Search

Understanding species distributions and predicting future range shifts requires considering all relevant abiotic factors and biotic interactions. Resource competition has received the most attention, but reproductive interference is another widespread biotic interaction that could influence species ranges. Rubyspot damselflies (Hetaerina spp.) exhibit a biogeographic pattern consistent with the hypothesis that reproductive interference has limited range expansion. Here, we use ecological niche models to evaluate whether this pattern could have instead been caused by niche differentiation. We found evidence for climatic niche differentiation, but the species that encounters the least reproductive interference has one of the narrowest and most peripheral niches. These findings strengthen the case that reproductive interference has limited range expansion and also provide a counterexample to the idea that release from negative species interactions triggers niche expansion. We propose that release from reproductive interference enables species to expand in range while specializing on the habitats most suitable for breeding.

The Bolkar Mountain Viper, Montivipera bulgardaghica (Nilson & Andren, 1985), is a mountain viper found in the eastern Mediterranean region. In this study, we present data on the seasonal variation in diet composition across two different habitats in the Central Taurus Mountains of Anatolia, Türkiye. The Karboğazı population inhabits a subalpine shrubland, while the Göller Yaylası population resides in forested land. The vipers primarily consumed Lacertidae (47%), followed by Orthoptera (27%), Chilopoda (18%), and Scincidae (8%) in number. In spring, the diet of the Karboğazı population was mainly composed of Lacertidae but shifts toward Orthoptera during summer and autumn. In contrast, the Göller Yaylası population fed on Lacertidae throughout the entire active season. Overall, the Karboğazı population primarily consumed invertebrates, whereas the Göller Yaylası population predominantly fed on lizards. Both populations exhibited partial niche overlap. There was no significant difference in diet composition between sexes, but prey type and quantity varied with the season. Prey diversity increased in summer and decreased in autumn and spring, corresponding with the prey availability in the environment. [ABSTRACT FROM AUTHOR]

ABSTRACT Climate change and human influence are transforming mountain ecosystems, significantly impacting species distributions and biodiversity. Among these changes, the upward migration of lowland species into mountain regions stands out. This study examines the ecogeographical niche overlap and genetic diversity among three Leucanthemum species distributed along an altitudinal gradient in the Carpathian Mountains: the lowland L. ircutianum (4x), the montane L. rotundifolium (2x) and the alpine L. gaudinii (2x). By genotyping over 600 individuals using SNP analysis, followed by principal coordinate analysis (PCoA), Neighbour‐Net Network and Structure clustering, we reveal not just distinct genetic groups but also hybridisation across all species, suggesting the potential for triple hybrids. Genetic admixture is further supported by environmental background and niche overlap analyses that reveal substantial overlap among species, particularly in line with their vertical distribution. Climate envelope plots indicate a likely reduction in available habitat for mountainous species due to climate change, leading to an increase in competition and an intensification of hybridisation. Anthropogenic influences are further intensifying these hybridisation trends. Among the studied species, L. gaudinii is most at risk of overwhelming hybridisation, whereas L. ircutianum may experience habitat expansion. By providing a comprehensive genetic and ecological overview, our research highlights the significance of hybridisation in biodiversity conservation and the challenges posed by environmental changes and anthropogenic activities in mountain environments. This study not only contributes to the understanding of genetic diversity in the Carpathians but also underscores the broader implications for molecular ecology and conservation strategies in mountain ecosystems. [ABSTRACT FROM AUTHOR]

Functional traits offer a potential avenue to generalize and forecast the impacts of changing competition on plant communities, including changing outcomes of competition among species that currently interact (current competition) or that will interact in the future following range shifts (novel competition). However, it remains unclear how well traits explain variation in the outcomes of current and novel competition as well as the underlying processes determining coexistence or competitive exclusion, under changing climate. Here, we interacted pairs of high and low‐elevation species in three sites across an elevation gradient in the Swiss Alps. For each species pair, we quantified the population‐level outcomes of competition (invasion growth rates), relative fitness differences, and niche overlap and related these to 15 functional traits that were measured in each site. Most traits were significantly associated with invasion growth rates at the low elevation, where species had greater relative fitness differences, but these associations were much weaker towards higher elevations. This appears to be because traits, particularly those associated with light competition, captured species' relative fitness differences at lower elevations, but not at the high elevation site, highlighting that the predictive ability of traits can depend on environmental context. The amplified relative fitness differences towards lower elevations suggest that climate warming may increase the likelihood of competitive exclusion. In addition, novel competitors tended to show greater niche overlap than current competitors, leading to stronger overall competitive effects. However, in general, trait differences predicted competitive outcomes of novel and current competitors similarly well, suggesting that traits can predict interactions between species that do not yet interact. Our study reinforces the importance of considering changing interactions for predicting species responses to climate change and provides experimental evidence supporting the usefulness of functional trait differences in forecasting the impacts of future plant interactions under changing climate. [ABSTRACT FROM AUTHOR]

Ecosystems worldwide are increasingly being invaded by multiple species, and the rate of biological invasion is accelerating, leading to more interactions among invasive species. One such interaction that has received little attention is the phenomenon of 'serial replacement' or 'over-invasion', where an established invasive species is supplanted by a second invasive species. Understanding this interaction is important as controlling the second species could inadvertently lead to an increase in the abundance of the first species. We used a hierarchical state-space model to analyse changes in annual abundances (commercial catch-per-unit-effort) of three invasive fish species, tench (Tinca tinca), common carp (Cyprinus carpio) and redfin perch (Perca fluviatilis), in the Murray-Darling River system (MDRS), Australia between 1954–2002. Tench were present at low abundances until the mid-1970 s, before declining to the point of no commercial catch post-1989. This rapid decline coincided with a significant increase in carp abundance, suggesting that carp may have driven the tench decline through habitat modification (particularly the destruction of aquatic plants), consistent with findings from European studies that show the disappearance of tench from ponds with intensive carp farming. Redfin perch populations, were inferred to be much less impacted by the invading carp population. While carp were present in the MDRS for the duration of the study, the rapid increase in carp abundance in the early 1970 s coincided with the introduction of a specific genetic lineage—the "Boolarra strain". Our analysis provides compelling evidence of serial replacement of long-established tench by invading common carp triggered by the introduction of a novel carp strain. [ABSTRACT FROM AUTHOR]

Local adaptation is common in plant species, and knowing whether a population is locally adapted has fundamental and applied relevance. However, local adaptation in tropical plants remains largely less studied, and covering this gap is not simple since reciprocal transplantation – the gold standard for detecting local adaptation – is not feasible for most species. Here, we combined genetic, climatic and phenotypic data to investigate ecotypic differentiation, an important aspect of local adaptation, in coastal and inland populations of the orchid Epidendrum fulgens Brongn., a long‐lived tropical plant for which reciprocal transplantation would not be feasible.We used nine microsatellite markers to estimate genetic divergence between inland and coastal populations. Moreover, occurrence data and climate data were used to test for differences in the realized niche of those populations. Finally, we assessed saturated water content, leaf specific area, height, and stomatal density in common garden and in situ to investigate the effects of ecotypic differentiation and plasticity on the phenotype.Coastal and inland groups' niches do not overlap, the former occupying a wetter and warmer area. However, this differentiation does not seem to be driven by ecotypic differentiation since there was no positive correlation between genetic structure and climate dissimilarity. Moreover, specific leaf area and leaf saturated water content, which are important phenotypic traits related to soil fertility and drought stress, were rather plastic.We conclude that ecotypic differentiation is absent, since phenotypic plasticity is an important mechanism explaining the niche broadness of this species. [ABSTRACT FROM AUTHOR]

Aim: We studied the niche evolution and diversification modes in transisthmian Alpheus shrimps by examining the interplay between environmental niche divergence and conservatism in allopatric sister species. In a broader perspective, the current study analysed the evolution of climatic niche and the role of the environment in species diversification of Alpheus transisthmian shrimp. Location: Atlantic and Eastern‐Pacific oceans. Taxon: Alpheus shrimps (Caridea: Alpheidae). Methods: We assembled georeferenced occurrences for 33 species of Alpheus (with 24 sister species) from a time‐calibrated molecular phylogeny. We modelled their ecological niches and assessed niche overlap through pairwise comparisons. Additionally, we performed phylogenetic reconstructions of the ancestral environmental niche, for each niche axis. Results: Our results demonstrate that thermal tolerances, food availability and hydrodynamic forces were relevant environmental axes in evolutionary processes in transisthmian species of Alpheus. Among the 528 paired comparisons, we found that most niches were divergent, including in 12 clades formed by pairs of sister species (in only two of these clades were the niches fully equivalent). Phylogenetic reconstructions of ancestral niches showed an initial niche conservatism in all axes, with divergences intensifying in the last 12 million years. Main Conclusions: We found evidence that confirms the relevance of the environmental changes that occurred in the West Atlantic and East Pacific for niche evolution in transisthmian Alpheus species, as well as for the emergence of some lineages. Our findings provide evidence for different modes of Alpheus species speciation in a period consistent with the closure of the Isthmus of Panama. [ABSTRACT FROM AUTHOR]

Introduced species may exhibit variations in their preferred climatic niches between their native and introduced ranges, which can have important implications for the transferability of distribution models. In the Himalayan ecoregion, little is known about the geographic distribution and climatic niche overlap between native and introduced cold‐water species. Here, we used the COUE (centroid shift, overlap, unfilling, and expansion) framework to explore the invasive potential of rainbow (Oncorhynchus mykiss) and brown (Salmo trutta fario) trout and corresponding climatic niche overlap with native snow trout (Schizothorax plagiostomus and Schizothorax richardsonii) in the Indus and Ganges River basins. Although we found more stability in the climatic niche for O. mykiss (93%) than S. trutta (58%), both species do not conserve their climatic niches in this region (p > 0.05). S. trutta has expanded more toward new environmental conditions (42%) compared to O. mykiss (7%). However, there are still available environmental gaps that O. mykiss and S. trutta can potentially occupy in the future. There was a higher overlap in climatic niches between S. plagiostomus and O. mykiss and between S. richardsonii and S. trutta. Observed shifts in climatic niches of these introduced species can negatively affect the transferability of distribution models, which may underestimate the assessments of habitat suitability for introduced trout in the Himalayas. Our study demonstrates that the information on climatic niche dynamics can inform the model‐building process and improve the transferability and predictive performance to better assess vulnerability of sensitive habitats to introduced species in the Himalayas and elsewhere. [ABSTRACT FROM AUTHOR]

Dominant technology in high-tech industries refers to the technology that can break the stability and balance of the original technology system within a certain period and is widely adopted under the interaction of technological possibility and market choice. It is of theoretical and practical necessity to explore dominant technology's formation under overlapping niche. Thus, based on niche theory and competitive game theory, we established a competitive game model of dominant technology formation, and dynamically simulated the shape of dominant technology. This paper uses 'the proportion of user adoption' to measure dominant technology market share in high-tech industry and maintains that obtaining over 50% confers an obvious competitive advantage. Therefore, we draw three main conclusions: (1) Dominant technology formation in high-tech industry is influenced by R&D input, adopter preferences, adoption returns and the decision-making cost; (2) dominant technology formation under niche overlap can be described as a continuous accumulation and complex dynamic process; and (3) The main goal in the new technology competitive game is to obtain a larger market share, and the interaction in this game, which has two possible results, is complex, dynamic, diverse, and nonlinear. [ABSTRACT FROM AUTHOR]

Understanding how climate conditions variation influences the pollination network structure is important for predicting the response of the plant and the pollinator communities, especially for alpine ecosystems, which are sensitive to climate change. Here, we investigated the pollination network of a sub-alpine meadow community by separating the pollinators into categories for ten years, from 2008 to 2010 and 2015 to 2021, and examined the relationships between precipitation or temperature and network metrics at the network, group and species-level. The results showed that the plant-pollinator networks were relatively stable across years, and the variation of network structure metrics were larger than that of growing-season and annual precipitation or temperature. The precipitation and temperature have different effects on the network metrics. Reduced precipitations increase competition among pollinator categories, leading to higher niche overlap of pollinator categories. While increased temperatures resulted in less pollinator sharing, leading to a more specialized network with decreased nestedness. This study contributes to the understanding of how interannual climate change affect plant-pollinator network, and emphasizes the importance of predicting the impact of climate change on ecosystem services. [ABSTRACT FROM AUTHOR]

Breeding seabirds challenge the concept of niche segregation among competing species because similar competitors with comparable life histories can coexist in large multi‐species colonies. This makes them an ideal model organism for studying the Hutchisonian niche model, which proposes interspecific niche segregation, across n‐dimensions. Recent advances in assessment of ecological niches have improved our understanding of the mechanisms leading to at‐sea segregation. We examine 152 published studies investigating one or more of three niche spaces in breeding seabirds: dietary items, stable isotopes (isotopic niche) and spatial distribution (horizontal and vertical). Most studies focused on one rather then multiple niche spaces in combination. When multiple niche spaces were combined, higher segregation than overlap was reported, compared with when niche spaces were assessed individually, as is predicted by the n‐dimensional hypervolume concept. Studies investigating vertical (diving) foraging dimensions in addition to the more traditional horizontal (spatial) assessment reported more spatial segregation than overlap, compared with studies focusing only on horizontal or vertical dimensions. Segregation increased with colony size, suggesting an effect of competition. Segregation also increased during chick‐rearing, when taxa were more phylogenetically distant, and when foraging ecology was more similar. To gain a comprehensive understanding of sympatric competitors' interactions and their ecological niche space, it is important to combine approaches and standardize methodologies. Embracing multidimensional approaches to assess niche segregation in seabird species can inform effective conservation and management practices in marine ecosystems. [ABSTRACT FROM AUTHOR]

[Objective] The study aims to explore the influence of spring rest grazing on the niche of Carex tibetikobresia meadow plants, and to provide data and theoretical guidance for grassland restoration and biodiversity protection. [Methods] Grazing and four grazing-off time treatments (20, 30, 40, and 50 d) were set during the green-returning period. Plant community was investigated in the middle of July of the second year, and the grazing-off time were taken as the environmental gradient to study the niche of plant populations in the C. tibetikobresia meadow. [Results] After 30, 40, and 50 days of rest grazing, the importance value and aboveground biomass of Cyperaceae were significantly increased compared to grazing, while the importance value of poisonous weeds showed the opposite trend. The aboveground biomass of Cyperaceae, Gramineae, and broad-leaved edible grasses were increased most significantly after 50 days of rest grazing, increasing by 220.99%, 69.73%, and 139.37%, respectively. The niche width (NB) of C. tibetikobresia S. R. Zhang, Helictotrichon tibeticum (Roshev) Holub, Elymus nutans Griseb, and Festuca rubra were the largest (0.999), while that of Ranunculus indivisus (Maxim.) Hand.-Mazz. was the smallest (0.889). There were 55 pairs with niche overlap value (N O) greater than 0.990, accounting for 26.10% of the total, and 3 pairs with N O less than 0.75, accounting for 1.43%. [Conclusion] Longer rest grazing time in spring promotes the growth of Cyperaceae and Gramineae, and inhibites the growth of poisonous weeds. The higher the importance value of C. tibetikobresia meadow species, the wider its niche width, which is more conducive to the growth of excellent pasture and can effectively promote the restoration of grassland.

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]

In this study, we estimate the niche overlap between native and invaded ranges of 36 Lessepsian fish, focusing on how this estimate might vary in relation to the temporal resolution of sea surface temperature and salinity, which are the main niche axes determining their distribution. Specifically, we wanted to address the following questions: (i) Does the choice of temporal averaging method of variables influence the estimation of niche overlap for individual variables? (ii) Does this temporal resolution effect persist when conducting bivariate niche estimations?Niches overlap was estimated by calculating two indices and these analyses were repeated at two temporal resolutions, matching observations to the classic 'multidecadal' average of environmental conditions and to the corresponding annual average of records. Results are compared with verify whether differences can be detected in the magnitude of niche commonality measured at annual or multidecadal temporal resolution.The findings show that the temporal resolution of the data significantly influences estimates of overlap in the thermal niche. Specifically, our analysis indicates a considerable disparity between native and invasive niche regions for most species, particularly when evaluated over multidecadal periods compared with matching occurrence data to the annual mean values of years the occurrence was observed, that is matching occurrence data to a common average of 'present' conditions or to the annual mean values of years of observation. In particular, the largest overlaps between native and invaded niches occur along the salinity axis, regardless of temporal resolution. When considering both temperature and salinity together, the results remain unaffected by the temporal resolution of the environmental data. Almost 30% of the species show a different niche in their introduced range, and for the other species, the overlap between native and invaded ranges was reduced with respect to the univariate analyses. [ABSTRACT FROM AUTHOR]

Sympatric species within a community often compete for limited resources, such as food items and habitat. The reliance by semi-aquatic snakes on resources in both terrestrial and aquatic habitats might influence either the frequency or intensity of interspecific interactions and also cause sympatric species to be disproportionately vulnerable to habitat alterations. To reduce competition, species might partition specific resources. Three watersnake species—Nerodia erythrogaster, N. harteri, and N. rhombifer—occur in the upper-middle reaches of the Brazos River, in central Texas. We examined the nature of coexistence among these watersnakes by (1) identifying habitat features that predicted site-level occupancy, (2) assessing microhabitat selection in relation to features such as riffle presence and canopy closure, and (3) quantifying environmental variables that influenced detection probabilities of the watersnakes. In-stream riffles were important for all three watersnake species at either the site or microhabitat level, or both. These three species of Nerodia appear to partition their habitat, however, because the snakes were distributed differently with respect to microhabitat features such as canopy closure and invasive saltcedar (Tamarix spp.). Regular assessment of the community composition is needed because N. harteri continues to experience local population declines and extirpations. Habitat management, such as the removal of saltcedar and preservation of in-stream riffles, might promote long-term stability in the populations of all three species. [ABSTRACT FROM AUTHOR]

Climate change has significantly altered in the distribution of plant and animal species, potentially resulting in either species expansion or extinction. The genus Chimonanthus, an economically significant and endemic group in China, holds substantial medicinal and ornamental value; however, its wild resources are limited. There is a paucity of knowledge regarding the distribution characteristics of the genus Chimonanthus species and the critical ecological factors influencing habitat suitability. Utilizing species distribution data and environmental variables, we performed simulations and analyses to identify suitable habitats, evaluate the primary environmental factors influencing distribution, determine potential distribution areas and centroids, and predict changes in suitable areas under three future climate scenarios (SSP-126, SSP-245, SSP-585) employing MaxEnt and ArcGIS. These findings indicated that the Area Under Curve (AUC) values exceeded 0.97 for all five Chimonanthus species, suggesting that the model predictions are highly accurate. The primary environmental variables influencing the distribution of C. grammatus are temperature, particularly isothermality (BIO3), and the mean temperature of warmest quarter (BIO10). However, precipitation of warmest quarter (BIO18) was an important environmental factor limiting the distributions of C. praecox, C. nitens, C. salicifolius and C. zhejiangensis. In the current period, the area of habitat suitability for C. praecox is the largest, at 2,498,600 km2, while that for C. zhejiangensis is the smallest, at 700,400 km2. The five Chimonanthus species are distributed mainly in southern China under the current climate scenario and will migrate to higher latitudes under future climate scenarios. C. nitens had high niche overlap and range overlap with C. zhejiangensis and C. salicifolius, respectively. A similar situation occurs between C. zhejiangensis and C. salicifolius. These findings suggest that there may be strong interspecific competition among adjacent species. Our results indicate that the establishment of nature reserves at current distribution sites within optimal areas is crucial for the conservation of germplasm resources, particularly for C. grammatus and C. salicifolius. The data generated from this research can serve as a valuable reference for the selection of in situ conservation sites, the determination of appropriate planting locations, the scientific introduction of species, and the development of long-term conservation and management strategies for Chimonanthus. [ABSTRACT FROM AUTHOR]

This study used a novel approach combining stable isotope data and condensed multivariate fatty acid data to define comparative niche space and overlap of six sympatric sharks from the south‐west Indian Ocean: Galeocerdo cuvier, Sphyrna zygaena, Sphyrna lewini, Carcharias taurus, Carcharodon carcharias and Carcharhinus obscurus. G. cuvier had the smallest fatty acid niche space but exhibited the largest range in δ13C, suggestive of foraging across multiple environments (habitat generalist) but on nutritionally similar prey in a narrow trophic band (nutritional specialist). The remaining five species had comparatively higher δ15N, pelagic‐based fatty acids and larger fatty acid niche spaces, suggesting they are nutritional generalists with a preference for higher trophic level prey. Niche space was not associated with conservation status despite declining populations for half of the species studied. This suggests that resource availability is not a limiting factor for these species and that their mobile nature provides them access to diverse habitats and resources, while exposing them to a broad range of anthropogenic threats, muting the relationship between conservation status and resource use. The combined approach allowed for a comprehensive representation of niche space, distinguishing species based on trophic level, basal carbon sources and pelagic and coastal prey consumption. The presented integrated approach provides greater detail and resolution of elasmobranch trophic ecology that could not be achieved with either fatty acid or stable isotope analysis alone. [ABSTRACT FROM AUTHOR]

For quantifying m-dimensional ( m ≥ 3 ) niche regions and niche overlaps using a copula-based approach, commonly used copulas, including Archimedean and elliptical copula families, are unsatisfactory alternatives in characterizing a complex dependence structure among multiple variables, especially when bi-variate copulas characterizing dependency structures of two-dimensional sub-variables differ. To solve the problem, we improve the copula-based niche space modeling approach using simplified vine copulas, a powerful tool containing various bi-variate dependence structures in one multivariate copula. Using four simulated data sets, we then check the performance of simplified vine copula approximation when the simplifying assumption is invalid. Finally, we apply the improved copula-based approach to quantifying a three-dimensional niche space of a real case of Swanson et al. (Ecology 96(2):318–324, 2015. https://doi.org/10.1890/14-0235.1) and discover that among various simplified vine and other flexible multi-dimensional copulas, non-parametric simplified vine copula approximation performs best in fitting the data set. In the discussion, to analyze differences in calculating niche overlaps caused by using different copulas, we compare non-parametric simplified vine copula approximation with non-parametric and parametric simplified vine copula approximation, elliptical copula, Hierarchical Archimedean copula estimation, and empirical beta copula and give some comments on the results. [ABSTRACT FROM AUTHOR]

In this study, we described and compared the diet, monthly feeding intensity, and condition of west coast steenbras (Lithognathus aureti) and silver kob (Argyrosomus inodorus) caught at a unique habitat in the northern Benguela. Stomach contents of 179 west coast steenbras and 114 silver kob caught from October 2020 to September 2022 were investigated. The peak in feeding intensity of west coast steenbras appeared to be opportunistic during winter and summer periods depending on food availability. The fish condition, however, peaked at the beginning (October) and at the end (April) of the austral summer spawning period, with the hepatosomatic index (HSI) at 1.5% and the condition factor (CF) at 0.022%. Seven prey taxa were found in the diet of west coast steenbras (bivalves, bony fishes, other mollusks, algae, crustaceans, cnidaria, and polychaetas) and six taxa in the diet of silver kob (bivalves, crustaceans, bony fishes, algae, starfish, and zooplankton), indicating generalist feeding behavior in both the species. The bivalves were the most important prey items in the diet of west coast steenbras (95.9% index of relative importance [IRI]). The most important prey items in the diet of silver kob were crustaceans (83.1% IRI) and bony fishes (16.0% IRI). Crustaceans were most important in the diet of small‐to‐medium‐sized silver kob, whereas bony fishes were most important in the diet of larger silver kob (>75 cm), with significant differences of IRI% by size class. Schoener's index of niche overlap indicated a relatively low overall niche overlap (0.11) between west coast steenbras and silver kob. This allows them to coexist as their feeding habits allow them to occupy unique niches in the coastal reef and sandy habitat and reduce competition for resources. [ABSTRACT FROM AUTHOR]

Bumblebees are important pollinators for many natural and agricultural systems in temperate regions. Interspecific and intraspecific variation in floral resource preferences have been proposed to influence bumblebee community structure. In particular, sexual dimorphism is a major source of intraspecific niche variation. Although interspecific resource partitioning is well studied, few studies have explored the intraspecific dynamics between workers and males. Here, we report a study on a total of 11 528 workers and 2220 males of 14 bumblebee species recorded over 5 years in the Hengduan Mountains of Southwest China. We first compared the potential for interspecific and intraspecific competition between workers and males using visitation records and resource partitioning indices (overlap index). We then evaluated the influence of nectar traits on flower preference, including nectar volume and the levels of hexose, sucrose and 10 essential amino acids (EAAs). We found that the niche overlap between intraspecific workers and males was higher than that between different species, and temporal overlap alone did not strongly determine diet overlap. Males of most species preferred flowers with high levels of EAAs and hexose, whereas workers of some species preferred flowers with high nectar volume and sucrose levels. This study suggests that there is floral resource partitioning among bumblebee species, and between workers and males, which may play a key role in alleviating interspecific and intraspecific competition. These findings also provide a useful guide for which kinds of plants might be most valuable for bumblebees, especially the understudied males, in this biodiversity hotspot. [ABSTRACT FROM AUTHOR]

Social entities are linked and interdependent through shared members, a phenomenon described as niche overlap. Using archival data on yearly affiliations of International Communication Association (ICA) members with divisions and interest groups over a 9-year period, this study conducts a longitudinal network analysis to examine the formation mechanisms of intra-organizational niche overlap among organizational subunits. The results of the temporal exponential random graph model suggest the absence of dominant ICA subunits whose topic areas are broad enough to integrate different specializations through membership overlap. Triadic closure facilitates the sharing of members among three subunits, leading to a cohesive internal structure and limited brokerage opportunities. Subunits with smaller membership sizes are more likely to have membership overlap, particularly with larger subunits. Positive affinity relations between subunits, characterized by the sharing of scarce resources within the organization, contribute to the formation of membership overlap. [ABSTRACT FROM AUTHOR]

Simple Summary: We used the line transect method and infrared camera traps to research the sable and yellow-throated marten in Taipinggou National Nature Reserve, Heilongjiang, China, to understand the distribution and overlap of their habitats and niches. In our study, the results showed that the habitat suitable for sables was larger than that for yellow-throated martens and that there is a partial overlap in terms of the suitable habitat for both species. There was a high degree of niche overlap between the sable and yellow-throated marten, primarily influenced by four environmental variables, i.e., "Distance from Settlements", "Distance from Roads", "Slope", and "Distance from Coniferous and Broadleaved Mixed Forest". This study can offer valuable insights for the development of policies aimed at conserving and managing sables and yellow-throated martens. The global focus on fostering harmonious interactions and promoting rational coexistence among wildlife species to uphold or reinstate biodiversity remains a prominent area of interest. We conducted a study on the sable and yellow-throated marten in Taipinggou National Nature Reserve, Heilongjiang, China, using the line transect method and infrared camera traps from 2022 to 2023. We then analyzed the overlap of their suitable habitats and niches with the aim of gaining insight into the interspecific competition between these two species. We found that the suitable habitat areas for the sable and yellow-throated marten were 55.20 km2 and 23.28 km2, accounting for 24.86% and 10.48% of the total area of this study, respectively. The overlap between the suitable habitats for the sable and yellow-throated marten was 15.73 km2, accounting for 28.5% and 67.6% of their suitable habitat, supporting our Hypothesis 1. The first principal component (Dim1) of the niche explained 35.4% of the overall variability, which is mainly related to the environmental variables "Distance from Settlements" and "Distance from Roads". Overall, 25.5% of the total variability was explained by the second principal component (Dim2), associated with "Slope" and "Distance from Coniferous and Broadleaved Mixed Forest". The niches occupied by the sable and yellow-throated marten were both off-center of the environmental background space, with the niches of the sable being larger than those of the yellow-throated marten. Schoener's D index was 0.56, indicating a high degree of niche overlap between the sable and yellow-throated marten, supporting our Hypothesis 2. Our study is helpful in terms of formulating conservation and management policies for the sable and yellow-throated marten. [ABSTRACT FROM AUTHOR]

Simple Summary: Alpine musk deer, red serow, and white-lipped deer coexist in the Nyenchen Tanglha Mountains of Tibet. We aimed to understand the mechanisms of their coexistence by studying their dietary preferences using DNA barcoding. All of the species exhibited broad dietary ranges with distinct food preferences. Furthermore, our findings revealed genus-level dietary specializations and the mechanisms facilitating their coexistence. The results of this study provide valuable insights for the development and implementation of effective conservation strategies and management measures in the local area. Wild ungulates play crucial roles in maintaining the structure and function of local ecosystems. The alpine musk deer (Moschus chrysogaste), white-lipped deer (Przewalskium albirostris), and red serow (Capricornis rubidus) are widely distributed throughout the Nyenchen Tanglha Mountains of Tibet. However, research on the mechanisms underlying their coexistence in the same habitat remains lacking. This study aimed to investigate the mechanisms underlying the coexistence of these species based on their dietary preferences through DNA barcoding using the fecal samples of these animals collected from the study area. These species consume a wide variety of food types. Alpine musk deer, white-lipped deer, and red serow consume plants belonging to 74 families and 114 genera, 62 families and 122 genera, and 63 families and 113 genera, respectively. Furthermore, significant differences were observed in the nutritional ecological niche among these species, primarily manifested in the differentiation of food types and selection of food at the genus level. Owing to differences in social behavior, body size, and habitat selection, these three species further expand their differentiation in resource selection, thereby making more efficient use of environmental resources. Our findings indicate these factors are the primary reasons for the stable coexistence of these species. [ABSTRACT FROM AUTHOR]

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]

Sympatric species reduce competitive interactions by segregating their ecological niche as a strategy that promotes coexistence. The main dimensions in which niche differentiation occurs are spatial, trophic, and temporal axes. Thus, describing the spatiotemporal patterns of sympatric species help us better grasp how species coexist. In Mexico, coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) are sympatric and widely distributed, and information about their temporal and spatiotemporal interactions is still needed to explain their coexistence throughout their distribution. The evaluation of the ecological niche in temperate forests where both species coexist has shown high spatial and trophic overlap. Therefore, more pronounced segregation must occur in other niche dimensions, such as temporal and spatiotemporal axes, to maintain the coexistence between coyotes and gray foxes. As an approach to exploring the coexistence between these species in temperate forests, we pose the following question: Is there temporal or spatiotemporal segregation between sympatric coyotes and gray foxes? We hypothesized that both species maintain coexistence due to differences in their daily activity patterns (temporal segregation) and the presence of avoidance behaviors at the spatiotemporal level (spatiotemporal segregation), thereby reducing agonistic interactions. We aimed to evaluate indicators of niche segregation through two approaches: (i) temporal niche partitioning, measuring the overlap of the daily activity patterns and activity levels; and (ii) spatiotemporal niche partitioning, through temporal co-occurrence analysis and time to encounter analysis. In 2018, we used a camera-trap array (n = 43) to evaluate spatiotemporal interactions of coyotes and gray foxes in temperate forests of northern Mexico. We found that coyotes exhibited a diurnal daily activity pattern, whereas gray foxes were nocturnal, showing low overlap between daily activity patterns. Temporal co-occurrence and time to encounter analysis showed that coyotes and gray foxes occurred independently of each other. Therefore, we demonstrated that the spatiotemporal interactions between both species is a result of random species associations. In conclusion, here we provide evidence that ecological segregation occurred in the temporal niche and not in the spatiotemporal niche of the species. Thus, the temporal niche segregation represents one of the ecological strategies that facilitates the coexistence between coyotes and gray foxes and therefore promotes their sympatry in the temperate forests of northern Mexico. [ABSTRACT FROM AUTHOR]

Premise: Hybridization is recognized as an important mechanism in fern speciation, with many allopolyploids known among congeners, as well as evidence of ancient genome duplications. Several contemporary instances of deep (intergeneric) hybridization have been noted, invariably resulting in sterile progeny. We chose the christelloid lineage of the family Thelypteridaceae, recognized for its high frequency of both intra‐ and intergeneric hybrids, to investigate recent hybrid speciation between deeply diverged lineages. We also seek to understand the ecological and evolutionary outcomes of resulting lineages across the landscape. Methods: By phasing captured reads within a phylogenomic data set of GoFlag 408 nuclear loci using HybPhaser, we investigated candidate hybrids to identify parental lineages. We estimated divergence ages by inferring a dated phylogeny using fossil calibrations with treePL. We investigated ecological niche conservatism between one confirmed intergeneric allotetraploid and its diploid progenitors using the centroid, overlap, unfilling, and expansion (COUE) framework. Results: We provide evidence for at least six instances of intergeneric hybrid speciation within the christelloid clade and estimate up to 45 million years of divergence between progenitors. The niche quantification analysis showed moderate niche overlap between an allopolyploid species and its progenitors, with significant divergence from the niche of one progenitor and conservatism to the other. Conclusions: The examples provided here highlight the overlooked role that allopolyploidization following intergeneric hybridization may play in fern diversification and range and niche expansions. Applying this approach to other fern taxa may reveal a similar pattern of deep hybridization resulting in highly successful novel lineages. [ABSTRACT FROM AUTHOR]

One of the most common environmental impacts that has caused irreversible effects on ecosystems is the introduction of exotic species. In addition to the ecological disasters that can be caused, such as the decline and extinction of native species, this phenomenon can generate significant economic losses and the possibility of the spread of parasites that are transmitted by these exotic species. These processes can be accentuated by climate change, which over time alters the global distribution pattern of the affected species, generating cases of niche overlap with species that share similar niches. In this sense, the knowledge about the areas with possible occurrence these species can direct the monitoring and control measures. In this study, we developed current and future prediction models to identify areas of suitability in the Neotropics for Melanoides tuberculata (Müller, 1774) and nine species of mollusks native to the American continent using the ecological niche modeling tool. In addition, we evaluated the ecological niche overlap between the invasive species and the native species of freshwater mollusks to verify whether the effects of climate change would alter the distribution of these organisms. The following methodological procedures were adopted to prepare the forecasting models: records of occurrence of the mollusks in different databases and search of environmental data for climate conditions in current and future scenarios in WorldClim 2.0 (SSP2-4.5 and SSP2-8.5). Besides, modeling procedures using seven packages of R software, evaluation of the models using the true skill statistic (TSS) metric, construction of maps and quantification and overlapping of ecological niche of the species included in the analysis. The results indicated that several areas of the Neotropics are suitable for the occurrence of M. tuberculata in the current scenarios. Moreover, the suitable areas for its occurrence will probably be expanded in both future scenarios. For native species, there were significant differences in relation to the areas of suitability, with a reduction for some species. Niche similarity tests indicated significant overlap only between M. tuberculata and the planorbid Biomphalaria straminea (Dunker, 1848). We discuss that the expansion of M. tuberculata can have negative consequences, including the reduction of native gastropod species and the spread of trematodes of medical and veterinary importance that this mollusk can transmit. [ABSTRACT FROM AUTHOR]

This study contributes to filling knowledge gaps regarding recent information on the diet of the European hake, Merluccius merluccius Linnaeus, 1758, in the Greek seas, particularly its ontogenetic shifts and its spatiotemporal variability. The trophic preferences of M. merluccius were investigated in the North Aegean Sea during the summers of 2019 to 2023 with visual stomach content analysis to assess its composition, diversity, and variability across body-size classes, years, and subareas. The identified prey are functionally diverse and in many cases also primary targets for local fisheries. The ontogenetic trophic niche of hake was characterized by two distinct shifts, delineated by 10 and 50 cm body-size thresholds. Cephalopods were a prevalent dietary component for large hake individuals. The intermediate body-size classes demonstrated greater trophic niche breadth concerning prey diversity and absolute prey-size ranges. A feeding strategy characterized by the specialization of individuals was also revealed. The effect of the temporal and spatial context on the hake diet was occasionally correlated with spatiotemporal variations in the sizes of their populations. In conclusion, ontogenetic and spatiotemporal variability in the hake diet were found to be significant and should be considered in the data collection design and analyses of the trophic interactions of the species. [ABSTRACT FROM AUTHOR]

This study delves into the concept of niche conservatism (NC) and its implications for how hornets (Hymenoptera: Vespidae) and honeybees respond to climate change. Our primary objectives are threefold: firstly, to assess whether distinct environmental niche spaces (E‐space) exist between 12 hornets and honeybees like Apis cerana and Apis mellifera in Asia; Secondly, to explore the degree to which Asian hornets have attained geographic equilibrium alongside honeybee species. Lastly, is to investigate how the geographic niche overlap (G‐space) between hornets and honeybees could potentially change under climate change scenarios. To accomplish these goals, we employed ordination and ecological niche modeling techniques to analyze 91 pairs of hornets and honeybees in both geographic (G‐space) and environmental (E‐space) contexts. Then, we projected the potential impacts of climate change on the future geographic overlap between hornets and honeybees, specifically under the SSP585 climate scenario for the year 2070. Our results demonstrated that the environmental niches (E‐space) of hornets and honeybees can be treated as interchangeable, indicating they have similar environmental preferences despite being unrelated taxa. We found that Vespa velutina currently exhibits a moderate geographic niche overlap (G‐space) of 0.63 with both honeybee species. Meanwhile, Vespa mandarinia demonstrates an overlap of 0.46 with Apis cerana and 0.63 with Apis mellifera. The overlap of Vespa velutina with Apis cerana might potentially decrease to 0.51 and 0.56 with Apis mellifera. For Vespa mandarinia, the overlap could reach 0.41 with Apis cerana and 0.6 with Apis mellifera under a climate change scenario. This study indicates that the limited spatial overlap between honeybees and hornets across certain areas in Asia is more likely influenced by geographical barriers rather than solely environmental unsuitability for hornets. In this study, we delve into the concept of niche conservatism (NC) and its implications for how hornets (Hymenoptera: Vespidae) and honeybees respond to climate change. [ABSTRACT FROM AUTHOR]

Yellow-phase Japanese eel Anguilla japonica (Temminck & Schlegel, 1846) utilize a variety of anthropogenically impacted habitats. An extensive understanding of the trophic ecology and habitat use is necessary for the conservation of this endangered species. In this study, we analysed the trophic ecology and feeding habitat of Japanese eels in two small rivers, the Akugawa River and Takase River in Wakayama Prefecture, Japan, dominated by an urban landscape and agricultural land use, respectively. The main goals were to assess the dietary diversity and trophic niche width for eels of two size classes (small eels: ≤ 240 mm total length, large eels: > 240 mm total length) in both habitats. The suitability of both rivers as a feeding habitat for eels was also evaluated. The trophic ecology of eels was inferred based on analysis of carbon and nitrogen stable isotopes, as well as stomach contents. Our results indicated that both rivers are suitable habitats to accommodate this eel, but to varying degrees. The dietary diversity of small eels and trophic niche width differed between rivers, indicating limiting factors, such as insufficient food sources and unfavourable abiotic habitat requirements for small eels in urban rivers. Also, the body condition of eels was found to be lower in the urban Akugawa River than in the Takase River. [ABSTRACT FROM AUTHOR]

Elucidating changes in the structure and function of plant communities along different elevation ranges will help researchers to analyze the strategies plant communities use in environments and processes influencing niche differentiation. The aims of this paper are to reveal the underlying mechanisms and ecological processes governing the development of subtropical forest ecosystem plant communities. This paper analyzes the forest vegetation of the Wuyi Mountains across the following three elevation ranges: low elevation, mid elevation, and high elevation, spanning from 560 to 2150 m. Twenty and twenty-three dominant tree and shrub layer species, respectively, were identified based on their importance values, and their niches and species associations were further analyzed based on the elevation range. The results showed interspecific associations between tree and shrub species, with the strongest associations observed at mid-elevations. The analysis of niche width and overlap showed that the number of pairs of species with a higher degree of niche overlap decreased with increasing elevation, suggesting that resource use varied at different elevations for both tree and shrub layer species, which may be related to the adaptive capacity of plants at different elevations to the environment and resource use strategies. These findings should contribute to a deeper understanding of the ecological functioning and structural framework of plant communities on Wuyi Mountain. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Introducing invasive alien species can reduce biodiversity by interfering with native species or spreading disease and having socioeconomic consequences. Therefore, international society has set goals for preventing and suppressing the introduction and spread of invasive alien species. Nevertheless, humans intentionally introduce and release alien species into the wild, facilitating their invasion. Procambarus virginalis (marbled crayfish) is a Decapoda invertebrate sold for ornamental purposes. Ecological repercussions are anticipated because individuals have been verified to exist in the wild in South Korea. P. virginalis, believed to have originated in Europe and North America, is parthenogenetic. Therefore, there is concern that its population may quickly expand in the natural environment. Results: This study examined the invasion risk of P. virginalis in South Korea and predicted its dispersal under future climatic circumstances. The habitat suitability for P. virginalis in Europe, North America, and Northeast Asia was determined using an ensemble species distribution model, and climatic niches were compared. Furthermore, the distributions of South Korea under the SSP2-4.5 and SSP5-8.5 scenarios are provided. The Northeast Asian region had habitat suitability comparable to that of Europe, and there was evidence that its climatic niche overlapped Europe (Schoener's D = 0.29). In the future climatic scenario, 38% of South Korea is at risk of moderate to low invasion. The human disturbance index was the most critical variable in the distribution. Conclusions: We believe the hazards of its invasion of South Korea are significant. Additionally, there is a high possibility that they will be established in nature due to artificial releases. Therefore, continuous monitoring and appropriate management are needed for areas with a high risk of P. virginalis invasion.

The papaya mealybug, Paracoccus marginatus, is a highly polyphagous invasive pest that affects at least 133 economically important crops, and causes economic losses worldwide. Acerophagus papayae (Noyes and Schauff), a parasitic wasp, has proven to be a successful biocontrol agent, but its use in Africa is limited. Here, we use a predictive correlative model to explore the potential distribution of A. papayae and relate it to data showing the potential distribution of P. marginatus, to highlight potentially suitable areas for biological control of P. marginatus, for its current distribution, as well as its potential future distribution.The resulting model performed well with a test AUC of 0.89. Areas that were highly suitable for P. marginatus and were also suitable for A. papayae were highest across West Africa. Whilst there were areas which were suitable for both species in both East Africa and Central Africa, there were large areas of cropping land which were highly suitable for P. marginatus although not suitable for A. papayae. Across Northern and Southern Africa, there were limited cropping areas which were suitable for P. marginatus and where there was suitability, it was only moderate. Across these areas, there was limited suitability for A. papayae.Our results offer refined information on the potential suitability for A. papayae across Africa with the aim to help guide decisions on the areas where use of A. papayae could be used effectively as a part of an integrated pest management programme against P. marginatus.

The introduction of new species can have unpredictable effects on native communities. Understanding the potential for competitive interactions between widow spiders (Theridiidae: Latrodectus), and how they may have shaped species’ geographic distributions, is critical for predicting the impacts of biological invasions in this historically cryptic group. North America is home to three native widows (L. hesperus, L. mactans, L. variolus) and one invasive widow (L. geometricus) with distributions that are at least partly sympatric. Given the relative novelty of L. geometricus in native communities as they expand their range, it is unclear if and how they share resources with their congeners, and competition for climatic resources (space) could result in ecological impacts to native widows. Here we aim to model niche differentiation and niche dynamics between native widows, that have coevolved over time, and between native and brown widows to assess the potential for ecological impact. We investigated the potential for climatic niche partitioning to shape sympatric geographic distributions of native widows compared to each other and to L. geometricus. We aggregated photographed occurrences from social media communities and online repositories to quantify climatic niche overlap for all four species on a continental scale, to assess niche dynamics among native species and between invasive and nativespecies. We found that native species had distributions that were more strongly partitioned, showing weaker niche overlap, except for the two eastern widows, which showed strong overlap and niche equivalency. Conversely, we found greater niche overlap between L. geometricus and native widows, possibly because it is too soon to see the effect of competition on species’ geographic distributions, or because differences in diet or partitioning of urban versus nonurban microhabitats promote coexistence.

Aim: The response of South American seasonally dry tropical forest (SDTF) and savanna species to the Quaternary climate changes is still poorly understood. Here we use multi‐model inference approach to compare the phylogeography and demographic history of five trumpet tree species (also known as pau‐d'arco) and draw general biogeographical patterns: Handroanthus impetiginosus, H. ochraceus, H. serratifolius, Tabebuia aurea and T. roseoalba. Location: Amazonia, Atlantic Forest, Cerrado and Caatinga ecoregions, South America and Brazil. Taxa: Bignoniaceae, Tabebuia Alliance, trees. Methods: We compiled genetic data, occurrence records and ecological niche modelling (ENM) from published articles. We used coalescent modelling to test patterns of co‐divergence, and analysed niche breadth and overlap and spatial patterns in genetic diversity using quantile regressions. Results: Species showed concordant lineage divergence times in the Pleistocene. Lineage diversification and phylogeographical patterns are more related to species niche breadth than to biome (savanna or SDTF). Differences in genetic diversity among species matches the expected for the demographic scenarios obtained with coalescent simulations and ENMs: species with wider range expansion during the Last Glacial Maximum had higher diversity than species with range retraction or multiple refugia. Main Conclusions: Diversification burst in the Pliocene, and major diversification of lineages during the Pleistocene seems to be a general pattern in SDTF and savannas in the South America. The high number of haplotypes at the Central Brazil, corresponding to the Cerrado ecoregion, highlights the importance of Protected Areas for SDTFs and savannas, highly threatened biomes in Brazil. [ABSTRACT FROM AUTHOR]

Co-occurring predators often exhibit ecological niche partitioning, resulting from competition over evolutionary time. However, in productive estuarine ecosystems with high resource availability, predators may occupy similar niches without conflict. Determining the degree of niche partitioning and overlap among co-occurring predators can provide insights into a food web's function and its potential resiliency to perturbations. This study used stable isotope analysis to assess the trophic ecology of four predators in Galveston Bay, Texas, USA: spotted seatrout, black drum, bull shark, and alligator gar. Spatially distinct primary producer isotopic ratios emerged for both δ13C and δ15N following salinity regimes, which translated to similar patterns in predator tissue. The volume and overlap among species' trophic niches also varied spatially, with species-specific expansion and contraction of niches across the freshwater-marine continuum. The observed niche patterns were likely related to movements, with implications for trophic coupling across the estuarine landscape. Using regional delineations for baseline values yielded trophic position estimates that were validated by compound-specific stable isotopes and were similar (3.77 to 3.96) for all species but black drum (3.25). Trophic position increased with body length for all species but black drum, and these relationships differed when using estuary-wide versus regionally distinct baselines. Alligator gar gut contents were examined, which primarily aligned with piscivory but also included previously unreported taxa (insect, mammal). Collectively, these results provide evidence for spatial and ontogenetic shifts in trophic ecology within this predator assemblage and highlight the importance of spatial scale when using stable isotopes to examine estuarine food webs. [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]

The ability of community species to adapt to the environment and use resources and the importance of species in the ecological system in time and space are generally represented by ecological niche. In order to study the niche characteristics and dynamic changes of the dominant species in the arbor layer of the 4hm² Pinus tabuliformis-Quercus wutaishansea mixed forest sample plot in Lingkong Mountain,and to gain a better understanding of the competition and coexistence among species in the sample plot, this study was conducted based on a typical community investigation. Four indices of important value, niche width, niche overlap, and niche similarity were chosen to calculate and analyze the niche characteristics and examine dynamic changes over a period of 10 years from 2011 to 2021. The results showed that: (1) In 2021, the important values for Quercus wutaishansea and Pinus tabuliformis were 19.906 and 13.906, respectively.The niche widths were 0.962 and 0.555, which showed difference compared to those in 2011. Both were much larger than other species, indicating that they occupied an absolutely dominant position in the community. (2) The mean values of niche overlap and similarity of dominant species in the arbor layer of the Lingkong Mountain sample plot have both increased over the past 10 years. Additionally, the species pairs with the highest overlap and similarity values have changed, suggesting an intensification of competition among these species. [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]

The continuous growth and movement of the human population is increasing the frequency of translocating species from their native ranges to novel environments. However, biological invasions offer a rare opportunity to investigate how species can colonise and adapt to new conditions. In that sense, Ecological Niche Models (ENMs) can be a powerful tool to predict where invasive species will spread over the next decades, although they depend heavily on climatic niche conservatism between native and exotic ranges. To reduce these uncertainties, ENMs can be refined by accounting for dispersal constraints. The common wall gecko, Tarentola mauritanica is a native and widespread Mediterranean lizard that has been introduced across different tropical and sub-tropical regions. In this study, we aim to predict the potential and future distribution of T. mauritanica geckos using correlative models, its potential colonization regions under a dispersal model, and the niche overlap between native and introduced populations. The correlative models predict that the most suitable geographic areas for this gecko correspond to Mediterranean-type ecosystems, such as California, central Chile, the Cape Region of South Africa, around the Caspian Sea, south-eastern Asia, and south-western and southern Australia. The species distribution models projected to 2061–2080, forecast that the range of T. mauritanica is likely to shift towards northern latitudes but, surprisingly, not to expand. According to the dispersal models, T. mauritanica will be able to colonise a similar geographic range compared to the one obtained with the correlative models for the future. Finally, the niche overlap results demonstrate that T. mauritanica's realised niche has not been conserved over space, as the naturalised climatic niche of the introduced populations differs significantly from its native one. The latter results suggest that there has been no climatic niche conservatism during the several introductions of T. mauritanica and that this species seems to be able to cope with novel and more humid environments, typical from the tropics. [ABSTRACT FROM AUTHOR]

Knowledge of the large carnivore guild is important in view of a possible lion reintroduction into the Comoé National Park (CNP), northern Côte d’Ivoire. We used camera trapping to assess activity patterns, habitat selection, and ecological factors influencing the occupancy of the spotted hyena Crocuta crocuta. Our results showed that the presence of leopard Panthera pardus, the only current other large carnivore and thus potential competitor, did not influence hyena occupancy. Hyena occupancy was only significantly related to Euclidian distance to nearest water point. Manly’s alpha habitat selection index values show a preference of spotted hyena for shrub savannah (αSa = 0.71), and Pianka’s overlap index showed low spatial competition with leopard (OIJ(PNC) = 0.12). Our findings showed that spotted hyena were mostly nocturnal, and generally active at the same time slots with leopard, leading to a high index of temporal overlap (OIJ(time) = 0.78). The kernel density estimation confirmed that spotted hyenas and leopard shared almost half of their activity patterns (Δ1 = 0.49 and 95% CI = 0.26–0.71). Prey diversity is high in CNP but anthropogenic threats appear to suppress population growth of prey and predators. Conservation efforts should continue to reduce pressures before contemplating a potential lion Panthera leo reintroduction. [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.

Corybas Salisb. is a widespread plant genus in the family Orchidaceae, known for its small, beautiful flowers. Most species in this genus are narrow endemics. China is home to six Corybas species, five of which are endangered, covering southern China from Taiwan to the western Himalayas. Niche overlap analysis was conducted on global Corybas species to assess the conservation value of Chinese Corybas species from evolutionary, adaptive, and niche diversity perspectives. The results revealed that Chinese Corybas species have formed a unique niche lineage, warranting conservation efforts. Due to challenges in field investigations, the potential distribution patterns of Chinese Corybas species remain unclear. The Species Distribution Model (SDM) using MaxEnt and Ensembles of Small Models (ESMs) was employed to analyze the potential distributions of five Corybas species in southern China and guide genus conservation. Both MaxEnt and ESMs analyses indicated that Chinese Corybas species may face significant environmental challenges in the future. This study identified gaps in fieldwork, highlighting the need to explore new populations of Corybas species in these areas. Conservation recommendations considering future climate change were proposed to aid programs aimed at preserving Chinese Corybas species.

Abstract Climate change and other extinction facilitators have caused significant shifts in the distribution patterns of many species during the past few decades. Restoring and protecting lesser-known species may be more challenging without adequate biogeographical information. To address this knowledge gap, the current study set out to determine the global spatial distribution patterns of Indigofera oblongifolia (Forssk) a relatively lesser-known leguminous species. This was accomplished by utilizing three distinct bioclimatic temporal frames (current, 2050, and 2070) and four greenhouse gas scenarios (RCPs 2.6, 4.5, 6.0, and 8.5), in addition to non-climatic predictors such as global livestock population, human modification of terrestrial ecosystems, and global fertilizers application (nitrogen and phosphorus). Furthermore, we evaluate the degree of indigenousness using the geographical area, habitat suitability categories, and number of polygons. This research reveals that climatic predictors outperform non-climatic predictors in terms of improving model quality. Precipitation Seasonality is one of the most important factors influencing this species' optimum habitat suitability up to 150 mm for the current, 2050 RCP 8.5 and 2070-RCPs 2.6, 4.5, and 8.5. Our ellipsoid niche modelling extends the range of precipitation during the wettest quarter and maximum temperature during the warmest month to 637 mm and 26.5–31.80 degrees Celsius, respectively. India has a higher indigenous score in the optimal class than the African region. This findings suggest that the species in question tends to occupy contiguous regions in Africa, while in India, it is dispersed into several smaller meta-populations.

The relationship between spatial distribution and phylogeny has been widely debated in recent decades. To understand biogeographic and evolutionary history relationships and to explore the interspecific similarities and phylogenetic correlations of niche characteristics, we collected and recorded all distribution points for eight species of rhubarb on the Qinghai‐Tibet Plateau, used different methods to describe the ecological niche, and explored the relationship between phylogeny, ecological niche, and distribution range. The results reveal that: (1) the ranges of optimal environmental variables for species with close kinship are not exactly the same, ecologically similar species are not necessarily sister species, and the overlap of rhubarb has no significant correlation with phylogeny. Therefore, the impact of ecological dimensions on species formation is greater than that of geographical latitude for the eight species of rhubarb. (2) Among the eight species of rhubarb, the breadth of ecological niche is positively correlated with the current suitable habitat area and negatively correlated with fluctuations in future suitable habitat area. In the future, except for Rheum tanguticum and Rheum palmatum, the suitable planting areas for the other six species of rhubarb will decrease as greenhouse gas emissions concentrations and time increase. Therefore, species with smaller ecological niches are at a greater risk of habitat loss compared to species with larger ecological niches. (3) In both existing and future distribution prediction models of rhubarb, we observed that both the widely distributed Rheum spiciforme and the niche narrow Rheum nobile, all eight species of rhubarb are present in the Hengduan Mountains, based on our analysis, we propose that the Hengduan Mountains should be regarded as a priority conservation area for rhubarb, to preserve the species' biodiversity. Our study lays the groundwork for identifying evolutionary trends in ecological specialization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: Falcons are keystone species that maintain ecosystem structures, functions, and services. With the help of phylogenetic comparative methods, climatic data, and species distribution modeling, we investigated how European falcon climatic niches have changed over evolutionary time. Convergent evolution and niche divergence have played an important role in the evolutionary history of these species, with speciation being influenced by climatic niche differentiation, more prevalent in the last 4 million years, with the main climatic niche shifts occurring between closely related falcon species. By integrating species distribution modeling techniques, phylogenetic comparative methods, and climatic data, we analyzed how European falcon climatic niches have changed over evolutionary time in order to understand their tempo and mode of evolution and gain phylogenetic insights related to the ecological context of falcon evolution. For this purpose, we tested the relative contributions of niche conservatism, convergent evolution, and divergent evolution in the evolutionary history of this group of species in Europe. The occupation of climatic niche spaces by falcon species in Europe was not similar, considering that their climatic niche evolution was characterized by heterotachy, especially after ca. 4 Mya. Our results indicate that convergent evolution and niche divergence played an important role in the evolutionary history of these species, with no significant evidence of closely related species retaining their fundamental niche over time (phylogenetic niche conservatism). In most analyses, less closely related falcon species occupied similar climatic environments. We found that speciation in the European genus Falco was influenced by climatic niche differentiation, more prevalent in the last 4 million years, with the main climatic niche shifts occurring between closely related falcon species. [ABSTRACT FROM AUTHOR]