Search

In recent years, it has been suggested that Cybister tripunctatus lateralis is increasing in abundance and expanding its distribution, and there is concern about the effects of interspecific competition with another congeneric species, Cybister brevis. Although the two species appear to have overlapping niches, they are often observed sympatrically. Larval habitat use by the two species was investigated in a paddy field water system. The results display that C. brevis was more abundant in ditches and C. tripunctatus lateralis was more abundant in paddy fields. It is thought that C. tripunctatus lateralis, which has an ecology suited to high temperatures, has selected paddy fields, where water temperatures tend to rise, as its reproductive habitat. In contrast, phenology was generally synchronized, and no differences in underwater position in the rice paddies were observed. Thus, niches overlap in paddy fields and interspecific competition may occur. [ABSTRACT FROM AUTHOR]

One strand of modern coexistence theory (MCT) partitions invader growth rates (IGR) to quantify how different mechanisms contribute to species coexistence, highlighting fluctuation‐dependent mechanisms. A general conclusion from the classical analytic MCT theory is that coexistence mechanisms relying on temporal variation (such as the temporal storage effect) are generally less effective at promoting coexistence than mechanisms relying on spatial or spatiotemporal variation (primarily growth‐density covariance). However, the analytic theory assumes continuous population density, and IGRs are calculated for infinitesimally rare invaders that have infinite time to find their preferred habitat and regrow, without ever experiencing intraspecific competition. Here we ask if the disparity between spatial and temporal mechanisms persists when individuals are, instead, discrete and occupy finite amounts of space. We present a simulation‐based approach to quantifying IGRs in this situation, building on our previous approach for spatially non‐varying habitats. As expected, we found that spatial mechanisms are weakened; unexpectedly, the contribution to IGR from growth‐density covariance could even become negative, opposing coexistence. We also found shifts in which demographic parameters had the largest effect on the strength of spatial coexistence mechanisms. Our substantive conclusions are statements about one model, across parameter ranges that we subjectively considered realistic. Using the methods developed here, effects of individual discreteness should be explored theoretically across a broader range of conditions, and in models parameterized from empirical data on real communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Predation relationships and competition relationships shape interspecies coexistence in wild animal communities. Studying the temporal and spatial activity patterns of wild animals is crucial for understanding their behavior, species interactions, and resource requirements. We evaluated the spatiotemporal overlap between 15 different dominant species in the southwestern mountains of China, including Carnivora (such as Panthera pardus and Lynx lynx), Artiodactyla (such as Moschus spp. and Rusa unicolor), Primate (Macaca mulatta), and Galliformes (Crossoptilon crossoptilon, Ithaginis cruentus). We found that different species exhibit different activity patterns to reduce intense resource competition, with competition being more intense in cold seasons than warm seasons. This may be due to abundant resources in summer but scarce food in winter, as well as increased energy demands during cold seasons, as expected using physiology theory. Temporal and spatial factors regulate the interactions between apex predators, mesocarnivores, and herbivores. Prey adjust their activity patterns and spatial utilization based on predator activities; in turn, predators also adapt to the activities of their prey. To elucidate the factors influencing the daily activity rhythms of animals, 115 camera traps were established from September 2019 to June 2023 to assess the influences of interspecific relationships and seasons on the daily activity rhythms of animals in the southwest mountains of China. The species captured by the cameras included six Carnivora (such as Panthera pardus and Lynx lynx), six Artiodactyla (such as Moschus spp. and Rusa unicolor), one Primate (Macaca mulatta), and two Galliformes (Crossoptilon crossoptilon, Ithaginis cruentus). The results demonstrated that the 15 species exhibited different activity rhythms and peak activities to reduce intense resource competition. There were differences in the species' activity rhythms in different seasons, with competition among different species being more intense in the cold season than in the warm season. In predation relationships, the overlap coefficient in the cold season exceeded that of the warm season, possibly due to the abundant resources in summer and food scarcity in winter. In competitive relationships, 15 pairs of species exhibited significantly higher overlap coefficients in the cold season compared to the warm season, possibly due to increased demands for energy during the cold period or seasonal changes in predatory behavior. By analyzing the daily and seasonal activity patterns of dominant species in the study area, temporal niche overlaps were established to compare the competition levels between species. These findings indicate that the activity rhythms of the animals in this area not only result from evolutionary adaptation but are also influenced by season, food resources, and interspecific relationships (predation and competition). Thus, efforts should be made to reduce human interference, protect food resources in the winter, and monitor animals' interspecific relationships to protect animal diversity and maintain the stability of the ecosystem in this biodiversity hotspot in China. [ABSTRACT FROM AUTHOR]

Invasive species often have harmful effects on human activities and biodiversity. The Tapinoma nigerrimum complex includes three species that exhibit invasive traits and the ability to form supercolonies, including Tapinoma magnum and Tapinoma darioi. While these species are native to the Mediterranean basin, they have recently been reported as invasive in more northern regions of Europe. However, T. magnum and T. darioi show different invasion patterns in Europe, suggesting differences in thermal preferences between these species. We aimed to determine whether there was any difference in activity pattern depending on temperature or season between the two Tapinoma species and between Tapinoma and co‐occurring native Mediterranean ants.We measured ambient temperature and ant foraging activity around the nest entrances of T. darioi and T. magnum in urbanised sites around Montpellier, southern France, over almost 1 year.We did not detect differences in activity between the two species according to temperature, but T. magnum was more active than T. darioi in winter. Compared to the co‐occurring native species, the two Tapinoma species were more active at low temperatures and earlier in the year.These results suggest that the difference in invasion success between T. magnum and T. darioi may not be explained by temperature preference. The difference in activity between native Mediterranean species and invasive Tapinoma suggests a coexistence through niche partitioning. In addition, our results suggest that control measures against invasive Tapinoma species would be more effective if applied at the end of winter. [ABSTRACT FROM AUTHOR]

Saguinus bicolor is one of the most endangered primates in the Amazon, mainly due to threats related to human activities, such as deforestation and habitat fragmentation. Moreover, the encroachment of Saguinus midas, a widely distributed species, into the restricted range of S. bicolor, poses further conservation challenges and extinction risks. This study focuses on the potential niche overlap and competition between these two species, which are closely related callitrichid primates with a parapatric distribution. We employed the support vector machine (SVM) algorithm to investigate the potential of invasion by S. midas into the area of occurrence of S. bicolor by quantifying and comparing the habitat suitability for both species. We used environmental variables that are known to be relevant descriptors of callitrichid niches and a similarity test was applied to assess niche overlap between the two species. Our analysis reveals that the majority of the area occupied by S. bicolor exhibits higher habitat suitability for S. midas than for S. bicolor. Furthermore, we found a high niche similarity between the species. These results suggest a significant invasive potential of S. midas into the range of S. bicolor. The research highlights the concerning prospects for the long-term persistence of S. bicolor, emphasizing the urgent need for conservation measures. The conservation and maintenance of an ecologically functional urban forest matrix, along with the preservation of habitat quality and connectivity in rural areas, are crucial. Monitoring the current contact areas between the two species and the areas indicated as highly and moderately suitable for S.midas in the range of S. bicolor is also essential, and the observed trends in the occupation of these areas need to be incorporated into adaptive conservation strategies to protect less anthropogenically impacted areas. The findings are expected to contribute to the ongoing National Action Plan for the conservation of S. bicolor and support the management and conservation efforts for the species. [ABSTRACT FROM AUTHOR]

Resource partitioning through temporal, spatial and/or trophic dimensions is suggested as a mechanism for long‐term coexistence among sympatric species. However, how the combined effects of the different dimensions contribute to the partitioning during the ontogenetic process is unclear.We sampled two sympatric icefish species [Protosalanx hyalocranius (Abbott, 1901) and Neosalanx taihuensis (Chen, 1956)] monthly from July 2015 to June 2016 in Hongze Lake, China. We evaluated the hypothesis that combined effects of separation in gonad development dynamics and ontogenetic diet shifts facilitate resource partitioning in temporal and trophic dimensions during the entire life cycle process of the two icefish species.Increased gonadosomatic index (GSI) of female P. hyalocranius occurred during October 2015 to January 2016, and that of female N. taihuensis occurred during January to March 2016. Thus, energy and nutrition investments in gonad development separated seasonally between the two species. Consequently, temporal separations in gonad development between P. hyalocranius (GSI peaked in January) and N. taihuensis (GSI peaked in March) indicated potential segregations in spawning time and consequent larval abundance peaks, suggesting reduced overlap of prey consumption during the early life stages.The dominant diet of P. hyalocranius shifted from cladocerans to copepods, and then shrimp, and finally to fish during its ontogeny, whereas the dominant diet of N. taihuensis changed gradually from cladocerans to copepods during its ontogeny. The diet overlap in cladocerans during May was high between the two species.Our findings support the hypothesis of an associative strategy, combining temporal (separations in gonad development and subsequently spawning time) and trophic (ontogenetic diet shifts) dimensions, for the resource partitioning between P. hyalocranius and N. taihuensis, which may be an important mechanism for long‐term coexistence among sympatric short‐lived fishes. [ABSTRACT FROM AUTHOR]

The outcome of species competition strongly depends on the traits of the competitors and associated trade‐offs, as well as on environmental variability. Here, we investigate the relevance of consumer trait variation for species coexistence in a ciliate consumer–microalgal prey system under fluctuating regimes of resource supply. We focus on consumer competition and feeding traits, and specifically on the consumer's ability to overcome periods of resource limitation by mixotrophy, that is, the ability of photosynthetic carbon fixation via algal symbionts in addition to phagotrophy. In a 48‐day chemostat experiment, we investigated competitive interactions of different heterotrophic and mixotrophic ciliates of the genera Euplotes and Coleps under different resource regimes, providing prey either continuously or in pulses under constant or fluctuating light, entailing periods of resource depletion in fluctuating environments, but overall providing the same amount of prey and light. Although ultimate competition results remained unaffected, population dynamics of mixotrophic and heterotrophic ciliates were significantly altered by resource supply mode. However, the effects differed among species combinations and changed over time. Whether mixotrophs or heterotrophs dominated in competition strongly depended on the genera of the competing species and thus, species‐specific differences in the minimum resource requirements that are associated with feeding on shared prey, nutrient uptake, light harvesting, and access to additional resources such as bacteria. Potential differences in the curvature of the species' resource‐dependent growth functions may have further mediated the species‐specific responses to the different resource supply modes. Overall, our study demonstrates that genus‐ or species‐specific traits other than that related to nutritional mode may override the relevance of acquired phototrophy by heterotrophs in competitive interactions, and that the potential advantage of photosynthetic carbon fixation of symbiont‐bearing mixotrophs in competition with pure heterotrophs may differ greatly among different mixotrophs, playing out under different environmental conditions and depending on the specific requirements of the species. Complex trophic interactions determine the outcome of competition, which can only be understood by taking on a multidimensional trait perspective. [ABSTRACT FROM AUTHOR]

Resource partitioning is considered a key factor in alleviating competitive interactions, enabling coexistence among consumer species. However, most studies have focused on resource partitioning between species, ignoring the potentially critical role of intraspecific variation in resource use. We investigated floral resource partitioning across species, colonies, and individuals in a species‐rich bumblebee community in the diversification center of bumblebees. We used a total of 10,598 bumblebees belonging to 13 species across 5 years in the Hengduan Mountains of southwest China. First, we evaluated the influence of a comprehensive set of floral traits, including both those related to attractiveness (flower color and shape) and rewards (pollen, sugar ratio, nectar volume, sugar concentration, and amino acid content) on resource partitioning at the species level in bumblebee–plant networks. Then, we explored intraspecific resource partitioning on the colony and individual levels. Our results suggest that bumblebee species differ substantially in their use of the available floral resources, and that this mainly depends on flower attractiveness (floral color and shape). Interestingly, we also detected floral resource partitioning at the colony level within all commonest bumblebee species evaluated. In general, floral resource partitioning between bumblebee individuals decreased with species‐ and individual‐level variation in body size (intertegular span). These results suggest that bumblebee species may coexist via the flexibility in their preferences for specific floral traits, which filters up to support the co‐occurrence of high numbers of species and individuals in this global hotspot of species richness. [ABSTRACT FROM AUTHOR]

We present a mechanistic model of coexistence among a mycorrhizal fungus and one or two plant species that compete for a single nutrient. Plant–fungal coexistence is more likely if the fungus is better at extracting the environmental nutrient than the plant and the fungus acquires carbon from the plant above a minimum rate. When they coexist, their interaction can shift from mutualistic to parasitic at high nutrient availability. The fungus is a second nutrient source for plants and can promote the coexistence of two plant competitors if one is better at environmental nutrient extraction and the other is better at acquiring the nutrient from the fungus. Because it extracts carbon from both plants, the fungus also serves as a conduit of apparent competition between the plants. Consequently, the plant with the lower environmental nutrient extraction rate can drive the plant with the higher environmental nutrient extraction rate extinct at high carbon supply rates. This model illustrates mechanisms to explain several observed patterns, including shifts in plant–mycorrhizal growth responses and coexistence along nutrient gradients, equivocal results among experiments testing the effect of mycorrhizal fungi on plant diversity, and differences in plant diversity among ecosystems dominated by different mycorrhizal groups. [ABSTRACT FROM AUTHOR]

Species coexistence is a major issue in ecology. We disentangled the role of individual interference when competing in the classical interference competition model. For the first time, we considered simultaneously intra- and inter-species interference by introducing the Beddington–DeAngelis competitive response into the classical competition model. We found a trade-off between intra- and inter-species interference that refines in a sense the well-known balance of intra- and inter-species competition coefficients. As a result, we found that (i) global coexistence is possible for a larger range of values of the inter-/intra-species competition coefficients and contributes to explaining the high prevalence of species coexistence in nature. This feature is exclusively due to intra-species interference. (ii) We found multi-stability scenarios previously described in the literature that can be reinterpreted in terms of individuals interference. [ABSTRACT FROM AUTHOR]

Species interactions are key drivers of biodiversity and ecosystem stability. Current theoretical frameworks for understanding the role of interactions make many assumptions which unfortunately, do not always hold in natural, diverse communities. This mismatch extends to annual plants, a common model system for studying coexistence, where interactions are typically averaged across environmental conditions and transitive competitive hierarchies are assumed to dominate. We quantify interaction networks for a community of annual wildflowers in Western Australia across a natural shade gradient at local scales. Whilst competition dominated, intraspecific and interspecific facilitation were widespread in all shade categories. Interaction strengths and directions varied substantially despite close spatial proximity and similar levels of local species richness, with most species interacting in different ways under different environmental conditions. Contrary to expectations, all networks were predominantly intransitive. These findings encourage us to rethink how we conceive of and categorize the mechanisms driving biodiversity in plant systems. [ABSTRACT FROM AUTHOR]

Competition can be keen within and between closely related species but can be reduced when sympatric individuals differ in resource use. To determine how sympatric, closely related species coexist, we examined movement and activity of foraging individuals, developing detailed profiles for males of three species (Acanthodactylus boskianus, A.dumerilii and A.scutellatus) and for female A. boskianus in arid sub-desert steppes of southern Tunisia. All three species were active concurrently with different peak activity times. Males varied markedly in their movement, as did A. boskianus sexes. Interspecifically, male A.boskianus moved most frequently, for the most time, covering the greatest distance and searching the largest area, while male A. dumerilii moved the least often, travelled the shortest distances and intensively searched small areas. Acanthodactylus scutellatus males generally were intermediate between the other species but dug more frequently and had movement rates comparable to A. boskianus. Intraspecifically, A. boskianus females moved less frequently, for a smaller percentage of time, covering shorter distances and searching smaller areas than male A. boskianus. Habitat use varied among species and by sex within A.boskianus. Differences in movement and activity likely reflect differences in resource use that promote coexistence between and within species. [ABSTRACT FROM AUTHOR]

The evolutionary impact of both temporal periodicity and spatial heterogeneity on population ecology is a challenging problem. Hutson et al. (2001) [12] and Bai et al. (2022) [2] studied the effects of diffusion rates on the dynamics of a time-periodic Lotka-Volterra competition-diffusion system with identical interspecific competition abilities. In this paper, we consider the case of different interspecific competition coefficients. The obtained results can be divided into two groups. The first part focuses on the interplay between the diffusion intensities and the interspecific competition coefficients on the dynamics in the weak competition case. We provide some sufficient conditions on coexistence and competitive exclusion. The second part considers the dynamics for fixed diffusion coefficients and varying competition coefficients. We not only provide a complete classification on the dynamics when one of the interspecific competition coefficients is small, but also show the multiple coexistence periodic patterns by applying the bifurcation method. [ABSTRACT FROM AUTHOR]

Despite the well known scale‐dependency of ecological interactions, relatively little attention has been paid to understanding the dynamic interplay between various spatial scales. This is especially notable in metacommunity theory, where births and deaths dominate dynamics within patches (the local scale), and dispersal and environmental stochasticity dominate dynamics between patches (the regional scale). By considering the interplay of local and regional scales in metacommunities, the fundamental processes of community ecology—selection, drift, and dispersal—can be unified into a single theoretical framework. Here, we analyze three related spatial models that build on the classic two‐species Lotka–Volterra competition model. Two open‐system models focus on a single patch coupled to a larger fixed landscape by dispersal. The first is deterministic, while the second adds demographic stochasticity to allow ecological drift. Finally, the third model is a true metacommunity model with dispersal between a large number of local patches, which allows feedback between local and regional scales and captures the well studied metacommunity paradigms as special cases. Unlike previous simulation models, our metacommunity model allows the numerical calculation of equilibria and invasion criteria to precisely determine the outcome of competition at the regional scale. We show that both dispersal and stochasticity can lead to regional outcomes that are different than predicted by the classic Lotka–Volterra competition model. Regional exclusion can occur when the nonspatial model predicts coexistence or founder control, due to ecological drift or asymmetric stochastic switching between basins of attraction, respectively. Regional coexistence can result from local coexistence mechanisms or through competition‐colonization or successional‐niche trade‐offs. Larger dispersal rates are typically competitively advantageous, except in the case of local founder control, which can favor intermediate dispersal rates. Broadly, our models demonstrate the importance of feedback between local and regional scales in competitive metacommunities and provide a unifying framework for understanding how selection, drift, and dispersal jointly shape ecological communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Deforestation is increasingly forcing primates into proximity with people. It is vitally important, especially for globally threatened species, that we understand how species navigate human-dominated environments and if these interactions incur threats to their populations. Local knowledge is a valuable source of information on underrepresented and cryptic species, and studies relating to nocturnal species are limited in Thailand, including those of the Endangered slow lorises (Nycticebus bengalensis and N. coucang). Here, we analyze data regarding the knowledge, beliefs, and experiences of local people from Khao Lak, in southern Thailand, an area that is composed of rural and urban areas. We conducted 36 interviews using photo cards to determine (1) where and how often people see slow lorises, (2) what they see them doing, and (3) what they know about them. We analyzed meaningful common words and how they clustered together. We identified 11 key concepts that define the local beliefs about slow lorises. We found that people believed that slow lorises ate fruit, were not aggressive, but were "bad omens"; they also reported that there used to be more lorises, but the interviewees did not specify how recently. We also determined that slow lorises were often seen in rural and urban areas and we posit that the people of Khao Lak live in passive coexistence with lorises with minimal conflict and exploitation. Lastly, we determined that electrocutions and road accidents are the principal threats to slow lorises in Khao Lak. We discuss how local knowledge can be a vital first step in developing conservation action plans for the species. Natural landscapes are being converted for agriculture and other human uses across Asia and this development presents potential threats for specialist species of primates, like the Endangered slow lorises of Thailand (Nycticebus bengalensis and N. coucang). It is crucial to understand the interface between humans and slow lorises in order to conserve these primates. Local ecological knowledge provides valuable information about these cryptic nocturnal species. We conducted 36 semi-structured interviews in Khao Lak, in southern Thailand, asking (1) where slow lorises were seen, (2) what they were doing, (3) how often people see slow lorises, and (4) what people knew about them. We converted the interviews to free lists and determined the importance of key words. Our results show that the informants saw lorises frequently in six general locations: forests/trees (58%), electric wires (47%), towns/villages (36%), plantations (33%), homesteads (28%), and roads (17%). The most prominent places were forests/trees, wires, and plantations. Eleven key concepts defined local beliefs, with the most prominent being that lorises are awake at night (69%), eat fruit (42%), are not aggressive (25%), are bad omens (25%), and there used to be more of them (25%). Due to a minimal presence of persecution or exploitation of slow lorises by humans in the study area and general tolerance in the face of competition for the same resources and spaces, we suggest that, despite extensive persecution for the illegal photo prop trade in nearby Phuket, the people of Khao Lak seem to live in a state of passive coexistence with slow lorises. However, we did find some evidence that the pet and photo prop trade are still present in the area. It is crucial that coexistence be struck within the context of deforestation and urbanization so that conservation initiatives can take place within the community to further improve the lives of humans and the status of lorises. [ABSTRACT FROM AUTHOR]

Simple Summary: The endangered San Joaquin kit fox (Vulpes macrotis mutica; SJKF) occurs in the city of Bakersfield, CA, along with other species such as domestic cats (Felis catus), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), and opossums (Didephis virginiana). We used data from camera stations deployed throughout the city during 2015–2022 to assess whether the other species compete with SJKF or coexist syntopically (i.e., occur in the same habitats without competing). Detections of the other species were not associated with those of SJKF, either in areas of high, medium, or low suitability for SJKF or for all areas combined. Also, the abundance of the other species did not increase when SJKF declined from a sarcoptic mange epidemic. The other species were detected at camera stations, with SJKF indicating that they used the same areas. Competition between the SJKF and the other species may be negligible, likely due to high resource abundance. Thus, SJKF and the other species appear to coexist syntopically in the urban environment. This additional SJKF population contributes to the conservation and recovery of this endangered species. The endangered San Joaquin kit fox (Vulpes macrotis mutica; SJKF) occurs in the city of Bakersfield, CA, where several putative competitors also occur, including domestic cats (Felis catus), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), and opossums (Didephis virginiana). We used data from a multi-year (2015–2022) city-wide camera station survey to assess whether the other species were simply sympatric with SJKF or coexisting syntopically (i.e., occurring in the same habitats without apparent competition). Annual detection rates for the other species were not correlated with SJKF rates either within SJKF habitat suitability categories (low, medium, and high) or for all categories combined. Also, detection rates for the other species did not increase in response to a significant decline in SJKF abundance caused by sarcoptic mange. The use of all SJKF habitat suitability categories by the other species and co-detections with SJKF at camera stations indicate high spatial overlap. Interference and exploitative competition between the species are apparently negligible, likely due to similar body sizes and high resource abundance. Thus, SJKF and the other species appear to be coexisting syntopically in the urban environment, resulting in a significant additional SJKF population that facilitates range-wide conservation and recovery of this endangered species. [ABSTRACT FROM AUTHOR]

Pollinators mediate interspecific and intraspecific plant–plant indirect interactions (competition vs. facilitation) via density-dependent processes, potentially shaping the dynamics of plant communities. However, it is still unclear which ecological drivers regulate density-dependent patterns, including scale, pollination niches (i.e., the main pollinator functional group) and floral attractiveness to pollinators. In this study, we conducted three-year field observations in Hengduan Mountains of southwest China. By gathering data for more than 100 animal-pollinated plant species, we quantified the effect (positive vs. negative) of conspecific and heterospecific flower density on pollination at two scales: plot-level (4 m2) and site-level (100–5000 m2). Then, we investigated how pollination niches and floral attractiveness to pollinators (estimated here as average per-flower visitation rates) modulated density-dependent pollination interactions. Pollinator visitation depended on conspecific and heterospecific flower density, with rare plants subjected to interspecific competition at the plot-level and interspecific facilitation at the site-level. Such interspecific competition at the plot-level was stronger for plants pollinated by diverse insects, while interspecific facilitation at the site-level was stronger for bee-pollinated plants. Moreover, we also found stronger positive conspecific density-dependence for plants with lower floral attractiveness at the site-level, meaning that they become more frequently visited when abundant. Our study indicates that the role of pollination in maintaining rare plants and plant diversity depends on the balance of density-dependent processes in species-rich communities. We show here that such balance is modulated by scale, pollination niches and floral attractiveness to pollinators, indicating the context-dependency of diversity maintenance mechanisms. [ABSTRACT FROM AUTHOR]

Research on facilitation has not had the advantage of being explicitly underpinned by mathematical population dynamic theory. This has limited understanding of the role of facilitation on ecological dynamics and the integration of facilitation into general theory.I show that facilitative interactions can be classified into four categories likely to be dynamically similar to interaction types for which population‐dynamic theory does exist. This classification provides a useful population‐dynamic foundation for facilitation studies and reveals several fundamental questions unanswered by existing empirical work.While facilitation has typically been excluded from studies of 'competitive' coexistence, I also describe how coexistence theory does not always default to the assumption that species only compete; recent developments in coexistence theory fully accommodate the potentially important influence of facilitation.Simple models of multispecies population dynamics emphasize the importance of reciprocal interspecific interactions, intraspecific interactions, and density dependence for understanding the outcome of facilitative interactions. I point to approaches for aligning future empirical studies of facilitation with these features.Synthesis: Closely aligning at least some future empirical work on facilitation with existing mathematical population dynamic theory will further improve understanding of the effects of facilitation on ecological dynamics. [ABSTRACT FROM AUTHOR]

Plant community productivity generally increases with biodiversity, but the strength of this relationship exhibits strong empirical variation. In meta‐food‐web simulations, we addressed if the spatial overlap in plants' resource access and animal space‐use can explain such variability. We found that spatial overlap of plant resource access is a prerequisite for positive diversity–productivity relationships, but causes exploitative competition that can lead to competitive exclusion. Space‐use of herbivores causes apparent competition among plants, resulting in negative relationships. However, space‐use of larger top predators integrates sub‐food webs composed of smaller species, offsetting the negative effects of exploitative and apparent competition and leading to strongly positive diversity–productivity relationships. Overall, our results show that spatial overlap of plants' resource access and animal space‐use can greatly alter the strength and sign of such relationships. In particular, the scaling of animal space‐use effects opens new perspectives for linking landscape processes without effects on biodiversity to productivity patterns. [ABSTRACT FROM AUTHOR]

The mutualism between plants and pollinators is built upon the trophic ecology of flowers and florivores. Yet the ecology of flowers‐as‐food is left implicit in most studies of plant–pollinator ecology, and it has been largely neglected in mainstream trophic ecology. This deficit is especially evident in an emerging issue of basic and applied significance: competition between pollinators for floral resources. In this synthesis, we start by exploring the notion of floral resource limitation upon which most studies concerning competition between pollinators are tacitly predicated. Both theoretical and empirical lines of evidence indicate that floral resource limitation must be understood as a complex ecological contingency; the question is not simply whether but when, where and in what regions of floral trait space resources are limiting. Based on this premise, we propose a framework for understanding floral resource availability in terms of temporal, spatial and functional structure. While this framework is conceptually intuitive, it is empirically and analytically demanding. We review existing methods for measuring and summarizing the multi‐dimensional structure of floral resources, highlight their strengths and weaknesses, and identify opportunities for future methods development. We then discuss the causal relationships linking floral resource structure to species coexistence, plant–pollinator community dynamics, and exogenous drivers like climate, land use, and episodic disturbances. In its role as both cause and effect, floral resource structure mediates the relationship between behavioral ecology, landscape ecology, and coexistence theory with respect to flowers and florivores. Establishing floral resource structure as an object of study and application will both shed light on basic questions of coexistence and guide management decisions concerning contentious issues such as the compatibility of apiculture with wild pollinator conservation and the appropriate use of floral enhancements in agri‐environment schemes. [ABSTRACT FROM AUTHOR]

Finding the conditions that ensure the survival of species has occupied ecologists for decades. Theoretically, for mechanistic models such as MacArthur's consumer-resource model, most of the efforts have concentrated on proving the stability of an equilibrium assuming that it is feasible, but overlooking the conditions that ensure its feasibility. Here, we address this gap by finding the range of conditions that lead to a feasible equilibrium of MacArthur's consumer-resource model, where species competition is mediated by their consumption of similar resources, and study how changes in the system's structural and parametric properties affect those ranges for communities of any size. We characterize the relationship between the loss of feasibility and the increase in complexity (measured by the system's richness and connectance) by a power law that can be extended to random competition matrices. Focusing on the pool of consumers, we find that while the feasibility of the entire system decreases with the size of the pool, the expected fraction of feasible consumers increases—safety in consumer numbers. Focusing on the pool of resources, we find that if resources grow linearly, the larger the pool of resources, the lower the feasibility of the system and the expected fraction of feasible consumers—danger in resource numbers. However, if resources grow logistically, this pattern is reversed with a sublinear increase in feasibility, as it has been previously reported in experimental work. This work provides testable predictions for consumer-resource systems and is a gateway to exploring feasibility in other mechanistic models. [ABSTRACT FROM AUTHOR]

Aim: Ecological refuges buffer organisms against stressors and mediate a range of species interactions. However, their role in the context of biological invasions has yet to be synthesized, despite the increasing prevalence and impact of non‐native species. To address this, we conducted a systematic review aiming to determine the extent to which refuges are considered explicitly in the invasion literature and to synthesize their function. Location: Global. Time period: Present day. Major taxa studied: All. Methods: Our search of the literature was conducted using the SCOPUS and Web of Science databases and followed the preferred reporting items for systematic reviews and meta‐analyses (PRISMA) protocol. We obtained 315 records of refuge use in biological invasions from 300 studies. From each record, we extracted information relating to the experimental design, species characteristics and refuge type, where available. Results: Refuges and refuge‐mediated processes are widely reported in the invasion literature. Native species commonly use refuges to avoid non‐native predation and competition, with spatial complexity and habitat heterogeneity key factors in facilitating their coexistence. Records show that artificial structures safeguard non‐natives in their introduced range. However, there were key differences in the use of such structures in marine and terrestrial environments. Moreover, the enhanced structural complexity created by non‐native plants and bivalves is often reported to act as a predation refuge for other species. Main conclusions: The ubiquity of refuge‐based processes suggests that refuges can play an important role in affecting the persistence, spread and impacts of non‐native species, either through previously described mechanisms (i.e. refuge‐mediated apparent competition and the persistent pressure scenario) or through a mechanism we describe (i.e. when non‐native species use existing refuges), or both. [ABSTRACT FROM AUTHOR]

In this paper, we incorporate the dispersal of one species between two patches into a two‐species competition model. The dispersal process is assumed to involve time delay and population loss. We show that the dispersal rate and the loss during the dispersal jointly affect the stability and instability of model equilibria and induce the phenomena of multi‐stability and transient coexistence of both competing species in both patches. [ABSTRACT FROM AUTHOR]

Invasive exotic plants often impact native plant species through strong competition, yet their effects can vary across different native populations. Previous exposure to invasive species but also differentiation along abiotic gradients may determine to what extent native populations are competitively suppressed by plant invasive species. Here, we experimentally investigated whether competitive effects of the invasive exotic jewelweed Impatiens parviflora on its native congener Impatiens noli‐tangere are related to previous exposure to the invader or rather to topography of the source populations, i.e. to terrain features such as elevation, aspect or slope. We also asked whether, in return, topographic settings of invasive I. parviflora populations may explain competitive effects of the native jewelweed. In a common garden competition experiment we found that populations of native jewelweed from colder, higher altitude sites and from drier sites were on average seven and six times, respectively, more tolerant to interspecific competition than populations from warmer and wetter sites. In contrast, previous exposure of native jewelweed populations to the invader was not a significant predictor of invader's competitive effects. Further, topographic settings of populations of invasive jewelweed were not significantly related to the native's competitive effects. Our study suggests that the native jewelweed's population differentiation along topographic gradients is more important in determining competitive interactions with an invasive congener than invasion‐induced selection. As fine‐scale environmental variation can shape adaptation of native species to the effects of invasive species, such variation should be considered when predicting invasive species' impact on native plant communities. [ABSTRACT FROM AUTHOR]

The coexistence of ecologically and morphologically similar species is often facilitated by the partitioning of ecological niches. While subordinate species can reduce competition with dominant competitors through spatial and/or trophic segregation, empirical support from wild settings, particularly those involving large-bodied taxa in marine ecosystems, are rare. Shark nursery areas provide an opportunity to investigate the mechanisms of coexistence. We used experimental and field studies of sympatric juvenile sharks (blacktip reef shark, Carcharhinus melanopterus; sicklefin lemon shark, Negaprion acutidens) to investigate how competitive ability influenced realized niches at St. Joseph Atoll, Seychelles. Captive trials revealed that sicklefin lemon sharks were dominant over blacktip reef sharks, consistently taking food rewards. In the field, blacktip reef sharks were captured over a broader area than sicklefin lemon sharks, but daily space use of actively tracked sharks showed a high degree of overlap across microhabitats. While stomach contents analysis revealed that blacktip reef shark diets included a broader range of prey items, stable isotope analysis demonstrated significantly higher mean δ13C values for sicklefin lemon sharks, suggesting diverging dietary preferences. Overall, our results matched theoretical predictions of subordinate competitors using a greater range of habitats and displaying broader feeding niches than competitively dominant species. While separating the realized and fundamental niche of marine predators is complicated, we provide evidence that resource partitioning is at least partially driven by interspecific competition. [ABSTRACT FROM AUTHOR]

Changes in some combination of niche availability, niche overlap and the strength of interspecific interactions are thought to drive changes in plant composition along resource gradients. However, because these processes are difficult to measure in the field, their relative importance in driving compositional change in plant communities remains unclear. In an Australian temperate grassland, we added seeds of three native and three exotic grasses to 1875 experimental plots in a way that allowed us to simultaneously estimate niche availability, niche overlap and the strength of pairwise interspecific interactions along a gradient of nutrient availability, obtained by adding 0, 5 or 20 g m−2 each of nitrogen, phosphorous and potassium jointly to plots. Niche availability (the proportion of microsites suitable for establishment and growth) was generally low and did not vary in response to nutrient addition. Most species co‐occurred along the nutrient gradient by partitioning the available niche space. Where species interacted due to niche overlap, the abundance of one species, the native Chloris truncata, was usually facilitated by other species, with each of the five other species increasing the niche availability to C. truncata under at least one nutrient treatment. Chloris truncata also competitively excluded two species from some but not all sites they could otherwise have occupied. These outcomes did not clearly differ across nutrient treatments. Our results show that fine‐scale spatial heterogeneity in establishment microsites can enable species to co‐occur via niche partitioning, and competitive exclusion is rare. This finding contributes to an emerging picture that niche partitioning is common and frequently a stronger influence on recruitment outcomes than interspecific competition. The importance of competition in structuring plant communities may be overestimated if recruitment processes are overlooked. [ABSTRACT FROM AUTHOR]

Both intra- and interspecific competition influence the partitioning of limited resources; the relative importance of each type of competition in resource distribution is influenced by several factors, including resource availability and population abundance. Several hermit crab species of the genera Calcinus and Clibanarius coexist, competing for the shells of the same gastropod species. The relative abundance of these species varies along the intertidal gradient, from a bias toward Clibanarius in the upper intertidal to a tendency toward Calcinus in the lower intertidal. We assessed the strength of intra- versus interspecific competition in Cli. albidigitus and Cal. californiensis by comparing the number of successful usurpations of preferred shells in single-species versus mixed-species trials. We performed these comparisons under four scenarios, varying the total individuals and their relative abundance (1.7:1, 1:1, or 1:1.7 ratio) to simulate demographic conditions along the intertidal gradient. There were more shell usurpations in mixed-species trials under all scenarios except for the 1:1 ratio at high total abundance. Calcinus californiensis usurped more shells than Cli. albidigitus in all mixed-species treatments, even in cases where Cli. albidigitus was more abundant. Our results show that interspecific competition is stronger than intraspecific competition, which could drive the competitive exclusion of Cli. albidigitus , the comparatively weaker species. [Display omitted] • Cli. albidigitus and Cal. californiensis share a preference for the same gastropod shells. • Clibanarius species are subrogate to Calcinus species when fighting for shells. • Interspecific competition is significantly stronger than intraspecific competition. • Interspecific competition could drive the competitive exclusion of Cli. albidigitus. [ABSTRACT FROM AUTHOR]

Understanding the factors that allow multiple species to coexist and share resources is an outstanding question in community ecology. Animals that share resources tend to use different strategies to decrease potential competition, through morphological adaptations, establishment of hierarchies, behavioral adaptations or spatial or temporal segregation. The main objective of this study was to infer interspecific processes of competition and facilitation through the study of species co‐occurrence patterns in a vertebrate scavenger guild in de Brazilian cerrado. We analyzed patterns of spatial and temporal co‐occurrence between species pairs, both qualitatively and quantitatively, and determined the activity patterns of the different scavenger species. For this purpose, we placed and monitored 11 large (i.e. goat) and 45 small (i.e. chicken) carcasses by camera‐trapping, obtaining a total of 27 448 images. Our results show complex competitive and facilitative relationships among scavenging species in the Brazilian cerrado that are influenced by carcass size and change depending on the spatial and temporal scale at which they are analyzed. The scavenger assemblages that consumed large and small carcasses were different, evidencing resource partitioning between obligate and facultative scavengers. Furthermore, as an alternative to reduce competition levels, most species showed differences in their scavenging patterns, in addition to a strong temporal segregation during carcass consumption. Regarding New World vultures, our results suggest a strong interference competition between species with clear differences in their ecological traits (e.g. size, social behavior). However, we also found evidence of facilitation processes between vulture species in the location and access to the interior of the carcasses. Our findings highlight the role of obligate scavengers both in competition and facilitation processes in this vertebrate scavenger community. Future research should focus on investigating which species play the most important role in the structure and dynamics of this community, also considering intraspecific and behavioral patterns. [ABSTRACT FROM AUTHOR]

Climate warming and land-use change are reshuffling the distribution of wild organisms on a global scale. Some species may expand their ranges and colonize new regions, which may greatly affect ecological interactions among pre-existing species and colonizers. In the last decades, such processes have originated a unique condition of sympatry among three Eurasian small Falco species (common kestrel F. tinnunculus, lesser kestrel F. naumanni, red-footed falcon F. vespertinus) in the intensively cultivated farmland habitats of the Po Plain (Northern Italy). This provides an excellent opportunity to investigate patterns of spatial niche overlap during the initial phases of the establishment of sympatry. To investigate spatial niche overlap of the three falcon species, we relied on Environmental Niche Models (ENMs) based on widespread breeding occurrence data obtained through field surveys and citizen science programs (during the 2018–2020 period). ENMs were based on bioclimatic and land-use variables in an ensemble modelling framework. We estimated species-specific relative contributions of each climatic and land-use variable and its response curves effect. Eventually, we generated spatial correlation maps of the potential species' distributions to derive spatially-explicit predictions of potential co-occurrence areas among the three species. Overall, eco-climatic determinants of the distribution of lesser kestrel and red-footed falcon were similar, resulting in a strong association with intensive arable lands and dry continental climate. Consistently, we found a high spatial correlation between the suitability maps of the two species, with highly suitable areas located in the Central-Eastern area of the Po Plain, corresponding to the core range of both species. Conversely, the common kestrel emerged as a habitat generalist and was widely distributed throughout the Po Plain. Our findings suggest that the recent sympatry between lesser kestrels and red-footed falcons in the Po Plain may promote ecological interactions and intra-guild competition. [ABSTRACT FROM AUTHOR]

Clustering of species with similar niches or traits occurs in communities, but the mechanisms behind this pattern are still unclear. In the emergent neutrality model, species with similar niches and competitive ability self‐organise into clusters. In the hidden‐niche model, unaccounted‐for niche differences stabilise coexistence within clusters. Finally, clustering may occur through alliances of species that facilitate each other. We tested these hypotheses using population‐growth models that consider interspecific interactions parameterised for 35 species using field data. We simulated the expected community dynamics under different species‐interaction scenarios. Interspecific competition was weaker within rather than between clusters, suggesting that differences in unmeasured niche axes stabilise coexistence within clusters. Direct facilitation did not drive clustering. In contrast, indirect facilitation seemingly promoted species alliances in clusters whose members suppressed common competitors in other clusters. Such alliances have been overlooked in the literature on clustering, but may arise easily when within cluster competition is weak. [ABSTRACT FROM AUTHOR]

Over the last 4 decades, the rate of discovery of novel antibiotics has decreased drastically, ending the era of fortuitous antibiotic discovery. A better understanding of the biology of bacteriogenic toxins potentially helps to prospect for new antibiotics. To initiate this line of research, we quantified antagonists from two different sites at two different depths of soil and found the relative number of antagonists to correlate with the bacterial load and carbon-to-nitrogen (C/N) ratio of the soil. Consecutive studies show the importance of antagonist interactions between soil isolates and the lack of a predicted role for nutrient availability and, therefore, support an in situ role in offense for the production of toxins in environments of high bacterial loads. In addition, the production of extracellular DNAses (exDNases) and the ability to antagonize correlate strongly. Using an in domum-developed probabilistic cellular automaton model, we studied the consequences of exDNase production for both coexistence and diversity within a dynamic equilibrium. Our model demonstrates that exDNase-producing isolates involved in amensal interactions act to stabilize a community, leading to increased coexistence within a competitor-sensing interference competition environment. Our results signify that the environmental and biological cues that control natural-product formation are important for understanding antagonism and community dynamics, structure, and function, permitting the development of directed searches and the use of these insights for drug discovery. [ABSTRACT FROM AUTHOR]

The usual theoretical condition for coexistence is that each species in a community can increase when it is rare (mutual invasibility). Traditional coexistence theory implicitly assumes that the invading species is common enough that we can ignore demographic stochasticity but rare enough that it does not compete with itself, even after it has reached a stationary spatial distribution. However, short‐distance dispersal of discrete individuals leads to locally dense population clusters, and existing theory breaks down. We have an intuition that when we account for invader–invader competition, shorter‐range dispersal should reduce the invader's ability to escape competition, but exactly how does this translate into lower population growth? And how will invader discreteness affect outcomes? We need a way of partitioning the contributions to coexistence, but current modern coexistence theory (MCT) does not apply under these conditions. Here we present a computationally based partitioning method to quantify the contributions to coexistence from different mechanisms, as in MCT. We also build up an intuition for how invader clumping and discreteness will affect these contributions by analyzing a case study, a lattice‐based spatial lottery model. We first consider fluctuation‐dependent coexistence, partitioning the contributions of variable environment, variable competition, demographic stochasticity, and their correlations and interactions. Our second example examines fluctuation‐independent coexistence maintained by a fecundity–survival trade‐off, and partitions the contributions to coexistence from interspecific differences in fecundity, in mortality, and in dispersal. We find that demographic stochasticity harms an invader, but only slightly. Localized invader dispersal, on the other hand, can have a strong effect. When invaders are more clumped, they compete with each other more intensely when rare, so they too become limited by environment‐competition covariance. More invader clumping also means that variation in competition changes from helping the invader to harming it. More broadly, invader clumping is likely to weaken any coexistence mechanism that relies on the invader escaping competition from the resident, because invader clumping means that the resident is no longer the only source of competition. [ABSTRACT FROM AUTHOR]

An understanding of the mechanisms that facilitate coexistence in ecological communities poses a major challenge to theoretical ecology. A popular paradigmatic scheme distinguishes between two qualitatively different processes that help species to coexist: stabilizing mechanisms increase niche differentiation, making the intraspecific competition stronger than the interspecific one, while equalizing mechanisms diminish fitness differences, making the competition less decisive. Here, we provide an analytic and numeric examination of the quantitative features associated with this scheme for a simple, two-species competition model. We show that the main metrics of persistence change only slightly along the stabilizing-equalizing continuum, where niche overlap increases while fitness differences decreases. Therefore, persistence properties cannot indicate the dominant mechanism that promotes coexistence and vice versa. Cross correlations between abundance time series are shown to provide a decent characterization of the mechanisms that promote coexistence. The relevance of these insights to the analysis of diverse assemblages is discussed. [ABSTRACT FROM AUTHOR]

Theorists have identified several mechanisms through which species that compete exploitatively for resources could coexist. By contrast, under the current theory, interference competitors could coexist only in rare circumstances. Yet, some types of interference competition, such as interspecific territoriality, are common. This mismatch between theory and nature inspired us to model interference competition in an eco‐evolutionary framework. We based the model on the life cycle of territorial birds and ran simulations to examine whether natural selection could rescue a superior interference competitor from extinction without driving a superior exploitative competitor extinct. We found that coexistence between interference competitors can occur over a wide range of ecologically plausible scenarios, and up to the highest levels of resource overlap. An important caveat is that coexistence requires the species to co‐evolve. Reductions in population size and levels of genetic variation could destabilise coexistence between interference competitors, and thereby increase extinction rates over current estimates. [ABSTRACT FROM AUTHOR]

Background Despite many studies on the importance of competition and plants' associations with mutualists and pathogens on plant performance and community organization, the joint effects of these two factors remain largely unexplored. Even less is known about how these joint effects vary through a plant's life in different environmental conditions and how they contribute to the long-term coexistence of species. Methods We investigated the role of plant–soil feedback (PSF) in intra- and interspecific competition, using two co-occurring dry grassland species as models. A two-phase PSF experiment was used. In the first phase, soil was conditioned by the two plant species. In the second, we assessed the effect of soil conditioning, competition and drought stress on seedling establishment, plant growth in the first and second vegetation season, and fruit production. We also estimated effects of different treatments on overall population growth rates and predicted the species' potential coexistence. Results Soil conditioning played a more important role in the early stages of the plants' life (seedling establishment and early growth) than competition. Specifically, we found strong negative intraspecific PSF for biomass production in the first year in both species. Although the effects of soil conditioning persisted in later stages of plant's life, competition and drought stress became more important. Surprisingly, models predicting species coexistence contrasted with the effects on individual life stages, showing that our model species benefit from their self-conditioned soil in the long run. Conclusions We provide evidence that the effects of PSF vary through plants' life stages. Our study suggests that we cannot easily predict the effects of soil conditioning on long-term coexistence of species using data only on performance at a single time as commonly done in PSF studies. We also show the importance of using as realistic environmental conditions as possible (such as drought stress experienced in dry grasslands) to draw reasonable conclusions on species coexistence. [ABSTRACT FROM AUTHOR]

The introduction and spread of non-indigenous species may have ecological, environmental and economic impacts where they invade. This work aims to study the morphological characteristics, the quantitative variables, the possibility of coexistence with other native species and the pathways of introduction of non-indigenous cladoceran Evadne nordmanni (Lovén, 1836) in the middle part of the Caspian Sea. Ballast water is a possible vector for the introduction of cladoceran Evadne nordmanni into the Caspian Sea. The abundance of Evadne nordmanni in all surveyed areas reached an average of 799 individuals/m3. Its biomass was 257.58 mg/m3. Evadne nordmanni significantly contributes to the abundance and biomass of zooplankton in the Middle Caspian Sea. The proportion of the dominant calanoida Acartia tonsa decreased from 71–90% to 40% with the appearance of Evadne nordmanni. Further investigations are needed to analyze the responsible route of Evadne nordmanni introduction to the Caspian Sea and its consequences on biodiversity; since this species is a predator and could have consequences on the feeding conditions of planktivorous fish in the Caspian Sea. [ABSTRACT FROM AUTHOR]

Intraspecific variation may be key to coexistence in diverse communities, with some even suggesting it is necessary for large numbers of competitors to coexist. However, theory provides little support for this argument, instead finding that intraspecific variation generally makes it more difficult for species to coexist. Here we present a model of competition where two species compete for two essential resources and individuals within populations vary in their ability to take up different resources. We found a range of cases where intraspecific variation expands the range of conditions under which coexistence can occur, which provides a mechanism that allows the ecologically neutral evolutionary stable strategy (ESS) to become ecologically stable. We demonstrate that this result relies on nonlinearity in the function that describes how traits map onto ecological function. A sigmoid mapping function is necessary in order to model essential resources because it allows for variation in an unbounded trait while maintaining biologically realistic boundaries on uptake rates, and differs from other kinds of nonlinearity, which only unidirectionally increase or decrease ecological function. The sigmoid function's nonlinearity spreads individuals unevenly along the growth function, which allows positive growth contributions from some individuals to compensate for growth loses from others, akin to source-sink dynamics, leading to coexistence. In this way, intraspecific trait variation is able to amplify niche differences, thereby strengthening coexistence. We discuss empirical systems beyond competition for essential resources in which piecewise functions (i.e., thresholds) are important. [ABSTRACT FROM AUTHOR]

• Competition among bees for floral resources influences visits to flower patches. • Fewer floral resources delay the switch to queen production and limit colony size. • Competition for floral resources not important for nest-site establishment success. • Spatial patterns of nest-site establishment influence consequences of competition. • Evidence of competition is strongly scale-dependent. Agricultural intensification is widely recognised as a primary driver of pollinator loss, but the success of land-management actions designed to remediate its impact is often mixed. Payments to farmers to increase habitat connectivity or the availability of floral and nesting resources may only result in short-term gains or even unintended consequences. The reasons may lie in changes to interaction networks or competition intensity that remain poorly understood. Models of pollination service typically implicitly assume pollinator population dynamics are regulated by nest-site availability, even though empirical evidence suggests nest-site occupancy is likely at least in part dependent on floral resource availability. To investigate the consequences of competition for floral resources in coarse-grained agricultural landscapes we extended an established model for bees combining optimal foraging and population dynamics, to include new functions for floral resource depletion and realistic colony dynamics. We find that intra-specific competition occurs late in the season forcing bees to forage underutilised sites situated further towards their foraging range limits. A lower rate of energy acquisition ultimately limits the size of the colony peak and delays its timing. Consequently, competition for floral resources can limit population size and distribution while at the same time contributing to a more stable and efficacious pollination service. Although competition was not found to be important in nest-site establishment success, the effect of a hunger gap early in the season on nest-site occupancy indirectly influences competition later in the season leading to complex outcomes. [ABSTRACT FROM AUTHOR]

Competition is a major determinant of where species occur and how species interact. Among carnivorans, interspecific competition is particularly apparent, as many of these species have evolved to be efficient killers. Theoretically, phylogenetically related carnivorans that occupy seasonal habitats, share common resources, and differ in body size by a factor of 2.5–10× should exhibit the most interference competition.Fishers Pekania pennanti and martens Martes americana and Martes caurina are members of the subfamily Guloninae (Mustelidae, Carnivora) that occupy forests throughout northern North America. These taxa occur sympatrically throughout much of their range, utilise similar habitats, and consume similar prey; fishers and martens also differ in body size by a factor 2–5×. Consequently, these two taxa appear to be locked in particularly strong interspecific competition and should attempt to limit competitive overlap.We review the current knowledge of this dyadic interaction in the framework of ecological niches and niche partitioning. In particular, we explore the three critical niche axes of diet, space, and time.We found that, in contrast to the traditional view of them being highly specialised, both martens and fishers are dietary generalists; however, they also appear to be specialists in complexity, at least in space and habitats. Collectively, martens and fishers exhibit high degrees of diet and habitat niche overlap across their ranges, and this overlap is likely to have the greatest fitness consequences for the smaller and subordinate martens. Nevertheless, fine‐scale habitat and prey partitioning, and especially partitioning along snow clines, seem to be the mechanisms by which these two taxa can coexist.We predict that rapid ecological change – especially from increasingly homogenised forests and prey communities, as well as from declining snow cover and snowpack due to climate warming – is likely to destabilise marten–fisher coexistence. As the climate continues to change, fishers and martens are likely to experience distributional and numerical shifts and increased isolation at their southern range boundaries, and vulnerable populations – especially of martens – will be driven to local extirpation. [ABSTRACT FROM AUTHOR]

Simple Summary: Information on species' niche differentiation will contribute to a greater understanding of the mechanisms of coexistence benefitting the conservation and management of ecological communities. The widespread reduction in apex predators and more restricted hunting management has con-tributed to an increase in the abundance of wild ungulates in the Qinling Mountains, presumably resulting in an intensifying interspecific competition pressure. However, the activity patterns of the species in this region are completely unknown due to difficulty in accessing the locations where they occur. Thus, we used camera trapping to systematically investigate spatial and temporal activity patterns of sympatric ungulates in the Qinling Mountains, where top predators are virtually absent. This intensive camera-trap survey elucidated much more detailed studies of spatial and temporal activity patterns in multiple sympatric wild ungulates under natural conditions. Further, our results provided detailed information of the spatial and temporal ecology of ungulate communities in forest ecosystems, which would be a guide to establishing conservation priorities as well as efficient management programs. Dramatic increases in populations of wild ungulates have brought a new ecological issue in the Qinling mountains. Information on species' niche differentiation will contribute to a greater understanding of the mechanisms of coexistence, so as to ultimately benefit the conservation and management of ecological communities. In this study, camera trapping was used to investigate spatial and temporal activity patterns of sympatric wild ungulates in the Qinling Mountains of China, where top predators were virtually absent. We obtained 15,584 independent detections of seven wild ungulate species during 93,606 camera-trap days from April 2014 to October 2017. Results showed that (i) the capture rate differed significantly across species, with the capture rate of reeve muntjac being significantly higher than that of other species; (ii) the wild boar had a higher occupancy rates (ψ = 0.888) than other six ungulates, and distance to settlements had a negative relationship with wild boar (β = −0.24 ± 0.17); (iii) the forest musk deer and mainland serow had low spatial overlaps with other five wild ungulates, while spatial overlap indices of any two given pairs of wild ungulates were relatively high; (iv) all wild ungulates species (expect wild boar) were mainly active during crepuscular and diurnal periods, and showed bimodal activity peaks at around 05:00–07:00 and 17:00–19:00; and finally, (v) all wild ungulates showed moderate to high temporal overlaps. The results provided detailed information of the spatial and temporal ecology of wild ungulate communities in forest ecosystems of China, which also would be a guide to establish conservation priorities as well as efficient management programs. [ABSTRACT FROM AUTHOR]

The genus Placobdella (Glossiphoniidae) has a centre of species concentration in North America. The type species P. costata is the only representative in the Palaearctic region. American Placobdella which feed on turtles are represented predominantly by two common species, P. parasitica and P. rugosa, which geographically overlap in eastern USA and southern Canada. The latter species is morphologically indistinguishable from P. multilineata of southeast USA. These two tuberculated forms are recognised herein as a clade and treated as a single 'species' for comparative purposes. Both P. parasitica and P. rugosa clade commonly coexist and feed on the same turtle species without host preference. This paper addresses morphological differences between them. An unexpected finding is that hatchlings of both species are very difficult to distinguish. A morphologically significant observation is that developmental divergence results in tubercle prominence in P. rugosa clade, but tubercle suppression in P. parasitica, the first example of character displacement in the Hirudinea. Morphological differences are interpreted as reflecting interspecific competition, a phenomenon not found in their Palaearctic counterpart. Why do the two American turtle leech species coexist rather than reduce competition by partitioning their food supply? [ABSTRACT FROM AUTHOR]

Sympatric carnivores compete for similar resources which may lead to dominant species influencing the ecology of subordinate ones. However, carnivores often make use of coevolutionary strategies which enable them to minimise competition with dominant competitors and thus facilitate coexistence. We used camera trapping and scat analysis to investigate the potential competition between leopards (Panthera pardus) and caracals (Caracal caracal) along spatial, temporal and dietary axes to determine the mechanisms of their coexistence in the Cederberg, South Africa. Our results showed that both carnivores co‐occurred at 39.73% of camera trapping sites, but spatial overlap based on Pianka's index was relatively low. We found a high overlap in daily activity patterns between these carnivore species both during winter and summer. Leopards and caracals exhibited fine‐scale behavioural avoidance of one another, with time‐to‐encounters between interspecific competitors being significantly larger compared to intraspecific competitors. The two carnivores had a relatively high diet overlap, although this was largely due to one prey species, namely rock hyrax (Procavia capensis), which appears to be an important shared prey item. However, we did find evidence of dietary niche segregation, as leopards consumed larger prey compared to caracals. Our study suggests that carnivore coexistence in the Cederberg is facilitated by a combination of population‐level partitioning in space‐use and dietary habits, as well as fine‐scale behavioural avoidance at the individual level to reduce interference competition. This study provides insights into the competition and coexistence mechanisms between sympatric carnivores and broadens our understanding of these ecological processes in carnivore guild systems. [ABSTRACT FROM AUTHOR]

Competition is often highlighted as a major force influencing plant species diversity. However, there are multiple facets of competition (e.g., strength, intransitivity, and size asymmetry) that may have independent and differential impacts on diversity, making understanding the degree to which competition structures communities difficult. Unfortunately, field‐based experiments that decouple multiple facets of competition are lacking, limiting our ability to test theoretical frameworks and reducing understanding of the actual linkages among competition and coexistence. Here, we experimentally manipulate the size structure of local grassland communities to examine the relative impacts of competitive size asymmetry (i.e., competitive advantage based on relative size) and intensity (i.e., mean effect of neighbors on plant growth) on species loss and gain. Increased competitive size asymmetry was associated with increased species loss and decreased species gain, while no relationship was found between competitive intensity and species loss and gain. Furthermore, the probability of loss was not dependent on a species initial size, suggesting that small species may not always be the losers of size‐asymmetric interactions. Instead, loss was dependent on species rarity, where loss was higher for rare species. Overall, these results suggest that competitive size asymmetry may be more important for species loss than intensity in some plant communities and demonstrates the importance of decoupling different aspects of competition to better understand their drivers and ecological consequences. [ABSTRACT FROM AUTHOR]

Simple Summary: The mechanisms of coexistence between large carnivores are critical for conservation and the management of endangered species. In northeastern China, the distributions of Asiatic black bears (Ursus thibetanus) and brown bears (Ursus arctos) overlap widely. To better understand the mechanisms of coexistence among sympatric Asiatic black bears and brown bears, we assessed their spatial–temporal patterns using camera trapping data in Taipinggou National Nature Reserve, Heilongjiang Province, China. We found evidence for spatial and temporal divergences among the two Ursidae species. Asiatic black bears avoided brown bears by occupying higher elevations and being more diurnal where they coexisted. This study demonstrated how two bear species coexist through spatial and temporal niche separation, which will facilitate future studies on the mechanisms determining the coexistence of species and provide new basic data for animal conservation. Studying the spatial and temporal interactions between sympatric animal species is essential for understanding the mechanisms of interspecific coexistence. Both Asiatic black bears (Ursus thibetanus) and brown bears (Ursus arctos) inhabit northeastern China, but their spatial–temporal patterns and the mechanism of coexistence were unclear until now. Camera traps were set in Heilongjiang Taipinggou National Nature Reserve (TPGNR) from January 2017 to December 2017 to collect photos of the two sympatric bear species. The Pianka index, kernel density estimation, and the coefficient of overlap were used to analyze the spatial and temporal patterns of the two sympatric species. Our findings indicated that the spatial overlap between Asiatic black bears and brown bears was low, as Asiatic black bears occupied higher elevations than brown bears. The two species' temporal activity patterns were similar at sites where only one species existed, yet they were different at the co–occurrence sites. Asiatic black bears and brown bears are competitors in this area, but they can coexist by changing their daily activity patterns. Compared to brown bears, Asiatic black bears behaved more diurnally. Our study revealed distinct spatial and temporal differentiation within the two species in TPGNR, which can reduce interspecific competition and facilitate coexistence between them. [ABSTRACT FROM AUTHOR]

Plant competition may intensify with climate warming, but whether this will occur equally for conspecific and heterospecific competition remains unknown. Competitive shifts have the potential to instigate community change because the relative strengths of conspecific and heterospecific negative density dependence mediate the stabilizing mechanisms underpinning species coexistence. We examined a mature temperate forest to assess both direct and indirect climate effects at multiple scales: individual species, interspecies relationships, and community stability mechanisms. Our coupled approach (1) quantified tree mortality risk dependence on the interactive effects of competition, climatic water deficit, snowpack, and soil moisture for 28,913 trees over 8 years (3149 mortalities), then (2) used a climate‐projection ensemble to forecast changes in conspecific and heterospecific competition from 2020 to 2100. We predict that projected climate warming will destabilize the foundational forest community by increasing the strength of heterospecific competition at a greater rate and to a greater degree than conspecific competition for four of five abundant tree species, particularly on dry microsites. Modeling showed that these findings were most pronounced after the year 2038, at which point snowpacks were projected to be too small to ameliorate the effects of drought on competitive interactions. Our finding that heterospecific competition is more sensitive than conspecific competition to climate warming may indicate the impending loss of ecosystem functioning. We join the growing body of work showing a predominance of indirect drought effects, yet coupled climate models still fail to consider how changing community dynamics may impact forest cover and, in turn, disrupt forest–climate carbon feedbacks. Ecosystems sharing characteristics with our example forest—those with low species richness and therefore a limited biodiversity insurance effect—may be similarly vulnerable to climate‐mediated destabilization. In such communities, increased heterospecific competition among even a small number of species can more easily destabilize communities without recourse from redundant species. This study of an overlooked but vital mechanism of community change can be adapted by research in a range of ecosystems to improve the understanding of climate change consequences. [ABSTRACT FROM AUTHOR]

Although early theoretical work suggests that competition for light erodes successional diversity in forests, verbal models and recent numerical work with complex mechanistic forest simulators suggest that disturbance in such systems can maintain successional diversity. Nonetheless, if and how allocation trade‐offs between competitors interact with disturbance to maintain high diversity in successional systems remains poorly understood. Here, using mechanistic and analytically tractable models, we show that a theoretically unlimited number of coexisting species can be maintained by allocational trade‐offs such as investing in light‐harvesting organs versus height growth, investing in reproduction versus growth or survival versus growth. The models describe the successional dynamics of a forest composed of many patches subjected to random or periodic disturbance, and are consistent with physiologically mechanistic terrestrial ecosystem models, including the terrestrial components of recent Earth System Models. We show that coexistence arises in our models because species specialize in the successional time they best exploit the light environment and convert resources into seeds or contribute to advance regeneration. We also show that our results are relevant to non‐forested ecosystems by demonstrating the emergence of similar dynamics in a mechanistic model of competition for light among annual plant species. Finally, we show that coexistence in our models is relatively robust to the introduction of intraspecific variability that weakens the competitive hierarchy caused by asymmetric competition for light. [ABSTRACT FROM AUTHOR]

Eastern spotted skunks are of conservation concern, where competition and predation are possible causes of their decline. Using camera traps at a food subsidy, we investigated nocturnal temporal overlap of spotted skunks with co-occurring predators. Spotted skunks were more active during dark nights, when their activity overlapped with the largest predator (coyotes), but not with other mesopredators, thus possibly avoiding interspecific competition. Spotted skunk activity shifted during moonlit nights, where overlap with all predators was reduced, suggesting avoidance of both predators and competitors. This implies that both predation and interspecific competition could limit spotted skunk populations, and one mechanism they apply to coexist is nocturnal light-specific temporal partitioning. [ABSTRACT FROM AUTHOR]

Both competition for water and phenological variation are important determinants of plant community structure, but ecologists lack a synthetic theory for how they affect coexistence outcomes. We developed an analytically tractable model of water competition for Mediterranean annual communities and demonstrated that variation in phenology alone can maintain high diversity in spatially homogenous assemblages of water‐limited plants. We modelled a system where all water arrives early in the season and species vary in their ability to grow under drying conditions. As a consequence, species differ in growing season length and compete by shortening the growing season of their competitors. This model replicates and offers mechanistic explanations for patterns observed in empirical studies of how phenology influences coexistence among Mediterranean annuals. Additionally, we found that a decreasing, concave‐up trade‐off between growth rate and access to water can maintain high diversity under simple but realistic assumptions. High diversity is possible because: (1) later plants escape competition after their earlier season competitors have gone to seed and (2) early‐season species are more than compensated for their shortened growing season by a growth rate advantage. Together, these mechanisms provide an explanation for how phenologically variable annual plant species might coexist when competing only for water. [ABSTRACT FROM AUTHOR]

Unravelling how biodiversity is maintained despite species competition for shared resources has been a central question in community ecology, and is gaining relevance amidst the current biodiversity crisis. Yet, we have still a poor understanding of the mechanisms that regulate species coexistence and shape the structure of assemblages in highly competitive environments such as carrion pulsed resources. Here, we study how large vertebrates coexist in scavenger assemblages by adapting their diel activity at large ungulate carcasses in NW Spain. We used camera traps to record vertebrate scavengers consuming 34 carcasses of livestock and hunted wild ungulates, which allowed us to assess also differences regarding carcass origin. To evaluate temporal resource partition among species, we estimated the overlap of diel activity patterns and the mean times of each scavenger at carcasses. We recorded 16 species of scavengers, 7 mammals and 9 birds, and found similar richness at both types of carcasses. Birds and mammals showed contrasting diel activity patterns, with birds using carcasses during daytime (mean= 11:38 h) and mammals mostly at night (23:09 h). The unimodal activity patterns of scavengers showed asynchronous peaks among species. Subordinate species modified their activity patterns at carcasses used by apex species to reduce temporal overlap. Also, diel activity patterns of vultures closely followed those of corvids, suggesting facilitation processes in which corvids would enhance carcass detection by vultures. Two mammal species (12.5%) increased nocturnality at carcasses of hunted ungulates, which could be a response to human disturbance. Our results suggest that both temporal segregation and coupling mediate the coexistence of large vertebrates at carcasses. These mechanisms might lead to richer scavenger assemblages and thereby more efficient ones in driving critical ecosystem functions related to carrion consumption, such as energy and nutrient recycling and biodiversity maintenance. [ABSTRACT FROM AUTHOR]

Many different analyses have shown how antagonistic interactions (e.g. predation, disease, interference competition) can foster the coexistence of two species that compete for a single resource. In contrast, whether interactions with mutualist partners can similarly foster coexistence between resource competitors has been little considered. Here, we derive a mechanistic model of two plant species that compete for a single abiotic resource and that each produce nectar that supports a single shared pollinator species. In our model, plant coexistence requires three relationships: 1) one plant species must be better at utilizing the abiotic resource to produce more ovules; 2) this better resource competitor must also be more pollen‐limited in the absence of the pollinator; and 3) this species must produce much less nectar, such that pollinator abundance depends primarily on nectar produced by the less pollen‐limited species. Pollinators can also shape the competitive hierarchy among plant species without promoting coexistence, an influence determined by the amount of nectar produced by the entire plant assemblage that supports pollinator abundance. Our results show that patterns of pollen limitation and nectar production across competing plant species will be essential data to evaluating whether pollinators may foster the plants' coexistence. [ABSTRACT FROM AUTHOR]