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The fundamental ecological niche is determined by individuals' ability to cope with abiotic conditions; however, biotic interactions (e.g., competition) can also influence species' distribution ranges, reducing the fundamental niche to the realized niche. Several species of the genera Clibanarius and Calcinus overlap in their distributions. The agonistically dominant Calcinus species inhabits mostly lower intertidal levels, while Clibanarius is more abundant in the abiotically demanding upper strata. Additionally, evidence of microhabitat competitive exclusion shows that the superior competitor, Ca. californiensis, causes the vertical displacement of Cl. albidigitus. However, it is unknown whether competitive exclusion between species of these genera has influenced their distributions at the macroecological scale. We used ecological niche models to compare the distribution and the habitat suitability of species of these genera. We used databases of species occurrences and bioclimatic and geophysical variables to model and map the species' niches. Species of the two hermit crab genera showed strong overlap in their habitat suitability. Calcinus and Clibanarius species occur in broad sympatry at the regional scale without regions of partial overlap that would indicate competitive exclusion. Therefore, competitive exclusion among species of these genera seems to act only on a microhabitat scale in the most dynamic shoreline areas. [ABSTRACT FROM AUTHOR]

Benthic amphipod feeding groups are a well-established trophic classification that is mostly based on field observations and laboratory tests and are used in ecological studies to monitor the ecological state of benthic ecosystems. Globally, carbon and nitrogen stable isotope ratio investigations have provided confirmation of, and novel insights into, the trophic ecology of benthic animals, such as polychaetes. However, stable isotopic examinations of benthic amphipods have been limited. Here, we used microgram samples to compare the species-specific dietary sources, trophic positions, and isotopic niche overlap of selected benthic amphipods from the Gulf of Kachchh, Marine National Park, using elemental analyser-isotopic ratio mass spectrometry (EA-IRMS) of carbon and nitrogen. Overall, all primary carbon sources presented wide variation in the isotopic values of δ13C (6.3‰) and δ15N (greater than 13‰). Conversely, the amphipod taxa displayed relatively narrow range for δ13C (3.9‰) and wider range for δ15N (more than 10‰). The results of the Bayesian mixing model revealed that the benthic amphipods had species-specific feeding preferences. However, the predominant carbon source was organic matter in sediment which reinforced benthic pathways for energy flow for most species. According to the estimated trophic level values (1.62–3.39), these species play a significant role as primary and secondary consumers serving as crucial trophic intermediaries in the food chain, connecting the base to the top consumers. High overlapping ecological niche amongst species was detected by SIBER analysis which indicated co-existence of the benthic amphipods in their respective microhabitats. This signifies wider utilisation of resources and inter-specific feeding preferences with minimal competition amongst amphipod species. [ABSTRACT FROM AUTHOR]

Motivation for abandoning the ‘environmental filtering’ metaphor has been increasing in the literature, yet it remains a widely used conceptual tool to guide research and education within ecological disciplines. I consider the possible origins of the filtering paradigm through linkages to hypotheses about the potentially oversized role of localized competition in the early development of niche concepts, as well as assumptions about the scale dependence of factors influencing the species distributions at large scales. I believe that these perspectives may have discounted the relevance of non‐competitive interactions to the structure and maintenance of local communities, and the role of biotic interactions in large‐scale ecological processes more generally. I describe the types of ecological phenomena not readily captured by the filtering model, as well as the potential for biotic factors to interact with abiotic gradients (at scale) and influence broad ecological patterns. Lastly, I pose an alternative model of community assembly which emphasizes biotic–abiotic interactions and non‐filtering mechanisms to serve as a springboard for future renovations of the filtering metaphor. [ABSTRACT FROM AUTHOR]

Understanding species coexistence requires information about how species interact and partition their ecological niche. Niches of closely related species tend to be quite similar and thereby, when syntopic, overlap can result in competition when shared resources are limiting. Brocket deer of tropical forests are ecologically similar species due to convergence or relatedness. As a group, what little is known about their ecology suggests spatial and temporal niche separation while dietary differences among species remain largely unknown. The possibility of competition has been suggested, as it is rare for more than two species to co‐occur. If competition is important, then it may limit syntopy of more species and its importance should increase with relatedness between species. Based on analyses of faecal samples, camera traps, and stable isotopes and multidimensional analysis of niche space, we test spatial, temporal and dietary niche differences and compare niche breadth in two syntopic species pairs: Mazama rufa with M. nana (both of subtribe Odocoileina) and M. jucunda (Odocoileina) with Subulo gouazoubira (Blastocerina). In 2007–2008 and 2017–2019, 240 faecal samples and 375 records were collected in the Brazilian Atlantic Forest. Spatial partitioning among both species pairs was found, with S. gouazoubira and M. nana having greater niche breadth, which may permit or facilitate coexistence. Odocoileina tend to be nocturnal, while Blastocerina tend to be diurnal, which suggests that phylogeny may influence species coexistence. Furthermore, the species tended to overlap with respect to diet. These results suggest interference competition avoidance by niche partitioning at the level of habitat and time, allowing coexistence. Thereby, despite the morphological similarities, brocket deer species of evolutionarily convergent subtribes preserve differences in ecological niche dimensions that facilitate the coexistence of their populations. [ABSTRACT FROM AUTHOR]

A new stage in promoting the construction of the Silk Road Economic Belt Core Area, and Xinjiang has been transformed from a relatively closed inland area into an open border. In order to promote the high-quality development of Southern Xinjiang and solve the imbalance contradiction between the development of the Northern Xinjiang and Southern Xinjiang, taking the four districts in Southern Xinjiang as the study area, constructing a high-quality development ecological niche index system of three levels, namely economic, social and ecological, adopting the entropy method to assign weights to the evaluation indexes, and measuring the ecological niche width and the degree of ecological niche overlap of this region in the period from 2011 to 2020. The results show that: Firstly, tourism has the greatest impact on the ecological niche of economic development in state N, with a weighting of 14.18%; Secondly, the ecological status width of economic development in state N demonstrates a structural characteristic of "low level and low gap". The average value of ecological niche width is at class III, indicating a low development status and weak regional influence; Thirdly, the ecological niche overlap of state N is significantly influenced by spatial factors. Regions Z and S are closer together, resulting in higher competition for resource utilization and an average ecological niche overlap at class II. The other two regions are at class III. According to the theory of ecological niche expansion and separation, a specialization separation strategy should be adopted for areas with "low width and high overlap", and a strengthening expansion strategy should be adopted for areas with "low width and low overlap", to optimize the structure of ecological niches and promote high-quality development of the region. [ABSTRACT FROM AUTHOR]

Competition is a prominent mechanism driving population dynamics and structuring community assemblage, which can be investigated by linking shifts in species' ecological niche and the densities of sympatric species because the ecological release from competitive constraints is a density‐dependent process. In this work we determine how a steppe passerine community segregates their ecological niches and evaluate the role of competition in inducing changes in the ecological niche of species. We built multidimensional ecological niches (with Gaussian kernel density estimators) using data on the habitat features used by 10 bird species collected from seven sites in the natural steppes of Central Spain over 2 consecutive years. We computed distance and niche similarity metrics to explore the ecological niche partitioning of the bird community. Next, we ran multivariate linear regression models to evaluate the effects of conspecific and heterospecific density (as proxies of intraspecific and interspecific competition, respectively) on niche breadth and/or position of the three most abundant species. We found low niche overlap in the community assemblage but varying levels of niche similarity among pairs of species, which could increase the likelihood of current competition operating in the community. However, we found no effect of heterospecific density on niche breadth or position, although conspecific density was negatively related to niche breadth. Contrary to predictions of competition theory, increased density of conspecifics caused niche contraction. Our results from a multispecies system contribute to advanced knowledge of the biotic mechanisms structuring wildlife communities within the framework of ecological niche theory. [ABSTRACT FROM AUTHOR]

Alpine wetland degradation threatens riparian biodiversity and ecological balance. Our study, conducted in July 2020 along the northern and eastern shores of Qinghai Lake, seeks to unravel the impacts of such degradation on plant species dominance and ecological niches, using advanced network analysis methods to explore the dynamics and survival strategies of plant species. We applied a space-to-time method to delineate three wetland degradation stage: a healthy swamp wetland, a slightly degraded wet meadow, and a degraded dry meadow. Six representative sampling points were chosen. At each point, three sample lines were randomly established, radiating outward from the center of the lake wetland, with each stage of degradation meticulously examined through three replicates to assess the plant communities in terms of species composition, plant height, coverage, and abundance. The results indicated: Species such as Kobresia tibetica and Leymus secalinus exhibit remarkable abundance across various stages of wetland degradation, indicating a robust tolerance to these conditions. This observation, coupled with the complexity of plant community structures in degrading wetlands, suggests that such intricacy cannot be solely attributed to the dominance of particular species. Instead, it is the result of a diverse array of species adapting to fluctuating water levels, which promotes increased species richness. Despite the prominence of species that exhibit rapid growth and reproduction, the ecological significance of less abundant species in contributing to the community's complexity is also notable. Changes in habitat conditions due to wetland degradation facilitate both competitive and cooperative interactions among species, highlighting the dynamic nature of these ecosystems. Our analysis shows no significant linear relationship between the ecological niche overlap values and niche widths of plant species. However, the strategies employed by dominant species for competition and resource acquisition, as observed in the ecological niche overlap networks, underscore the adaptive capacity of plant communities. These insights underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide. Our findings underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide. [ABSTRACT FROM AUTHOR]

Because spiders have a great variety of strategies to capture their prey they have been grouped into ecological guilds. The objective of this study was to determine the composition and structure of spider communities in coffee plantations with different management systems (monoculture and polyculture shade), through their classification into ecological guilds and their graphic categorization. Polyculture was the site with the highest species richness. In general, the abundance of spiders was significantly lower in the polyculture. The guild of diurnal space web-weavers spiders was the most abundant in both coffee sites. Abundance of the guilds of nocturnal aerial runners and nocturnal aerial ambushers were significantly lower in the polyculture, while the guild of diurnal ambushers was significantly lower in the monoculture. Abundance dif ferences were observed between guild hierarchies across sites and seasons. This first analysis of guilds allows us to understand the competition for resources and the ecological niche requirements of spiders in coffee plantations in Oaxaca, Mexico. [ABSTRACT FROM AUTHOR]

Ecological niche partitioning is crucial in reducing interspecific competition, fostering species coexistence, and preserving biodiversity. Our research, conducted in a hybrid mixed oak forest in Yushan, Jiangsu, China, focuses on Quercus acutissima, Q. variabilis, Q. fabri, and Q. serrata var. brevipetiolata. Using Point Pattern Analysis, we investigated the spatial relationships and ecological trait autocorrelation, including total carbon (TC), nitrogen (TN), phosphorus (TP), potassium (TK), and breast height diameter (DBH). Our findings show aggregated distribution patterns within the oak populations. The Inhomogeneous Poisson Point model highlights the impact of environmental heterogeneity on Q. variabilis, leading to distinct distribution patterns, while other species showed wider dispersion. This study reveals aggregated interspecific interactions, with a notable dispersal pattern between Q. acutissima and Q. variabilis. We observed significant variability in nutrient elements, indicating distinct nutrient dynamics and uptake processes. The variations in total carbon (TC), nitrogen (TN), phosphorus (TP), and potassium (TK) suggest distinct nutrient dynamics, with TK showing the highest variability. Despite variations in TC, TK, and TP, the species did not form distinct classes, suggesting overlapping nutritional strategies and environmental adaptations. Furthermore, spatial autocorrelation analysis indicates strong positive correlations for DBH, TC, and TP, whereas TK and TN correlations are non-significant. The results suggest habitat filtering as a key driver in intraspecific relationships, with a finer spatial scale of ecological niche division through TC and TP, which is crucial for maintaining coexistence among these oak species. [ABSTRACT FROM AUTHOR]

Background: Semi-enclosed bays are important links in the material cycle and energy flow between terrestrial and marine ecosystems. They are also areas of intense human activities and heavily influenced by such activities as aquaculture, industrial and agricultural wastewater discharge. The rate of biodiversity loss and changes in ecosystems have prompted research into the relationship between species diversity and ecosystem functioning. Studies have shown that application of functional diversity indices is useful for assessing the status of ecosystem functioning. We quantitatively sampled macrofauna in a semi-enclosed bay in four seasons and analyzed the relationship between species, functional diversity and secondary production, biomass and feeding functional groups of macrofauna. Results: The annual secondary production was 325.01 kJ m−2 year−1. Detritivorous, carnivorous and planktophagous feeders were the main functional groups of macrofauna. Differences in the spatial–temporal distribution of functional groups were influenced by Ruditapes philippinarum and Hemileucon bidentatus. Functional richness had significant negative correlations with macrofaunal biomass and secondary production. Functional divergence, functional dispersion and Rao's quadratic entropy had highly significant negative correlations with macrofaunal biomass and secondary production. Conclusion: The results showed that high overlap of ecological niches can increase competition for habitat resources, leading to a decline in biomass and secondary production. In addition, aquaculture could promote the use of habitat resources to some extent, while it could increase competition for ecosystem resources (including habitat resources, atmospheric resources, water resources, etc.). Functional diversity is a good indicator for the ecosystem functioning and the competition status for habitat resources, which can provide insights into the current state of ecosystem function. [ABSTRACT FROM AUTHOR]

Context: Invasive species can threaten native species through exploitative and interference competition if they occupy similar ecological niches. The invasive plague skink (Lampropholis delicata) has been accidently introduced to New Zealand, Lord Howe Island, and the Hawaiian Islands. Resource usage overlaps between plague skinks and several New Zealand skinks, suggesting the potential for exploitative and interference competition. However, no competitive mechanism or population impact has been identified. In 2014–15, plague skinks colonised Bream Head Scenic Reserve, Northland, New Zealand, where they overlap in occupancy and habitat with the 'Nationally Critical' kakerakau skink (Oligosoma kakerakau). Aims: We investigated intra- and interspecific interference competition between kakerakau and plague skinks in the wild. Methods: We recorded naturally occurring encounters and quantified aggression at a short-lived resource (sun-basking sites). Key results: Behavioural interactions were observed in 72% of all encounters with similar proportions of encounters resulting in agonistic interactions between intraspecific kakerakau skink encounters and interspecific kakerakau-plague encounters. Although kakerakau skinks and plague skinks reacted equally aggressively in an interspecific interaction, kakerakau skinks behaved significantly more aggressively in an interaction with a plague skink than with a conspecific. Juvenile kakerakau skinks were more likely than adults to exhibit submissive behaviours such as fleeing during interspecific interactions. Conclusions: This is the first evidence of interference competition occurring between plague skinks and a native skink. Our study suggests that kakerakau skinks, particularly juveniles, may experience competitive exclusion at important resources. Implications: Our findings indicate that plague skinks may pose a threat to native skink populations when habitat use overlaps. Biological invasions are a major cause of biodiversity loss. However, the behavioural interactions occurring between native and invasive species are often unknown. We report aggression in the wild between the invasive plague skink and a native New Zealand skink. Our study demonstrates that plague skinks may pose a threat to native skinks. [ABSTRACT FROM AUTHOR]

Rodents are important reservoirs for zoonotic pathogens that cause diseases in humans. Biodiversity is hypothesized to be closely related to pathogen prevalence through multiple direct and indirect pathways. For example, the presence of non‐host species can reduce contact rates of the main reservoir host and thus reduce the risk of transmission ("dilution effect"). In addition, an overlap in ecological niches between two species could lead to increased interspecific competition, potentially limiting host densities and reducing density‐dependent pathogen transmission processes. In this study, we investigated the relative impact of population‐level regulation of direct and indirect drivers of the prevalence of Puumala orthohantavirus (PUUV) in bank voles (Clethrionomys glareolus) during years with high abundance. We compiled data on small mammal community composition from four regions in Germany between 2010 and 2013. Structural equation modeling revealed a strong seasonality in PUUV control mechanisms in bank voles. The abundance of shrews tended to have a negative relationship with host abundance, and host abundance positively influenced PUUV seroprevalence, while at the same time increasing the abundance of competing non‐hosts like the wood mouse (Apodemus sylvaticus) and the yellow‐necked field mouse (Apodemus flavicollis) were associated with reduced PUUV seroprevalence in the host. These results indicate that for PUUV in bank voles, dilution is associated with increased interspecific competition. Anthropogenic pressures leading to the decline of Apodemus spp. in a specific habitat could lead to the amplification of mechanisms promoting PUUV transmission within the host populations. [ABSTRACT FROM AUTHOR]

Multi-species assemblages can help identify key resources in their habitat by evaluating how they are partitioning their resources. Here we used the isotopic niche of loggerhead, Kemp's ridley, and green sea turtles to assess their ecological niche within a Gulf of Mexico bay. Additionally, we assessed temporal and size-class variation in their diets by comparing the δ13C and δ15N values over various capture years and size classes. Based on the isotopic niche overlap results, interspecific competition occurs among loggerhead, Kemp's ridley, and smaller green turtles. Green turtle and Kemp's ridley diet varied by size class, while Kemp's ridley diet also varied temporally. The three species partition resources by selecting different preferred diet items, although some overlap in diet, including between the herbivorous (green) and carnivorous (Kemp's ridley, loggerhead) species, appears to occur. The high quality of this habitat may allow species co-existence and population recovery despite the possible use of shared resources. [ABSTRACT FROM AUTHOR]

Species within the same ecological guild exhibit niche attributes that vary in association with their diet, spatial occupancy, and temporal activity to reduce competition. In the case of the tropical felid community, many species exhibit substantial overlap in these niche dimensions. Consequently, jaguars (Panthera onca) will sometimes kill the smaller ocelot (Leopardus pardalis) competitor in a phenomenon called intraguild predation (IGP), which is a major structuring force in tropical forests. We developed a spatially explicit agent-based model to understand IGP with the expectation that ocelots employ spatial avoidance strategies using available forest canopy as the more arboreal species. We parameterized model agents with realistic behaviors to replicate the real-world environment. Jaguar and ocelot agents were allowed to move, hunt, and reproduce with varying numbers, heights, and canopy thickness of trees as we recorded IGP events and ocelot canopy occupancy. We used structural equation modeling (SEM) to demonstrate how the number and height of trees significantly affected IGP occurrence. In accordance with our hypothesis, we found that the main contributor mediating coexistence between the two species was spatial avoidance of jaguars by ocelots by using available canopy refuges. Our modeling approach has broad application to different environments with similar intraguild interactions to predict the importance of forest structure and can inform policy directed toward forest management and habitat conservation. [ABSTRACT FROM AUTHOR]

Microbial interactions affect community stability and niche spaces in all ecosystems. However, it is not clear what factors influence these interactions, leading to changes in species fitness and ecological niches. Here, we utilized 16 monocultures and their corresponding pairwise co-cultures to measure niche changes among 16 cultivable bacterial species in a wide range of carbon sources, and we used resource availability as a parameter to alter the interactions of the synthetic bacterial community. Our results suggest that metabolic similarity drives niche deformation between bacterial species. We further found that resource limitation resulted in increased microbial inhibition and more negative interactions. At high resource availability, bacteria exhibited little inhibitory potential and stronger facilitation (in 71% of cases), promoting niche expansion. Overall, our results show that metabolic similarity induces different degrees of resource competition, altering pairwise interactions within the synthetic community and potentially modulating bacterial niches. This framework may lay the basis for understanding complex niche deformation and microbial interactions as modulated by metabolic similarity and resource availability. [ABSTRACT FROM AUTHOR]

Competition arises when species share a limited resource, but this can be avoided through niche partitioning. Despite the large body of literature on diadromous fishes, very few studies have focused on niche partitioning when competing for resources. Diadromous fishes are suffering a global decline throughout their range in part due to their peculiar life history traits as they migrate from the sea to freshwater to spawn or the reverse. They are particularly sensitive to river fragmentation induced by barriers. Dams for instance are expected to alter the spatial distribution and resource exploitation of diadromous fishes as well as other organisms. Here, we studied the ecological niche of six taxa of diadromous fishes, temporally co-occurring in the same land-sea continuum obstructed by two river dams. We used Bayesian mixing models run on C and N isotopes to infer the various habitats used and the origin of the trophic carbon in muscle and scale tissues of diadromous fishes. Results showed that the sub-adults of Anguilla anguilla, juveniles of Petromyzon marinus, and Salmo trutta exploit mainly the freshwater, or marine part for adults of Lampetra fluviatilis, whereas juveniles of Platichthys flesus and Mugilidae use all the habitats of the land-sea continuum. In the freshwater habitat, the microphytobenthos and biofilm are the main sources of carbon used, while in the marine habitat, the basal carbon sources are more diverse. The analyses of niche overlaps between diadromous fishes demonstrate that the widest isotopic niches, observed for A. anguilla and P. flesus, also have more impact within the community. Results are discussed in terms of intra- and interspecific competition between these diadromous fishes and their generalist/specialist strategies in an obstructed catchment. [ABSTRACT FROM AUTHOR]

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Aim: Quantifying niche shifts of non‐native species and their interactions with natives is vital in evaluating invasion risk yet remains difficult. Climate filtering and competition with native congeners are two important processes impacting niche changes and yielding contradictory predictions for the coexistence of non‐native and native species. Closely related species representing the Eastern Asia (EA)–Eastern North America (ENA) floristic disjunction provide a powerful yet unexplored system for assessing the relative roles of these two processes. Here, we tested three niche change scenarios (unfilling, expansion and stable) using EA species naturalized in ENA. We aim to answer: (1) which scenario is observed for naturalized species? and (2) how has niche overlap between EA and ENA congeners changed after naturalization? Location: ENA and EA. Time Period: Present. Major Taxa Studied: Angiosperms. Methods: Niches were estimated using both occurrences and predictions generated by ecological niche models. Niche changes of naturalized species and their niche overlap with natives were measured using Schoener's D. Contributions of niche expansion and unfilling on niche changes of naturalized niches were evaluated using hierarchical partitioning and linear regressions. We further measured pairwise phylogenetic distances among EA and ENA congeners and evaluated the association with niche overlap. Results: Unfilling‐dominated postintroduction niche changes of the naturalized species. EA species naturalized in ENA exhibited lower niche overlap with ENA native congeners compared with native range populations in EA. These results remain when considering time since introduction and potential physical dispersal limitations interpreted by projecting suitable niche space between EA and ENA. However, dispersal limitation may contribute to the degree of niche unfilling. Main Conclusions: Using intercontinental disjunct species as a study system, we found that naturalization is shaped jointly by climate filtering and competition with native congeners, providing valuable insights for evaluating invasion risk underlying global floristic exchanges. [ABSTRACT FROM AUTHOR]

Phylogenetic diversity of plant communities can influence the interaction between plants, herbivores, and their natural enemies. Plant communities with phylogenetically distant species tend to present a wide variety of functional traits and ecological niches, which in turn can influence competitive interactions among plants as well as food and habitat quality for herbivores and their natural enemies. To assess some different mechanisms by which phylogenetic diversity of plant communities can influence herbivores and their natural enemies, we established 12 experimental plots of tropical trees with two treatments: high and low phylogenetic diversity. We measured plant growth and anti-herbivore defenses, herbivore foliar damage, and predator activity in seven species that were present in both treatments. We found significant differences in the expression of plant traits as a function of species identity and their life history, but also depending on the phylogenetic context in which they grew. Pioneer species had higher growth and produced more phenolics in plots with high phylogenetic diversity versus plants in plots with low phylogenetic diversity. Accordingly, herbivore damage in these species was greater in plots with low phylogenetic diversity. Finally, predator activity on caterpillar clay models placed on plants was greater within the low phylogenetic diversity treatment, but only for non-myrmecophytic species. These results suggest that plant phylogenetic diversity can influence the expression of growth and defensive traits and further modify the interaction between plants, herbivores, and their natural enemies. However, such effects depend on plant life history and the presence of mutualistic interaction with ants. [ABSTRACT FROM AUTHOR]

Background: The influence of microbiota in ecological interactions, and in particular competition, is poorly known. We studied competition between two insect species, the invasive pest Drosophila suzukii and the model Drosophila melanogaster, whose larval ecological niches overlap in ripe, but not rotten, fruit. Results: We discovered D. suzukii females prevent costly interspecific larval competition by avoiding oviposition on substrates previously visited by D. melanogaster. More precisely, D. melanogaster association with gut bacteria of the genus Lactobacillus triggered D. suzukii avoidance. However, D. suzukii avoidance behavior is condition-dependent, and D. suzukii females that themselves carry D. melanogaster bacteria stop avoiding sites visited by D. melanogaster. The adaptive significance of avoiding cues from the competitor's microbiota was revealed by experimentally reproducing in-fruit larval competition: reduced survival of D. suzukii larvae only occurred if the competitor had its normal microbiota. Conclusions: This study establishes microbiotas as potent mediators of interspecific competition and reveals a central role for context-dependent behaviors under bacterial influence. 8rnTpNHTJmc8sxfvPzrBu3 Video Abstract [ABSTRACT FROM AUTHOR]

The coexistence of species with similar ecological niches implies that species must segregate along one or more niche axes in order to avoid competition. Partitioning of time, space, or resources is an essential niche dimension along which competitor species tend to coexist. The intensity of interspecific competition may vary under varying anthropogenic pressures, but such knowledge is scarce. We investigated the co‐occurrence patterns of two bear species, Asiatic Black Bear Ursus thibetanus and Himalayan Brown Bear Ursus arctos isabellinus, at two sites in the Western Himalayan region of India with similar ecological conditions and varying anthropogenic pressures. Camera trap datasets from the Great Himalayan National Park (GHNP) in Himachal Pradesh and the Bhagirathi basin in Uttarakhand were used to assess the species interactions. We used two species interaction models and kernel density estimates to understand the co‐occurrence pattern of the bear species and their interactions with humans. Our results provide insights into the spatiotemporal behavior of the two bear species and reveal their sympatric and allopatric relationships in two different anthropogenic environments. We found (1) a prominent association between the two bear species (98%) indicating spatial overlap in GHNP, but found spatial separation among the two species (93%) in Bhagirathi basin (2). In GHNP, the spatially co‐occurring bear species were found to be temporarily segregated, whereas in Bhagirathi, they showed spatial avoidance and similar activity patterns (3). In GHNP, human activities in the alpine habitat had a significant negative impact on brown bear presence. The comparative study revealed that the brown bear uses the forested habitats of GHNP due to high anthropogenic disturbances in the alpine areas, whereas no spatial association was observed in the Bhagirathi basin with comparatively low anthropogenic disturbances. The results highlight that, in addition to biological factors, anthropogenic pressures can also influence interspecific competition. [ABSTRACT FROM AUTHOR]

In order to reveal the status of habitat resource utilization and the degree of competition among lichens in Dabancheng mountainous areas. In this work, 30 plots were sampled in the field and the species cover data of the plots were investigated, and the niche characteristics and environmental factors of lichen community species were analyzed by using niche width, niche overlap index and ordination analysis in this Dabancheng mountainous area. The results were as follows:(1)The niche width of Rusavskia elegans and Circinaria contorta were the widest in Dabancheng mountainous area, indicating that they were more adaptable to different environments. The niche widths of other lichen species were narrow, indicating that the species used the environmental resources to a less extent.(2)The niche overlap value between species was generally low, with only a few species pairs having a high niche overlap value. The degree of niche differentiation between lichen species was high, indicating that the competition between species was not intense.(3)Although niche overlap was common among species with wider niche widths, niche overlap values were lower. However, some species with narrower niche widths had higher niche overlap values with other species. As a result, there was no clear linear relationship between niche overlap and niche width.(4)The distribution of lichen species varied along the altitudinal gradient, and altitude, light intensity, humidity, wind speed, and human disturbance were the dominant environmental factors for the different niche characteristics of lichen community species in the study area. In conclusion, as a result of habitat resource competition in Dabancheng mountainous area, lichen species occupied their own distinct niches, resulting in niche differentiation and relatively stable communities. The distribution of species differed significantly due to differences in habitat conditions along the altitudinal gradient. The results of this paper provides a theoretical basis for the study of lichen community assembly, which are of great significance to the conservation of lichen species diversity and habitat in the region. [ABSTRACT FROM AUTHOR]

The decapod fauna on intertidal shores in northern Chile is characterized by its relatively high diversity and abundance due to the presence of continuous upwelling by the Humboldt Current, which results in a high productivity. The decapod fauna on intertidal rocky shores is characterized by coexisting species that inhabits in natural shelters such as cracks and eroded rocks, as well as among macroalgae. We aimed to monitor the brachyuran and anomuran (porcellanid) crabs in three intertidal sites during two periods of time in September-December 2019 in the Antofagasta region, one site without human intervention and two sites in the city of Antofagasta, for which we applied null models in ecology. We assumed that the communities are random, a viewpoint that is more robust because it reduces the risk of error type I. The results of the application of null models on the co-occurrence species revealed that species associations are mainly structured for all sites, whereas the niche-sharing null model revealed that the reported species did not share ecological niches and in consequence there is not interspecific competition. The results would probably indicate that the species of intertidal decapods have a micro-specific ecological-niche differentiation, which would explain the existence of structured pattern in species associations. The results were compared with information for other sites along the continental Chilean coast. [ABSTRACT FROM AUTHOR]

Disentangling the multiple factors that shape the ecological niche of a species is often difficult, especially when in contact with other similar and potentially competing species. Ecological niche models (ENMs), albeit originally developed for environmental factors only, can help in assessing competition by comparing the niches of ecologically similar species. Here, we use ENMs and niche overlap tests to compare the ecological niches of the Western Mediterranean vipers, Vipera aspis and V. latastei, in the secondary contact zone of the High Ebro (Northern Spain), partitioning the species occurrences in sympatric and allopatric subsets. We considered nine geomorphological and landcover variables, obtained from remote sensing, and gathered at the meso‐habitat scale (100 × 100 m). Our ENMs showed partial interspecific divergence in habitat requirements between these two closely related species, with V. aspis selecting more canopied areas and V. latastei preferring more open habitats. No intraspecific differences in ecological requirements were found when sympatric and allopatric subsets were compared, that is, the two species are not experiencing ecological shift when in contact, which suggests weak competition in habitat use. Our findings, therefore, suggest that species distributions in this contact zone are mainly determined by the environmental conditions, with almost no contribution of competitive pressure. Still, a localized competition might exist due to minor differences in the ecological niches and a marked and unequal reduction of suitable areas for the sympatric populations, which could be favouring V. aspis in small regions of the contact zone. [ABSTRACT FROM AUTHOR]

Two thrips, Megalurothrips usitatus (Bagnall) and Frankliniella intonsa (Trybom) are major pests of cowpea in South China. To realistically compare the growth, development and reproductive characteristics of these two thrips species, we compared their age-stage, two-sex life tables on cowpea pods under summer and winter natural environmental regimes. The results showed that the total preadult period of M. usitatus was 8.09 days, which was significantly longer than that of F. intonsa (7.06 days), while the adult female longevity of M. usitatus (21.14 days) was significantly shorter than that of F. intonsa (25.77 days). Significant differences were showed in male adult longevity (10.68 days for F. intonsa and 16.95 days for M. usitatus) and the female ratio of offspring (0.67 for F. intonsa and 0.51 for M. usitatus), and the total preadult period of M. usitatus (16.20 days) was significantly longer than that of F. intonsa (13.66 days) in the winter regime. The net reproductive rate (summer: R 0 = 85.62, winter: R 0 = 105.22), intrinsic rate of increase (summer: r = 0.3020 day−1, winter: r = 0.2115 day−1), finite rate of increase (summer: λ = 1.3526 day−1, winter: λ = 1.2356 day−1) and gross reproduction rate (summer: GRR = 139.34, winter: GRR = 159.88) of F. intonsa were higher than those of M. usitatus (summer: R 0 = 82.91, r = 0.2741, λ = 1.3155, GRR = 135.71; winter: R 0 = 80.62, r = 0.1672, λ = 1.1820, GRR = 131.26), and the mean generation times (summer: T = 14.73 days, winter: T = 22.01 days) of F. intonsa were significantly shorter than those of M. usitatus (summer: T = 16.11 days, winter: T = 26.25 days). These results may contribute to a better understanding of the bioecology of different thrips species, especially the interspecific competition between two economically important cowpea thrips with the same ecological niche in a changing environment. [ABSTRACT FROM AUTHOR]

The niche variation hypothesis (NVH) suggests that populations released from competition are able to expand their realized ecological niche. This increase in total niche width (TNW) can arise by 1) increasing heterogeneity among individuals' niche through individual specialization, i.e. inter‐individual variation in resource use, (IS) occurring when different individuals of a population use a subset of the population's resource pool, or 2) by expanding the niche of all individuals within the population. Although several morphological and phenotypical studies have confuted the NVH, there is generally strong support for this hypothesis when behavioural or ecological traits are considered, and in particular when the trophic niche is measured at the individual level. In this study our primary aim is to corroborate the NVH, providing robust evidence for a significant and positive relationship between population TNW and IS in amphibian populations, at a global scale. [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]

【Objective】By investigating the ecological niche characteristics of the dominant species of the forest communities in the coastal zone of Dapeng Peninsula, Shenzhen, the ability and similarity of the species to use environmental resources are understood, providing a scientific basis for forest management in this area. 【Method】On the basis of the field survey, by using the calculation methods of Levins niche breadth, Shannon-Wiener niche breadth, Pianka niche overlap and niche similarity, dominant species from tree layer and shrub layer in the Egong Village sample site and Luowutian Reservoir sample site in the coastal zone were selected for niche quantitative research.【Result】In the communities of the Egong Village sample site and the Luowutian Reservoir sample site, (1) the species with the larger niche breadth in the tree layer were Litsea rotundifolia var. oblongifolia and Aporosa dioica, with Levins indices of 16.40 and 22.70, and Shannon-Wiener indices of 2.89 and 3.16, respectively; the species with the larger niche breadth in the shrub layer were Diplospora dubia and Syzygium rehderianum, with Levins indices of 19.10 and 23.97 and Shannon indices of 3.07 and 3.20, respectively. (2) The overall mean values of niche overlap in the tree layer were 0.434 and 0.641, respectively, and the species with the larger niche overlap were Ilex pubescens and Rhodomyrtus tomentosa (0.997), Psydrax dicocca and Garcinia oblongifolia (0.923); the overall mean values of niche overlap in the shrub layer were 0.441 and 0.468, respectively, and species with the larger niche overlap were Pavetta hongkongensis and Sterculia lanceolata (0.910), Aporosa dioica and Psychotria asiatica (0.959). (3) The tree species with larger niche similarity were Pavetta hongkongensis and Mallotus paniculatus (0.820), Psydrax dicocca and Garcinia oblongifolia (0.817), Rhaphiolepis indica and Diplospora dubia (0.751), Syzygium rehderianum and Psychotria asiatica (0.878).【Conclusion】In coastal zone forest communities, Litsea rotundifolia var. Oblongifolia, Diplospora duia, Syzygium rehderianum have larger ecological niche breadth. The community structure and species composition in the Egong Village sample site are in a relatively stable state, and most species in the Egong Village sample site have widely varying needs for environmental resources. Interspecific competition is more intense in the tree layer than that in the shrub layer in the Luowutian Reservoir sample site, the forest communities in this site are still in the successional stage as a whole, and the ecological niche differentiation has not yet been stabilized. [ABSTRACT FROM AUTHOR]

The present paper deals with the ecomorphological characteristics of two sympatric species of ictitheres: Ictitherium viverrinum Roth & Wagner, 1854 and Hyaenictitherium wongii (Zdansky, 1924) from the Late Miocene of the Eastern Mediterranean. These two species represent different taxonomic groups with allegedly distinct ecological roles. The values of 11 ecomorphological proxies were calculated using cranial and dental elements, in order to make an extensive comparison between them (body mass, bite force, canines' and incisors' bending strength, endocranial volume, relative rostral width, dental mesowear, intercuspid notches and carnassial vs grinding surfaces). The proxies show similar results for both species, pointing out that they had a similar ecological niche in the Late Miocene ecosystems. Carnivorans are usually in the top of the food chain, so the existence of two ecologically similar species in the same spatiotemporal range results in interspecific competition. This explains the geographical distinction of the two species with several localities being dominated by only one of the two (e.g. Samos for Hyaenictitherium Kretzoi, 1938 and Pikermi for Ictitherium Wagner, 1848). The reason for the prevalence of each genus can be associated with their postcranial morphology, as Hyaenictitherium has been proposed to be better adapted to chase hunting, because of its longer limbs, while Ictitherium is characterized by shorter and stouter limbs. [ABSTRACT FROM AUTHOR]

Background: Many insectivorous bats have flexible diets, and the difference in prey item consumption among species is one of the key mechanisms that allows for the avoidance of interspecies competition and promotes coexistence within a microhabitat. In Korea, of the 24 bat species that are known to be distributed, eight insectivorous bats use forest areas as both roosting and foraging sites. Here, we aimed to understand the resource partitioning and coexistence strategies between two bat species, Myotis ikonnikovi and Plecotus ognevi, cohabiting the Mt. Jumbong forests, by comparing the differences in dietary consumption based on habitat utilization. Results: Upon examining their dietary composition using the DNA meta-barcoding approach, we identified 403 prey items (amplicon sequence variants). A greater prey diversity including Lepidoptera, Diptera, Coleoptera, and Ephemeroptera, was detected from M. ikonnikovi, whereas most prey items identified from P. ognevi belonged to Lepidoptera. The diversity index of prey items was higher for M. ikonnikovi (H': 5.67, D: 0.995) than that for P. ognevi (H': 4.31, D: 0.985). Pianka's index value was 0.207, indicating little overlap in the dietary composition of these bat species. Our results suggest that M. ikonnikovi has a wider diet composition than P. ognevi. Conclusions: Based on the dietary analysis results, our results suggests the possibility of differences in foraging site preferences or microhabitat utilization between two bat species cohabiting the Mt. Jumbong. In addition, these differences may represent one of the important mechanism in reducing interspecific competition and enabling coexistence between the two bat species. We expected that our results will be valuable for understanding resource partitioning and the coexistence of bats inhabiting the Korean forests. [ABSTRACT FROM AUTHOR]

Nonsessile animals could partition the use of resources in different axes, reducing the effects of competition and allowing coexistence. Here, we investigated the spatial and trophic niche dimensions in four lizard assemblages in the Neotropical semiarid Caatinga to investigate the determinants of resource use and the extent to which lizards partition their niches. We sampled each lizard assemblage once, for 10 days, in the dry season of 2017 and 2018. In two lizard assemblages, we detected nonrandom niche overlap patterns that were higher or lower than expected by chance. The high niche overlap patterns suggest that either there is intense current competition for available microhabitats or an abundance of microhabitats. The lower niche overlap may be influenced by the presence of species adapted to sandy habitats (psammophilous), suggesting that spatial partitioning detected has historical basis, which is supported by the pPCA results and by the lack of patterns in the realized niche distribution of species across niche space. We detected trophic niche partitioning in three lizard assemblages. In one assemblage, we discovered random spatial and trophic niche overlap patterns, revealing that competition is not a determining factor in the structure of that assemblage. In fact, phylogenetic effects were predominantly the main determinants of resource use in the four studied lizard assemblages. Arid and semiarid habitats cover about one third of land surface of the world. Comparisons between our findings and those from other regions of the world may aid identify general trends in the lizard ecology of dry environments. [ABSTRACT FROM AUTHOR]

We describe a partial skeleton of a fossil owl (Strigiformes) from the early Eocene London Clay of Walton‐on‐the‐Naze (Essex, UK). The holotype of Ypresiglaux michaeldanielsi, gen. et sp. nov. is one of the most complete specimens of a Palaeogene owl and elucidates the poorly known ecomorphology of stem group Strigiformes. Whereas most of the postcranial bones show the characteristic strigiform morphology, the new species exhibits plesiomorphic features of the skull and cervical vertebrae that differ distinctly from extant owls. A well‐developed supraorbital process of the lacrimal bone suggests that the eyes were not as greatly enlarged and forward‐facing as in extant owls. A plesiomorphic quadrate morphology indicates differences in the otic region, and a proportionally longer axis suggests that the fossil species was not able to rotate its head to the degree found in crown group Strigiformes. Therefore, the fossil documents a mosaic evolution of the strigiform body plan, with owls developing raptorial adaptations before specializations of the visual and acoustic systems evolved. Because the latter relate to a crespuscular or nocturnal activity pattern, we hypothesize that Ypresiglaux was diurnal. Nocturnality in owls may have evolved in response to the emergence of evolutionary opportunities, which enabled owls to exploit new ecological niches, or owls may have been driven into nocturnal habits by ecological competition. [ABSTRACT FROM AUTHOR]

Faunal turnover is a pattern of diversification and extinction in taxa throughout the geologic record. Patterns of repeated faunal turnovers are referred to as faunal progression, demonstrated by Decapoda in clawed lobsters and podotrematous and heterotrematous crabs. The transition between podotrematous and heterotrematous crabs is the most recent. Among these, section Raninoida Ahyong, Lai, Sharkey, Colgan & Ng, 2007, commonly called "frog crabs," constitutes a major monophyletic group with podotrematous body forms, and the focus of our study. Declines in raninoidan diversity were aligned with mass extinction events and major climate shifts, especially cooling. Likewise, diversification within Raninoida occurred in warm, greenhouse climates. Thus, a major factor in patterns of faunal turnover in Decapoda is shown to be environmental conditions. Raninoidan families exhibiting adaptations facilitating back-burrowing preferentially survived the end-Cretaceous mass extinction event, whereas raninoidans lacking such adaptions did not go completely extinct at the end-Cretaceous but failed to recover diversity. Given the diversification of heterotrematous crabs into a wide variety of ecological niches throughout the Cenozoic, competition may be a secondary, but still crucial, factor in this faunal turnover. [ABSTRACT FROM AUTHOR]

Species coexist only when occupying different ecological niches. We evaluated habitat and trophic niches in two recently diverged hybridizing avian apex predators, the declining Greater Spotted Eagle Clanga clanga (mainly found in contracting wetlands) and the more numerous Lesser Spotted Eagle Clanga pomarina (inhabiting mosaic farmlands). We tracked 24 Spotted Eagles, including interspecific hybrids, by GPS to estimate the home‐range size, land use composition and landscape structure in sympatric populations. In addition to information for landscape utilization, data for diet composition were evaluated. Home‐ranges of the two species were similar in size and open foraging habitats consisted mostly of agricultural landscape. However, landscape utilization of the Greater Spotted Eagle was largely driven by the composition of land‐use types, whereas the Lesser Spotted Eagle was mostly influenced by structural components of the landscape. Farmland‐dwelling voles accounted for the bulk of the diet in both species; however, subdominant prey classes differed. Hybrids exhibited intermediate or mixed features of home‐ranges and diets. Our results provide evidence for reduced niche partitioning and potential competition between the two Spotted Eagles, which may have been reinforced by anthropogenic habitat alteration. A closer examination of movement patterns revealed previously overlooked differences between closely related species with respect to landscape utilization strategies. [ABSTRACT FROM AUTHOR]

Although successful at recovering endangered populations, conservation actions based on nest provisioning seldom consider how they shape the composition of communities and alter interspecific interactions. Specifically, the extent to which dietary overlap within these communities may affect the conservation of target species has rarely been assessed. In Southern Europe, sites of large‐scale nest‐site provisioning aimed at recovering Lesser Kestrels Falco naumanni populations have attracted non‐target bird species, resulting in mixed breeding assemblages that might promote interspecific competition for resources during breeding. Here we used stable isotope analysis (δ15N and δ13C) to assess inter‐ and intraspecific dietary segregation in these assemblages and investigate the mechanisms allowing species coexistence. We examined resource partitioning and trophic niche overlap among Lesser Kestrels, Common Kestrels Falco tinnunculus, European Rollers Coracias garrulus, Western Barn Owls Tyto alba, Little Owls Athene noctua and Spotless Starlings Sturnus unicolor; and within species between parents and their offspring. Similar isotope ratios and highly overlapped niches, particularly among Lesser Kestrels, Rollers and Starlings, suggest limited dietary segregation and use of similar prey. Within species, parent–offspring segregation was marked across all species. Our results indicate that species breeding in these assemblages occupy similar ecological niches, despite a potential increase in competition. High resource availability in the area may permit coexistence but the viability of mixed‐species groups may be compromised in areas with limited resources, which are predicted to expand with ongoing human‐ and climate‐induced changes. Conservation practices based on nest provisioning should consider the ecological niches of target and non‐target species as well as their interactions. [ABSTRACT FROM AUTHOR]

Climate change has had a significant impact on many marine organisms. To investigate the effects of environmental changes on deep-water benthic fishes, we selected the genus Oplegnathus and applied species distribution modeling and ecological niche modeling. From the last glacial maximum to the present, the three Oplegnathus species (O. conwayi , O. robinsoni , and O. peaolopesi) distributed in the Cape of Good Hope region of southern Africa experienced fitness zone fluctuations of 39.9%, 13%, and 5.7%, respectively. In contrast, O. fasciatus and O. punctatus , which were primarily distributed in the western Pacific Ocean, had fitness zone fluctuations of −6.5% and 11.7%, respectively. Neither the O. insignis nor the O. woodward varied by more than 5% over the period. Under future environmental conditions, the range of variation in fitness zones for the three southern African Oplegnathus species was expected to be between −30.8% and −26.5%, while the range of variation in fitness zones for the two western Pacific stonefish species was expected to remain below 13%. In addition, the range of variation in the fitness zones of the O. insignis was projected to be between −2.3% and 7.1%, and the range of variation in the fitness zones of the O. woodward is projected to be between −5.7% and −2%. The results indicated that O. fasciatus and O. punctatus had a wide distribution and high expansion potential, while Oplegnathus species might have originated in western Pacific waters. Our results showed that benthic fishes were highly adaptable to extreme environments, such as the last glacial maximum. The high ecological niche overlap between Oplegnathus species in the same region suggested that they competed with each other. Future research could explore the impacts of environmental change on marine organisms and make conservation and management recommendations. • Widespread distribution and high potential for expansion of O. fasciatus and O. punctatus. • The western Pacific Ocean may have been the origin of Oplegnathus. • Oplegnathus have greater buffers to cope with the changing climate. • Oplegnathus is highly adaptable to the extreme environment of the last glacial maximum. • Strong ecological niche competition exists between Oplegnathus fish in the same range. [ABSTRACT FROM AUTHOR]

Metacommunity structure reflects the interplay of various processes, including niche filtering, extinction/colonization and interspecific interactions. Spatial patterns of species distributions are often analyzed to infer these processes. However, such inferences rely on often unrealistic equilibrium assumptions, and remain ambiguous, as different processes can produce similar patterns. Temporal data may improve these inferences. For example, stochastic species turnover may occur in local communities, while, on the long run, temporal changes are kept within limits set by locally available niches. Our objective is to explore how the joint analysis of spatial and temporal patterns can clarify the contribution of different processes to metacommunity structure. We recorded the occurrences of 21 freshwater mollusc species, and environmental data, in 250 sites over 17 successive years in a network of ponds in Guadeloupe (Lesser Antilles). We analyzed variation in α and β‐diversities in space and time, and used a joint‐species distribution mode to characterize species–environment and species–species relationships. Local communities showed pronounced temporal variation reflecting both imperfect species detection and true stochastic species turnover. On the long term however, local communities were largely controlled by niche filtering along two main environmental gradients, one driven by site connectivity, the other by hydrological stability and aquatic vegetation. Two gastropod clades, caenogastropods and pulmonates, showed contrasted spatio–temporal distributions resulting from different responses to these gradients, and these distributions seemed little altered by interspecific competition. Our study illustrates the benefit of using spatiotemporal metacommunity data to discern long‐term impacts of niche filtering and species interactions behind short‐term stochasticity. [ABSTRACT FROM AUTHOR]

Besides competition, positive interactions also play an important role in shaping the social structure of mixed‐species bird flocks. This study aimed to illuminate the interspecific interactions of competition and facilitation in mixed‐species bird flocks. We recorded the foraging behavior and microhabitat use of flocking species in montane coniferous forests of Taiwan under different social contexts. Foraging niche breadth and niche‐overlap with other flocking species were compared between individuals inside and outside of mixed flocks. For the three microhabitat variables (foraging locations, vertical strata and horizontal strata), relationships between niche‐overlaps of heterospecific pairs of these flocking species and their corresponding interspecific associations were determined using a simple linear regression. While in mixed flocks, two understory species, Taiwan fulvetta Fulvetta formosana and yellowish‐bellied bush warbler Horornis acanthizoides, shifted their foraging from shrubs upwards into coniferous trees. Meanwhile, flamecrests Regulus goodfellowi moved downwards vertically within the canopy, and black‐throated tits Aegithalos concinnus spread out horizontally along branches. In addition, flamecrests applied many more sally‐hovers inside of mixed flocks than outside of flocks. All four species are insectivores which might find it more difficult to obtain sufficient food during the colder winters when food resources become scarcer. Therefore, they may be using the increased vigilance afforded by the flock to expand their foraging niches and thus to increase their foraging opportunities inside mixed flocks. Furthermore, niche‐overlaps of heterospecific pairs of the 11 common flocking species were positively correlated with their corresponding interspecific associations on all three microhabitat variables. These results indicate that a greater foraging niche‐overlap between two flocking species would result in higher coexistence of the two species in mixed flocks. Consequently, facilitative interactions occurred in these mixed‐species flocks in addition to competitive interactions. [ABSTRACT FROM AUTHOR]

Coexistence between species within plant communities is a key issue in the practice of revegetation, forest management, and biodiversity conservation. Vegetation restoration is critical to control soil erosion and improve the ecological environment on the Loess Plateau. Here, we investigate the interspecific relationships of dominant plants during natural vegetation succession on the Loess Plateau. The results suggest that, under the ecological process of environmental filtering, species within communities can reduce interspecific competition and promote species coexistence via spatial heterogeneity and temporal asynchronous differences. The ecological niche overlap index (Oik) significantly and positively correlated with the strength of interspecific associations. Most species pairs had weak competition and more stable interspecific relationships. The results of the χ2 test showed that 317 species pairs were positively associated and 118 were negatively associated. The community is in a positive succession process, and the interaction relationship between species tends to be neutral. We should enhance the protection of positively associated species and pay attention to negatively associated species during forest management. Results revealed that Carex lanceolata Boott and Lespedeza bicolor Turcz coexisted easily with other species for mutual benefit, which could help build artificial forestland of native species to improve the ecological function. [ABSTRACT FROM AUTHOR]

Climate change is a major factor influencing the species distribution and population diversity of living creatures. In this study, the ecological niche model (ENM) MaxEnt was used to evaluate habitat suitability and predict potential habitats of two sympatric fig species, i.e., Ficus squamosa and F. heterostyla, in the Xishuangbanna region of China. Results indicated that mean diurnal range, isothermality, cation exchange capacity (at pH 7), and temperature seasonality were key variables influencing habitat suitability for F. squamosa. However, temperature seasonality and precipitation of the driest quarter showed the greatest contributions to F. heterostyla distribution. During the current period, the habitat suitability distributions of both Ficus species were considerably higher than known occurrences. In the future, potentially suitable distribution areas for both species will reduce overall across the whole study area, although some expansion may occur by 2070. Niche overlap of suitable areas for both species was initially high and then declined in the current period and future epochs in the RCP 2.6 scenario, but increased in the RCP 8.5 scenario. In short, the responses of both Ficus species to climate change differed. Thus, specific actions such as ex situ conservation and assisted migration may be needed to conserve both species. [ABSTRACT FROM AUTHOR]

Here we describe the fossil remains of Cainotherium aff. huerzeleri and Lagopsis penai from the Ribesalbes-Alcora Basin (Castelló, Spain). We also compare the relative abundance of cainotheriids vs. lagomorphs and discuss the possible direct interaction between both taxa, possibly indicating the competition between both families. The oldest locality in study has a predominance of Cainotherium followed by a dominance of Lagopsis in the next localities. Afterwards we see another interval where the relative abundance of Cainotherium is higher. However, after this period the relative abundance of Lagopsis increases again in one of the most recent sites, with a posterior modest increase in Cainotherium in the youngest locality that also sees a decrease in the abundance of Lagopsis. We can observe a pattern of one taxon attaining higher relative abundance when the other shows a decrease at the same time period, possibly indicating a direct competition between Lagopsis and Cainotherium. [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]

This article describes a data-driven framework based on spatiotemporal machine learning to produce distribution maps for 16 tree species (Abies alba Mill., Castanea sativa Mill., Corylus avellana L., Fagus sylvatica L., Olea europaea L., Picea abies L. H. Karst., Pinus halepensis Mill., Pinus nigra J. F. Arnold, Pinus pinea L., Pinus sylvestris L., Prunus avium L., Quercus cerris L., Quercus ilex L., Quercus robur L., Quercus suber L. and Salix caprea L.) at high spatial resolution (30 m). Tree occurrence data for a total of three million of points was used to train different algorithms: random forest, gradient-boosted trees, generalized linear models, k-nearest neighbors, CART and an artificial neural network. A stack of 305 coarse and high resolution covariates representing spectral reflectance, different biophysical conditions and biotic competition was used as predictors for realized distributions, while potential distribution was modelled with environmental predictors only. Logloss and computing time were used to select the three best algorithms to tune and train an ensemble model based on stacking with a logistic regressor as a meta-learner. An ensemble model was trained for each species: probability and model uncertainty maps of realized distribution were produced for each species using a time window of 4 years for a total of six distribution maps per species, while for potential distributions only one map per species was produced. Results of spatial cross validation show that the ensemble model consistently outperformed or performed as good as the best individual model in both potential and realized distribution tasks, with potential distribution models achieving higher predictive performances (TSS = 0.898, R²logloss = 0.857) than realized distribution ones on average (TSS = 0.874, R²logloss = 0.839). Ensemble models for Q. suber achieved the best performances in both potential (TSS = 0.968, R²logloss = 0.952) and realized (TSS = 0.959, R²logloss = 0.949) distribution, while P. sylvestris (TSS = 0.731, 0.785, R²logloss = 0.585, 0.670, respectively, for potential and realized distribution) and P. nigra (TSS = 0.658, 0.686, R²logloss = 0.623, 0.664) achieved the worst. Importance of predictor variables differed across species and models, with the green band for summer and the Normalized Difference Vegetation Index (NDVI) for fall for realized distribution and the diffuse irradiation and precipitation of the driest quarter (BIO17) being the most frequent and important for potential distribution. On average, fine-resolution models outperformed coarse resolution models (250 m) for realized distribution (TSS = +6.5%, R²logloss = +7.5%). The framework shows how combining continuous and consistent Earth Observation time series data with state of the art machine learning can be used to derive dynamic distribution maps. The produced predictions can be used to quantify temporal trends of potential forest degradation and species composition change. [ABSTRACT FROM AUTHOR]

Habitat quality early in life determines individual fitness, with possible long-term evolutionary effects on groups and populations. In holometabolous insects, larval ecology plays a major role in determining the expression of traits in adulthood, but how ecological conditions during the larval stage interact to shape adult life history and fitness, particularly in nonmodel organisms, remains subject to scrutiny. Consequently, our knowledge of the interactive effects of ecological factors on insect development is limited. Here, using the polyphagous fly Bactrocera tryoni , we conducted a fully factorial design where we manipulated larval density and larval diet (protein rich, standard, and sugar rich) to gain insights into how these ecological factors interact to modulate adult fitness. As expected, a protein-rich diet resulted in faster larval development and heavier and leaner adults that were more fecund compared with the standard and sugar-rich diets, irrespective of larval density. Females from the protein-rich larval diet had overall higher reproductive rate (i.e., eggs per day) than females from other diets, and reproductive rate decreased linearly with density for females from the protein-rich diet but nonlinearly for females from the standard and sugar-rich diets over time. Surprisingly, adult lipid reserve increased with larval density for adults from the sugar-rich diet (as opposed to decreasing as in other diets), possibly because of a stress response to an extremely adverse condition during development (i.e., high intraspecific competition and poor nutrition). Together, our results provide insights into how ecological factors early in life interact and shape the fate of individuals through life stages in holometabolous insects. [ABSTRACT FROM AUTHOR]

Species' ranges are limited by both ecological and evolutionary constraints. While there is a growing appreciation that ecological constraints include interactions among species, like competition, we know relatively little about how interactions contribute to evolutionary constraints at species' niche and range limits. Building on concepts from community ecology and evolutionary biology, we review how biotic interactions can influence adaptation at range limits by impeding the demographic conditions that facilitate evolution (which we term a 'demographic pathway to adaptation'), and/or by imposing evolutionary trade-offs with the abiotic environment (a 'trade-offs pathway'). While theory for the former is well-developed, theory for the trade-offs pathway is not, and empirical evidence is scarce for both. Therefore, we develop a model to illustrate how fitness trade-offs along biotic and abiotic gradients could affect the potential for range expansion and niche evolution following ecological release. The model shows that which genotypes are favoured at species' range edges can depend strongly on the biotic context and the nature of fitness trade-offs. Experiments that characterize trade-offs and properly account for biotic context are needed to predict which species will expand their niche or range in response to environmental change. This article is part of the theme issue 'Species' ranges in the face of changing environments (Part II)'. [ABSTRACT FROM AUTHOR]

Theory predicts that species can only coexist if they are sufficiently different in their resource and/or microhabitat utilization; if their needs are too similar, the stronger population will exclude the weaker, unless the two species are equally strong competitors. This hypothesis is difficult to assess in most species because populations are limited by multiple resources simultaneously. In hermit crabs, however, fitness is overwhelmingly limited by gastropod shells, which are their only shelter from external pressures, from predation to harsh environmental conditions. Several hermit crab species have similar shell requirements and occupy the same habitat. Here, we examine the degree of overlap in shell use and microhabitat occupation between two species, one of which (Calcinus californiensis) is clearly dominant over the other (Clibanarius albidigitus) in direct fights over shells. We hypothesized that these species should show microhabitat separation or shell partitioning. We sampled hermit crabs' presence and shell use in the high- and mid-intertidal. The species overlapped in the two intertidal sites, especially at the higher intertidal, and they occupied preferred and suboptimal shells with similar frequency. The co-occurrence and strong overlap in shell use of these two species could be explained by a resource exploitation versus interference trade-off, relaxed selection pressure on shell characteristics due to small body size, spatial/temporal niche segregation, or dominance by Ca. californiensis that has yet to result in habitat displacement of Cl. albidigitus. Further research is needed to determine which of these hypotheses explain the apparent coexistence of ecologically similar species. [ABSTRACT FROM AUTHOR]

Water turbidity can significantly influence interspecific interactions in aquatic ecosystems. We tested the hypothesis that the turbidity gradient significantly differentiates the dynamics, significance and type of relationships in the structure of zooplankton communities colonizing mine pit reservoirs. The interactions between zooplankton species were evaluated by network graph analysis for three water turbidity classes: high turbidity (HT), moderate turbidity (MT) and low turbidity (LT). The HT network was most cohesive, and it was controlled by taxa grazing on various food sources within one ecological niche (Polyarthra longiremis, Brachionus angularis, Cyclops vicinus, Codonella cratera) and the positive and negative relationships between them were balanced. The MT biocenotic network was composed of three sub-networks connected by nodes with high communication attributes (Polyarthra vulgaris, Bosmina longirostris, C. vicinus), and antagonistic interactions (predation and competition) were less important. The LT network was most heterogeneous, and Daphnia cuculllata exerted the strongest influence on the network's structure by forming numerous positive (coexistence with predators) and negative (interference competition with microphagous rotifers) interspecific relationships. The study provides new information about the ecology of aquatic ecosystems, that are disturbed by changes in water turbidity. [ABSTRACT FROM AUTHOR]

Tropical species, many of which have limited thermal tolerances and narrow ecological niches, are likely to experience elevational shifts due to climate change. However, our ability to predict these shifts is limited by a scarcity of baseline data on current distributions and a lack of understanding of drivers of species ranges. To characterize the elevational distributions of a suite of Afromontane birds, we conducted annual point counts between 2013 and 2018 at 297 plots across habitats and elevations (2416–4303 m) in Volcanoes National Park, Rwanda. We assessed elevational and habitat preferences via indicator analyses, and modeled abundance distributions as a function of temperature, precipitation, habitat availability, and congeneric competition. Although most of the 35 focal species were distributed across habitats and elevational ranges, 20 species particularly associated with narrow elevational range (<300 m) and 24 species were strongly associated with one to three habitat types. Abiotic factors significantly correlated with abundance distributions of 33 species (temperature 33, precipitation 17), and biotic factors with distributions of 31 species (habitat 30, competition 7). Temperature and habitat availability were particularly associated with upper elevational limits (31 and 26 species, respectively, vs. 10 and 6 at lower limits), whereas precipitation affected both limits similarly (17 lower, 16 upper), and competition had a limited role at either limit (4 lower, 3 upper). That the elevational distribution of Afromontane birds results from a species‐specific combination of biotic and abiotic factors is crucial information in our effort to predict climate change effects in this region. [ABSTRACT FROM AUTHOR]

Following the end-Permian crisis, microbialites were ubiquitous worldwide. For instance, Triassic deposits in the Germanic Basin provide a rich record of stromatolites as well as of microbe-metazoan build-ups with nonspicular demosponges. Despite their palaeoecological significance, however, all of these microbialites have only rarely been studied. This study aims to fill this gap by examining and comparing microbialites from the Upper Buntsandstein (Olenekian, Lower Triassic) and the lower Middle Muschelkalk (Anisian, Middle Triassic) in Germany. By combining analytical petrography (optical microscopy, micro X-ray fluorescence, and Raman spectroscopy) and geochemistry (δ13Ccarb, δ18Ocarb), we show that all the studied microbialites formed in slightly evaporitic environments. Olenekian deposits in the Jena area and Anisian strata at Werbach contain stromatolites. Anisian successions at Hardheim, in contrast, host microbe-metazoan build-ups. Thus, the key difference is the absence or presence of nonspicular demosponges in microbialites. It is plausible that microbes and nonspicular demosponges had a mutualistic relationship, and it is tempting to speculate that the investigated microbial-metazoan build-ups reflect an ancient evolutionary and ecological association. The widespread occurrence of microbialites (e.g., stromatolites/microbe-metazoan build-ups) after the catastrophe may have resulted from suppressed ecological competition and the presence of vacant ecological niches. The distribution of stromatolites and/or microbe-metazoan build-ups might have been controlled by subtle differences in salinity and water depth, the latter influencing hydrodynamic processes and nutrient supply down to the microscale. To obtain a more complete picture of the distribution of such build-ups in the earth's history, more fossil records need to be (re)investigated. For the time being, environmental and taphonomic studies of modern nonspicular demosponges are urgently required. [ABSTRACT FROM AUTHOR]

According to the stress gradient hypothesis (SGH), ecological interactions between organisms shift positively as environmental stress increases. In the case of associational resistance, habitat is modified to ameliorate stress, benefitting other organisms. The SGH is contentious due to conflicting evidence and theoretical perspectives, so we adopted a meta‐analytic approach to determine if it is widely supported across a variety of contexts, including different kingdoms, ecosystems, habitats, interactions, stressors, and life history stages. We developed an extensive list of Boolean search criteria to search the published ecological literature and successfully detect studies that both directly tested the hypothesis, and those that were relevant but never mentioned it. We found that the SGH is well supported by studies that feature bacteria, plants, terrestrial ecosystems, interspecific negative interactions, adults, survival instead of growth or reproduction, and drought, fire, and nutrient stress. We conclude that the SGH is indeed a broadly relevant ecological hypothesis that is currently held back by cross‐disciplinary communication barriers. More SGH research is needed beyond the scope of interspecific plant competition, and more SGH research should feature multifactor stress. There remains a need to account for positive interactions in scientific pursuits, such as associational resistance in tests of the SGH. [ABSTRACT FROM AUTHOR]