Dietary analysis has contributed to our understanding of animal niches, interspecific interactions, community structure and the flow of matter and energy in food webs. We employed three methods of dietary analysis to estimate trophic niche overlap between two peacock bass species, Cichla cataractae and Cichla ocellaris, across sympatric (Essequibo River) and allopatric (Rupununi and Rewa Rivers) populations in Guyana - visual gut contents analysis, gut contents metabarcoding and stable isotope (δ13C, δ15N) analysis. During the dry season, both piscivorous species exhibited generalist feeding strategies and little evidence of trophic niche segregation with respect to prey taxonomic diversity. Metabarcoding identified 92 prey taxa spanning 28 genera, with Characiformes, Siluriformes and Cichliformes dominant in diets of all populations. Visual gut contents analyses corresponded with metabarcoding results but revealed C. cataractae consumed significantly larger prey than C. ocellaris, consistent with the larger mouth gape of C. cataractae. Stable isotope analysis indicated C. cataractae had higher nitrogen ratios than C. ocellaris, and the two species overlapped broadly with respect to carbon ratios. Overall, there was broad isotopic overlap between species and between allopatric and sympatric populations of C. ocellaris (≥ 70%). These findings suggest food resource partitioning with respect to taxonomic diversity is relatively unimportant for coexistence of these cryptic species, and prey size and habitat selection are the principal mechanisms of niche partitioning during the annual low-water season.

Protected areas often use a zoning management to balance conservation and sustainable development, yet its effectiveness for animal communities remains a critical knowledge gap. We investigated how reserve zoning and human disturbance jointly shape bird diversity in a restored subtropical forest in Southeast China. Using a suite of statistical models on grid-based survey data, we analyzed community, functional groups, and species-level responses to zoning, human disturbance, and other landscape factors. Our findings revealed a significant mismatch between management areas and avian diversity patterns. Bird diversity hotspots were not in the strictly protected core areas but in experimental areas near human settlements. This pattern is driven by contrasting responses within the bird community: higher productivity primarily supports abundant core species, whereas proximity to human settlements strongly attracts occasional species. The presence of human settlements could augment vegetation complexity and resource availability, potentially driving higher levels of species coexistence. In contrast, in the study, birds exhibit a strong avoidance of edge areas in protected areas, as these zones often signify intense human disturbance from the surrounding landscape. We conclude that static zoning has limitations in recovering ecosystems. Effective management must balance the enhancement of habitat heterogeneity to support broad community richness with the preservation of core areas, which serve as irreplaceable refugia for disturbance-sensitive species despite not being richness hotspots.

Zoos worldwide use natural man-made landscapes to enhance visitor experiences while focusing on exhibited animals. These landscapes also attract free-ranging animals. However, the presence of free-ranging animals in zoos has not been thoroughly documented, necessitating further exploration. This study aimed to identify free-ranging mammals and birds in Zoo Melaka, one of Malaysia's oldest zoos with mature natural landscapes and to examine factors influencing their distribution. Point-count observations and cage-trapping were conducted across five zones, recording 11 mammals and 40 bird species. Mammals exhibited a higher Shannon diversity index in closed-enclosure zones (H' = 1.943), although no significant differences were detected between open and closed enclosures (U = 99.5, Z = -0.716, p > 0.1). In contrast, birds showed significantly higher diversity in open enclosures. Overall, enclosure types and habitat zones were significantly correlated with the abundance of free-ranging birds, reflecting the influence of habitat heterogeneity and complexity in providing food and shelter. The presence of several species of conservation concern in the zoo also highlights the role of zoos in supporting biodiversity. These findings indicate that enclosure type, habitat complexity and management strongly shape free-ranging animal communities, with closed enclosures serving as refuges for habitat-sensitive mammals while open enclosures with structurally complex areas favoring birds. Effective management, like control of peri-domestic pest rodents, is crucial to reduce risks particularly zoonotic disease transmission while maintaining balanced and sustainable zoo ecosystems. These results underscore the importance of integrated landscape and enclosure management in promoting the coexistence of free-ranging and captive species in zoo environments.

Delay-induced multiple stability scenarios, species coexistence, and predator extinction in an ecological system

Dynamic evolution of titanosilicate precursors: Dual Ti species and their catalytic advantages in selective oxidation.

Predation risk varies through space and time due to changing refuge quality, predator communities, and prey traits. Despite this, ecological research is often focused on measuring average predation risk at the community level. While this can give important information about overall trophic transfer and ecological efficiency, it ignores differences in predation risk among prey species within a community, which may be important determinants of species coexistence and local diversity. We used crustaceans associated with temperate seagrass in Northern California to explore the relationship between seasonal variation in among-species and community-level predation risk for a community of morphologically distinct prey. We measured predation risk of the four most abundant and widespread prey species at six field sites every 2-6 weeks for 1 year. At the community level, sites differed significantly in their annual variation in predation risk, and these differences were correlated with the amount of variation in the among-species predation risk. When there was greater within-year variation in predation risk among the four prey species, predation risk at the community level was more stable across the year. On the other hand, when each prey species in the community had similar levels of predation risk throughout the year, predation as a community-level process was much more seasonal and variable. Variation in predation risk also changed across a gradient of seagrass cover, a proxy for refuge quality. Sites with greater seagrass cover had less annual variation in community-level predation risk and more variation in predation risk among the four species at any given time point. In contrast, at sites with less eelgrass, all species were consumed at the same rate throughout the year, suggesting previously demonstrated differences in antipredator strategies among species are less relevant in the absence of habitat-forming species. We suggest that larger species-specific differences in predation risk throughout a year result in a more stable level of predation risk for the whole community. This may be driven by the increased refuge provided by seagrass habitat mediating different prey species' relative levels of susceptibility to predation.

A bioeconomic delay model is developed for an algae–fish ecosystem in which the time delay τ represents the lag required for nutrients released by fish decomposition to become bioavailable. The model incorporates logistic growth for both populations together with a Holling type-II functional response to describe trophic interactions. The well-posedness of the system is established by proving the existence, uniqueness, positivity, and boundedness of solutions. The local stability of biologically relevant equilibria is then analyzed, including the boundary equilibrium associated with algal extinction and the interior equilibrium corresponding to species coexistence. The influence of the delay parameter on system stability is investigated, and explicit conditions for the occurrence of Hopf bifurcations are derived. Numerical simulations illustrate the destabilizing impact of increasing delay and support the analytical results. Finally, an optimal control framework is introduced to address long-term resource management, and Pontryagin's maximum principle is applied to characterize harvesting strategies that balance economic performance with ecological sustainability.

Abstract Understanding how closely related sympatric species achieve coexistence through niche partitioning is a central question in ecology. Lepidopteran larvae provide powerful models for studying niche differentiation owing to their host-plant specificity, diverse feeding strategies, and pronounced morphological adaptations. We investigated the coexistence of two congeneric butterfly larvae, Papilio xuthus Linnaeus, 1767 and P. machaon Linnaeus, 1758, on their shared host plant Dictamnus dasycarpus by integrating field surveys, ultrastructural morphological analyses, and quantitative color measurements. The two species exhibited clear niche differentiation across temporal, spatial, trophic, and defensive dimensions. P. xuthus emerged earlier, fed cryptically on leaves, and possessed mouthparts and crochets suited for horizontal movement. By contrast, P. machaon emerged later, fed openly on flowers and fruits, displayed stronger grasping adaptations, and showed conspicuous coloration consistent with aposematism. These multidimensional differences are consistent with niche partitioning and may facilitate coexistence between the two sympatric congeners, providing an empirical case that advances understanding of niche differentiation and species coexistence.

Niche theory is a cornerstone of ecology for understanding species coexistence. However, its application to guide conservation remains challenging. This study focuses on Rosa anemoniflora , a threatened plant endemic to China, and adopts a novel perspective by shifting from traditional interspecific niche comparisons to the analysis of intraspecific variation in niche breadth. We quantified niche breadth across different habitats using a newly developed circular sliding window technique, and then applied correlation, regression, and structural equation modeling to identify key soil factors associated with greater expression of intraspecific niche breadth. Our results indicate that high niche overlap in the herb layer may constrain population regeneration. Notably, soil total potassium (TK) and available potassium (AK) showed contrasting associations with niche breadth: TK was positively correlated, while AK was negatively correlated. This pattern suggests that variation in soil potassium status is closely associated with differences in the realized niche breadth of R. anemoniflora . Our sliding window–based analytical approach provides a methodological pathway for applying niche theory to precision conservation by linking fine-scale environmental variation to intraspecific niche expression. The approach offers a potentially transferable strategy and practical guidance for conserving other threatened species.

Indirect monitoring of heterogeneous tropical agroforestry systems using active and passive remote sensing

Interface-modified graphitic carbon nitride/2-mercaptobenzimidazole/gold nanoparticles hybrids for efficient piezo-catalytic hydrogen peroxide production.

The storage effect is a general explanation for ecological coexistence, wherein different species specialise on different states of a fluctuating environment, for example, hot versus cold years. Despite the storage effect's prominence in theoretical ecology, we lack evidence on whether it maintains biodiversity in nature. Here, we examine five storage effect pathways in a community of 11 coral species from the Great Barrier Reef, using detailed size-structured demographic data collected over 5 years. We parameterize integral projection models, simulate coral communities, and quantify coexistence mechanisms through Modern Coexistence Theory. Fluctuations in survival and fecundity promote coexistence via the storage effect, but this stabilising mechanism is typically small compared to fitness differences. Despite exhibiting prerequisites for strong temporal niche partitioning, the storage effect cannot explain the coexistence of many species. Diversity maintenance likely requires large net contributions from other mechanisms, such as specialist natural enemies or spatial heterogeneity coupled with source-sink dynamics.

We investigate the adaptive Ambush strategy in cyclic models following the rules of the spatial rock-paper-scissors game. In our model, individuals of one species possess cognitive abilities to perceive environmental cues and assess the local density of the species they dominate in the spatial competition for natural resources. Based on this assessment, they either initiate a direct attack or, if the local concentration of target individuals does not justify the risk, reposition strategically to prepare an ambush. To quantify the evolutionary consequences of these behavioural strategies, we perform stochastic simulations, analysing emergent spatial patterns and the dependence of species densities on the threshold used by individuals to decide between immediate attack or anticipation. Our findings reveal that, despite being designed to enhance efficiency, cognitive strategies can reduce the abundance of the species due to the constraints of cyclic dominance. We identify an optimal decision threshold: attacking only when the local density of target individuals exceeds 15% provides the best balance between selection risk and long-term persistence. Furthermore, the Ambush strategy benefits low-mobility organisms, increasing coexistence probabilities by up to 53%. These results deepen the understanding of adaptive decision-making in spatial ecology, linking cognitive complexity to ecosystem resilience and extinction risk.

Gut microbiota provide various benefits to their mammalian hosts; however, knowledge regarding interspecific differences in gut microecology remains limited. This study employed 16S rRNA sequencing combined with metagenomic functional prediction (potential functions or functional potential) to conduct a comparative analysis of the gut microbial composition and functional adaptability of two sympatrically distributed gerbil species with distinct diets: the herbivorous Rhombomys opimus (RO) and the omnivorous Meriones meridianus (MM). The results revealed that the omnivorous MM exhibited a level of gut microbial alpha diversity comparable to that of the herbivorous RO, whereas RO showed significant enrichment of norank_f__Muribaculaceae, a taxon associated with fiber degradation, and demonstrated higher abundance of genes related to complex fiber degradation. Notably, bacterial genera significantly enriched in the gut of MM, such as Lachnospiraceae_NK4A136_group and Desulfovibrio, may play important roles in maintaining gut health and enhancing chitin degradation efficiency. Furthermore, the abundance of genes related to monosaccharide and chitin degradation was significantly higher in MM than in RO. Functional network analysis indicated that the cellulose degradation gene networks in both gerbil species were predominantly synergistic, but the synergistic effect was stronger in RO than in MM (ratios of positive to negative correlation edges: 2.44: 1.59). Further analysis revealed that the monosaccharide and chitin degradation gene networks in MM both exhibited synergistic interaction patterns (ratios of positive to negative correlation edges: 1.69 and 2.95, respectively), whereas these two networks in RO were primarily antagonistic (ratios of positive to negative correlation edges: 0.831 and 0.73, respectively). This suggests that the gut microbiota of RO are more conducive to digesting complex plant fibers, while those of MM are better adapted for digesting starch and chitin. This differentiation in gut microbiota optimizes the utilization of different food resources by the two species, thereby promoting their sympatric coexistence. This study enhances our understanding of the adaptive mechanisms of gut microecology in rodents with different diets and provides an important foundation for further research on the microbial ecology of wild rodents and the mechanisms underlying sympatric species coexistence.

Coexistence of competing species may be influenced by environmental variation. Specifically, theory suggests that short-term environmental variability can contribute to long-term coexistence among competitors. Here, we address the role of environmental variation on competitive interactions between two zooplankton species (Daphnia magna and D. pulex) which are found sympatrically, but where mechanisms allowing for such coexistence remain unclear. Using competition experiments, we show that under constant temperature conditions, one of the species (D. magna) was greatly outnumbered by their competitor (D. pulex). Furthermore, population simulations showed a significant possibility for extinction of the inferior competitor, and distributions of estimated niche differences and relative fitness differences included parameter sets that precluded stable coexistence. Under fluctuating temperature conditions, however, the numerical dominance by D. pulex was considerably reduced. Moreover, under these conditions the occurrence of extinction of D. magna in the simulations became negligible, and all parameter sets drawn from the estimated distributions of niche differences and relative fitness differences met the requirements for stable coexistence. Our results provide empirical support for previous model results showing how short-term variation in temperature can promote species coexistence.

In river ecosystems, unidirectional flow and habitat fragmentation threaten prey persistence, necessitating protection zones. This study explores the dynamics of a generalist predator-prey model with a boundary-upstream protection zone for prey and Holling-II type functional response in open advective environments. Firstly, we establish complete system dynamics driven by the interplay of variable advection rates, protection zone lengths and predator carrying capacity, revealing their coupled effects on population persistence and extinction. We identify a critical protection zone length, beyond which predator take-over is prevented within a prey advection range, regardless of predator strength, thereby promoting species coexistence. Furthermore, through bifurcation analysis, the existence and multiplicity for positive steady states are studied, linking prey attack-evasion ability and predator advection rate to bistable outcomes. The asymptotic behaviors of positive steady states induced by large diffusion rates are characterized, showing that enhanced dispersal counteracts flow-induced washout. This study uniquely integrates Holling-II response with upstream refuge effects, revealing critical thresholds for predator control. The findings guide designing flow-adaptive protection zones to mitigate generalist predator dominance in aquatic ecosystems, offering actionable management strategies.

ABSTRACT The main difficulty in modeling turbulence/soot production interaction (TSI) in non-premixed flames stems from the strong correlation between soot quantities and mixture fraction in the soot oxidation region. This is due to the fast nature of the oxidation process, which limits the coexistence of soot and oxidative species in mixture fraction space. Consequently, the “uncorrelated” model, which neglects this correlation, overestimates soot oxidation rates by more than an order of magnitude. In the RANS context, a presumed-probability density function (PDF) model is proposed. This model combines the flamelet approach to express the gas-phase part of soot production rates as a function of a reduced set of parameters, with the conditional source-term estimation (CSE) model to obtain the conditional mean of soot mass fraction in mixture fraction space. This model is more general than existing presumed PDF models in the literature because the conditional means of soot mass fraction are retrieved from the CSE inverse problem without presuming their shape. It is, therefore, applicable to situations with both infinitely fast and finite-rate soot oxidation. The model relies on several hypotheses: 1) The first-order conditional moment closure (CMC) hypothesis; 2) A presumed-PDF for the flamelet parameters; 3) The conditional mean of the number density of soot primary particles is set equal to its mean value; 4) The conditional mean of soot mass fraction is decomposed into Bernstein basis polynomials and 5) A strategy based on temporal samples at a fixed location is proposed to build the CSE ensembles used to retrieve the Bernstein coefficients from the CSE inverse problem. This alternative definition of the CSE ensemble substitutes the classical one based on the radial homogeneity assumption, as soot does not strictly satisfy this assumption. These assumptions, along with the accuracy of the corresponding predicted mean soot oxidation by OH and soot surface growth rates, are assessed in the case of the Sandia ethylene non-premixed turbulent jet flame by comparison with reference solutions obtained from RANS/TPDF simulations. The hybrid flamelet/CSE-based model predicts reasonably well the mean soot oxidation and surface growth rates within about 30% and 20% of the TPDF solutions, respectively. It significantly improves the prediction of the “uncorrelated” model and outperforms flamelet-based presumed PDF models from the literature, while being more flexible. The model can be readily extended to large eddy simulation.

Atlantic Forest alluvial ecosystems experience strong environmental filtering driven by seasonal flooding and hydrological variability, shaping their structure and functioning. This study investigated how leaf and demographic traits organize functional groups and structure functional diversity in an 11.5-ha urban fragment in Guarapuava, Paraná, southern Brazil. We surveyed 103 permanent plots (1.03 ha), assessing 34 species based on six traits (specific leaf area – SLA, leaf length – LL, leaf dry matter content – LDMC, leaf thickness – LT, mortality rate (M), and relative growth rate (RGR)). Functional groups were identified using Ward’s clustering and PCoA, group comparisons were tested using Generalized Linear Models (GLMs), and functional diversity was assessed with FRic, FEve, FDiv, FDis, and RaoQ indices. The community was dominated by Gymnanthes klotzschiana, Ligustrum lucidum, and Matayba elaeagnoides. Clustering revealed four coherent functional groups along the acquisition–conservation axis. The PCoA explained 64.64% of trait variation, highlighting the coexistence of acquisitive species (high SLA, elevated mortality) and conservative species (thicker leaves, reduced mortality), with partial overlap among groups and complementary niches. Overall, the community maintained moderate to high functional diversity (FRic = 4.62; FEve = 0.67; FDiv = 0.79; FDis = 1.33; RaoQ = 2.71). We conclude that both functional redundancy and differentiation underpin the resilience of this system under hydrological variability and anthropogenic disturbance. We propose prioritizing acquisitive species in early restoration phases and conservative ones in advanced stages to optimize resource-use efficiency and ensure long-term ecosystem stability.

Invasive fungal diseases (IFDs) are common and often fatal in severe burn patients due to skin barrier loss and immune dysfunction. However, current definitions of invasive mold infections are poorly adapted to this population. This study evaluated the characteristics of various diagnostic criteria and their combinations in relation to clinical outcomes in burn patients. We conducted a retrospective cohort study of all patients admitted to the Burn ICU from 2014 to 2023 with ≥15% total burn surface area and at least one sample sent to the mycology lab. Criteria included direct microscopy, culture (respiratory, skin, or tissue), species-specific quantitative PCR (qPCR) (Aspergillus, Mucorales, and Fusarium) on plasma/tissue/bronchoalveolar lavage fluid, and serum galactomannan. Among 276 patients, 489/6,184 samples were positive, including 281 skin biopsies (direct examination and conventional culture) and 132 plasma specimens (qPCR). Positive diagnostic criteria ≥1 was found in 93 patients (33.7%): Aspergillus (25.7%), Mucorales (10.9%), and Fusarium (9.8%). Twenty-seven patients (9.8%) had ≥2 criteria involving ≥2 mold types. Mortality rose with the number of positive criteria: 12.7% (0), 10.7% (1, 2), 27.3% (3, 4), and 46.7% (≥5) (P < 0.001). Plasma qPCR was positive in 81.3% of Mucorales, 40% of Aspergillus, and 15.4% of Fusarium cases with skin involvement. Skin biopsies (direct examination and conventional culture) combined with species-specific plasma qPCR enhance timely and reliable IFD diagnosis in burn patients. Mortality correlated with the number of positive criteria and coexistence of multiple mold species, underscoring the need for broad antifungal coverage and the value of multi-criteria diagnostics to guide treatment.IMPORTANCEInvasive mold infections are frequent and often fatal complications in patients with severe burns, occurring in up to 20% of cases with a total burn surface area exceeding 15%. Despite their severity, no standardized case definition currently exists to guide research or clinical management in this population. The performance of existing mycological diagnostic criteria remains unknown in burn patients. In this 10-year retrospective study, we evaluated the diagnostic performance of individual and combined mold-related criteria in relation to patient outcomes, analyzing more than 6,000 clinical samples. These findings provide a first comprehensive assessment of mold diagnostic markers in the burn population.

Neoplasia of the cornea is overall rare, with corneal squamous-cell carcinoma (c-SCC) being most commonly reported in all species. C-SCC pathogenesis has been related to UV exposure in humans and horses, and to papillomavirus infection in humans. In dogs, brachycephalic conformation and chronic keratitis were associated with c-SCC. Corneal vascular tumors have also been exceptionally reported in humans, and rarely in animals. In dogs, they have been suggested to be UV-related. Except for equine c-SCCs, most studies on corneal neoplasms are case reports. The present study aimed to review the literature on epithelial and vascular corneal tumors in dogs, cats, and horses, adding new cases from our archives. Pubmed and Web of Science were searched (1980-2025) using the following keywords: cornea, neoplasia, carcinoma, hemangioma, hemangiosarcoma, dog, cat, and horse. Additionally, 94 new cases of corneal neoplasia were retrieved: 47 dogs (40 epithelial and seven vascular); 29 cats (14 epithelial and 15 vascular) and 18 horses. Signalment, clinical history, and histopathological characteristics were analyzed and compared with the literature. The combined results supported a strong association between brachycephalic dogs and c-SCC occurrence and highlighted the frequent coexistence in the feline species of symblepharon and corneal perforation, with corneal tumors.