability and instability of the model system around the biologically feasible equilibria. Coexistence of equilibrium solutions under different conditions. We also consider refugia and allee in prey species of our model system. Our numerical results show that the system shows chao: for higher values of half-saturation constant. We also observe that chaotic dynamics can be preventet by increasing infection in intermediate predators. Also, the nutritional value is of great importance for controlling chaos in our model system. [ABSTRACT FROM AUTHOR]

Elasmobranchs play a significant role in structuring the marine food webs in many marine habitats. Estuaries provide an essential habitat primarily as nurseries for elasmobranchs. The present study investigates the feeding preferences of megabenthic predatory elasmobranchs from Caranzalem Bay, Goa. The elasmobranchs in this habitat were represented by guitarfishes, Glaucostegus granulatus and Glaucostegus obtusus; rays, Brevitrygon walga, Pastinachus sephen, Neotrygon kuhlii, and Maculabatis gerrardi; and bamboo sharks, Chiloscyllium griseum and Chiloscyllium spp. Crustaceans were the major prey of these predators followed by teleosts and cephalopods. The bamboo shark was an opportunistic predator while rays and guitarfish were specialised feeders on penaeid shrimps. Indices suggest that bamboo sharks occupy the highest trophic level in this benthic food chain while guitarfishes and rays function as mesopredators. Ontogenetic dietary changes were observed in all predators, indicating the feeding niche segregation among size classes. Low resource overlap was observed between and within species probably due to high prey availability in the bay. These elasmobranch species frequently occur in bycatch, which can negatively affect their populations and thereby impact the lower trophic strata resulting in large-scale ecological repercussions. [ABSTRACT FROM AUTHOR]

Although many upstream effects of a dam on the trophic ecology of fish have been reported, little is known about their downstream effects on the isotopic niche of Amazonian predator fish. The authors used stable isotope analysis of δ13C and δ15N to determine the downstream effects of damming of the Uatumã River on the niche width, carbon energy sources and trophic position of peacock bass Cichla temensis comparing with a free‐flowing river in the Amazon basin, Brazil, during the peak flood and early falling water period of 2020. They found that the C. temensis population of the undammed river had a smaller niche width than the C. temensis population of the dammed river, despite the greater number of prey trophic levels utilized and the higher trophic position of C. temensis individuals. The results demonstrate that in both rivers there is a gradual shift in the contribution of prey fish sources to the diet of C. temensis throughout its growth, even among adult individuals. They conclude that the isotopic niche of C. temensis was altered by damming during the period of late high water to early low water in the Uatumã River. [ABSTRACT FROM AUTHOR]

Evaluating the patterns and generality of ontogenetic dietary shifts (ODSs) contributes to understanding prey–predator interactions and food web dynamics. Numerous studies have focused on predators that target distinctively lower trophic‐level organisms. However, the ODS of predators that routinely prey on organisms at similar trophic levels (i.e., predator‐eating predators) have been neglected in ODS research. The ODS patterns of predator eaters may not fit into conventional frameworks owing to constraints of potential capture risk (e.g., deadly counterattack from prey) and body size. We aimed to reveal the ODS patterns of predator eaters and determine whether the patterns were affected by body size and capture risk. Assuming that capture risk is a significant factor in ODS patterns, we expected: (1) juvenile araneophagic spiders to forage on non‐dangerous prey (insects) and capture larger non‐dangerous prey more frequently than dangerous prey (spiders); and (2) as they grow, their prey types will shift from non‐dangerous to dangerous prey because larger predators will be able to capture dangerous prey as the optimal food. As a result of field observations, we revealed that the major ODS pattern in these spiders changed from a mixed (both insect and spider) to a spider‐dominant diet. The model selection approach showed that this diet shift was partly due to predator size, and the relative importance of predator size was higher than the life stage per se and almost equal to species identity. In these spiders, the body size of spider prey tended to be smaller than that of insects when the predators were small, suggesting that capture risk may be a critical factor in determining the ODS patterns of these predators. Therefore, our study adds to the evidence that the capture risk is crucial in comprehensively understanding the mechanisms determining ODS patterns in natural systems. [ABSTRACT FROM AUTHOR]

A striking feature of predatory complex in soil communities is a domination of generalist predators and a wide overlap in the prey spectra of the major predators, combined with usual intraguild predation and cannibalism. This suggests a probability of tense trophic relationships between the major predator taxa, in particular during the periods of community reorganisations and/or prey scarcity caused by natural or anthropogenic disturbance. On an example of a field experiment modelling the process of mesofauna community development after the ploughing of an organic fertiliser into soil, dynamics of major predators (Mesostigmata and trombidiform mites, insect larvae) was followed in detail. It was shown that patterns of population dynamics of the dominant predatory taxa markedly differed and their density peaks were distinctly separated. A preliminary explanation suggests that this differentiation was determined to a large extent by the interactions between the predatory taxa (like partitioning of prey objects and/or avoidance of intraguild predation). [ABSTRACT FROM AUTHOR]

The only wetland in Europe colonized successfully by the apple snail Pomacea maculata Perry, 1810, is the Ebro Delta (Spain). After 10 years, it has become widespread there, despite significant eradication attempts. In spite of its great negative ecological and economic impacts, its incorporation into food webs can result in an abundant potential resource for native and exotic predators. We identified the potential predators, including fishes, amphibians, crustaceans, birds, turtles and mammals in natural conditions using stable isotopic analyses (δ13C and δ15N). Six predator species, three native (two birds and one frog) and three invasive (one crustacean, one turtle and one mammal), were confirmed to consume apple snails. None of the 10 fish species analyzed consumed apple snails, although some have been previously observed consuming this snail under laboratory conditions. This study emphasizes the need to assess the consumption of apple snail, as well as other invasive organisms, by potential predators in natural conditions to confirm the establishment of new trophic relationships and to understand whether these potential predators actually act as biological control agents in nature. [ABSTRACT FROM AUTHOR]

Climate warming may alter predator–prey interactions and predator feeding behaviour due to increased metabolic demands. How predators meet these increased demands may depend on trade‐offs in prey energy content and body size, handling time and other functional constraints.We tested hypotheses associated with these trade‐offs with the predatory mite Stratiolaelaps scimitus, and three prey that differed in body size, energy content, and defenses (Folsomia candida, Oppia nitens, and Carpoglyphus lactis). We estimated metabolic rate, predation in choice and no choice feeding trials, movement rate, and lipid and protein content for all four species at 16°C and 24°C. We used these data to estimate the predator's energy demands and compared these to estimated energy intake in the choice feeding trials.Predators had greater metabolic demands at 24°C than at 16°C, but temperature did not affect predator or prey movement rates. Warming decreased lipid content, but not protein content, of all three prey species, leading to lower energy content for C. lactis and O. nitens, but not F. candida. In both feeding trials at 24°C, predators increased their feeding on the smaller, energy‐poor C. lactis, but not the larger, energy‐rich F. candida, resulting in lower estimated energy intake. S. scimitus did not feed on O. nitens at either temperature.Predators increasingly fed on small‐bodied prey under warming and not the large‐bodied prey despite the potential for greater energetic gains from larger prey. We posit that predators minimized energy lost during feeding through lower handling costs associated with C. lactis, rather than maximize energy gain. We conclude that selection of prey based on body size changes with temperature as a trade‐off for predators to balance increased metabolic demands. As predators provide top‐down control and regulate energy flow through the consumption of their prey, changes to predator feeding behaviour with climate warming may affect food web dynamics and ecosystem‐level processes. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The Patagonian region, from the Andes to the steppe, includes a profuse hydrographic network with deep and shallow lakes. Here, we analyze the stoichiometric constraints for the large predaceous copepod Parabroteas sarsi in fish and fishless lakes. For this purpose, we examined previous literature data on the composition of the zooplankton community in different Patagonian lakes with and without fish (mainly introduced in the XX century) and own laboratory and field experiments. The ecological stoichiometry theory predicts that consumers need to attain specific elemental ratios to achieve maximum growth, and the geometric framework of nutrition proposes that consumers may need to combine food items to fulfill nutrient requirements. We show that the predaceous copepod does not necessarily encounter prey that fulfills their stoichiometric requirements, thus growth is impaired. However, through the combination of different prey, this predator can fulfill its requirements. In the presence of fishes, food webs change towards smaller-sized zooplankton species with the loss of low C:nutrient ratio species. In this sense, we demonstrate the direct and indirect impact of fish introduction on the stoichiometric balances and the disappearance of this invertebrate predator in lacustrine food webs. [ABSTRACT FROM AUTHOR]

Rice‐fish co‐culture system has a history of more than 2,000 years in Asia and has been recognized as one of FAO's Globally Important Agricultural Heritage Systems (GIAHS). To date, few studies have explored rice‐fish co‐culture effects on the relationship between predator–prey aggregations and associated tri‐trophic cascades of predatory spiders, insect herbivores and rice. Indeed, predators have been shown to increase prey spatial aggregation but it is still not clear how fish (tertiary consumers) affect aggregations and interactions of their prey on multiple trophic levels (i.e. predatory spiders and rice insect herbivores).Here, we conducted a 2‐year experiment to measure the abundance and distribution of herbivores (leafrollers, stemborers and planthoppers) and their predators (spiders) along with rice yield in rice‐fish co‐culture versus monoculture‐rice (fish free) systems in eastern China. We analysed spatial aggregations of herbivores and predators using geostatistics and used correlations to examine tri‐trophic interactions.Results showed that co‐culture enhanced predatory spider and herbivore spatial aggregations, which in turn increased biocontrol of herbivores by predators, decreased herbivore damage and increased rice productivity.Synthesis and applications. Fish presence increased spatial aggregation of two different trophic levels, which enhanced a tri‐trophic cascade of predatory spiders, insect herbivores and rice in co‐culture systems. Our approach linking spatial aggregations of herbivores and predators with trophic cascades can be applied to study trophic interactions in other ecosystems. Incorporating fish into monoculture paddy fields can increase both natural pest control by predatory spiders and crop productivity via aggregation, and thus increase multiple ecosystem services. [ABSTRACT FROM AUTHOR]

Predator-prey interactions are fundamental to the understanding of ecological communities. The non-consumptive effects of predators on the food web can be more prominent than direct killing. However, the non-consumptive effects in intraguild interaction have rarely been studied. This study determined the non-consumptive effects of an intraguild predator Blattisocius dentriticus on Neoseiulus cucumeris. The responses of N. cucumeris to the predation risk of B. dentriticus adult females were examined in a laboratory test. The developmental response of N. cucumeris to predation risk was sex-specific: the presence of B. dentriticus cues prolonged the immature development of N. cucumeris males and increased their consumption rates of Tyrophagus putrescentiae eggs, but did not affect the development and prey consumption of female N. cucumeris. The size at maturity of N. cucumeris was not affected by predation risk from B. dentriticus. This study demonstrated that intraguild predators can have substantial non-consumptive influence on intraguild prey. [ABSTRACT FROM AUTHOR]

Understanding coexistence within community modules such as intraguild predation (IGP), where an omnivore both preys on and competes with an intermediate consumer for a shared resource, has provided insight into the mechanisms that promote the persistence of complex food webs. Adaptive, predator-specific defense has been shown theoretically to enhance coexistence of IGP communities when employed by shared prey. Yet to date, all such theory has assumed that prey have an accurate perception of predation risk and appropriate antipredator responses, assumptions that may not be justified when considering a novel predator. We therefore consider the effects of an introduced predator on IGP coexistence, describing two invasion scenarios: suboptimal defense, whereby a similar invader elicits an ineffective antipredator response; and naïveté toward an unfamiliar invader, for which prey fail to accurately estimate predation risk. We examine predictions for native predator persistence across gradients of enrichment and defense costs. The model predicts that predator novelty can weaken the effect of adaptive defense, causing exclusion of native predators that would persist in the absence of novelty and inducing unstable dynamics in previously stable regions of parameter space. Coexistence is predicted to be more sensitive to the effects of suboptimal defense than to naïveté, and differentially leads to the exclusion of native predators in highly productive environments and when defense costs are low. Moderate novelty of the omnivore can increase resource density via a trophic cascade, while consumer novelty can either lead to omnivore exclusion or facilitate three-species coexistence by providing a subsidy to the otherwise excluded native omnivore. Our analyses suggest that models of adaptive defense are sensitive to assumptions regarding predator–prey eco-evolutionary experience and that predator novelty has significant implications for food web dynamics. [ABSTRACT FROM AUTHOR]

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The presence of edible and inedible prey species in a food web can influence the strength that nutrients (bottom‐up) or herbivores (top‐down) have on primary production. In boreal peatlands, wetter more nutrient‐rich conditions associated with ongoing climate change are expanding consumer access to aquatic habitat and promoting sources of primary production (i.e., algae) that are susceptible to trophic regulation. Here, we used an in situ mesocosm experiment to evaluate the consequences of enhanced nutrient availability and food‐web manipulation (herbivore and predator exclusion) on algal assemblage structure in an Alaskan fen. Owing to the potential for herbivores to selectively consume edible algae (small cells) in favor of more resistant forms, we predicted that the proportion of less‐edible algae (large cells) would determine the strength of top‐down or bottom‐up effects. Consistent with these expectations, we observed an increase in algal‐cell size in the presence of herbivores (2‐tiered food web) that was absent in the presence of a trophic cascade (3‐tiered food web), suggesting that predators indirectly prevented morphological changes in the algal assemblage by limiting herbivory. Increases in algal‐cell size with herbivory were driven by a greater proportion of filamentous green algae and nitrogen‐fixing cyanobacteria, whose size and morphological characteristics mechanically minimize consumption. While consumer‐driven shifts in algal assemblage structure were significant, they did not prevent top‐down regulation of biofilm development by herbivores. Our findings show that increasing wet periods in northern peatlands will provide new avenues for trophic regulation of algal production, including directly through consumption and indirectly via a trophic cascade. [ABSTRACT FROM AUTHOR]

The intensified expansion of the Baltic Sea's hypoxic zone has been proposed as one reason for the current poor status of cod (Gadus morhua) in the Baltic Sea, with repercussions throughout the food web and on ecosystem services. We examined the links between increased hypoxic areas and the decline in maximum length of Baltic cod, a demographic proxy for services generation. We analysed the effect of different predictors on maximum length of Baltic cod during 1978–2014 using a generalized additive model. The extent of minimally suitable areas for cod (oxygen concentration ≥ 1 ml l−1) is the most important predictor of decreased cod maximum length. We also show, with simulations, the potential for Baltic cod to increase its maximum length if hypoxic areal extent is reduced to levels comparable to the beginning of the 1990s. We discuss our findings in relation to ecosystem services affected by the decrease of cod maximum length. [ABSTRACT FROM AUTHOR]

It is predicted that ecological communities will become unstable with increasing species numbers and subsequent interspecific interactions; however, this is contrary to how natural ecosystems with diverse species respond to changes in species numbers. This contradiction has steered ecologists toward exploring what underlying processes allow complex communities to stabilize even through varying pressures. In this study, a food web model is used to show an overlooked role of interference among multiple predator species in solving this complexity–stability problem. Predator interference in large communities weakens species interactions due to a reduction in consumption rates by prey-sharing species in the presence of predators in response to territorial and aggressive behavior, thereby playing a key stabilizing role in communities. Especially when interspecific interference is strong and a community has diverse species and dense species interactions, stabilization is likely to work and creates a positive complexity–stability relationship within a community. The clear positive effect of complexity on community stability is not reflected by/intraspecific interference, emphasizing the key role of interspecific interference among multiple predator species in maintaining larger systems. [ABSTRACT FROM AUTHOR]

Predators are generally under selective pressure to get better at foraging, leading to steeper functional responses and stronger predator–prey interactions. Yet strong interactions can de‐stabilize food webs, and most interactions across ecological communities are thought to be weak. This conflict between evolutionary and community expectations for the strength of predator–prey interactions represents a fundamental gap in our understanding of how the evolution of foraging plays out in food webs. Here we help to resolve the conflict by showing analytically that the expectation for the evolution of steeper functional responses is relaxed in communities with diverse prey types. We simulate communities with varying prey richness and show that increasing prey richness can indeed constrain the adaptive potential of predator foraging traits, but that at low prey richness predators can evolve to have a stronger interaction with prey that have high net energy yields. Our results also indicate that handling time plays a role in determining whether predators may evolve to have a stronger interaction with abundant prey, suggesting that the evolution of keystone predator modules in food webs is most likely when handling times are negligible. Our results also provide a new mechanism predicting more diffuse interactions in diverse tropical communities relative to more species‐poor communities at higher latitudes. [ABSTRACT FROM AUTHOR]

The balance between risk and benefit of exploiting resources drives life‐history evolution in organisms. Predators are naturally recognized as major drivers of the life‐history evolution of their prey. Although prey may also influence the life‐history evolution of their predators in the context of an evolutionary arms race, there is far more evidence of the role of predators than of prey.The goal of this study was to investigate the role of prey in life‐history evolution of predators using ladybird beetle predators of aphids and coccids. These particular ladybirds and their prey were chosen because literature shows that the pace of life of aphids is faster than that of coccids and this difference is reflected in the life histories of the ladybirds that specialize on feeding on aphids or coccids.Thirty‐four species of ladybird predators of aphids and eight of coccids belonging to five different tribes were collected and reared in the laboratory. The females were weighed as well as their eggs, and their reproductive investment estimated as the number of ovarioles. Phylogenetic relatedness was controlled for in the statistical analyses.Controlling for female mass revealed that ladybird predators of aphids lay bigger eggs than ladybird predators of coccids. This difference is not influenced by phylogenetic relatedness but only by the type of prey eaten. We suggest that ladybird predators of coccids lay smaller eggs because neonate larvae do not have to search, catch, and subdue prey. Both types of ladybirds have a similar reproductive investment relative to their body mass when phylogeny is controlled for.Recognizing the influence of prey on the life‐history evolution of predators is important for understanding food web dynamics. From an applied perspective, this fine evolutionary tuning of prey–predator relationships should be used to guide and increase the efficiency of biological control programs. [ABSTRACT FROM AUTHOR]

Species interactions mediate how warming affects community composition via individual growth and population size structure. While predictions on how warming affects composition of size- or stage-structured communities have so far focused on linear (food chain) communities, mixed competition-predation interactions, such as intraguild predation, are common. Intraguild predation often results from changes in diet over ontogeny ("ontogenetic diet shifts") and strongly affects community composition and dynamics. Here, we study how warming affects a community of intraguild predators with ontogenetic diet shifts, consumers, and shared prey by analyzing a stage-structured bioenergetics multispecies model with temperature- and body size–dependent individual-level rates. We find that warming can strengthen competition and decrease predation, leading to a loss of a cultivation mechanism (the feedback between predation on and competition with consumers exerted by predators) and ultimately predator collapse. Furthermore, we show that the effect of warming on community composition depends on the extent of the ontogenetic diet shift and that warming can cause a sequence of community reconfigurations in species with partial diet shifts. Our findings contrast previous predictions concerning individual growth of predators and the mechanisms behind predator loss in warmer environments and highlight how feedbacks between temperature and intraspecific size structure are important for understanding such effects on community composition. [ABSTRACT FROM AUTHOR]

Pathogens can modify many aspects of host behavior or physiology with cascading impacts across trophic levels in terrestrial food webs. These changes include thermal tolerance of hosts, however the effects of fungal infections on thermal tolerances and behavioral responses to extreme temperatures (ET) across trophic levels have rarely been studied. We examined how a fungal pathogen, Beauveria bassiana, affects upper and lower thermal tolerance, and behavior of an herbivorous insect, Acyrthosiphon pisum, and its predator beetle, Hippodamia convergens. We compared changes in thermal tolerance limits (CTMin and CTMax), thermal boldness (voluntary exposure to ET), energetic cost (ATP) posed by each response (thermal tolerance and boldness) between healthy insects and insects infected with two fungal loads. Fungal infection reduced CTMax of both aphids and beetles, as well as CTMin of beetles. Fungal infection modified the tendency, or boldness, of aphids and predator beetles to cross either warm or cold ET zones (ETZ). ATP levels increased with pathogen infection in both insect species, and the highest ATP levels were found in individuals that crossed cold ETZ. Fungal infection narrowed the thermal tolerance range and inhibited thermal boldness behaviors to cross ET. As environmental temperatures rise, response to thermal stress will be asymmetric among members of a food web at different trophic levels, which may have implications for predator–prey interactions, food web structures, and species distributions. [ABSTRACT FROM AUTHOR]

In this paper, a three-species food chain model has been developed by considering the interaction between prey, predator and super-predator species. It is assumed that in the absence of predator and super-predator species, the prey species grow logistically. It is also assumed that predator and super-predator consume prey and predator, respectively. It is assumed that the predator shows refuge behavior to the super-predator. Again, harvesting of super-predator population has been considered. It is assumed that the consumption of prey and predator follows Crowley–Martin-type functional form. Boundedness of the solution of the system has been studied and different equilibrium points are determined and the stability of the system around these equilibrium points has been investigated. Existence conditions of Hopf bifurcation with respect to γ 1 of the system have been studied. It is found that the system shows some complex and critical dynamics due to increase of handling time of prey. It is also found that the system moves towards stable steady state due to increase of predator interference. It is observed that predator refuge may be responsible for the stability of the system. The chaotic dynamics of the system have been found due to the increase of the harvesting rate of super-predator. [ABSTRACT FROM AUTHOR]

Changes in the distribution and abundance of invasive species can have far-reaching ecological consequences. Programs to control invaders are common but gauging the effectiveness of such programs using carefully controlled, large-scale field experiments is rare, especially at higher trophic levels. Experimental manipulations coupled with long-term demographic monitoring can reveal the mechanistic underpinnings of interspecific competition among apex predators and suggest mitigation options for invasive species. We used a large-scale before-after control-impact removal experiment to investigate the effects of an invasive competitor, the barred owl (Strix varia), on the population dynamics of an iconic old-forest native species, the northern spotted owl (Strix occidentalis caurina). Removal of barred owls had a strong, positive effect on survival of sympatric spotted owls and a weaker but positive effect on spotted owl dispersal and recruitment. After removals, the estimated mean annual rate of population change for spotted owls stabilized in areas with removals (0.2% decline per year), but continued to decline sharply in areas without removals (12.1% decline per year). The results demonstrated that the most substantial changes in population dynamics of northern spotted owls over the past two decades were associated with the invasion, population expansion, and subsequent removal of barred owls. Our study provides experimental evidence of the demographic consequences of competitive release, where a threatened avian predator was freed from restrictions imposed on its population dynamics with the removal of a competitively dominant invasive species. [ABSTRACT FROM AUTHOR]

The fear large carnivores inspire in large ungulates has been argued to have cascading effects down food webs. However, a direct link between ungulate habitat use and their fear of large carnivores has not been experimentally tested. To fill this critical gap, we conducted a bi-factorial experiment in an African savanna. We removed shrub cover and broadcast large carnivore vocalizations (leopard, hyena, dog) or non-threatening control vocalizations in both experimentally cleared and shrubby control sites. We recorded the proactive (frequency of visitation) and reactive (fleeing or vigilance) responses of multiple prey (impala, warthog, nyala and bushbuck). Critically, we found a significant proactive–reactive interaction. Ungulates were 47% more likely to run after hearing a predator vocalization in shrubby control sites than experimental clearings, demonstrating that ungulates perceived less fear from large carnivores in open habitat (clearings). Consistent with this finding, ungulates visited clearings 2.4 times more often than shrubby control sites and visited shrubby control sites less often at night, when large carnivores are most active. Combined with results from previous experiments demonstrating that the disproportionate use of available habitats by large ungulates can alter ecosystem properties, our experiment provides critical evidence that the fear large carnivores inspire in large ungulates can cause trophic cascades. [ABSTRACT FROM AUTHOR]

Invasive predators can alter community structure and dynamics in their invaded communities through direct consumption of prey and by inducing prey to alter traits, such as behavior or morphology, to avoid predation. These changes can modify the strength or even the direction of species interactions which can have cascading effects throughout a community. On rocky shores in the Gulf of Maine, an important mesopredator, the whelk Nucella lapillus, alters its feeding behavior when it detects waterborne chemical cues of a long-established invasive crab, Carcinus maenas , potentially impacting the abundance and distribution patterns of sessile species and energy flow through the food web. A more recent invasive crab, Hemigrapsus sanguineus , has become a dominant predator in the southern Gulf of Maine rocky intertidal, but our understanding of its impacts on community structure and dynamics remains incomplete. I examined whether chemical cues from Hemigrapsus alter the feeding behavior of Nucella to better understand how native fauna are responding to this relatively new invasive predator and its potential impacts on the community. Nucella exhibited a risk-induced change in feeding behavior by significantly reducing its feeding rate on blue mussels (Mytilus edulis) when Hemigrapsus cues were detected. These findings demonstrate the capacity for rapid behavioral responses to new invasive species and highlight the potential for such interactions to alter community structure and dynamics. • Dogwhelks perceived cues from invasive Asian shore crabs as a predation risk. • Exposure to crab cues induced dogwhelks to reduce feeding on mussels. • Presence of crab cues reduced dogwhelk feeding regardless of crab diet. • Asian shore crabs may influence invaded communities by altering native prey behavior. [ABSTRACT FROM AUTHOR]

The extent to which prey traits combine to influence the abundance of predators is still poorly understood, particularly for mixed predators in sympatry and in aquatic ecosystems. In this study, we characterise prey use and distribution in iconic bird (grey wagtails and Eurasian dippers) and fish species (brown trout and Atlantic salmon) to assess whether prey traits could predict populations of these four riverine predators. Specifically, we hypothesised that: 1) prey key traits would predict predator populations more effectively than 2) diversity of prey traits, 3) the taxonomic abundance or richness of prey (known as traditional or mass‐effect types of biodiversity) or 4) the prevailing environmental conditions. Combined predator population sizes were predicted better by a few key traits – specifically those revealing prey habitat use, size and drifting behaviour – than by prey diversity or prey trait diversity or environmental conditions. Our findings demonstrate that the complex relationships between prey assemblages and multiple predator species can be represented mechanistically when the key prey traits that govern encounter and consumption rates are identified. Given their apparent potential to reveal trophic relationships, and to complement more traditional measures of prey abundance, we advocate further development of trait‐based approaches in predator–prey research. [ABSTRACT FROM AUTHOR]

Trophic interactions of cave arthropods have been understudied. We used molecular methods (NGS) to decipher the food web in the subterranean ecosystem of the Ardovská Cave (Western Carpathians, Slovakia). We collected five arthropod predators of the species Parasitus loricatus (gamasid mites), Eukoenenia spelaea (palpigrades), Quedius mesomelinus (beetles), and Porrhomma profundum and Centromerus cavernarum (both spiders) and prey belonging to several orders. Various arthropod orders were exploited as prey, and trophic interactions differed among the predators. Linear models were used to compare absolute and relative prey body sizes among the predators. Quedius exploited relatively small prey, while Eukoenenia and Parasitus fed on relatively large prey. Exploitation of eggs or cadavers is discussed. In contrast to previous studies, Eukoenenia was found to be carnivorous. A high proportion of intraguild predation was found in all predators. Intraspecific consumption (most likely cannibalism) was detected only in mites and beetles. Using Pianka's index, the highest trophic niche overlaps were found between Porrhomma and Parasitus and between Centromerus and Eukoenenia, while the lowest niche overlap was found between Parasitus and Quedius. Contrary to what we expected, the high availability of Diptera and Isopoda as a potential prey in the studied system was not corroborated. Our work demonstrates that intraguild diet plays an important role in predators occupying subterranean ecosystems. [ABSTRACT FROM AUTHOR]