Search

This study presents a comprehensive model of predator–prey interactions within a toxic environment, with a particular focus on the effect of toxicant compounds on the development of populations. By incorporating environmental disturbances, the dynamics of the model are investigated to enhance the system’s authenticity. Analytical explanations have been provided for the deterministic system solutions, including positivity, uniform boundedness and persistence. The deterministic portion of the investigation entails a comprehensive examination of occurrence and stability criteria pertaining to every possible equlibria. The bifurcation studies conducted on the system exhibit the appearance of local bifurcations, including transcritical, saddle-node and Hopf bifurcations. Moreover, these evaluations establish the parametric region in which Bautin, Bogdanov–Takens and cusp bifurcation occur. Under a relevant selection of parametric values, the suggested system has the capacity to manifest a wide range of dynamic phenomena, such as bi-stable behavior, emergence of limit cycles, and presence of homoclinic loops. Furthermore, in a stochastic environment, the use of Lyapunov functions explains the existence of a global positive solution. It has additionally been argued that the proposed system exhibits ultimate stochastic boundedness. Subsequently, specific and adequate criteria demonstrate the eradication of both species as well as the long-term survival of prey communities. We have also investigated the impact of the exogenous input rate of toxic substances and the coefficient of toxic substances in both species on the behavior of the whole system, both in deterministic and stochastic scenarios. Theoretical findings have been confirmed by various numerical investigations. [ABSTRACT FROM AUTHOR]

ABSTRACT Spatiotemporal interactions between predators and prey are central to maintaining sustainable functioning ecosystems and community stability. For wild ungulates and their predators, livestock grazing is an important anthropogenic disturbance causing population declines and modifying their interactions over time and space. However, it is poorly understood how fine‐scale grazing affects the spatiotemporal responses of predators, prey, and their interactions. Two opposing hypotheses describe a dichotomy of possible effects. The human shield hypothesis states that people can protect prey because predators avoid areas with high human‐induced mortality risk, whereas in the human competitor hypothesis, humans compete for prey and negatively impact predators through reduced prey availability. We used camera‐trapping data from the Gansu Qilianshan National Nature Reserve in Northwest China to measure occupancy, daily activity patterns, and spatiotemporal interactions between snow leopards (Panthera uncia), the dominant predator, and their ungulate prey in areas with contrasting grazing intensities. The results of grazing were consistent with both the human‐shield and human‐competitor hypotheses, affecting spatiotemporal patterns and interactions of predators and prey. For the primary prey species, blue sheep (Pseudois nayaur), their spatial and temporal patterns were affected by grazing, which led to a reduction in interaction frequencies with snow leopards. For secondary prey, grazing led to reduced interaction frequencies with snow leopards for white‐lipped deer (Przewalskium albirostris) and red deer (Cervus yarkandensis), but increased frequencies for alpine musk deer (Moschus chrysogaster). Our results indicate how both competition among livestock and prey and predator or prey avoidance of grazed areas can impact populations and predator–prey interactions. Our findings are relevant to grazing management and snow leopard conservation. [ABSTRACT FROM AUTHOR]

Gut content metabarcoding has provided important insights into the food web ecology of spiders, the most dominant terrestrial arthropod predators. In small invertebrates, like spiders, gut content analysis is often performed on whole body DNA extracts of individual predators, from which prey sequences are selectively enriched and sequenced.Since many spider species are generalist predators, large numbers of samples comprising individual spider specimens must be analysed to recover an exhaustive image of a spider species' prey spectrum, which is costly and time‐consuming.Pooled processing of bulk samples of multiple specimens has been suggested to reduce the necessary workload and cost while still recovering a representative estimate of the prey diversity. However, it is still unclear if pooling approaches lead to bias in recovering the prey spectrum and if the results are comparable with data from individually processed spiders.Here, we test the effects of metabarcoding pooled spider gut content on the recovered taxonomic diversity and composition of prey. Using a newly adapted primer pair, which efficiently enriches COI barcode sequences of diverse arthropod prey groups while suppressing spider amplification, we test if pooling leads to reduced taxonomic diversity or skewed estimates of prey composition.Our results show that pooling and individual processing recover highly correlated taxonomic diversity and composition of prey. The only exception are very rare prey items which were less well recovered by pooling. Our results support pooling as a cost‐effective and time‐efficient approach to recover the diet of generalist predators for population‐level studies of spider trophic interactions. [ABSTRACT FROM AUTHOR]

The freshwater raphidophyte Gonyostomum semen forms extensive summer blooms in northern European humic lakes. The development of these blooms might be facilitated by a lack of natural top-down control, as few zooplankton species are able to prey on these large algal cells (up to 100 μm) that expel trichocysts upon physical stress. In this study, we describe a small ciliate species (< 17 μm) that preys on G. semen by damaging the cell membrane until cytoplasm and organelles spill out. Sequencing of clonal cultures of the ciliate tentatively identified it as the prostomatid species Urotricha pseudofurcata. Grazing experiments illustrated that feeding by U. cf. pseudofurcata can significantly reduce cell concentrations of the microalga. However, differences in cell size and growth rate between two investigated ciliate strains resulted in noticeably different grazing pressure. Environmental sequencing data from five different lakes supported potential interactions between the two species. Urotricha cf. pseudofurcata might, thus, play an important role in aquatic ecosystems that are regularly dominated by G. semen, reducing the abundance of this bloom-forming microalga and enabling transfer of organic carbon to higher trophic levels. [ABSTRACT FROM AUTHOR]

Anthropogenic habitat modification is a major contributor to global change. While the modification of natural habitats to agroecosystems attracts most of the attention, little is known about the conversion of one natural ecosystem to another. Dry dipterocarp forest is the key dry forest type across Southeast Asia. Moderate fire disturbance is essential for its regeneration, but humans often prevent fire in these forests. Consequently, dry dipterocarps can change to dry evergreen forests through succession. The consequences of this conversion on food webs are unknown. Using the network approach, we compared the food webs of web-building spiders and their prey in the understory between dry dipterocarp (open canopy, uniform understory) and dry evergreen forests (closed canopy, heterogeneous understory) in north-eastern Thailand. Overall, we collected 560 individual web-building spiders belonging to 37 genera. Further, we collected 1139 prey items from spider webs belonging to 16 arthropod orders. The composition of captured prey and the network structure differed between the forest types. Specifically, the web-building spiders were more specialized and their niches overlapped less in dry dipterocarps than in dry evergreens. The differences in food-web structure were driven mostly by trophic groups turnover rather than interaction rewiring. Implications for insect conservation: The transformation of dry dipterocarp to dry evergreen forests from the prevention of fire disturbance may lead to an altered ecological function of web-building spiders in forest understories. As trophic links and their strength are rewired, habitat modification may also lead to changes in nutrient and energy flow in forest understories. [ABSTRACT FROM AUTHOR]

We used echosounders to assess krill (Meganyctiphanes norvegica) responses to sampling gear and predators. Towing pelagic trawls above autonomous submerged, upward-looking echosounders revealed instantaneous diving by the krill during daytime but not at night. The krill dived at 10–30 cm s−1 with a near-simultaneous response throughout the krill layer below the gear (>10 m). Traversing the paths of the previous sampling revealed long-lasting voids in the krill distribution during the daytime. Such voids were less apparent at night. Backscatter increased in the wake of the gear during nocturnal sampling, possibly due to changes in individual backscatter related to variation in swimming behaviour. During daytime, krill responded to fish schools with instantaneous coherent diving, spanning tens of meters at speeds of 10–27 cm s−1. Coordinated and far-ranging responses indicate that even loose krill aggregations may facilitate predator avoidance by enabling efficient signal transmission between individuals. The krill antipredator behaviour instigated marked daytime krill patchiness. Krill patchiness will vary relative to the predator regime and reflect recent encounters. [ABSTRACT FROM AUTHOR]

The article discusses the use of artificial sentinel prey in studying predation rates and predator-prey interactions in ecosystems. It highlights the challenges in quantifying predation and the benefits of using artificial sentinels for biological control and ecosystem service assessments. The authors critique a study by Rodriguez-Campbell et al. that found inconsistencies in predation rates measured with artificial sentinel prey compared to real prey, suggesting that artificial sentinel prey may not be suitable for biogeographical studies. The article emphasizes the importance of relative comparisons in ecological research and provides recommendations for improving the use of artificial sentinel prey in experiments. [Extracted from the article]

Understanding diets of aquatic fauna is crucial to interpretation of their ecological roles and contributions to ecosystem function. The Kanawha darter (Etheostoma kanawhae) is a vibrantly colored, endemic fish found only in the New River (Kanawha Basin, USA) and its tributaries. In this study, the diet of the Kanawha darter was determined by analyzing gut contents from museum specimens. A total of 75 Kanawha darter stomachs were dissected and prey items were identified and enumerated. Additionally, gut contents of 40 fantail darters (Etheostoma flabellare) were also quantified to compare diets of these sympatric species. Numerical and presence-absence methods were used to calculate total prey abundances, percent prey abundances, prey-specific abundance, and frequencies of occurrence. Kanawha darter diets were composed of aquatic dipteran and ephemeropteran larvae. Standard length and meteorological season affected Kanawha darter gut contents with few differences seen among males and females. Dietary comparisons revealed that Kanawha darters incorporate greater proportions of ephemeropteran prey while fantail darters prey upon trichopterans more often. Additionally, Costello-Amundsen plots displayed considerable overlap in dietary composition among these sympatric congeners. Results provide novel insight with regard to Kanawha darter natural history and their ecological role in stream communities. Moreover, interspecific comparisons may indicate that niche partitioning is occurring between the two species. Subsequent investigations should attempt to reveal potential ontogenetic shifts in dietary composition, determine Kanawha darter trophic position, and examine their influence on ecosystem processes. Conservation stakeholders should also consider how the absence of this environmentally sensitive species might impact stream communities. [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]

Aim: Species distribution models (SDMs) can be correlative or mechanistic, which have very different assumptions, leading to potentially different estimates of the ecological niches and distributions of the species. The model predictions from correlative and mechanistic approaches are incomparable due to their distinct assumptions. Yet, seeking their agreements can identify robust predictions that are relatively independent of the assumptions used to generate them. However, the search for robust model predictions among SDM models remains understudied and rarely considers the effect of biotic interactions. It is essential to identify robust predictions from SDMs for policy making. Location: Global. Time Period: 1970–2000/1980–2000 and 2081–2100. Major Taxa Studies: Aphids. Methods: In this study, we selected five aphid species as examples, and applied an ensemble model of multiple correlative SDMs (eC‐SDM), a mechanistic SDM of the prey species alone (M‐SDM) and a mechanistic SDM of the predator–prey interactions (M‐BI‐SDM), to predict the habitat suitability of these aphids under climate change and seek robust predictions from both approaches, as well as evaluate the importance of biotic interactions in SDM studies. Results: Our results show that the five aphid species have different habitat suitability patterns predicted by both correlative and mechanistic approaches. However, there is a notable consensus between the model predictions for parts of North America and eastern Asia, indicating that the predictions in these regions are robust. Additionally, our mechanistic models allow us to assess the importance of predation on SDM predictions, revealing that predation can quantitatively affect species' habitat suitability both directly and indirectly. Main Conclusions: Our study suggests that mechanistic SDM could serve as a valuable addition to assess the robustness of the correlative SDM predictions, by providing additional biological realism. It highlights the importance of using diverse modelling approaches to achieve robust model predictions. [ABSTRACT FROM AUTHOR]

Predation is a key process that influences the structure and functioning of ecosystems. Tethering experiments, which involve restraining prey or prey analogs in field settings, are used to evaluate predation with minimal manipulation of predators and the environment. However, tethering experiments alter the behavior of mobile prey, an issue that increases in severity with prey mobility and reliance on that mobility to evade predators, resulting in artifacts that complicate the interpretation of experimental findings. Given their widespread and rapidly evolving use, we review and reconsider the applications of tethering experiments in marine ecosystems, their utility in measuring predation, associated artifacts, theoretical, methodological, and statistical considerations and challenges, and how to overcome these. Breaking down the predation process into its successive stages (encounter, attack, capture, and consumption), we consider that tethering experiments effectively measure two major aspects of predation: (1) relative predation rates (requiring all four stages, and resulting in successful predation) and (2) predation risk (requiring only encounter and attack). We suggest that tethering experiments be designed to test hypotheses that target particular stages or all stages of the predation process and its drivers, through manipulating tethering experimental designs, conducting direct observations of tethering experiments, collecting additional community or environmental data, combining tethering with other experimental approaches, and through statistical analyses. This general approach facilitates both our understanding of the limitations and utility of tethering experiments to compare patterns and identify drivers of predation rates and risk in the field, topics of study that remain underrepresented in the literature. [ABSTRACT FROM AUTHOR]

Consecutive and even concurrent captures of prey items are very likely to make better use of prey in high densities and frequencies. We experimentally tested the hypothesis that mantids are able to attack another prey item while predating on a previous one (multi-task predation). Observations confirmed this ability and revealed that such actions could be extended to additional prey items if available. Analyses of behavioural timelines were conducted by quantifying the behavioural flexibility and effects of an upcoming prey item on efficiency and pauses while predating on the current prey. The behavioural elements exhibited by multi-task predators towards prey were flexible, and their order was partially independent on the order of capture. They also coordinated the flow of overlapping predation by arranging behavioural tasks, by adjusting efficiency, and by using pauses. Computational simulations demonstrated that multi-task predators make use of frequent prey encounters more efficiently than serial predators, and the ultimate limiting factor could be the satiation points. The strategy of multi-task predators introduces a new perspective about how well a predator could be physically and cognitively evolved for prey abundant opportunities. Significance statement: Our study explored the behavioural ecology of multi-task predatory behaviour in mantids through field surveys demonstrating their prey-busy patch choices, laboratory experiments examining cognitive control levels by testing a few critical hypotheses, and computational simulations quantifying respective foraging gains. Previous studies on vertebrate predators pursuing multiple prey items mostly revealed their physical tricks for reducing cognitive demands, while our findings on multi-task predation, in contrast, demonstrated the critical role of behavioural regulation and attentional processes in making use of prey-abundant scenarios in an invertebrate predator. Besides, the present study used the clear behavioural indicators of mantids as an innovative alternative to quantify the function of attention transitions in a multi-task animal. [ABSTRACT FROM AUTHOR]

As sperm whales are important predators that control energy flux in the oceans, changes in their population can be used as a sentinel to measure of ecosystem health. The present study conducted a sperm whale survey of the eastern Midriff Islands Region in the Gulf of California over the course of nine years, recording sightings and collecting photographs of the fluke of sperm whale individuals. A photo-identification catalog was compiled, while individual recapture data were used to estimate the population size in the central portion of the Gulf of California, using a Jolly-Seber POPAN open population model. The results obtained show a yearly population of between 20 and 167 sperm whales, with a super population of 354 sperm whales observed between 2009 and 2015. However, from 2016 to 2018, no sightings of the species were recorded, which coincides with the decline observed in landings of their main prey, the jumbo squid, in the region. General additive model conducted on sperm whale sightings per unit of effort vs jumbo squid landings obtained an adjusted R2 of 0.644 and a deviance explained of 60.3%, indicating a good non-linear relationship between sightings of this odontocete and its prey availability. This evidence suggests that sperm whales departed the region between 2016 and 2018, due to a documented fishery collapse alongside changes of their main prey into its small phenotype, possibly as the result of increase warming conditions in surface and subsurface waters in the Gulf of California in the last three decades. [ABSTRACT FROM AUTHOR]

Toe tapping is performed by certain anuran species while foraging for their prey. This behavior has been described in different frog families, with some hypotheses regarding its function, including predator-prey communication, still unverified. To understand the function of toe tapping and its potential relationship with foraging in anurans, the present research focuses on descriptive analysis of vibrational parameters of toe tapping produced during foraging in the poison dart frog Dendrobates truncatus. We implemented an experimentally designed arena that allowed us to record toe tapping vibrations using an accelerometer attached to an artificial substrate. Continuous recordings of toe tapping were obtained from 19 individuals, enabling us to identify and define the vibrational parameters, with reference to the time between attacks on prey. The average tap duration was 0.06 ± 0.01 s with an inter-tap interval of 0.15 ± 0.07 s. We also identified a pattern, displayed in 36.5% of the analyzed attacks, of progressive acceleration of toe tapping before an attack. Furthermore, we found that individuals with longer third toes were more likely to accelerate their taps. Lastly, we found no evidence of sexual dimorphism in the toe tapping behavior of Dendrobates truncatus. Describing the vibrational parameters of toe tapping in Dendrobates truncatus represents a new frontier of research in the field of foraging behavior and paves the way for hypothesis testing regarding its functionality. [ABSTRACT FROM AUTHOR]

Prey must balance resource acquisition with predator avoidance for survival and reproduction. To reduce risk of predation, prey may avoid areas with high predator use, but if they are unable to due to resource acquisition requirements, they may instead change their habitat use or movement speed to mitigate predation risk. Prey risk response may depend on spatially or temporally varying forage availability as well as seasonal variation in prey vulnerability and availability of alternate foods for predators. To quantify how prey respond to spatial and temporal variation in risk of brown bear predation, we examined Roosevelt elk (Cervus canadensis roosevelti) spatiotemporal behavior responses to brown bear (Ursus arctos) habitat use on Afognak and Raspberry islands, Alaska, using Global Positioning System location data during elk parturition (20 May–15 June), summer (16 June–20 September), and autumn (21 September–10 November). During parturition and summer, elk used forest and shrub landcover in areas of higher brown bear probability of use. During parturition, elk used areas with lower forage productivity in areas of higher bear probability of use, and movement speed decreased with higher bear probability of use, especially in shrub landcover. During summer, elk used areas with higher forage productivity in areas of higher brown bear probability of use. During autumn, elk were less likely to use areas with higher bear habitat probability of use across landcover categories and forage productivity. During summer and autumn, elk movement speed increased with higher brown bear probability of use. Elk behavioral response to risk of brown bear predation could increase energy expenditure and decrease their ability to acquire forage, therefore negatively impacting survival and reproduction with spatiotemporal variation in risk response potentially amplifying these impacts. [ABSTRACT FROM AUTHOR]

Invasive species can become key trophic resources for native predators, and thus understanding predator-invasive prey interactions is relevant to assess invasion impacts. The Atlantic blue crab (Callinectes sapidus) has recently invaded coasts and lower stretches of rivers across the Western Palearctic, often establishing very abundant populations. The blue crab is an important prey for a large number of predators within its native range, but predation upon invasive populations is still virtually unknown. The Eurasian otter (Lutra lutra) is a flexible predator, known to incorporate invasive prey into its diet when they become available. We studied otter diet in a small estuary of southern Spain hosting a very abundant blue crab population. The role of the blue crab as otter prey was only anecdotal since, out of 223 spraints (otter faeces) collected between 2021 and 2023, its remains were found in a single one. The avoidance of the blue crab by otters, and also by other predators, seems to be a generalised phenomenon in the invaded range of this crustacean. Predation on invasive blue crabs may require a long-lasting learning process to overcome the crab’s anti-predatory structures and behaviours. Trophic interactions between invasive blue crabs and native predators deserves attention for three main aspects: (i) its implications for the functioning and structure of invaded food webs, (ii) its potential role in limiting the invasion, and (iii) the interest in the generation of new predatory traits among animal populations. [ABSTRACT FROM AUTHOR]

Secondary consumers meet their nutritional needs via their prey and are limited by the dietary resources available for their prey. This is especially relevant in ecosystems which cannot be abandoned, such as in small water bodies. In this work, I studied how urodele larval growth, development and behavior are affected by the diet of their prey. I reared Salamandra salamandra larvae in captivity, feeding them mosquito larvae fed either a plant-based (vegetal treatment) diet, a meat-based (animal treatment) diet or a combined diet (mixed treatment). I measured body size of salamander larvae and metamorphs, locomotor performance, flight initiation distance, and feeding rates of larvae, and time and survival until metamorphosis. The vegetal treatment showed reduced body size, lower foraging rates, and lower survival. Locomotor performance, flight initiation distance, and time to metamorphosis were not affected by treatment. These results highlight how prey diet affects secondary consumers. Thus, the success of a given individual can depend on the productivity of its ecosystem or the income of exogen matter. [ABSTRACT FROM AUTHOR]

Prey animals employ masquerade to avoid recognition by visual predators by developing a resemblance to inedible objects in their environment. Phytophagous flea beetles seem to resemble models of their own manufacture. While feeding they cause light- or dark-coloured hole-like damage on the leaves of their host plants that resembles the beetle's body in colour and size. Resemblance to the model and the frequency of the model can influence the efficiency of masquerade. To examine masquerade efficiency in light- and dark-coloured beetles, we evaluated their survival benefits from resembling feeding damage in the field. This was done by using two species of beetle of different colour as prey and a jumping spider as the predator. Dark-coloured species were more likely to avoid predation when they were placed on a background with damage similar in colour to their body, whereas increased survival was not recorded for light-coloured species. The extent of the feeding damage of 34 light- and dark-coloured species of beetle was compared. Variation in the extent of the damage was associated more with host plant taxa than beetle body colour. These results indicate that the efficiency of masquerade can vary among beetle species and/or phenotypes.

Regarding delay-induced predator-prey systems, extensive research has focused on the phenomenon of delayed destabilization. However, the question of whether delays contribute to stabilizing or destabilizing the system remains a subtle one. In this paper, the predator-prey interaction with discrete delay involving Ivlev-type functional response is studied by theoretical analysis and numerical simulations. The positivity and boundedness of the solution for the delayed model have been discussed. When time delay is accounted as a bifurcation parameter, stability analysis for the coexistence equilibrium is given in theoretical aspect. Supercritical Hopf bifurcation is detected by numerical simulation. Interestingly, by choosing suitable groups of parameter values, the chaotic solutions appear via a cascade of period-doubling bifurcations, which is also detected. The theoretical analysis and numerical conclusions demonstrate that the delay mechanism plays a crucial role in the exploration of chaotic solutions.

The hypothesis of slow–fast syndromes predicts a correlation between personality type and learning style; fast explorers would have a more proactive (fast but inflexible) learning style whereas slow explorers would be more reactive (slow but flexible) learners. Empirical evidence for this personality-cognition coupling remains inconclusive and heavily biased toward birds. Moreover, most studies did not examine the personality-cognition correlation when the cognitive task is discerning food quality, a scenario directly related to energy acquisition that underpins the evolution of slow–fast syndromes. In this study, we examined the exploration–cognition correlation in the context of avoidance learning in an opportunistic predator—the common sun skink Eutropis multifasciata. We quantified exploration tendencies of individuals in an unfamiliar environment and compared foraging behaviors when lizards associated prey color and taste during the initial learning trials and subsequent reverse learning trials, where the color–taste associations were switched. We found that fast explorers were less choosy and modified their foraging behaviors less with experience, conforming to a more proactive cognitive style. In contrast, slow explorers were reactive learners and were able to change foraging behaviors in both learning and reverse learning phases, even though the ability to do so depended on the color–taste treatment. Contrary to conventional predictions, the proactive–reactive learning styles in our focal species were not differentiated by a learning speed-flexibility trade-off. Our findings offer nuanced support to the slow–fast syndromes and suggest that the two types of exploration–cognition correlations could be different responses to fast-changing environmental predictability. [ABSTRACT FROM AUTHOR]

In the present study, we provide a checklist of the predators that may impact the population of the critically endangered Mandra shemaya (Alburnus mandrensis Drensky, 1943). This endemic fish only inhabits the basin of Mandra Lake in the Burgas district (SE Bulgaria) and data on its biology are scarce. We have confirmed the presence of the Mandra shemaya in Mandra Lake for the last six years (including 2024) and provided an analysis on the potential predatory pressures on A. mandrensis. The recently recorded presence of a highly invasive piscivorous predatory fish in Mandra Lake is considered potentially dangerous for the sustainability of native fish species. [ABSTRACT FROM AUTHOR]

Larvae of lacewings (Neuroptera) are known to be fierce predators today. Most characteristic are their prominent piercing-sucking stylets, which are used for venom injection and sucking out the fluids of the prey. Among lacewing larvae, aphidlions (larvae of the groups Chrysopidae and Hemerobiidae, green and brown lacewings) are today highly specialised to feed on aphids and evolved strategies to not be detected and attacked by, e.g., aphid-protecting ants. Fossil relatives of modern aphidlions seem to have also employed other strategies. For the species Pedanoptera arachnophila from about 100-million-year-old Kachin amber, Myanmar, an interaction of its larvae with spiders has been assumed. We present here new specimens resembling these larvae, including one piece of Cretaceous Kachin amber with a syn-inclusion of an aphidlion-like larva and an immature planthopper, indicating planthoppers as potential prey of the group about 100 million years ago. The morphology of the lacewing larva, with a trapezoid head capsule (in dorsal view), simple, toothless stylets, very elongate legs, and a spindle-shaped trunk, indicates that it is conspecific or at least closely related to P. arachnophila. We reconstruct the possible ontogenetic sequence of Pedanoptera arachnophila and discuss its ecology. [ABSTRACT FROM AUTHOR]

Metabarcoding is emerging as an alternative to morphological methods in noninvasive carnivore diet analysis based on scats. A number of metabarcoding markers have been developed but their comparative performance to recover DNA from scats remains mostly untested. We tested three markers covering a wide taxonomic range of prey items and compared them with the results of a morphological analysis. Morphological and genetic methods performed comparably regarding the identity of detected prey species, but the number of identified species varied strongly between markers. Only one, 12S-V5, amplified successfully in all samples and proved to be robust and reliable when working with the highly degraded DNA obtained from scats. [ABSTRACT FROM AUTHOR]

Arthropod–bat interactions are often considered as a base model for studying factors underlying predator–prey coevolutionary processes. Bats developed ultrasonic echolocation to hunt, and in response some arthropods developed defense mechanisms such as ultrasonic hearing, allowing them to elude bat predators. The present study analyzes the feeding patterns of bats, focusing on sonic-auditory sensory mechanisms in predator–prey interactions. Next-generation DNA sequence data from fecal samples were used to analyze the diet of 17 bat species from Mexico. Arthropod prey taxa were classified according to their auditory traits, and echolocation data were recompiled from literature review. We: (i) classified arthropod families according to their hearing ability; (ii) estimated arthropod taxon richness and proportion in the diet of each bat species; and (iii) used multidimensional scaling, principal component analysis, and regression to analyze prey consumption patterns in relation to their auditory traits and in relation to echolocation characteristics of bats. Finally, we analyzed the relationship between foraging time and auditory characteristics of prey. Families with hearing organs correspond to the orders Lepidoptera and Orthoptera. We registered 20 families of Lepidoptera and 5 of Orthoptera—7 and 3 with hearing organs, respectively. Of these orders, families lacking ears were recorded in the diet of a few bat species. Our results support the allotonic frequency hypothesis predicting a difference in emission frequency intervals between predator and prey. However, we found that the consumption of earless moths is less frequent and is related to diurnal and twilight activity—hence, their consumption is limited to bat species foraging early. Results indicate bats feed on arthropod prey successfully despite the ultrasonic hearing ability of the prey. These results may be due to counteradaptations that allow maintenance of an asymmetric "arms race" between bats and eared insects that favors the predator. [ABSTRACT FROM AUTHOR]

The tomato potato psyllid, Bactericera cockerelli Šulc, originating from North and Central America, poses a serious threat to Solanaceae crops in Australia. This study investigates the potential of the Australian native and commercially available green lacewing, Mallada signatus Schneider, as a biological control agent for B. cockerelli. The effect of feeding on B. cockerelli on the development rate and survival, of M. signatus were evaluated. Further, a greenhouse cage study was conducted to determine the optimal density of M. signatus larvae needed to effectively control an established B. cockerelli population. In our study, the third instar larvae of M. signatus consumed over 75 B. cockerelli nymphs in 24 h. Following the introduction of M. signatus larvae to caged tomato plants, eight M. signatus larvae per caged tomato plant decreased B. cockerelli population by 64% at the end of the sampling. These results indicated M. signatus, particularly at the larval stage, is an effective biological control option for B. cockerelli, especially in greenhouse tomato cultivation. This research offers valuable insights for the Australian horticultural industry, presenting a viable, eco‐friendly alternative to traditional, chemical pesticide‐reliant pest management strategies. [ABSTRACT FROM AUTHOR]

People's recreational activities in nature are essential to promote wildlife conservation. The interplay between humans and the environment is complex, as the presence of humans may impact wildlife both directly and by altering species interactions. Thus, conservation management in protected areas where people frequently interact with wildlife is challenging.We investigated the combined impact of different recreational activities of varying intensity, along with environmental and temporal factors, on the activity of the endangered mountain gazelle (Gazella gazella) and its predator, the golden Jackal (Canis aureus) in Ramat Hanadiv Nature Park—a protected area in northern Israel.We placed 109 camera traps in gazelles' activity centres over 5 years. We analysed the activity patterns of both species and how these patterns were affected by visitor activity.We found that gazelles became more nocturnal in areas with higher visitor activity, which led to greater overlap in their activity periods with golden Jackals. Both species were less active when there were more visitors in the park, but jackals were more attracted to disturbed areas, while gazelles avoided them. Furthermore, we found that gazelles' activity was primarily affected by visitor activity compared to environmental factors, study year or predator activity.Policy implications. We show direct and indirect effects of visitors on a predator–prey system and highlight the importance of understanding these impacts to manage protected areas and support human–wildlife coexistence. Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Predator-prey interactions in marine ecosystems control population sizes, maintain species richness, and provide intermediate disturbance. Such ecosystem structuring interactions may be rare in Antarctic epibenthic communities, which are unique among marine ecosystems worldwide for their dominance of soft bodied fauna (sponges, soft and hard corals, and echinoderms) and a simultaneous paucity of shell crushing predators (sharks, rays and durophagous decapods). In the shallow benthos, instead of durophagy, important Antarctic predators such as starfish, pycnogonids (sea spiders), nemertean worms, and nudibranchs employ grazing, scavenging, or sucking strategies. Far less is known about deep sea (>1000 m) Antarctic benthic communities due to the challenging nature of polar data collection, so that photographic surveys provide one of the only means of making in situ observations of these deep sea communities. We used seabed photographs of the deep (~2000m) slope of the Powell Basin, northwest Weddell Sea, taken by the Ocean Floor Observation and Bathymetry System on board the RV Polarstern (PS118, April 2019) to investigate the epibenthic community composition, and Bayesian Network Inference (BNI) to determine the ecological network, namely the ecological associations, including potential invertebrate predator-prey relationships between taxa. Photographs show that the rocky substrates of the basin slope support between 10-22 morphotaxa per photo, and highly abundant communities (density between 106 to 553 individuals/m2). BNI results reveal a network of associations between the sessile and mobile suspension and filter feeding organisms and their physical environment. However, associations between invertebrate predators like starfish, and other organisms, were not detected in the network. This lack of inclusion within the network suggests that, despite the presence of these normally important mobile predators, invertebrate predator-prey interactions on the rocky Powell Basin slope do not have the same ecosystem-regulating impact that they do on shallow Antarctic epibenthic communities. [ABSTRACT FROM AUTHOR]

Research on predator–prey interactions between sharks and cetaceans remain limited. Here, we report on a video of a shortfin mako shark circling a finless porpoise with a damaged caudal fin in the Seto Inland Sea, Japan. The finless porpoise was neither emaciated nor inactive, but unable to swim effectively due to the complete lack of a caudal fin. Some circumstantial evidence, including a bite mark on the porpoise's head, strongly suggests that the mako shark attacked it. Furthermore, the possible time difference between the two injuries the porpoise sustained may reflect the shark's hunting tactics. While mako sharks primarily feed on small fish and cephalopods, this observation suggests they also may prey on live cetaceans more often than previously thought. [ABSTRACT FROM AUTHOR]

Species distribution models (SDMs) are often built upon the "niche conservatism" assumption, such that they ignore the possibility of "evolutionary rescue" and may underestimate species' future range limits under climate change. We select aphids and ladybirds as model species and develop an eco‐evolutionary model to explore evolutionary rescue in a predator–prey system under climate change. We model the adaptive change of species' thermal performances, accounting for biotic interactions. Our study suggests that, without considering evolutionary adaptation, the warming climate will result in a reduction in aphid populations and the extinction of ladybirds in large parts of the United States. However, when incorporating evolutionary adaptation into the model, aphids can adapt to climate change, whereas ladybirds demonstrate geographic variation in their evolutionary rescue potential. Specifically, ladybirds in southern regions are more likely to be rescued than those in the north. In certain northern regions, ladybirds do not avoid extinction due to severe warming trends and seasonality of the climate. While higher warming trends do prompt stronger evolutionary changes in phenotype, they also lead to reduced aphid population abundance such that ecology constrains ladybird population growth. Higher seasonality induces an ecological effect by limiting the length of reproductive season, thereby reducing the capacity for evolutionary rescue. Together, these findings reveal the complex interplay between ecological and evolutionary dynamics in the context of evolutionary adaptation to climate change. [ABSTRACT FROM AUTHOR]

Various species of freshwater zooplankton feature defensive spines, spikes or spinules across a comparatively wide size range. Among those is Daphnia magna , which has previously been found to express an enhanced spinescence in response to the predatory tadpole shrimp Triops cancriformis. This involves an elongated tail-spine, further protruding fornices and elongated, as well as further spread spinules along its carapace margins. Of these, the predator-induced trait changes concerning the spinules of D. magna at the age of first reproduction are known. However, their morphological development throughout the juvenile instars, in comparison to the changes of the prominent tail spine during the same periods, has thus far been unclear. Our study shows that D. magna expresses spinules across all investigated juvenile instars. Furthermore, during ontogeny, the development of D. magna 's rather small spinescence traits, i.e. the dorsal and ventral mean spinule length, as well as the dorsal spinules bearing area, in response to predation pressure, differs distinctly from that of the prominent tail-spine. Thus, our study provides further insight into the connectedness of traits contributing to the overall defensively enhanced spinescence of D. magna , with possible implications for the functional benefit of the traits at certain developmental periods. [ABSTRACT FROM AUTHOR]

Animals exhibit a variety of strategies to avoid predation; spiders are no exception. We explored whether web-building spiders that differ in the architecture of their webs exhibit morphologies or behaviors suggestive of antipredator strategies that trade-off with the degree of protection offered by their webs. Spiders build webs of 3 types: the more protected tangles and sheet-and-tangles, which are three-dimensional (3D), and the more exposed orbs, which are two-dimensional (2D), both with or without a refuge. We hypothesize that spiders whose webs offer greater protection—a 3D architecture or a refuge—will be less likely to be armored or brightly colored when compared to spiders without these protections. We collected data on 446 spiders and their webs in 2 lowland tropical rainforest sites. We show that 2D web builders with no refuges tended to be brightly colored (background contrasting) and spiny (spiky), whereas those with refuges tended to blend against the background of their refuges. 3D web builders, on the other hand, were neither cryptic nor brightly colored nor armored but were more likely to drop out of the web upon simulated predator contact. These results support the hypothesis that web-building spiders tend to be protected either through the architecture of their webs or their morphology and behavior, suggesting a trade-off between different types of antipredator strategies. [ABSTRACT FROM AUTHOR]

Chrysoperla zastrowi sillemi, a common predator in agricultural ecosystems, exhibits significant potential for biological pest control. Study investigated the functional response of C. zastrowi sillemi to Brevicorynae brassicae, a destructive pest of cruciferous crops through laboratory experiments and field observations. Analysed the predatory behaviour of C. zastrowi sillemi in response to varying densities of B. brassicae. The functional response curves are constructed to elucidate the relationship between predator consumption rate and prey density. Factors influencing the predatory efficiency, including prey density, predator handling time, and environmental conditions, are comprehensively evaluated. The findings provided valuable insights into the potential of predator as a biological control agent against B. brassicae infestations, facilitating the development of sustainable pest management strategies in agriculture. [ABSTRACT FROM AUTHOR]

Chrysoperla zastrowi sillemi, a common predator in agricultural ecosystems, exhibits significant potential for biological pest control. Study investigated the functional response of C. zastrowi sillemi to Brevicorynae brassicae, a destructive pest of cruciferous crops through laboratory experiments and field observations. Analysed the predatory behaviour of C. zastrowi sillemi in response to varying densities of B. brassicae. The functional response curves are constructed to elucidate the relationship between predator consumption rate and prey density. Factors influencing the predatory efficiency, including prey density, predator handling time, and environmental conditions, are comprehensively evaluated. The findings provided valuable insights into the potential of predator as a biological control agent against B. brassicae infestations, facilitating the development of sustainable pest management strategies in agriculture. [ABSTRACT FROM AUTHOR]

Eyespot patterns have evolved in many prey species. These patterns were traditionally explained by the eye mimicry hypothesis, which proposes that eyespots resembling vertebrate eyes function as predator avoidance. However, it is possible that eyespots do not mimic eyes: according to the conspicuousness hypothesis, eyespots are just one form of vivid signals where only conspicuousness matters. They might work simply through neophobia or unfamiliarity, without necessarily implying aposematism or the unprofitability to potential predators. To test these hypotheses and explore factors influencing predators’ responses, we conducted a meta-analysis with 33 empirical papers that focused on bird responses to both real lepidopterans and artificial targets with conspicuous patterns (i.e. eyespots and non-eyespots). Supporting the latter hypothesis, the results showed no clear difference in predator avoidance efficacy between eyespots and non-eyespots. When comparing geometric pattern characteristics, bigger pattern sizes and smaller numbers of patterns were more effective in preventing avian predation. This finding indicates that single concentric patterns have stronger deterring effects than paired ones. Taken together, our study supports the conspicuousness hypothesis more than the eye mimicry hypothesis. Due to the number and species coverage of published studies so far, the generalisability of our conclusion may be limited. The findings highlight that pattern conspicuousness is key to eliciting avian avoidance responses, shedding a different light on this classic example of signal evolution.

As sperm whales are important predators that control energy flux in the oceans, changes in their population can be used as a sentinel to measure of ecosystem health. The present study conducted a sperm whale survey of the eastern Midriff Islands Region in the Gulf of California over the course of nine years, recording sightings and collecting photographs of the fluke of sperm whale individuals. A photo-identification catalog was compiled, while individual recapture data were used to estimate the population size in the central portion of the Gulf of California, using a Jolly-Seber POPAN open population model. The results obtained show a yearly population of between 20 and 167 sperm whales, with a super population of 354 sperm whales observed between 2009 and 2015. However, from 2016 to 2018, no sightings of the species were recorded, which coincides with the decline observed in landings of their main prey, the jumbo squid, in the region. General additive model conducted on sperm whale sightings per unit of effort vs jumbo squid landings obtained an adjusted R2 of 0.644 and a deviance explained of 60.3%, indicating a good non-linear relationship between sightings of this odontocete and its prey availability. This evidence suggests that sperm whales departed the region between 2016 and 2018, due to a documented fishery collapse alongside changes of their main prey into its small phenotype, possibly as the result of increase warming conditions in surface and subsurface waters in the Gulf of California in the last three decades.

Wildlife conflicts require robust quantitative data on incidence and impacts, particularly among species of conservation and cultural concern. We apply a multi-assay framework to quantify predation in a southeastern Australian scenario where complex management implications and calls for predator culling have grown despite a paucity of data on seabird predation by recovering populations of long-nosed fur seals (Arctocephalus forsteri). We apply two ecological surveillance techniques to analyze this predator's diet -- traditional morphometric (prey hard-part) and environmental DNA metabarcoding (genetic) analyses using an avian specific primer for the 12S ribosomal RNA (rRNA) gene -- to provide managers with estimated predation incidence, number of seabird species impacted and inter-prey species relative importance to the predator. DNA metabarcoding identified additional seabird taxa and provided relative quantitative information where multiple prey species occur within a sample; while parallel use of both genetic and hard-part analyses revealed a greater diversity of taxa than either method alone. Using data from both assays, the estimated frequency of occurrence of predation on seabirds by long-nosed fur seals ranged from 9.1--29.3% of samples and included up to 6 detected prey species. The most common seabird prey was the culturally valued little penguin (Eudyptula minor) that occurred in 6.1--25.3% of samples, higher than previously reported from traditional morphological assays alone. We then explored DNA haplotype diversity for little penguin genetic data, as a species of conservation concern, to provide a preliminary estimate of the number of individuals consumed. Polymorphism analysis of consumed little penguin DNA identified five distinct mitochondrial haplotypes -- representing a minimum of 16 individual penguins consumed across 10 fur seal scat samples (equivalent to 10.1% of samples). We recommend rapid uptake and development of cost-effective genetic techniques and broader spatiotemporal sampling of fur seal diets to further quantify predation and hotspots of concern for wildlife conflict management. [ABSTRACT FROM AUTHOR]

Evolutionary and ecological dynamics can occur on similar timescales and thus influence each other. While it has been shown that the relative contribution of ecological and evolutionary change to population dynamics can vary, it still remains unknown what influences these differences. Here, we test whether prey populations with increased variation in their defence and competitiveness traits will have a stronger impact on evolution for predator growth rates. We controlled trait variation by pairing distinct clonal lineages of the green alga Chlamydomonas reinhardtii with known traits as prey with the rotifer Brachionus calyciforus as predator and compared those results with a mechanistic model matching the empirical system. We measured the impact of evolution (shift in prey clonal frequency) and ecology (shift in prey population density) for predator growth rate and its dependency on trait variation using an approach based on a 2-way ANOVA. Our experimental results indicated that higher trait variation, i.e. a greater distance in trait space, increased the relative contribution of prey evolution to predator growth rate over 3–4 predator generations, which was also observed in model simulations spanning longer time periods. In our model, we also observed clone-specific results, where a more competitive undefended prey resulted in a higher evolutionary contribution, independent of the trait distance. Our results suggest that trait combinations and total prey trait variation combine to influence the contribution of evolution to predator population dynamics, and that trait variation can be used to identify and better predict the role of eco-evolutionary dynamics in predator–prey systems. [ABSTRACT FROM AUTHOR]

Species have developed several defensive strategies for survival in response to predation pressures, including chemical, acoustic, visual, and behavioral mechanisms. Anurans serve as prey for numerous species, leading to the evolution of a diverse array of antipredator strategies. Among these strategies, acoustic emission defenses are categorized into distress calls, alarm calls, and warning calls. Although distress calls in frogs have been recognized to occur within the audible spectrum, the occurrence of ultrasound calls has been suggested for one species, but not yet confirmed. Based on our observations, we confirmed the presence of ultrasound distress calls emitted by an adult Haddadus binotatus. The distress call exhibited a high-pitched tone with decreasing frequency modulation and ultrasonic harmonics extending up to approximately 44 kHz. The presence of ultrasound frequencies in distress calls may confer advantages in deterring a broader range of predators. The use of broad-band screams synchronously with other behaviors, as raising the front of the body while arching the back and extreme mouth-gaping, intensified the defensive display, likely being more efficient in deterring predation. We observed similar behavioral repertoire for an adult Ischnocnema cf. henselii. Therefore, it could be widespread across individuals of other Brachycephaloidea genera as well. [ABSTRACT FROM AUTHOR]

Predator–prey interactions are important for regulating populations and structuring communities but are affected by many dynamic, complex factors across large scales, making them difficult to study. Integrated population models (IPMs) offer a potential solution to understanding predator–prey relationships by providing a framework for leveraging many different datasets and testing hypotheses about interactive factors. Here, we evaluate the coyote–deer (Canis latrans–Odocoileus virginianus) predator–prey relationship across the state of North Carolina (NC). Because both species have similar habitat requirements and may respond to human disturbance, we considered net primary productivity (NPP) and urbanization as key mediating factors. We estimated deer survival and fecundity by integrating camera trap, harvest, and biological and hunter observation datasets into a two‐stage, two‐sex Lefkovich population projection matrix. We allowed survival and fecundity to vary as functions of urbanization, NPP, and coyote density, and projected abundance forward to test eight hypothetical scenarios. We estimated initial average deer and coyote densities to be 11.83 (95% CI: 5.64, 20.80) and 0.46 (95% CI: 0.02, 1.45) individuals/km2, respectively. We found a negative, though highly uncertain, relationship between the current levels of coyote density and deer fecundity in most areas that became more negative under hypothetical conditions of lower NPP or higher urbanization, leading to lower projected deer abundances. Though not conclusive, our results indicate the possibility that coyotes could have stronger effects on deer populations in NC if their densities rise, but primarily in less productive and/or more suburban habitats. Our case study provides an example of how IPMs can be used to better understand the complex relationships between predator and prey under changing environmental conditions. [ABSTRACT FROM AUTHOR]

The wolf (Canis lupus) is arguably the most successful species at recolonizing its now human‐dominated former ranges in Europe and North America. Over the centuries while the wolf was absent, humans have transformed ecosystems to a large extent. In this paper, we highlight key aspects of these human‐modified ecosystems that include changes to (meso)carnivore communities, wolves themselves (genetics, behaviour), woody plant communities and the playing field for predator–prey interactions (landscape structure).We argue that the recognition of the novelty of human‐modified ecosystems logically leads to novel pathways of how wolves can influence ecosystem functioning. Thus far, the ecological impacts of wolves in human‐dominated systems have largely been predicted based on the documented effects they have on prey species or lower trophic levels in well‐preserved systems with low human impact. However, wolves in human‐modified ecosystems will engage in an array of novel interactions and potential novel trophic cascades that do not occur in more natural ecosystems with lower human impact.This should encourage us to re‐assess the questions we ask about wolf impacts in novel systems. A promising direction for future studies is exploring what novel interactions establish and under what conditions wolves can exert their ecosystem impacts (context dependence) in the human‐modified ecosystems wolves are recolonizing.Policy implications. Understanding these novel interactions and the context dependence of ecosystem impacts could guide us to act to improve conditions to enable wolves to exert their ecosystem impacts again. These novel interactions may be the true ecological and societal value of having wolves returning to human‐modified landscapes. [ABSTRACT FROM AUTHOR]

Climate change may have diverse and complex impacts on species interactions, destabilizing food webs and ecosystem services. The effects of warming on the top‐down biological control of crop pests have been considerably less studied than bottom‐up effects through crop physiological changes.We studied the effect of a 2°C warming in the laboratory and in wheat fields on the predation and metabolism of Harmonia axyridis on wheat aphids using molecular gut content analysis. We also measured the effects of warming on the predation rate and functional response of H. axyridis on each aphid species in the laboratory, as well as on DNA degradation rate.Field densities of Sitobion avenae and Rhopalosiphum padi, the two most abundant wheat aphid species, were increased by 2 and 2.5 times, respectively, under experimental warming, but densities of H. axyridis were not. Field predation rate of H. axyridis on these two aphid was found to be about 25% lower under elevated temperature. This could have been due to faster prey digestion, since degradation of the preferred aphid species, Sitobion avenae, was 1.5 times faster under elevated temperature. However, the functional response of H. axyridis larvae on these two species was 1.5 times higher under warming over the range of prey densities tested (50–250 over 24 h). The total predation rate of H. axyridis larvae on a mixture of S. avenae, R. padi and Schizaphis graminum aphid prey was also increased by 1.4 times, but consumption of R. padi aphids was increased while that of S. graminum was decreased under warming.Overall, our results show that global warming could strongly increase pest outbreaks and destabilize biological pest control, which would likely result in accrued yield losses. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The function and evolutionary background of the hairs on the shells of terrestrial gastropods is largely unknown. Many hypotheses proposed by malacologists have never been proven, and the long-held hypothesis of mechanical stability in wet environments has been rejected by recent studies. It would therefore be worthwhile to reexamine other hypotheses regarding the adaptive significance of shell hairs. We investigated the defense function of shell hairs against a specialist predator, the snail-eating firefly, in the long-haired snail Moellendorffia diminuta. The firefly larvae, which hunt snails using abdominal suckers, were unable to attach to the shell because of the shell hairs but were able to attach to the shells that had lost their hairs. About half of the hairy snails successfully defended themselves by swinging their shells and dropping firefly larvae, but most of the snails without hair failed to defend. The hairs reduce the ability of the larva to attach to the shell and increase the effectiveness of the shell-swinging defense behavior in removing the larva from the shell. As shell hairs grow longer with shell development, they may confer an advantage based on the predator's growth stage. Our findings highlight the anti-predator defense role of shell hairs in land snails, introducing a hypothesis previously overlooked in the evolutionary context of hairy snails. [ABSTRACT FROM AUTHOR]

Food quality (e.g. the presence of cyanobacteria) may affect the behavior, morphology and life history of cladocerans. However, little is known about how diet quality may affect the effectiveness of Daphnia 's behavioral defenses against predators. Here we test the hypothesis that the presence of non-toxic cyanobacteria in Daphnia 's diet reduces its ability to escape fish attack. The animals cultured under two different food quality regimes (green alga vs. cyanobacteria) were subjected to two types of predation experiments. In the first, we tested Daphnia 's ability to avoid a predator whose feeding was simulated using a pipette, while in the second we tested Daphnia 's ability to escape when confronted with a foraging fish (Poecilia reticulata). In both types of experiments, the ability to avoid predator attack was greater in Daphnia fed high quality green algae than in Daphnia fed low quality cyanobacteria.. We conclude that low food quality can affect the fitness of Daphnia not only by slowing their growth and reproduction rates, but also by increasing their susceptibility to predation. [ABSTRACT FROM AUTHOR]

Background: To identify and avoid predators, amphibians rely on chemical cues. Onychodactylus koreanus undergo two to three years of the larval stage in mountainous streams, where they encounter various predators. We aimed to identify the potential predators of O. koreanus larvae based on their antipredator responses to predator odors. Additionally, we examined whether the response was innate or can be strengthened by predator olfactory learning. Results: In Experiment 1, O. koreanus larvae exhibited a substantial antipredator response to Chinese minnow (Rhynchocypris oxycephalus) odor but not to Korean freshwater crayfish (Cambaroides similis) odor. In Experiment 2, O. koreanus larvae, who did not previously expose to R. oxycephalus odor, demonstrated a substantial antipredator response to it. Experiment 3 indicated that predator olfactory learning of R. oxycephalus did not enhance the antipredator response of the larvae. Conclusions: Rhynchocypris oxycephalus could prey on O. koreanus larvae, whose antipredator response to R. oxycephalus odor is innate and not enhanced by olfactory learning. Further investigation into the olfactory system of this species may provide insights into the life cycle of O. koreanus, uncovering hidden underground breeding sites and unknown breeding periods.

Abstract Research on predator–prey interactions between sharks and cetaceans remain limited. Here, we report on a video of a shortfin mako shark circling a finless porpoise with a damaged caudal fin in the Seto Inland Sea, Japan. The finless porpoise was neither emaciated nor inactive, but unable to swim effectively due to the complete lack of a caudal fin. Some circumstantial evidence, including a bite mark on the porpoise's head, strongly suggests that the mako shark attacked it. Furthermore, the possible time difference between the two injuries the porpoise sustained may reflect the shark's hunting tactics. While mako sharks primarily feed on small fish and cephalopods, this observation suggests they also may prey on live cetaceans more often than previously thought.

Abstract Species distribution models (SDMs) are often built upon the “niche conservatism” assumption, such that they ignore the possibility of “evolutionary rescue” and may underestimate species' future range limits under climate change. We select aphids and ladybirds as model species and develop an eco‐evolutionary model to explore evolutionary rescue in a predator–prey system under climate change. We model the adaptive change of species' thermal performances, accounting for biotic interactions. Our study suggests that, without considering evolutionary adaptation, the warming climate will result in a reduction in aphid populations and the extinction of ladybirds in large parts of the United States. However, when incorporating evolutionary adaptation into the model, aphids can adapt to climate change, whereas ladybirds demonstrate geographic variation in their evolutionary rescue potential. Specifically, ladybirds in southern regions are more likely to be rescued than those in the north. In certain northern regions, ladybirds do not avoid extinction due to severe warming trends and seasonality of the climate. While higher warming trends do prompt stronger evolutionary changes in phenotype, they also lead to reduced aphid population abundance such that ecology constrains ladybird population growth. Higher seasonality induces an ecological effect by limiting the length of reproductive season, thereby reducing the capacity for evolutionary rescue. Together, these findings reveal the complex interplay between ecological and evolutionary dynamics in the context of evolutionary adaptation to climate change.

Predator-prey interactions in marine ecosystems control population sizes, maintain species richness, and provide intermediate disturbance. Such ecosystem structuring interactions may be rare in Antarctic epibenthic communities, which are unique among marine ecosystems worldwide for their dominance of soft bodied fauna (sponges, soft and hard corals, and echinoderms) and a simultaneous paucity of shell crushing predators (sharks, rays and durophagous decapods). In the shallow benthos, instead of durophagy, important Antarctic predators such as starfish, pycnogonids (sea spiders), nemertean worms, and nudibranchs employ grazing, scavenging, or sucking strategies. Far less is known about deep sea (>1000 m) Antarctic benthic communities due to the challenging nature of polar data collection, so that photographic surveys provide one of the only means of making in situ observations of these deep sea communities. We used seabed photographs of the deep (~2000m) slope of the Powell Basin, northwest Weddell Sea, taken by the Ocean Floor Observation and Bathymetry System on board the RV Polarstern (PS118, April 2019) to investigate the epibenthic community composition, and Bayesian Network Inference (BNI) to determine the ecological network, namely the ecological associations, including potential invertebrate predator-prey relationships between taxa. Photographs show that the rocky substrates of the basin slope support between 10-22 morphotaxa per photo, and highly abundant communities (density between 106 to 553 individuals/m2). BNI results reveal a network of associations between the sessile and mobile suspension and filter feeding organisms and their physical environment. However, associations between invertebrate predators like starfish, and other organisms, were not detected in the network. This lack of inclusion within the network suggests that, despite the presence of these normally important mobile predators, invertebrate predator-prey interactions on the rocky Powell Basin slope do not have the same ecosystem-regulating impact that they do on shallow Antarctic epibenthic communities.

The article explores the predatory behavior of Anthracalaus sakaguchii, a species of click beetle larvae found in the Ryukyu Islands of Japan. These larvae are unique in their ambush hunting technique, where they drag land snails into their underground burrows and consume their soft body parts. This behavior has not been observed in other snail-eating predators. The article provides detailed descriptions and images of the larvae and their burrows, and suggests further research on their feeding habits and attraction mechanisms. The conservation status of related species is also mentioned. [Extracted from the article]