Dynamics and drivers of fungal communities in a multipartite ant-plant association.

BACKGROUND: Fungi and ants belong to the most important organisms in terrestrial ecosystems on Earth. In nutrient-poor niches of tropical rainforests, they have developed steady ecological relationships as a successful survival strategy. In tropical ant-plant mutualisms worldwide, where resident ants provide the host plants with defense and nutrients in exchange for shelter and food, fungi are regularly found in the ant nesting space, inhabiting ant-made dark-colored piles ("patches"). Unlike the extensively investigated fungus-growing insects, where the fungi serve as the primary food source, the purpose of this ant-fungi association is less clear. To decipher the roles of fungi in these structures within ant nests, it is crucial to first understand the dynamics and drivers that influence fungal patch communities during ant colony development. RESULTS: In this study, we investigated how the ant colony age and the ant-plant species affect the fungal community in the patches. As model we selected one of the most common mutualisms in the Tropics of America, the Azteca-Cecropia complex. By amplicon sequencing of the internal transcribed spacer 2 (ITS2) region, we analyzed the patch fungal communities of 93 Azteca spp. colonies inhabiting Cecropia spp. trees. Our study demonstrates that the fungal diversity in patches increases as the ant colony grows and that a change in the prevalent fungal taxa occurs between initial and established patches. In addition, the ant species significantly influences the composition of the fungal community in established ant colonies, rather than the host plant species. CONCLUSIONS: The fungal patch communities become more complex as the ant colony develops, due to an acquisition of fungi from the environment and a substrate diversification. Our results suggest a successional progression of the fungal communities in the patches during ant colony growth and place the ant colony as the main driver shaping such communities. The findings of this study demonstrate the unexpectedly complex nature of ant-plant mutualisms in tropical regions at a micro scale.

Quantifying vulnerability to plant invasion across global ecosystems.

The widely referenced "tens rule" in invasion ecology suggests that approximately 10% of established, non-native species will become invasive. However, the accuracy of this estimate has been questioned, as the original analysis focused on small groups of plant species in Great Britain and Australia. Using a novel database of 9501 established plants and 2924 invasive plants, we provide a comprehensive evaluation of the tens rule and the first empirical analysis of how invasion rates vary across spatial scales, islands/mainlands, and climate zones. We found that invasion rates (the percentage of established species with negative impacts) are highly variable across the globe. Well-sampled environments (those with at least 2000 total non-native species recorded) had invasion rates that ranged from 7.2% to 33.8%. Invasion rates were strongly scale-dependent, averaging 17% at the country scale and 25% at the continental scale. We found significantly higher invasion rates on islands when compared with mainlands, regardless of scale. Tropical ecosystems are often considered to be resistant to invasion; however, our results showed significantly higher invasion rates on both tropical islands and mainlands, suggesting unexpectedly high vulnerability of these species-rich ecosystems. We conclude that the tens rule is a poor general estimate of invasion rates for plants, as calculated invasion rates vary widely and are frequently much higher than 10%. Most locations would be better served by using invasion rates that vary based on the recipient environment. Our updated estimates of invasion rates should be highly relevant for invasive species management strategies, including weed risk assessments, which can be adjusted to identify more species as high-risk in areas where invasion rates are higher. Assuming that 10% of established species will become invasive is likely to substantially underestimate invasion rates in most geographies.

Detection of echinostomatid trematode eggs at the forest-oil palm interface in Sabah, Malaysia.

In this study, we report the occurrence of echinostomatid eggs in feces of wildlife, domestic animals and humans frequenting the forest­oil palm plantation interface in the Kinabatangan (Sabah, Malaysia), and discuss potential implications for public health. Using microscopy, we detected echinostomatid eggs in six host species, including Asian palm civets (Paradoxurus hermaphroditus [13/18]), leopard cats (Prionailurus bengalensis [3/4]), long-tailed macaques (Macaca fascicularis [1/10]), domestic dogs [3/5] and cats [1/1], and humans [7/9]. Molecular analysis revealed a close genetic proximity of civet echinostomatids to Artyfechinostomum malayanum, a zoonotic parasite of public health relevance. The intermediate hosts for A. malayanum have been reported in at least 3 districts in Sabah, suggesting that all the necessary elements required for the completion of the parasite's life cycle are present. Our findings point at the presence of zoonotic trematodes in an area with high human­wildlife interaction and highlight the potential public and animal health concern of zoonotic trematode infection in the context of Southeast Asia's rapidly changing ecosystems.

Using Crocodylians for monitoring mercury in the tropics.

Mercury contamination is a widespread phenomenon that impacts ecosystems worldwide. Artisanal Small Scale Gold Mining (ASGM) activities are responsible for more than a third of atmospheric Hg emission. Due to Hg toxicity and its broad and elevated prevalence in the environment resulting from ASGM activities in the tropics, its biomonitoring is essential to better understand the availability of its methylmercury (MeHg) form in the environment. The Minamata Convention was ratified with the objective to "protect human health and the environment from anthropogenic emissions and releases of mercury compounds". Biomagnification of MeHg occurs through the trophic food web, where it biomagnifies and bioaccumulates in top predators. To monitor environmental MeHg contamination, studies have evaluated the use of living organisms; however, reptiles are among the least documented vertebrates regarding MeHg exposure. In this review we evaluate the use of crocodylians for Hg biomonitoring in tropical ecosystems. We found that out of the 28 crocodiles species, only 10 have been evaluated regarding Hg contamination. The remaining challenges when using this taxon for Hg biomonitoring are inconsistencies in the applied methodology (e.g., wet versus dry weight, tissues used, quantification method). However, due to their life history traits, crocodylians are particularly relevant for monitoring MeHg contamination in regions where ASGM activities occur. In conclusion and given their ecological and socio-economic importance, crocodylians are at great risk of MeHg contamination and are excellent bioindicators for tropical ecosystems.

Artificial neural networks and adaptive neuro-fuzzy inference systems for prediction of soil respiration in forested areas southern Brazil.

The purpose of this study was to estimate the temporal variability of CO2 emission (FCO2) from O2 influx into the soil (FO2) in a reforested area with native vegetation in the Brazilian Cerrado, as well as to understand the dynamics of soil respiration in this ecosystem. The database is composed of soil respiration data, agroclimatic variables, improved vegetation index (EVI), and soil attributes used to train machine learning algorithms: artificial neural network (ANN) and an adaptive neuro-fuzzy inference system (ANFIS). The predictive performance was evaluated based on the mean absolute error (MEA), root mean square error (RMSE), mean absolute percentage error (MAPE), agreement index (d), confidence coefficient (c), and coefficient of determination (R2). The best estimation results for validation were FCO2 with multilayer perceptron neural network (MLP) (R2 = 0.53, RMSE = 0.967 µmol m-2 s-1) and radial basis function neural network (RBF) (R2 = 0.54, RMSE = 0.884 µmol m-2 s-1) and FO2 with MLP (R2 = 0.45, RMSE = 0.093 mg m-2 s-1) and RBF (R2 = 0.74, 0.079 mg m-2 s-1). Soil temperature and macroporosity are important predictors of FCO2 and FO2. The best combination of variables for training the ANFIS was selected based on trial and error. The results were as follows: FCO2 (R2 = 16) and FO2 (R2 = 29). In all models, FCO2 outperformed FO2. A primary factor analysis was performed, and FCO2 and FO2 correlated best with the weather and soil attributes, respectively.

Safeguarding Imperiled Biodiversity and Evolutionary Processes in the Wallacea Center of Endemism.

Wallacea-the meeting point between the Asian and Australian fauna-is one of the world's largest centers of endemism. Twenty-three million years of complex geological history have given rise to a living laboratory for the study of evolution and biodiversity, highly vulnerable to anthropogenic pressures. In the present article, we review the historic and contemporary processes shaping Wallacea's biodiversity and explore ways to conserve its unique ecosystems. Although remoteness has spared many Wallacean islands from the severe overexploitation that characterizes many tropical regions, industrial-scale expansion of agriculture, mining, aquaculture and fisheries is damaging terrestrial and aquatic ecosystems, denuding endemics from communities, and threatening a long-term legacy of impoverished human populations. An impending biodiversity catastrophe demands collaborative actions to improve community-based management, minimize environmental impacts, monitor threatened species, and reduce wildlife trade. Securing a positive future for Wallacea's imperiled ecosystems requires a fundamental shift away from managing marine and terrestrial realms independently.

Indigenous knowledge networks in the face of global change.

Indigenous communities rely extensively on plants for food, shelter, and medicine. It is still unknown, however, to what degree their survival is jeopardized by the loss of either plant species or knowledge about their services. To fill this gap, here we introduce indigenous knowledge networks describing the wisdom of indigenous people on plant species and the services they provide. Our results across 57 Neotropical communities show that cultural heritage is as important as plants for preserving indigenous knowledge both locally and regionally. Indeed, knowledge networks collapse as fast when plant species are driven extinct as when cultural diffusion, either within or among communities, is lost. But it is the joint loss of plant species and knowledge that erodes these networks at a much higher rate. Our findings pave the road toward integrative policies that recognize more explicitly the inseparable links between cultural and biological heritage.

Antimicrobial Activity of Lipid Extracts of Echinoderms in the Nhatrang Bay (South China Sea).

The obtained results on the study of the antimicrobial activity of lipid extracts of tissues of starfishes Linckia laevigata and Culcita novaeguineae and sea urchin Diadema setosum collected in the Nhatrang Bay (South China Sea) against nosocomial strains of Klebsiella pneumoniae, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, Candida sp., Streptococcus pyogenes, and Staphylococcus aureus are presented. The effect of the investigated extracts on Gram-positive, Gram-negative microorganisms, as well as yeast of the genus Candida, was determined. It was found that lipid extracts of echinoderms of the Nhatrang Bay exhibit the highest antimicrobial activity against the Gram-positive microorganisms, namely Streptococcus pyogenes.

Are the interaction effects of warming and drought on nutritional status and biomass production in a tropical forage legume greater than their individual effects?

MAIN CONCLUSION: Drought alone and drought plus warming will change the nutrient requirements and biomass distributions of Stylosanthes capitata, while warming will be advantageous only under well-watered condition for the next decades. Climate change effects on natural and managed ecosystems are difficult to predict due to its multi-factor nature. However, most studies that investigate the impacts of climate change factors on plants, such as warming or drought, were conducted under one single stress and controlled environments. In this study, we evaluated the effects of elevated temperature (+ 2 °C) (T) under different conditions of soil water availability (W) to understand the interactive effects of both factors on leaf, stem, and inflorescence macro and micronutrients concentration and biomass allocation of a tropical forage species, Stylosanthes capitata Vogel under field conditions. Temperature control was performed by a temperature free-air controlled enhancement (T-FACE) system. We observed that warming changed nutrient concentrations and plant growth depending on soil moisture levels, but the responses were specific for each plant organ. In general, we found that warming under well-watered conditions greatly improved nutrient concentration and biomass production, whilst the opposite effect was observed under non-irrigated and non-warmed conditions. However, under warmed and non-irrigated conditions, leaf biomass and leaf nutrient concentration were greatly reduced when compared to non-warmed and irrigated plants. Our findings suggest that warming (2 °C above ambient temperature) and drought, as well as both combined stresses, will change the nutrient requirements and biomass distributions between plant aerial organs of S. capitata in tropical ecosystems, which may impact animal feeding in the future.

Mapping and Monitoring Zero-Deforestation Commitments.

A growing number of companies have announced zero-deforestation commitments (ZDCs) to eliminate commodities produced at the expense of forests from their supply chains. Translating these aspirational goals into forest conservation requires forest mapping and monitoring (M&M) systems that are technically adequate and therefore credible, salient so that they address the needs of decision makers, legitimate in that they are fair and unbiased, and scalable over space and time. We identify 12 attributes of M&M that contribute to these goals and assess how two prominent ZDC programs, the Amazon Soy Moratorium and the High Carbon Stock Approach, integrate these attributes into their M&M systems. These programs prioritize different attributes, highlighting fundamental trade-offs in M&M design. Rather than prescribe a one-size-fits-all solution, we provide policymakers and practitioners with guidance on the design of ZDC M&M systems that fit their specific use case and that may contribute to more effective implementation of ZDCs.

Pollination effectiveness of specialist and opportunistic nectar feeders influenced by invasive alien ants in the Seychelles.

PREMISE: Opportunistic nectar-feeders may act as effective pollinators; nonetheless, we still lack information on whether these opportunistic species differ in their pollination effectiveness from specialized nectarivorous vertebrates and insects. Many nectar specialists have coevolved with the plants on which they feed; therefore, we would expect higher pollination effectiveness in specialists than in opportunistic feeders. Here, we assessed quantity and quality components of pollination effectiveness in specialist and opportunistic vertebrate nectarivores and insects, focusing on three plants from the Seychelles: Thespesia populnea, Polyscias crassa, and Syzygium wrightii. METHODS: We determined the quantity component (QNC) of pollination effectiveness with pollinator observations, and the quality component (QLC) by measuring fruit and seed set resulting from single visits by each pollinator. To detect potential negative effects of invasive ants on native plant-pollinator interactions, we classified pollinator visits (quantity component) as disturbed (>6 ants/30 min) vs. undisturbed. RESULTS: All focal plants were visited by insects, and vertebrate specialist and opportunist nectarivores, yet their pollination effectiveness differed. Flying insects were the most effective pollinators of T. populnea. The other two plants were most effectively pollinated by vertebrates; i.e., sunbirds (nectar specialists) in S. wrightii and Phelsuma geckos (nectar opportunists) in P. crassa, despite marked variation in QNC and QLC. Ant presence was associated with lower pollinator visitation rate in P. crassa and S. wrightii. CONCLUSIONS: Our study highlights the importance of all pollinator guilds, including opportunist nectarivorous vertebrates as pollinators of island plants, and the vulnerability of such interactions to disruption by nonnative species.

Impacts of climate and land use on N2 O and CH4 fluxes from tropical ecosystems in the Mt. Kilimanjaro region, Tanzania.

In this study, we quantify the impacts of climate and land use on soil N2 O and CH4 fluxes from tropical forest, agroforest, arable and savanna ecosystems in Africa. To do so, we measured greenhouse gases (GHG) fluxes from 12 different ecosystems along climate and land-use gradients at Mt. Kilimanjaro, combining long-term in situ chamber and laboratory soil core incubation techniques. Both methods showed similar patterns of GHG exchange. Although there were distinct differences from ecosystem to ecosystem, soils generally functioned as net sources and sinks for N2 O and CH4 respectively. N2 O emissions correlated positively with soil moisture and total soil nitrogen content. CH4 uptake rates correlated negatively with soil moisture and clay content and positively with SOC. Due to moderate soil moisture contents and the dominance of nitrification in soil N turnover, N2 O emissions of tropical montane forests were generally low (<1.2 kg N ha-1  year-1 ), and it is likely that ecosystem N losses are driven instead by nitrate leaching (~10 kg N ha-1  year-1 ). Forest soils with well-aerated litter layers were a significant sink for atmospheric CH4 (up to 4 kg C ha-1  year-1 ) regardless of low mean annual temperatures at higher elevations. Land-use intensification significantly increased the soil N2 O source strength and significantly decreased the soil CH4 sink. Compared to decreases in aboveground and belowground carbon stocks enhanced soil non-CO2 GHG emissions following land-use conversion from tropical forests to homegardens and coffee plantations were only a small factor in the total GHG budget. However, due to lower ecosystem carbon stock changes, enhanced N2 O emissions significantly contributed to total GHG emissions following conversion of savanna into grassland and particularly maize. Overall, we found that the protection and sustainable management of aboveground and belowground carbon and nitrogen stocks of agroforestry and arable systems is most crucial for mitigating GHG emissions from land-use change.

Reserve design to optimize the long-term persistence of multiple species.

Protected areas form the cornerstone of global efforts to conserve biodiversity. Most current methods for designing reserve networks focus on maximizing the representation of species, but with no assurance that those species will persist in the protected landscapes into the future. We present a new strategy for reserve design that combines metapopulation theory with spatial conservation prioritization to estimate conservation solutions that minimize extinction risk across numerous species simultaneously. Our framework optimizes the spatial configuration of reserves to maximize metapopulation persistence for an entire assemblage of species by accounting for both species representation and landscape connectivity. As a case study, we design a reserve network for 114 terrestrial mammal species in Indonesian New Guinea. Our approach builds on Marxan, the flagship representation-based reserve design tool, improving estimated persistence (metapopulation capacity) by an average of 4.6-fold across species, without increasing the socioeconomic cost. We suggest that enhancing species persistence, rather than protecting arbitrary proportions of species' ranges, should be the ultimate objective of conservation planning.

Ecological niche modeling for a cultivated plant species: a case study on taro (Colocasia esculenta) in Hawaii.

Under the threat of ongoing and projected climate change, communities in the Pacific Islands face challenges of adapting culture and lifestyle to accommodate a changing landscape. Few models can effectively predict how biocultural livelihoods might be impacted. Here, we examine how environmental and anthropogenic factors influence an ecological niche model (ENM) for the realized niche of cultivated taro (Colocasia esculenta) in Hawaii. We created and tuned two sets of ENMs: one using only environmental variables, and one using both environmental and cultural characteristics of Hawaii. These models were projected under two different Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (RCPs) for 2070. Models were selected and evaluated using average omission rate and area under the receiver operating characteristic curve (AUC). We compared optimal model predictions by comparing the percentage of taro plots predicted present and measured ENM overlap using Schoener's D statistic. The model including only environmental variables consisted of 19 Worldclim bioclimatic variables, in addition to slope, altitude, distance to perennial streams, soil evaporation, and soil moisture. The optimal model with environmental variables plus anthropogenic features also included a road density variable (which we assumed as a proxy for urbanization) and a variable indicating agricultural lands of importance to the state of Hawaii. The model including anthropogenic features performed better than the environment-only model based on omission rate, AUC, and review of spatial projections. The two models also differed in spatial projections for taro under anticipated future climate change. Our results demonstrate how ENMs including anthropogenic features can predict which areas might be best suited to plant cultivated species in the future, and how these areas could change under various climate projections. These predictions might inform biocultural conservation priorities and initiatives. In addition, we discuss the incongruences that arise when traditional ENM theory is applied to species whose distribution has been significantly impacted by human intervention, particularly at a fine scale relevant to biocultural conservation initiatives.

Biphasic modulation of neuro- and interrenal steroidogenesis in juvenile African sharptooth catfish (Clarias gariepinus) exposed to waterborne di-(2-ethylhexyl) phthalate.

Receptor (i.e. genomic) and non-receptor (or non-genomic) effects of endocrine toxicology have received limited or almost non-existent attention for tropical species and regions. In the present study, we have evaluated the effects of di-(2-ethylhexyl) phthalate (DEHP) on neuro- and interrenal steroidogenesis of the African catfish (Clarias gariepinus) using molecular, immunochemical and physiological approaches. Juvenile fish (mean weight and length: 5.6±0.6g and 8.2±1.2cm, respectively), were randomly distributed into ten 120L rectangular glass tanks containing 60L of dechlorinated tap water, at 50 fish per exposure group. The fish were exposed to environmentally relevant concentrations of DEHP, consisting of 0 (ethanol solvent control), 10, 100, 200, and 400µg DEHP/L water and performed in two replicates. Brain, liver and head kidney samples were collected at day 3, 7 and 14 after exposure, and analysed for star, p450scc, cyp19a1, cyp17, cyp11ß-, 3ß-, 17ß- and 20ß-hsd, and 17ß-ohase mRNA expression using real-time PCR. The StAR, P450scc and CYP19 proteins were measured using immunoblotting method, while estradiol-17ß (E2) and testosterone (T) were measured in liver homogenate using enzyme immunoassay (EIA). Our data showed a consistent and unique pattern of biphasic effect on star and steroidogenic enzyme genes with increases at low concentration (10µg/L) and thereafter, a concentration-dependent decrease in both the brain and head kidney, that paralleled the expression of StAR, P450scc and CYP19 proteins. Cellular E2 and T levels showed an apparent DEHP concentration-dependent increase at day 14 of exposure. The observed consistency in the current findings and in view of previous reports on contaminants-induced alterations in neuro- and interrenal steroidogenesis, the broader toxicological and endocrine disruptor implication of our data indicate potentials for overt reproductive, metabolic, physiological and general health consequences for the exposed organisms.

Somatic mutation rates scale with time not growth rate in long-lived tropical trees.

The rates of appearance of new mutations play a central role in evolution. However, mutational processes in natural environments and their relationship with growth rates are largely unknown, particular in tropical ecosystems with high biodiversity. Here, we examined the somatic mutation landscapes of two tropical trees, Shorea laevis (slow-growing) and S. leprosula (fast-growing), in central Borneo, Indonesia. Using newly constructed genomes, we identified a greater number of somatic mutations in tropical trees than in temperate trees. In both species, we observed a linear increase in the number of somatic mutations with physical distance between branches. However, we found that the rate of somatic mutation accumulation per meter of growth was 3.7-fold higher in S. laevis than in S. leprosula. This difference in the somatic mutation rate was scaled with the slower growth rate of S. laevis compared to S. leprosula, resulting in a constant somatic mutation rate per year between the two species. We also found that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. These findings suggest that somatic mutations accumulate with absolute time and older trees have a greater contribution towards generating genetic variation.

Machine learning for prediction of soil CO2 emission in tropical forests in the Brazilian Cerrado.

Soil CO2 emission (FCO2) is a critical component of the global carbon cycle, but it is a source of great uncertainty due to the great spatial and temporal variability. Modeling of soil respiration can strongly contribute to reducing the uncertainties associated with the sources and sinks of carbon in the soil. In this study, we compared five machine learning (ML) models to predict the spatiotemporal variability of FCO2 in three reforested areas: eucalyptus (RE), pine (RP) and native species (RNS). The study also included a generalized scenario (GS) where all the data from RE, RP and RNS were included in one dataset. The ML models include generalized regression neural network (GRNN), radial basis function neural network (RBFNN), multilayer perceptron neural network (MLPNN), adaptive neuro-fuzzy inference system (ANFIS) and random forest (RF). Initially, we had 32 attributes and after pre-processing, including Pearson's correlation, canonical correlation analysis (CCA), and biophysical justification, only 21 variables remained. We used as input variables 19 soil properties and climate variables in reforested areas of eucalyptus, pine and native species. RF was the best model to predict soil respiration to RE [adjusted coefficient of determination (R2 adj): 0.70 and root mean square error (RMSE): 1.02 µmol m-2 s-1], RP (R2 adj: 0.48 and RMSE: 1.07 µmol m-2 s-1) and GS (R2 adj: 0.70 and RMSE: 1.05 µmol m-2 s-1). Our findings support that RF and GRNN are promising for predicting soil respiration of reforested areas which could help to identify and monitor potential sources and sinks of the main additional greenhouse gas over ecosystems.

Impact of different environmental pollution processes on bacterial key-indicators in tropical rivers: scoping review.

Freshwater ecosystems are an essential resource for human use and natural populations, but they are exposed to different sources of man-made pollution. This study analyses how different environmental pollution processes influence the structure of bacterial communities in tropical rivers. A scoping review was performed to characterize the bacterial communities in freshwater ecosystems in tropical regions that have been reported to be associated with pollution of different kinds. The statistical analyses allowed us to categorize the genera found into three large groups (pollution generalists, middle types, and pollution specialists) according to the types of pollutants with which they were associated. The results show that Escherichia has a greater association with fecal contamination, while Enterococcus is more associated with domestic wastewater and organic and synthetic chemicals. The present study proposes Streptomyces as a potential indicator of waters with microbial contamination, as well as some other genera as possible indicators of waters with heavy metal contamination.

Dung beetles from two sustainable-use protected forests in the Brazilian Amazon.

Background: The Amazon Forest is one of the world's most biodiverse ecosystems and yet its protected areas are understudied concerning insects and other invertebrates. These organisms are essential for tropical forests due to their ecological processes, with some species being very sensitive to habitat disturbances. Dung beetles (Coleoptera, Scarabaeidae, Scarabaeinae) have been used as bioindicators for more than 30 years and were surveyed to assess the insect biodiversity of two sustainable-use forest reserves in the Brazilian Amazon. New information: We report inventories of dung beetles from two Amazonian forest reserves in Pará State, Brazil: the Tapajós National Forest and the Carajás National Forest. Surveys were carried out with baited-pitfall traps installed in 2010, 2016, 2017 and 2019. We collected a total of 3,772 individuals from 19 genera and 96 species. We highlight the importance of Amazonian protected areas as refugia for insect biodiversity, particularly dung beetles, which contribute to many key ecosystem processes.

Topcats and underdogs: intraguild interactions among three apex carnivores across Asia's forestscapes.

Intraguild interactions among carnivores have long held the fascination of ecologists. Ranging from competition to facilitation and coexistence, these interactions and their complex interplay influence everything from species persistence to ecosystem functioning. Yet, the patterns and pathways of such interactions are far from understood in tropical forest systems, particularly across countries in the Global South. Here, we examined the determinants and consequences of competitive interactions between dholes Cuon alpinus and the two large felids (leopards Panthera pardus and tigers Panthera tigris) with which they most commonly co-occur across Asia. Using a combination of traditional and novel data sources (N = 118), we integrate information from spatial, temporal, and dietary niche dimensions. These three species have faced catastrophic declines in their extent of co-occurrence over the past century; most of their source populations are now confined to Protected Areas. Analysis of dyadic interactions between species pairs showed a clear social hierarchy. Tigers were dominant over dholes, although pack strength in dholes helped ameliorate some of these effects; leopards were subordinate to dholes. Population-level spatio-temporal interactions assessed at 25 locations across Asia did not show a clear pattern of overlap or avoidance between species pairs. Diet-profile assessments indicated that wild ungulate biomass consumption by tigers was highest, while leopards consumed more primate and livestock prey as compared to their co-predators. In terms of prey offtake (ratio of wild prey biomass consumed to biomass available), the three species together harvested 0.4-30.2% of available prey, with the highest offtake recorded from the location where the carnivores reach very high densities. When re-examined in the context of prey availability and offtake, locations with low wild prey availability showed spatial avoidance and temporal overlap among the carnivore pairs, and locations with high wild prey availability showed spatial overlap and temporal segregation. Based on these observations, we make predictions for 40 Protected Areas in India where temporally synchronous estimates of predator and prey densities are available. We expect that low prey availability will lead to higher competition, and in extreme cases, to the complete exclusion of one or more species. In Protected Areas with high prey availability, we expect intraguild coexistence and conspecific competition among carnivores, with spill-over to forest-edge habitats and subsequent prey-switching to livestock. We stress that dhole-leopard-tiger co-occurrence across their range is facilitated through an intricate yet fragile balance between prey availability, and intraguild and conspecific competition. Data gaps and limitations notwithstanding, our study shows how insights from fundamental ecology can be of immense utility for applied aspects like large predator conservation and management of human-carnivore interactions. Our findings also highlight potential avenues for future research on tropical carnivores that can broaden current understanding of intraguild competition in forest systems of Asia and beyond.