Search Results (994)

Understanding the biodiversity of aquatic communities and the underlying mechanisms that shape biodiversity patterns and community dynamics is crucial for the effective conservation and management of freshwater ecosystems. However, traditional survey methods often fail to comprehensively capture species diversity, particularly for low-abundance taxa. Moreover, studies integrating both metazoan and fish communities at fine spatial scales remain limited. To address these gaps, we employed a multi-marker eDNA metabarcoding approach, targeting both the 12S and 18S rRNA gene regions, to comprehensively investigate the composition of metazoan and fish communities in the Yujiang River. A total of 12 metazoan orders were detected, encompassing 15 families, 21 genera, and 19 species. For the fish community, 32 species were identified, belonging to 25 genera, 10 families, and 7 orders. Among these, Adula falcatoides and Coptodon zillii were identified as the most prevalent and abundant metazoan and fish species, respectively. Notably, the most prevalent fish species, C. zillii and Oreochromis niloticus, are both recognized as invasive species. The Bray–Curtis distance of metazoa (average: 0.464) was significantly lower than that of fish communities (average: 0.797), suggesting higher community heterogeneity among fish assemblages. Beta-diversity decomposition indicated that variations in the metazoan and fish communities were predominantly driven by species replacement (turnover) (65.4% and 70.9% for metazoa and fish, respectively) rather than nestedness. Mantel tests further revealed that species turnover in metazoan communities was most strongly influenced by water temperature, while fish community turnover was primarily affected by water transparency, likely reflecting the physiological sensitivity of metazoans to thermal gradients and the dependence of fish on visual cues for foraging and habitat selection. In addition, a co-occurrence network of metazoan and fish species was constructed, highlighting potential predator-prey interactions between native species and Corbicula fluminea, which emerged as a potential keystone species. Overall, this study demonstrates the utility of multi-marker eDNA metabarcoding in characterizing aquatic community structures and provides new insights into the spatial dynamics and species interactions within river ecosystems. Full article

Protists represent a major component of eukaryotic diversity within the soil microbiome, playing critical roles in mediating carbon and nitrogen cycling and influencing nutrient availability and soil health. Their diversity is shaped by multiple factors, including temperature, pH, organic matter content, and land use. In this study, we investigated the protist diversity in rhizosphere soils from both wild and cultivated date palm varieties. Our results identified nitrate, nitrite, calcium, and carbon content as key soil factors significantly correlated with protist diversity. Only 9.2% (42) of operational taxonomic units (OTUs) were shared across all soil samples, suggesting that these taxa possess traits enabling adaptation to extreme environmental conditions. The dominant protist families belonged to Rhizaria, Alveolata, Amoebozoa, and Archaeplastida, primarily comprising bacterial consumers, alongside taxa from Stramenopiles, Opisthokonta, Hacrobia, and Excavata. At the class level, Filosa-Sarcomonadea, Colpodea, Variosea, Tubulinea, and Chlorophyceae were the most abundant. Filosa-Sarcomonadea and Colpodea were positively correlated with bacterial and fungal genera, suggesting their role as consumers, while Variosea showed a negative correlation with bacteria, reflecting predator-prey dynamics. Notably, the protist community composition in wild date palm rhizosphere soils was distinct from that in cultivated soils, with Opisthokonta being particularly abundant, likely reflecting adaptation to drought conditions. Overall, this study highlights the significant differences in protist diversity and community structure between wild and cultivated date palm ecosystems. Full article

In this paper, an eco-epidemiological model with a weak Allee effect and prey disease dynamics is discussed. Mathematical features such as non-negativity, boundedness of solutions, and local stability of the feasible equilibria are discussed. Additionally, the transcritical bifurcation, saddle-node bifurcation, and Hopf bifurcation are proven using Sotomayor’s theorem and Poincare–Andronov–Hopf theorems. In addition, the correctness of the theoretical analysis is verified by numerical simulation. The numerical simulation results show that the eco-epidemiological model with a weak Allee effect has complex dynamics. If the prey population is not affected by disease, the predator becomes extinct due to a lack of food. Under low infection rates, all populations are maintained in a coexistent state. The Allee effect does not influence this coexistence. At high infection rates, if the prey population is not affected by the Allee effect, the infected prey is found to coexist in an oscillatory state. The predator population and the susceptible prey population will be extinct. If the prey population is affected by the Allee effect, all species will be extinct. Full article

We explore chaos, local dynamics, codimension-one, and codimension-two bifurcations of an asymmetric discrete predator–prey model. More precisely, for all the model’s parameters, it is proved that the model has two boundary fixed points and a trivial fixed point, and also under parametric conditions, it has an interior fixed point. We then constructed the linearized system at these fixed points. We explored the local behavior at equilibria by the linear stability theory. By the series of affine transformations, the center manifold theorem, and bifurcation theory, we investigated the detailed codimensions-one and two bifurcations at equilibria and examined that at boundary fixed points, no flip bifurcation exists. Furthermore, at the interior fixed point, it is proved that the discrete model exhibits codimension-one bifurcations like Neimark–Sacker and flip bifurcations, but fold bifurcation does not exist at this point. Next, for deeper understanding of the complex dynamics of the model, we also studied the codimension-two bifurcation at an interior fixed point and proved that the model exhibits the codimension-two 1:2, 1:3, and 1:4 strong resonances bifurcations. We then investigated the existence of chaos due to the appearance of codimension-one bifurcations like Neimark–Sacker and flip bifurcations by OGY and hybrid control strategies, respectively. The theoretical results are also interpreted biologically. Finally, theoretical findings are confirmed numerically. Full article

The analysis of activity patterns is a valuable tool for understanding the temporal organization of mammal communities, which is determined by biological requirements, resource availability, and competitive pressures both within and between species. Research on this ecological aspect can contribute to the development of effective conservation strategies. Cloud forest is an ecosystem of high biological relevance, as this provides habitat for a wide diversity of species in Mexico, including endemic, emblematic, and threatened taxa. Our main objectives were to analyze mammalian activity patterns and predator–prey relationships in the cloud forest of the El Cielo Biosphere Reserve, Tamaulipas, Mexico. From 2018 to 2020, twenty camera trap stations were installed, and independent photographic records were obtained, divided into 24 one-hour intervals, and subsequently classified as diurnal, nocturnal, crepuscular, or cathemeral. Temporal activity was estimated using circular statistics in RStudio v4.3.1, and activity overlap between major carnivores and their prey was assessed using the ‘overlap’ package in R. A total of 18 medium- and large-sized mammal species were recorded in this study. The activity of four species was seasonally influenced, with a predominantly nocturnal pattern observed during the dry season. The activity overlap analysis revealed potential temporal similarity between predators and their prey. For example, Panthera onca exhibited a high overlap with Mazama temama (Δ = 0.83), Puma concolor with Nasua narica (Δ = 0.91), and Ursus americanus with M. temama (Δ = 0.77). These findings suggest that the activity patterns of certain species can be influenced by seasonality and that large predators may favor specific prey whose activity overlaps with their own. Full article

In the scenario that requires the biological control of pests using predatory enemies, predators not only prey on pests directly but also can affect the population fitness of pests through indirect non-consumptive effects (predation risk effects). However, the impact of predation risk effects varies depending on the mode of stress imposed by natural enemies and the state of the stressed pests. Herein, we exposed aphids (Periphyllus koelreuteriae) at different stages to various cues from the multicolored Asian lady beetle (Harmonia axyridis) to assess the effects of different predation risks on P. koelreuteriae development and reproduction. We found that the effect of predation risk on aphid developmental time was clearly stage-dependent. When 1st-instar nymphs were exposed to predator cues, their developmental time was prolonged only in the early stages (1st–3rd instar nymphs). Similarly, when third-instar nymphs were stressed, only the current stage (third instar) showed a developmental delay, while fourth-instar nymphs and adult aphids were not significantly affected. Additionally, aphids at different stages perceive predation risk differently. Nymphs cannot recognize visual cues from predators, but can perceive odor cues. In contrast, adult aphids are sensitive to a variety of predator cues, including visual ones. Predation risk caused aphids to shorten their adult lifespan and reduce reproductive output, but it increased the proportion of diapause offspring. This study highlights the importance of considering how predation risk affects multiple life stages and physiological changes, which are important for gaining insights into the mechanisms of predator–prey interactions and for comprehensively assessing the ability of lady beetles to regulate aphid populations. Full article

In this paper, a class of two-delay predator–prey models with coefficient-dependent delay is studied. It examines the combined effect of fear-induced delay and post-predation biomass conversion delay on the stability of predator–prey systems. By analyzing the distribution of roots of the characteristic equation, the stability conditions for the internal equilibrium and the existence criteria for Hopf bifurcations are derived. Utilizing normal form theory and the central manifold theorem, the direction of Hopf bifurcations and the stability of periodic solutions are calculated. Finally, numerical simulations are conducted to verify the theoretical findings. This research reveals that varying delays can destabilize the predator–prey system, reflecting the dynamic complexity of real-world ecosystems more realistically. Full article

Ants are key drivers of biodiversity in both tropical and temperate forests, though the underlying mechanisms of this remain debated. In tropical lowland rainforests, ants dominate the canopy as opportunistic predators, shaping arthropod abundance and community structure. By contrast, few arboreal ant species exist in temperate forests due to climatic constraints, and predation pressure is generally low. This changes when ground-nesting Formica species enter the canopy to forage. Using insecticidal knockdown, we collected arthropod communities from trees with high and low ant abundance in both tropical and temperate forests and in different seasons. We found consistently higher arthropod abundances on trees with strong ant dominance, including preferred prey taxa such as Diptera, Psocoptera, and Lepidoptera. In temperate forests, high arthropod densities may be driven by aphid-produced honeydew, whereas in tropical rainforests, the absence of large hemipteran aggregations suggests that other mechanisms are involved. Consequently, this mechanism fails to explain high arthropod abundance in tropical primary forests. In contrast, secondary tropical forests host structurally and compositionally altered ant communities, resulting in reduced predation pressure and a marked increase in the abundance of individual species, including potential pest species. These findings suggest that biodiversity maintenance in the canopy depends on intact, diverse ant communities. Recolonization from nearby primary forests is essential for recovery, yet even after five decades, secondary forests remain ecologically distinct, rendering full restoration to primary forest conditions unlikely within a management-relevant timeframe. Full article

Understanding predator-prey coexistence mechanisms is essential for conserving endemic species in montane ecosystems. Galliformes serve as critical ecological indicator species, yet their populations are declining globally due to habitat fragmentation and anthropogenic pressures. Elliot’s pheasant (Syrmaticus ellioti, Swinhoe, 1872), a Galliformes species endemic to China, is primarily distributed south of the Yangtze River. However, its coexistence mechanisms with sympatric predators remain undocumented. Here, using six years (2019–2024) of camera-trap data from 90 stations in Jiemuxi National Nature Reserve, Hunan Province, Southwest China, we employed a MaxEnt model and kernel density estimation to investigate spatiotemporal coexistence mechanisms between Elliot’s pheasant and its primary predator, the leopard cat (Prionailurus bengalensis, Kerr, 1792). Across 36,946 camera-days, we obtained 227 independent detections of Elliot’s pheasant and 82 of the leopard cat. Spatial niche analysis revealed high overlap (Schoener’s D = 0.769; Hellinger’s I = 0.952). Both species exhibit similar preferences for main environmental variables. Conversely, significant temporal niche segregation occurred: Elliot’s pheasant displayed diurnal bimodal activity, whereas the leopard cat was strictly nocturnal, resulting in low overlap (Δ₄ = 0.379, p < 0.01). Critically, during Elliot’s pheasant’s breeding season, increased temporal overlap with the leopard cat (Δ₁ = 0.479, p < 0.01) suggested that reproductive behaviors elevate predation risk. Our findings demonstrate that temporal niche partitioning serves as the primary coexistence mechanism, while spatial niche overlap and behavioral adaptations under predation pressure drive dynamic predator-prey interactions. This provides a scientific foundation for targeted conservation strategies and predator management of these threatened Galliformes. Full article

This study investigated the impact of sublethal concentrations of dinotefuran on the predatory behavior and detoxification enzyme activity of Harmonia axyridis, aiming to establish a theoretical foundation for the conservation and utilization of natural enemies and the effective management of wheat aphids. This study treated wheat aphids with sublethal concentrations (LC₂₀ and LC₃₀) of dinotefuran via the leaf dipping method and subsequently used them as prey for the fourth-instar larvae of H. axyridis. The predation amount, instantaneous attack rate, handling time, daily maximum predation amount, and detoxification enzyme activity of H. axyridis were statistically analyzed. The results indicated that the predation of H. axyridis on wheat aphids conformed to the Holling II disc equation. Moreover, in comparison to the control group, the handling time of H. axyridis on wheat aphids was extended, and at the same time, the instantaneous attack rate, maximum daily predation amount, and predation efficiency were all diminished. After the ingestion of LC₂₀- and LC₃₀-dinotefuran-treated aphids, the carboxylesterase levels in H. axyridis were not significantly different from the control, with levels 0.97-fold and 0.94-fold that of the control, respectively. Glutathione-S-transferase (GST) demonstrated an induction impact compared to the control, reaching 1.96- and 1.47-fold higher than the control, respectively. The activity of mixed-functional oxidase (MFO) demonstrated an induction effect compared to the control, measuring 1.98- and 3.04-fold higher than that of the control, respectively. Consequently, the predation function and detoxification enzyme activity of H. axyridis were influenced when consuming wheat aphids treated with sublethal concentrations of dinotefuran, with significant variations across different concentrations, potentially reflecting the survival strategy of insects under dinotefuran stress. Full article

How humans perceive and interact with other animal species is critical in enhancing conservation initiatives. The study recorded and analyzed people’s knowledge and perceptions of birds of prey and their interactions in three rural communities in Paraíba, Brazil. The data were collected by face-to-face interviews using semi-structured questionnaires. One hundred ninety-one people were interviewed, and 19 species were recorded. Based on the answers to the questionnaires, the species are considered omens of climatic/ecological and supernatural events. They are important in the maintenance of ecosystems (predation of rodents and snakes and feeding on dead animals). However, most birds of prey are killed because they cause damage by preying upon domestic animals or for being associated with bad omens. The diversity of information listed here shows the need for complex and interdisciplinary studies to understand the human dimensions of knowledge and relationships between people and birds, contributing to species conservation and encouraging coexistence between people and birds of prey. Full article

The ability of terrestrial isopods (Crustacea: Isopoda: Oniscidea) to protect themselves effectively from predation by birds has never been tested. They are equipped with glands producing chemical substances; moreover, some species show conspicuous coloration, which might suffice as an aposematic signal. We evaluated the palatability of isopods to birds. We tested the responses of Parus major captured in the wild (and thus possessing some experience with common native isopod species) to the following isopod species: Porcellio scaber (native, inconspicuous), Oniscus asellus (native, moderately conspicuous), Armadillo officinalis (non-native, moderately conspicuous), Armadillidium versicolor (native, conspicuous), and Armadillidium gestroi (non-native, conspicuous). We compared bird responses to isopods with reactions to the Blaptica dubia, an edible roach very similar to isopods in size and appearance. Isopods were better protected from bird attacks than roaches; however, their color pattern did not affect the level of protection. Birds were able to differentiate isopods from the roach; in experiments, where we presented isopod and roach individuals together, the birds hesitated longer in attacking and observed both prey items for a longer time. Non-native species either profited from the generalization of the protection of native isopods or from neophobia. Some isopods elicited significantly more discomfort behavior in birds, suggesting differences in the chemical protection among the tested species. Full article

In this paper, a prey–predator diffusion model with isolation and drug treatment control measures for prey infection is studied. The main objective is to find an optimal control that minimizes the population density of infected prey and the costs of isolation and drug treatment for infected prey. Through analysis, the existence and uniqueness of weak solution, as well as the existence and local uniqueness of optimal controls are proven. The first-order necessary condition is derived, and the feasibility of the theoretical proof is verified through numerical simulations. Full article

The Galápagos Petrel (Pterodroma phaeopygia) is a long-lived Critically Endangered seabird endemic to the Galápagos Islands and faces severe threats from invasive species, particularly rodents. Until now, evidence of rat predation on Galápagos Petrel nestlings has been largely indirect, inferred from indirect evidence and predator control outcomes. Here, we present the first photographic documentation of a presumed black rat (Rattus rattus) preying on a Galápagos Petrel nestling, captured by a camera trap on private farmland on Santa Cruz Island. The predation event occurred during a period of parental absence, when the nestling was left unattended while adults foraged at sea. Notably, the parent Petrels continued returning to the nest for 91 days following nestling loss, suggesting strong nest fidelity and highlighting potential energetic costs associated with breeding failure. Our findings reveal critical vulnerabilities during the nestling-rearing phase and emphasize the urgent need to enhance rodent control efforts and protect nesting areas, particularly on farmland outside the Galápagos National Park boundaries. We conclude by providing targeted conservation recommendations to mitigate invasive predator impacts and improve breeding success for this emblematic and imperiled seabird. Full article

Casque-headed tree frogs (Lophyohylini) can have a very large and distinctive head characterised by hyperossification of their cranial skin. This type of skull was primarily associated with phragmosis, a behaviour in which the frog enters holes backwards and seals them with its head to prevent water loss in challenging environments. Further investigations revealed that hyperossification also gives rise to bony spines interspersed with skin poison glands. These peculiar anatomical features of the head make it challenging for predators to prey on the frogs in phragmosis. When bitten on the head, the bite pressure causes the spines to cross the poison glands, allowing the injection of toxins into the predator’s mouth. We studied the head morphology of different Lophyohylini species along with some characteristics of their cutaneous poison, both in the field and in the laboratory. These frogs exemplify distinct chemical defence strategies, highlighting the differences between venom and poison. Notably, some species can cause self-poisoning in predators by injecting poison (in this case, venom) through their head spines, similar to the use of fangs by snakes. Full article