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The emergence of metacommunity theory has provided a framework for studying the spatial structure of biological communities. To unravel the underlying driving mechanisms of macroinvertebrate metacommunity structure and diversity, this paper evaluates macroinvertebrate data from a water body in eastern China using variance decomposition and stratified partitioning. The results suggest that spatial processes dominate macroinvertebrate metacommunity structure, while the combined effects of spatial processes, aquatic environment, and geoclimatic factors also explain part of the macroinvertebrate community structure. Spatial processes, aquatic environment, and geoclimatic factors significantly influenced macroinvertebrate alpha diversity and indirectly influenced beta diversity through alpha diversity. Therefore, the significant effects of spatial processes and geoclimatic variables cannot be ignored in biological assessments, especially biodiversity assessments. Our findings elucidate the metacommunity dynamics in the region and provide crucial information for conservation planning in riverine ecosystems. [ABSTRACT FROM AUTHOR]

The emergence of metacommunity theory has provided a framework for studying the spatial structure of biological communities. To unravel the underlying driving mechanisms of macroinvertebrate metacommunity structure and diversity, this paper evaluates macroinvertebrate data from a water body in eastern China using variance decomposition and stratified partitioning. The results suggest that spatial processes dominate macroinvertebrate metacommunity structure, while the combined effects of spatial processes, aquatic environment, and geoclimatic factors also explain part of the macroinvertebrate community structure. Spatial processes, aquatic environment, and geoclimatic factors significantly influenced macroinvertebrate alpha diversity and indirectly influenced beta diversity through alpha diversity. Therefore, the significant effects of spatial processes and geoclimatic variables cannot be ignored in biological assessments, especially biodiversity assessments. Our findings elucidate the metacommunity dynamics in the region and provide crucial information for conservation planning in riverine ecosystems. [ABSTRACT FROM AUTHOR]

Bacterial communities in river sediments are shaped by a trade-off between dispersal from upstream or nearby land and selection by the local environmental conditions. In temporary rivers (i.e. those characterized by long drying periods and subsequent rewetting) seasonal hydrological dynamics shape bacterial communities by connecting or disconnecting different river habitats. In this study, we tracked and compared the temporal and spatial changes in the composition of bacterial communities in streambed sediments and floodplain habitats across both permanent and intermittent river segments. Our findings revealed that environmental selection played a key role in assembling bacterial communities in both segments. We argue that distinct environmental features act as filters at the local scale, favoring specific bacterial taxa in isolated pools and promoting some typically terrestrial taxa in dry areas. Considering the prospective extension of drying intervals due to climate change, our results suggest an emerging trend wherein bacterial assemblages in temporary streams progressively incorporate microorganisms of terrestrial origin, well-adapted to tolerate desiccation phases. This phenomenon may constitute an integral facet of the broader adaptive dynamics of temporary river ecosystems in response to the impacts of climate change. [ABSTRACT FROM AUTHOR]

Understanding spatial variation in species distribution and community structure is at the core of community ecology. Nevertheless, the effect of distance on metacommunity structure remains little studied. We examine how plant‐pollinator community structure changes across geographical distances at a regional scale and disentangle its underlying local and regional processes.We use a multilayer network to represent linked plant‐pollinator communities as a metacommunity in the Canary Islands. We used modularity (i.e. the extent to which the community is partitioned into groups of densely interacting species) to quantify distance decay in structure across space. In multilayer modularity, the same species can belong to different modules in different communities, and modules can span communities. This enabled quantifying how similarity in module composition varied with distance between islands. We developed three null models, each controlling for a separate component of the multilayer network, to disentangle the role of species turnover, interaction rewiring and local factors in driving distance decay in structure.We found a pattern of distance decay in structure, indicating that islands tended to share fewer modules with increasing distance. Species turnover (but not interaction rewiring) was the primary regional process triggering distance decay in structure. Local interaction structure also played an essential role in determining the structure similarity of communities at a regional scale. Therefore, local factors that determine species interactions occurring at a local scale drive distance decay in structure at a regional scale.Our work highlights the interplay between local and regional processes underlying community structure. The methodology, and specifically the null models, we developed provides a general framework for linking communities in space and testing different hypotheses regarding the factors generating spatial structure. [ABSTRACT FROM AUTHOR]

Co‐occurrence networks offer insights into the complexity of microbial interactions, particularly in highly diverse environments where direct observation is challenging. However, identifying the scale at which local and non‐local processes structure co‐occurrence networks remains challenging because it requires simultaneously analyzing network structure within and between local networks. In this context, the rumen microbiome is an excellent model system because each cow contains a physically confined microbial community, which is imperative for the host's livelihood and productivity. Employing the rumen microbiome of 1012 cows across seven European farms as our model system, we constructed and analyzed farm‐level co‐occurrence networks to reveal underlying microbial interaction patterns. Within each farm, microbes tended to close triangles but some microbial families were over‐represented while others under‐represented in these local interactions. Using stochastic block modeling we detected a group structure that reflected functional equivalence in co‐occurrence. Knowing the group composition in one farm provided significantly more information on the grouping in another farm than expected. Moreover, microbes strongly conserved co‐occurrence patterns across farms (also adjusted for phylogeny). We developed a meta‐co‐occurrence multilayer approach, which links farm‐level networks, to test scale signatures simultaneously at the farm and inter‐farm levels. Consistent with the comparison between groups, the multilayer network was not partitioned into clusters. This result was consistent even when artificially disconnecting farm‐level networks. Our results show a prominent signal of processes operating across farms to generate a non‐random, similar (yet not identical) co‐occurrence patterns. Comprehending the processes underlying rumen microbiome assembly can aid in developing strategies for its manipulation. More broadly, our results provide new evidence for the scale at which forces shape microbe co‐occurrence. Finally, the hypotheses‐based approach and methods we developed can be adopted in other systems to detect scale signatures in species interactions. [ABSTRACT FROM AUTHOR]

Aim Location Methods Results Main Conclusions The assembly of real‐world ecological communities in human‐modified landscapes is influenced by a complex interplay of spatial, temporal, environmental and invasion gradients. However, understanding the relative importance of these drivers and their interactions in shaping functional assembly remains elusive. Our study aimed to investigate the relative influence of these drivers on the functional assembly of a stream fish metacommunity.Streams of the Lake Balaton catchment, Hungary.We analysed a long‐term (18‐year) dataset of the stream fish metacommunity, focusing on changes in functional diversity (Q), redundancy (R) and species dominance (D). Ternary diagrams were utilized to decompose functional diversity into Q, R and D components and to visualize diversity patterns. Linear mixed‐effect regression and separate structural equation models were employed to identify significant drivers of Q, R and D.Native fish communities exhibited low functional diversity (Q) but high redundancy (R) and dominance (D), indicating functional convergence and dominance. Stream habitat size, network position and associated spatial, physical and chemical gradients emerged as consistently significant drivers of D and R. Changes in Q were additionally linked to non‐native community properties and subtle shifts in land use and within‐stream habitat characteristics.Our findings suggest that both environmental filtering and interspecies interactions, particularly trait similarity between invaders and natives shape functional assembly of stream fish metacommunities. Despite minimal temporal directional changes, environmental drivers predominantly influence long‐term diversity patterns of native fish communities, overshadowing invasion effects. Our findings underscore the importance of considering both environmental filtering mechanisms and interspecies interactions in understanding functional assembly. Additionally, the joint application of diversity decomposition frameworks with predictive modelling provides comprehensive insight into patterns of functional diversity and assembly across ecological communities. [ABSTRACT FROM AUTHOR]

Community drivers shift over time in response to changes in landscape and environmental conditions. Although dams alter the landscape (e.g., by flooding areas) and environment (e.g., by increasing transparency), their impact on the influence of community drivers remains unclear. We investigated how the construction of a large Amazonian River dam altered the influence of environment and space on planktonic communities. From 2005 to 2015, we monitored environmental parameters and collected phytoplankton and zooplankton from 15 locations along the Madeira River and its tributaries. We conducted twenty-nine samplings upstream of the Jirau dam before, during filling, and after its construction, evaluating the influence of environment and space on communities and assessing any changes with damming. We documented the frequency of significant variables to determine if their importance (frequency) changed post-damming. Following damming, environmental heterogeneity decreased and communities comprised species adapted to lentic habitats, with the environment exerting the main influence. Damming did not significantly alter environmental influence but shifted specific drivers, with some factors decreasing (e.g., nutrients) and others increasing (e.g., oxygen) in importance, indicating changes in the environmental mechanisms underlying community assemblage. Monitoring programs in dam-affected regions should be regularly evaluated due to the temporal variability of aquatic community drivers. [ABSTRACT FROM AUTHOR]

Understanding the drivers of community stability has been a central goal in ecology. Traditionally, emphasis has been placed on studying the effects of biotic interactions on community variability, and less is understood about how the spatial configuration of habitats promotes or hinders metacommunity stability. To test the effects of contrasting spatial configurations on metacommunity stability, I designed metacommunities with patches connected as random or scale-free networks. In these microcosms, two prey and one protist predator dispersed, and I evaluated community persistence, tracked biomass variations, and measured synchrony between local communities and the whole metacommunity. After 30 generations, scale-free metacommunities had lower global biomass variability and higher persistence, suggesting higher stability. Synchrony between patches was lower in scale-free metacommunities. Patches in scale-free metacommunities showed a positive relationship between variability and patch connectivity, indicating higher stability in isolated communities. No clear relationship between variability and patch connectivity was observed in random networks. These results suggest the increased heterogeneity in connectivity of scale-free networks favours the prevalence of isolated patches of the metacommunity, which likely act as refugia against competition—the dominant interaction in this system—resulting in higher global stability. These results highlight the importance of accounting for network topology in the study of spatial dynamics. [ABSTRACT FROM AUTHOR]

Rivers form meta‐ecosystems, in which disturbance and connectivity control biodiversity, ecosystem functioning and their interactions across the river network, but also across connected instream and riparian ecosystems. This aquatic–terrestrial linkage is modified by drying, a disturbance that also naturally fragments river networks and thereby modifies organism dispersal and organic matter (OM) transfers across the river network. However, little evidence of the effects of drying on river network‐scale OM cycling exists. Here, we assessed the effects of fragmentation by drying at the river meta‐ecosystem scale by monitoring leaf resource stocks, invertebrate communities and decomposition rates, across three seasons and 20 sites, in the instream and riparian habitats of a river network naturally fragmented by drying. Although instream leaf resource quantity and quality increased, leaf‐shredder invertebrate richness and abundance decreased with flow intermittence. Decomposition was, however, mainly driven by network‐scale fragmentation and connectivity. Shredder richness and invertebrate‐driven decomposition both peaked at sites with intermediate amounts of intermittent reaches upstream, suggesting that upstream drying can promote the biodiversity and functioning of downstream ecosystems. Shredder richness, however, had a negative effect on decomposition in perennial sites, likely due to interspecific competition. Leaf quantity, invertebrate communities and invertebrate‐driven decomposition became more similar between instream and riparian habitats as drying frequency increased, likely due to homogenization of environmental conditions between both habitats as the river dried. Our study demonstrates the paramount effects of drying on the dynamics of resources, communities and ecosystem functioning in rivers and presents evidence of one of the first network‐scale examples of the co‐drivers of ecosystem functions across terrestrial–aquatic boundaries. [ABSTRACT FROM AUTHOR]

River catchments are dynamic networks that contain multiple levels of spatial and temporal complexity. Benthic macroinvertebrates are key indicator taxa throughout catchments, and beta diversity has been used as a metric to explore determinants of community composition at the catchment scale. Although factors influencing spatial beta diversity have been explored, the determinants of temporal beta diversity have been understudied. In this study, we aimed to understand how shifts in benthic macroinvertebrate community composition over multiple years are related to local and regional variables. We used beta regression with a large, publicly available biomonitoring dataset from river networks in California, USA, to model the effects of local environmental variables, flow variability, and spatial network context on benthic macroinvertebrate temporal beta diversity. The spatial variables channel slope, drainage density, and upstream catchment area had the strongest relationships with macroinvertebrate beta diversity. Channel slope was negatively related to temporal beta diversity, whereas drainage density and upstream catchment area were positively related to temporal beta diversity. Temporal beta diversity was also higher when the rate and magnitude of rises and falls in flow were higher in the hydrograph, as well as when the number of zero-flow days and the duration of flow rises and falls were higher. Overall, our results indicate that temporal beta diversity of freshwater benthic macroinvertebrates is shaped by both long-term hydrological context and spatial context and that these factors may serve as better predictors of long-term community variability than variability in point estimates of environmental measurements. Our study supports the need for biomonitoring efforts at long spatial and temporal timescales and highlights the need to consider metacommunity change in the management of freshwater systems. [ABSTRACT FROM AUTHOR]

Spatial dynamics can promote persistence of strongly interacting predators and prey. Theory predicts that spatial predator-prey systems are prone to long transients, meaning that the dynamics leading to persistence or extinction manifest over hundreds of generations. Furthermore, the form and duration of transients may be altered by spatial network structure. Few empirical studies have examined the importance of transients in spatial food webs, especially in a network context, due to the difficulty in collecting the large scale and long-term data required. We examined predator-prey dynamics in protist microcosms using three experimental spatial structures: isolated, river-like dendritic networks and regular lattice networks. Densities and patterns of occupancy were followed for both predators and prey over a time scale that equates to >100 predator and >500 prey generations. We found that predators persisted in dendritic and lattice networks whereas they went extinct in the isolated treatment. The dynamics leading to predator persistence played out over long transients with three distinct phases. The transient phases showed differences between dendritic and lattice structures, as did underlying patterns of occupancy. Spatial dynamics differed among organisms in different trophic positions. Predators showed higher local persistence in more connected bottles while prey showed this in more spatially isolated ones. Predictions based on spatial patterns of connectivity derived from metapopulation theory explained predator occupancy, while prey occupancy was better explained by predator occupancy. Our results strongly support the hypothesized role of spatial dynamics in promoting persistence in food webs, but that the dynamics ultimately leading to persistence may occur with long transients which in turn may be influenced by spatial network structure and trophic interactions.

A tenet of ecology is that temporal variability in ecological structure and processes tends to decrease with increasing spatial scales (from locales to regions) and levels of biological organization (from populations to communities). However, patterns in temporal variability across trophic levels and the mechanisms that produce them remain poorly understood. Here we analyzed the abundance time series of spatially structured communities (i.e., metacommunities) spanning basal resources to top predators from 355 freshwater sites across three continents. Specifically, we used a hierarchical partitioning method to disentangle the propagation of temporal variability in abundance across spatial scales and trophic levels. We then used structural equation modeling to determine if the strength and direction of relationships between temporal variability, synchrony, biodiversity, and environmental and spatial settings depended on trophic level and spatial scale. We found that temporal variability in abundance decreased from producers to tertiary consumers but did so mainly at the local scale. Species population synchrony within sites increased with trophic level, whereas synchrony among communities decreased. At the local scale, temporal variability in precipitation and species diversity were associated with population variability (linear partial coefficient, β = 0.23) and population synchrony (β = −0.39) similarly across trophic levels, respectively. At the regional scale, community synchrony was not related to climatic or spatial predictors, but the strength of relationships between metacommunity variability and community synchrony decreased systematically from top predators (β = 0.73) to secondary consumers (β = 0.54), to primary consumers (β = 0.30) to producers (β = 0). Our results suggest that mobile predators may often stabilize metacommunities by buffering variability that originates at the base of food webs. This finding illustrates that the trophic structure of metacommunities, which integrates variation in organismal body size and its correlates, should be considered when investigating ecological stability in natural systems. More broadly, our work advances the notion that temporal stability is an emergent property of ecosystems that may be threatened in complex ways by biodiversity loss and habitat fragmentation. [ABSTRACT FROM AUTHOR]

The competition-colonization (CC) trade-off is a well-studied coexistence mechanism for metacommunities. In this setting, it is believed that the coexistence of all species requires their traits to satisfy restrictive conditions limiting their similarity. To investigate whether diverse metacommunities can assemble in a CC trade-off model, we study their assembly from a probabilistic perspective. From a pool of species with parameters (corresponding to traits) sampled at random, we compute the probability that any number of species coexist and characterize the set of species that emerges through assembly. Remarkably, almost exactly half of the species in a large pool typically coexist, with no saturation as the size of the pool grows, and with little dependence on the underlying distribution of traits. Through a mix of analytical results and simulations, we show that this unlimited niche packing emerges as assembly actively moves communities toward overdispersed configurations in niche space. Our findings also apply to a realistic assembly scenario where species invade one at a time from a fixed regional pool. When diversity arises de novo in the metacommunity, richness still grows without bound, but more slowly. Together, our results suggest that the CC trade-off can support the robust emergence of diverse communities, even when coexistence of the full species pool is exceedingly unlikely. [ABSTRACT FROM AUTHOR]

Microorganisms have the potential to affect plant seed germination and seedling fitness, ultimately impacting plant health and community dynamics. Because seed-associated microbiota are highly variable across individual plants, plant species, and environments, it is challenging to identify the dominant processes that underlie the assembly, composition, and influence of these communities. We propose here that metacommunity ecology provides a conceptually useful framework for studying the microbiota of developing seeds, by the application of metacommunity principles of filtering, species interactions, and dispersal at multiple scales. Many studies in seed microbial ecology already describe individual assembly processes in a pattern-based manner, such as correlating seed microbiome composition with genotype or tracking diversity metrics across treatments in dispersal limitation experiments. But we see a lot of opportunities to examine understudied aspects of seed microbiology, including trait-based research on mechanisms of filtering and dispersal at the micro-scale, the use of pollination exclusion experiments in macro-scale seed studies, and an in-depth evaluation of how these processes interact via priority effect experiments and joint species distribution modeling.

Understanding community assembly in habitat patches requires an integrative approach, considering the potential role of local and regional factors and organisms' dispersal abilities among patches. For this, assessing the degree of species overlap between patches (nestedness) can be particularly informative, especially regarding different taxa and distinct patch properties.We assessed the potential role of landscape‐patch structure in shaping the nestedness patterns of five taxonomic groups with distinct dispersal abilities (ants, bees, dung beetles, fruit‐feeding butterflies and aculeate wasps).We collected insects from 11 forest patches in the Espinhaço mountain range in southeast Brazil. We assessed the potential contribution of three forest island attributes (size, distance and shape) to the nestedness of insect communities and then tested if metacommunities were significantly nested with respect to habitat (forest islands). Finally, we evaluated how species of each taxonomic group contribute to metacommunity nestedness.While there was a substantial variation in the contribution to the nested pattern within each taxon, all taxa studied exhibited a significantly nested pattern of species distribution. The landscape‐patch structure and the vagility of the different taxa did not influence the contribution of sites to the metacommunity nested pattern.Our integrative approach provides critical data on the role of different factors in shaping species distribution in natural patches. Species with different dispersal abilities and patches with distinct landscape properties contributed similarly to nestedness, indicating the potential role of the vegetation matrix permeability in shaping the distribution of organisms in the studied forest archipelago. [ABSTRACT FROM AUTHOR]

The current biodiversity crisis requires efficient approaches to address the ongoing impoverishment of natural communities and the depletion of ecosystem services and functions. In this sense, identifying key species that promote the functioning of ecological processes can be strategic to guide actions aiming at the conservation and restoration of biodiversity. Node‐level metrics in interaction networks can be helpful to identify those key species, as they measure the role each species plays in organizing the interactions. Moreover, ecological correlates of species structural roles may vary between local and global networks of interactions, reflecting distinct mechanisms acting at different spatial scales. By studying local seed dispersal networks and one global meta‐network combining those local networks, Moulatlet et al. identified the most important traits explaining bird species centrality at varying spatial scales. They found that body mass was the main trait explaining centrality at the local scale, whereas range size was the main predictor of species centrality at the global scale. In this contribution, besides assessing local interaction networks, Moulatlet et al. adopt a biogeographical perspective to seed dispersal systems, extending our knowledge about the possible mechanisms that underlie the organization of interacting assemblages when changing the spatial scale of observation. Future efforts on this field could include an intermediate scale, comprising the level of metacommunities, shedding light on the interplay between local and spatial processes, both embedded in biogeographical realms, when determining the organization of interactions and the ecological correlates of species roles. [ABSTRACT FROM AUTHOR]

River–floodplain ecosystems play a crucial role in connecting landscape patches through hydrological connectivity, but they are among the most threatened ecosystems. Floodplains provide important habitat for amphibians by connecting aquatic and terrestrial habitats. Modifications to floodplain hydrology can impact amphibian communities, yet few studies have examined amphibian metacommunities in floodplain wetlands.In this study, we assessed patterns in amphibian breeding abundance in one of the largest floodplains of the Danube River, Hungary, relative to hydrological connectivity and multi‐scale variables at 30 waterbody sites. Our aim was to determine whether these patterns aligned with the pond‐permanence gradient hypothesis, where breeding amphibian abundance is predicted to be highest in ephemeral ponds without large predatory fish. We used Bayesian hierarchical modelling to estimate multi‐species abundance from repeated survey (count) data collected over one breeding season.We detected the eggs and larvae of four amphibian species. The best model of abundance included covariates describing two principal component axes associated with waterbody hydrology and landscape composition within a 500‐m radius of a site. There was a positive relationship between mean community abundance at a site and hydrological disconnection from the main river channel; however, the common toad (Bufo bufo) was associated with hydrologically connected waterbodies. There was a positive relationship between mean community abundance and a high proportion of forest cover and low cover of agricultural land within a 500‐m radius around a site, although this relationship was clear for only two species. There was no support for models containing the number of large predatory fish species detected at a site.Although our results showed that amphibian abundance declined with hydrological connectivity, based on model selection we could not ascribe this relationship to an increased number of large predatory fish species detected in waterbodies close to the main river channel. Differences in life history and habitat requirements are likely to have explained interspecific responses to hydrological connectivity. Our results underscore the importance of addressing amphibian abundance at multiple spatial scales in floodplain wetlands, as landscape composition partly explained patterns in abundance.Application of multi‐species abundance modelling allowed us to investigate environmental relationships for common and infrequently detected species. Habitat restoration programmes in floodplains should provide waterbodies disconnected from main river channels as potential amphibian breeding sites and protect or restore forest as terrestrial habitat. [ABSTRACT FROM AUTHOR]

Island biogeography theory has proved a robust approach to predicting island biodiversity on the assumption of species equivalency. However, species differ in their grouping behaviour and are entangled by complex interactions in island communities, such as competition and mutualism. We here investigated whether intra- and/or interspecific sociality may influence biogeographic patterns, by affecting movement between islands or persistence on them. We classified bird species in a subtropical reservoir island system into subcommunities based on their propensity to join monospecific and mixed-species flocks. We found that subcommunities which had high propensity to flock interspecifically had higher colonization rates and lower extinction rates over a 10-year period. Intraspecific sociality increased colonization in the same analysis. A phylogenetically corrected analysis confirmed the importance of interspecific sociality, but not intraspecific sociality. Group-living could enable higher risk crossings, with greater vigilance also linked to higher foraging efficiency, enabling colonization or long-term persistence on islands. Further, if group members are other species, competition can be minimized. Future studies should investigate different kinds of island systems, considering positive species interactions driven by social behaviour as potential drivers of community assembly on islands. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'. [ABSTRACT FROM AUTHOR]

Dispersal is a central life history trait that affects the ecological and evolutionary dynamics of populations and communities. The recent use of experimental evolution for the study of dispersal is a promising avenue for demonstrating valuable proofs of concept, bringing insight into alternative dispersal strategies and trade‐offs, and testing the repeatability of evolutionary outcomes.Practical constraints restrict experimental evolution studies of dispersal to a set of typically small, short‐lived organisms reared in artificial laboratory conditions. Here, we argue that despite these restrictions, inferences from these studies can reinforce links between theoretical predictions and empirical observations and advance our understanding of the eco‐evolutionary consequences of dispersal.We illustrate how applying an integrative framework of theory, experimental evolution and natural systems can improve our understanding of dispersal evolution under more complex and realistic biological scenarios, such as the role of biotic interactions and complex dispersal syndromes. [ABSTRACT FROM AUTHOR]

Climate change is known to affect regional weather patterns and phenology; however, we lack understanding of how climate drives phenological change across local spatial gradients. This spatial variation is critical for determining whether subpopulations and metacommunities are changing in unison or diverging in phenology. Divergent responses could reduce synchrony both within species (disrupting gene flow among subpopulations) and among species (disrupting interspecific interactions in communities). We also lack understanding of phenological change in environments where life history events are frequently aseasonal, such as the tropical, arid, and semi-arid ecosystems that cover vast areas. Using a 33-year-long dataset spanning a 1,267-m semi-arid elevational gradient in the southwestern United States, we test whether flowering phenology diverged among subpopulations within species and among five communities comprising 590 species. Applying circular statistics to test for changes in year-round flowering, we show flowering has become earlier for all communities except at the highest elevations. However, flowering times shifted at different rates across elevations likely because of elevation-specific changes in temperature and precipitation, indicating diverging phenologies of neighboring communities. Subpopulations of individual species also diverged at mid-elevation but converged in phenology at high elevation. These changes in flowering phenology among communities and subpopulations are undetectable when data are pooled across the gradient. Furthermore, we show that nonlinear changes in flowering times over the 33-year record are obscured by traditional calculations of long-term trends. These findings reveal greater spatiotemporal complexity in phenological responses than previously recognized and indicate climate is driving phenological reshuffling across local spatial gradients.

Abstract Estimating the strength of interactions among species in natural communities has always been a challenge for empirical ecologists. Sessile organisms, like plants or corals, often occur in metacommunities where they compete only with their immediate neighbours but disperse propagules over a wider area. To estimate the strength of competitive interactions, ecologists often count abundances in cells on a spatial grid for at least two time‐points. This data is then analysed using regression, by modelling the change in population size as a function of local densities, using cells as independent data‐points: a technique known as space‐for‐time substitution. These analyses generate estimates of competition coefficients; however, the method ignores dispersal among cells. To determine the impact of ignoring dispersal, we derived the bias that would arise when we apply regression methods to a metacommunity in which a fraction of seeds disperse beyond their natal cells but this dispersal is ignored in the model fitting process. We present results from a range of population models that make different assumptions about the nature of competition and assess the performance of our bias formulae by analysing data from simulated metacommunities. We reveal that: estimates of competition coefficients are biased when dispersal is not properly accounted for; and the resulting bias is often correlated with abundance, with rare species suffering the greatest overestimation. We also provide a standardized metric of competition that allows the bias to be calculated for a broad range of other population models. Our study suggests that regression methods that ignore dispersal produce biased estimates of competition coefficients when using space‐for‐time substitution. Our analytical bias formula allows empirical ecologists to potentially correct for biases, but it requires either tailored experiments in controlled conditions or an estimate of the average dispersal rate in a natural community, so may be challenging to apply to real datasets.

Abstract Background During range expansion in spatially distributed habitats, organisms differ from one another in terms of their patterns of localization versus propagation. To exploit locations or explore the landscape? This is the competition-colonization trade-off, a dichotomy at the core of ecological succession. In bacterial communities, this trade-off is a fundamental mechanism towards understanding spatio-temporal fluxes in microbiome composition. Results Using microfluidics devices as structured bacterial habitats, we show that, in a synthetic two-species community of motile strains, Escherichia coli is a fugitive species, whereas Pseudomonas aeruginosa is a slower colonizer but superior competitor. We provide evidence highlighting the role of succession and the relevance of this trade-off in the community assembly of bacteria in spatially distributed patchy landscapes. Furthermore, aggregation-dependent priority effects enhance coexistence which is not possible in well-mixed environments. Conclusions Our findings underscore the interplay between micron-scale landscape structure and dispersal in shaping biodiversity patterns in microbial ecosystems. Understanding this interplay is key to unleash the technological revolution of microbiome applications.

The spatial distribution of predators can affect both the distribution and diversity of their prey. Therefore, differences in predator dispersal ability that affect their spatial distribution, could also affect prey communities. Here, we use the microbial communities within pitcher plant leaves as a model system to test the relationship between predator (protozoa) dispersal ability and distribution, and its consequences for prey (bacteria) diversity and composition. We hypothesized that limited predator dispersal results in clustered distributions and heterogeneous patches for prey species, whereas wide predator dispersal and distribution could homogenize prey metacommunities. We analyzed the distribution of two prominent bacterivore protozoans from a 2‐year survey of an intact field of Sarracenia purpurea pitcher plants, and found a clustered distribution of Tetrahymena and homogeneous distribution of Poterioochromonas. We manipulated the sources of protozoan colonists and recorded protozoan recruitment and bacterial diversity in target leaves in a field experiment. We found the large ciliate, Tetrahymena, was dispersal limited and occupied few leaves, whereas the small flagellate Poterioochromonas was widely dispersed. However, the bacterial communities these protozoans feed on was unaffected by clustering of Tetrahymena, but likely influenced by Poterioochromonas and other bacterivores dispersing in the field. We propose that bacterial communities in this system are structured by a combination of well dispersed bacterivores, bacterial dispersal, and bottom‐up mechanisms. Clustered predators could become strong drivers of prey communities if they were specialists or keystone predators, or if they exerted a dominant influence on other predators in top‐down controlled systems. Linking dispersal ability within trophic levels and its consequences for trophic dynamics can lead to a more robust perspective on trophic metacommunities. [ABSTRACT FROM AUTHOR]

When investigating metacommunity dynamics, functional differences among species are often assumed to be as important as environmental differences between sites in determining β‐diversity. However, few studies have examined the influence of functional diversity on β‐diversity. We examine the relative importance of regional functional diversity partitioned by niche dimensions and environmental variation in structuring taxonomic β‐diversity of stream fishes using a large dataset of stream fish assemblages (hereafter, simply β‐diversity). We predicted that both functional diversity and environmental variation play a role in determining β‐diversity.We tested this prediction by modelling the patterns of stream fish β‐diversity as a function of environmental variation, functional diversity and γ‐richness across 10,220 sites for 329 fish species using a series of conceptual path models.Environmental variation consistently affected β‐diversity across all models, whereas functional diversity and γ‐richness influenced β‐diversity only in some models. We show that including relevant trait differences among species in path models can improve their ability to explain β‐diversity, suggesting that functional traits influence β‐diversity.The ability of path models to explain β‐diversity varied depending on the trait grouping included in the model, demonstrating that specific path models representing different niche dimensions can improve the ability of a model to explain β‐diversity. In addition, parsing traits into different niche dimensions revealed alternative patterns of functional diversity–β‐diversity relationships that otherwise would have been missed.The selection of relevant traits and linked niche dimensions is critical for detecting relationships between functional diversity and β‐diversity. Using traits associated with different niche dimensions allows for the identification of niche dimensions most strongly associated with species sorting and the detection of patterns missed by focusing on a single niche dimension. Determining the niche dimensions that influence β‐diversity could provide insights into the processes driving biodiversity and metacommunity dynamics, improving our ability to conserve or restore aquatic communities. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are among the most threatened ecosystems on Earth. Effective conservation strategies are essential to reverse this trend and should be based on sound knowledge of biodiversity patterns and the main drivers structuring them. In this study, we investigated the role of environmental and dispersal-connectivity controls on freshwater diatom and fish communities' variability. We used 441 biological samples obtained from Spanish biomonitoring datasets, which cover a highly variable environmental gradient across the national river network. We compared the taxonomic and trait-based spatial dependency of the two biotic groups using distance-decay relationships and variation partitioning with spatially constrained randomisations. Our findings showed that most of the diatoms and fish biological variation was attributed to pure spatial and spatially structured environmental variation. Compared to diatoms, fish community composition presented a stronger spatial dependency, likely because of their weaker dispersal ability. In addition, broad-scale environmental characteristics showed a higher predictive capacity for fish assemblages' variation. Trait-based similarities presented lower spatial dependency than taxonomic datasets, indicating that they are less susceptible to dispersal-connectivity effects. These findings contribute to understand the mechanisms underlying river community assembly at large spatial scales (i.e., at and beyond the river network) and point out the importance of dispersal-connectivity processes, which are usually neglected in traditional niche-based biomonitoring programmes but can influence their outcomes (e.g., masking the detection of anthropogenic impacts). Therefore, the integration of the dispersal-connectivity component, as well as information on organisms' dispersal abilities, are crucial when establishing effective conservation objectives and designing biomonitoring strategies. [ABSTRACT FROM AUTHOR]

Questions: The extent to which metacommunities contain species exhibiting metapopulation dynamics is poorly understood. We investigate this issue within sandstone outcrop plant communities scattered across an upland hardwood forest. We investigate the life forms of metapopulation species and relationships between taxonomic, phylogenetic, and functional diversity, composition, and environmental factors. Location: Twenty‐three sandstone outcrop communities in southern Illinois, USA. Methods: Following vegetation surveys, species exhibiting metapopulation dynamics were identified and compared to all species based on origin, growth form, and lifecycle. Cohesion, turnover, and boundary clumping were utilized to determine metacommunity structure. Correlations evaluated associations between site‐based variables, and regressions evaluated associations between diversity indices. Multivariate analyses compared sites to determine which variables contributed to compositional differences. Results: Twenty of 130 species exhibited metapopulation dynamics and were usually annual or biennial exotics. Metacommunity elements indicated a metacommunity structure where groups of species tended to replace one another across sites, in which species exhibiting metapopulation dynamics were subordinate as opposed to dominant or transient. The largest sites were the most regularly shaped, but not the most diverse. Species richness and species exhibiting metapopulation dynamics determined phylogenetic and functional diversity, but largely non‐standardized measures of diversity, indicating independence between types of diversity. Multivariate analyses showed that diversity metrics explained community composition differences, where more species‐rich sites with more metapopulation species were also more phylogenetically and functionally diverse. Conclusions: Sandstone outcrop communities exhibited diverse plant communities, where phylogenetic and functional diversity were driven by both the number of all species and the subset of metapopulation species independently. SM dynamics were usually short‐lived and exotic species with their low number likely constrained via dispersal limitations. The communities exhibited a metacommunity structure indicating predictable community assemblages which tend to be replaced with others as opposed to just individual species being replaced individually, consistent with the concept of an integrated community. Functional traits indicated that these communities include species adapted to xeric, substrate‐poor conditions. [ABSTRACT FROM AUTHOR]

Estimating the strength of interactions among species in natural communities has always been a challenge for empirical ecologists. Sessile organisms, like plants or corals, often occur in metacommunities where they compete only with their immediate neighbours but disperse propagules over a wider area. To estimate the strength of competitive interactions, ecologists often count abundances in cells on a spatial grid for at least two time‐points. This data is then analysed using regression, by modelling the change in population size as a function of local densities, using cells as independent data‐points: a technique known as space‐for‐time substitution. These analyses generate estimates of competition coefficients; however, the method ignores dispersal among cells.To determine the impact of ignoring dispersal, we derived the bias that would arise when we apply regression methods to a metacommunity in which a fraction of seeds disperse beyond their natal cells but this dispersal is ignored in the model fitting process. We present results from a range of population models that make different assumptions about the nature of competition and assess the performance of our bias formulae by analysing data from simulated metacommunities.We reveal that: estimates of competition coefficients are biased when dispersal is not properly accounted for; and the resulting bias is often correlated with abundance, with rare species suffering the greatest overestimation. We also provide a standardized metric of competition that allows the bias to be calculated for a broad range of other population models.Our study suggests that regression methods that ignore dispersal produce biased estimates of competition coefficients when using space‐for‐time substitution. Our analytical bias formula allows empirical ecologists to potentially correct for biases, but it requires either tailored experiments in controlled conditions or an estimate of the average dispersal rate in a natural community, so may be challenging to apply to real datasets. [ABSTRACT FROM AUTHOR]

Abstract Background The tonsil of the soft palate in pigs is the colonization site of both commensal and pathogenic microbial agents. Streptococcus suis infections are a significant economic problem in the swine industry. The development of S. suis disease remains poorly understood. The purpose of this study was to identify whether the tonsillar microbiota profile in nursery pigs is altered with S. suis disease. Here, the dynamics of the tonsillar microbiota from 20 healthy pigs and 43 diseased pigs with S. suis clinical signs was characterized. Results Based on the presence or absence of S. suis in the systemic sites, diseased pigs were classified into confirmed (n = 20) or probable (n = 23) group, respectively. Microbiota composition was assessed using the V3-V4 hypervariable region of the 16S rRNA, and results were analyzed to identify the diversity of the tonsillar microbiota. The taxonomic composition of the tonsil microbiota proved to be highly diverse between individuals, and the results showed statistically significant microbial community structure among the diagnosis groups. The confirmed group had the lowest observed species richness while the probable group had higher phylogenetics diversity level compared to the healthy group. Un-weighted Unifrac also demonstrated that the probable group had a higher beta diversity than both the healthy and the confirmed group. A Dirichlet-multinomial mixture (DMM) model-based clustering method partitioned the tonsil microbiota into two distinct community types that did not correspond with disease status. However, there was an association between Streptococcus suis serotype 2 and DMM community type 1 (p = 0.03). ANCOM-BC identified 24 Streptococcus amplicon sequence variants (ASVs) that were differentially abundant between the DMM community types. Conclusions This study provides a comprehensive analysis of the structure and membership of the tonsil microbiota in nursery pigs and uncovers differences and similarities across varying S. suis disease status. While the overall abundance of Streptococcus was not different among the diagnosis groups, the unique profile of DMM community type 1 and the observed correlation with S. suis serotype 2 could provide insight into potential tonsillar microbiota involvement in S. suis disease.

Dispersal within metacommunities can play a major role in species persistence by promoting asynchrony between communities. Understanding this role is crucial both for explaining species coexistence and managing landscapes that are increasingly fragmented by human activities. Here, we demonstrate that spatial patterning of dispersal connections can drastically alter both the tendency toward asynchrony and the effect of asynchrony on metacommunity dynamics commonly used to infer the potential for persistence. We also demonstrate that changes in dispersal connections in strictly homogeneous predator-prey metacommunities can generate an extremely rich variety of dynamics even when previously investigated properties of connectivity such as the magnitude and distribution of dispersal among patches are held constant. Furthermore, the dynamics we observe depend strongly on initial conditions. Our results illustrate the effectiveness of measures of spatial structure for predicting asynchrony and its effects on community dynamics, providing a deeper understanding of the relationship between spatial structure and species persistence in metacommunities.

River network structure influences many important population and community processes. Previous work examining ecological dynamics in river networks has focused on within-trophic-level dynamics, with less emphasis on food-web interactions. Yet, trophic interactions in rivers are influenced by processes that may interact with network structure and position. Using a spatially explicit consumer–resource model, we explore how trophic dynamics are influenced by the branching nature of river networks. We focus on cases where the consumer–resource interaction is prone to temporal oscillations and periodic low population sizes. In these cases, we find that the influence of network structure and dispersal can reduce temporal variability and increase persistence of consumers and resources at the metacommunity scale. The effects of network structure and dispersal on our observed metacommunity dynamics result from asynchrony among dynamics of local communities: when asynchronous local fluctuations are averaged, consumer–resource dynamics become less variable and bounded higher above zero at regional spatial scales. Fluctuations synchronise across clusters of linked local communities. Communities that connect to only one other downstream community typically vary independently of other patches and show high variability, while communities that are linked to multiple upstream and downstream habitats show greater clustering and less variability. These patterns suggest that headwater versus mainstem locations in river networks may show different levels of population variability and thus differential responses to management and restoration efforts.

Background: During range expansion in spatially distributed habitats, organisms differ from one another in terms of their patterns of localization versus propagation. To exploit locations or explore the landscape? This is the competition-colonization trade-off, a dichotomy at the core of ecological succession. In bacterial communities, this trade-off is a fundamental mechanism towards understanding spatio-temporal fluxes in microbiome composition. Results: Using microfluidics devices as structured bacterial habitats, we show that, in a synthetic two-species community of motile strains, Escherichia coli is a fugitive species, whereas Pseudomonas aeruginosa is a slower colonizer but superior competitor. We provide evidence highlighting the role of succession and the relevance of this trade-off in the community assembly of bacteria in spatially distributed patchy landscapes. Furthermore, aggregation-dependent priority effects enhance coexistence which is not possible in well-mixed environments. Conclusions: Our findings underscore the interplay between micron-scale landscape structure and dispersal in shaping biodiversity patterns in microbial ecosystems. Understanding this interplay is key to unleash the technological revolution of microbiome applications. [ABSTRACT FROM AUTHOR]

Macrophyte invasive alien species (IAS) fitness is often hypothesised to be associated with beneficial environmental conditions (environmental matching) or species‐poor communities. However, positive correlations between macrophyte IAS abundance and native plant richness can also arise, due to habitat heterogeneity (defined here as variation in abiotic and native biotic conditions over space and time). We analysed survey and palaeoecological data for macrophytes in satellite lakes along the Upper Lough Erne (ULE) system (Northern Ireland, UK), covering a gradient of eutrophication and connectivity to partition how environmental conditions, macrophyte diversity and habitat heterogeneity explained the abundance of Elodea canadensis, a widely distributed non‐native macrophyte in Europe. E. canadensis abundance positively correlated with macrophyte richness at both the within‐ and between‐lake scales indicating coexistence of native and invasive species over time. E. canadensis was also more prolific in highly connected and macrophyte‐rich lakes, but sparser in the more eutrophic‐isolated ones. Partial boosted regression trees revealed that in eutrophic‐isolated lakes, E. canadensis abundances correlated with water clarity (negatively), plant diversity (positively), and plant cover (negatively) whereas in diverse‐connected lakes, beta diversity (both positively and negatively) related to most greatly E. canadensis abundance. Dense macrophyte cover and unfavourable environmental conditions thus appear to confer invasibility resistance and sufficient habitat heterogeneity to mask any single effect of native biodiversity or environmental matching in controlling E. canadensis abundance. Therefore, in shallow lake landscapes, habitat heterogeneity variously enables the coexistence of native macrophytes and E. canadensis, reducing the often‐described homogenisation effects of invasive macrophytes. [ABSTRACT FROM AUTHOR]

Space and time promote variation in network structure by affecting the likelihood of potential interactions. However, little is known about the relative roles of ecological and biogeographical processes in determining how species interactions vary across space and time. Here we study the spatiotemporal variation in predator–prey interaction networks formed by anurans and arthropods and test for the effects of prey availability in determining interaction patterns, information that is often absent and limits the understanding of the determinants of network structure. We found that network dissimilarity between ecoregions and seasons was high and primarily driven by interaction rewiring.We also found that species turnover was positively related to geographical distance. Using a null model approach to disentangle the effect of prey availability on the spatial and temporal variation, we show that differences in prey availability were important in determining the variation in network structure between seasons and among areas. Our study reveals that fluctuations in prey abundance, alongside the limited dispersal abilities of anurans and their prey, may be responsible for the spatial patterns that emerged in our predator–prey metaweb. These findings contribute to our understanding of the assembly rules that maintain biotic processes in metacommunities and highlight the importance of prey availability to the structure of these systems. [ABSTRACT FROM AUTHOR]

Microorganisms have the potential to affect plant seed germination and seedling fitness, ultimately impacting plant health and community dynamics. Because seed-associated microbiota are highly variable across individual plants, plant species, and environments, it is challenging to identify the dominant processes that underlie the assembly, composition, and influence of these communities. We propose here that metacommunity ecology provides a conceptually useful framework for studying the microbiota of developing seeds, by the application of metacommunity principles of filtering, species interactions, and dispersal at multiple scales. Many studies in seed microbial ecology already describe individual assembly processes in a pattern-based manner, such as correlating seed microbiome composition with genotype or tracking diversity metrics across treatments in dispersal limitation experiments. But we see a lot of opportunities to examine understudied aspects of seed microbiology, including trait-based research on mechanisms of filtering and dispersal at the micro-scale, the use of pollination exclusion experiments in macro-scale seed studies, and an in-depth evaluation of how these processes interact via priority effect experiments and joint species distribution modeling. [ABSTRACT FROM AUTHOR]

Metacommunity theory predicts that the composition and diversity of a site depend on its characteristics and those of its neighborhood. Dispersal between plots in a field experiment could link responses observed in a focal plot to both its treatment and those of its neighbors. However, the diversity, composition, and treatments of neighboring plots are rarely included in analyses of experimental treatments. We analyzed a spatially gridded grassland nitrogen addition experiment and found that plant species richness and the composition of focal plots were influenced not just by their nitrogen treatment but also by the number of species in neighboring plots and their abundances. For each additional species in a focal plot's neighborhood, the species richness of the focal plot increased by 0.30 species. Control plots had a significant loss of species, at a rate of ~0.23 species per year during the 23‐year experiment, but only when their neighborhoods had low species richness. Changes in the abundance of the three dominant species depended both on the nitrogen treatment of a focal plot and on their abundance in adjacent plots. Our analyses suggested that both the experimental nitrogen treatments and metacommunity processes codetermined plant species richness and plant species' abundances. Our findings suggested that analyzing many traditional field experiments with a metacommunity perspective may reveal a confounding of experimental treatments and provide empirical data to test metacommunity theory. [ABSTRACT FROM AUTHOR]

Microorganisms have the potential to affect plant seed germination and seedling fitness, ultimately impacting plant health and community dynamics. Because seed-associated microbiota are highly variable across individual plants, plant species, and environments, it is challenging to identify the dominant processes that underlie the assembly, composition, and influence of these communities. We propose here that metacommunity ecology provides a conceptually useful framework for studying the microbiota of developing seeds, by the application of metacommunity principles of filtering, species interactions, and dispersal at multiple scales. Many studies in seed microbial ecology already describe individual assembly processes in a pattern-based manner, such as correlating seed microbiome composition with genotype or tracking diversity metrics across treatments in dispersal limitation experiments. But we see a lot of opportunities to examine understudied aspects of seed microbiology, including trait-based research on mechanisms of filtering and dispersal at the micro-scale, the use of pollination exclusion experiments in macro-scale seed studies, and an in-depth evaluation of how these processes interact via priority effect experiments and joint species distribution modeling.

The metacommunity theory includes processes that contribute, at different scales, to the understanding of the distribution of organisms in space and aims to assess the relative importance of spatial and environmental factors in the structuring of communities. Fluvial ecosystems of the Argentine Pampas are characterized by their environmental heterogeneity from slow water courses and variable development of aquatic vegetation to faster courses. They are affected by the different land uses, which are among the main threats to biodiversity and alter the dispersal of the species. Forty‐four species of aquatic oligochaete assemblages from 15 streams of nine Pampean basins were seasonally analyzed. The assemblages were characterized through estimations of taxonomic richness, α and β diversity. No differences were found in the assemblages of the substrates (sediments and aquatic vegetation) within each stream, except for Juan Blanco stream. However, differences were found between streams, as well as between basins. The oligochaetes that contributed most to the dissimilarity among streams and basins were Nais communis, Limnodrilus hoffmeisteri, Dero obtusa, and Stylaria fossularis. Two groups of sites were identified through the analysis of canonical correspondence: those of mountain basins and those of lowland basins. The variance partitioning showed that local environmental conditions (acting as environmental filters) accounted for 15.64% in the ordering of the assemblages, while 14.60% was explained by altitude and geographic factors (as a dispersal limitation). These results help to understand the processes that organize the distribution of organisms at different scales, which could have important implications when making decisions regarding biomonitoring and conservation. [ABSTRACT FROM AUTHOR]

Microbial foraging in patchy environments, where resources are fragmented into particles or pockets embedded in a large matrix, plays a key role in natural environments. In the oceans and freshwater systems, particle-associated bacteria can interact with particle surfaces in different ways: some colonize only during short transients, while others form long-lived, stable colonies. We do not yet understand the ecological mechanisms by which both short- and long-term colonizers can coexist. Here, we address this problem with a mathematical model that explains how marine populations with different detachment rates from particles can stably coexist. In our model, populations grow only while on particles, but also face the increased risk of mortality by predation and sinking. Key to coexistence is the idea that detachment from particles modulates both net growth and mortality, but in opposite directions, creating a trade-off between them. While slow-detaching populations show the highest growth return (i.e., produce more net offspring), they are more susceptible to suffer higher rates of mortality than fast-detaching populations. Surprisingly, fluctuating environments, manifesting as blooms of particles (favoring growth) and predators (favoring mortality) significantly expand the likelihood that populations with different detachment rates can coexist. Our study shows how the spatial ecology of microbes in the ocean can lead to a predictable diversification of foraging strategies and the coexistence of multiple taxa on a single growth-limiting resource.

Environmental factors and dispersal can influence the structure of biological communities. Their effects can depend on the functional features of the species in the community. Since species belonging to the same trophic level, such as phytoplankton, may show functional differences, we investigated whether the effects of environment and dispersal differ among phytoplankton species from different functional groups. We analyzed data from a rainy and a dry period in 30 reservoirs in a subtropical region. In both periods, the environment as well as high and limited dispersal influenced the metacommunity structure. The functional groups had a low correspondence in their response to both dispersal and environment. Our results showed that the influence of the processes underlying the structure of the metacommunities, such as species sorting (environment influence), mass effect (high dispersal), and neutral dynamics (limited dispersal), depended on the functional characteristics of the organisms and could vary even among species of the same trophic level. These findings suggested that species at the same trophic level could not be considered ecological equivalents. This paper includes a Portuguese and Spanish version of the abstract in the online resources. [ABSTRACT FROM AUTHOR]

One of the main factors that determines habitat suitability for sessile and territorial organisms is the presence or absence of another competing individual in that habitat. This type of competition arises in populations occupying patches in a metacommunity. Previous studies have looked at this process using a continuous-time modeling framework, where colonizations and extinctions occur simultaneously. However, different colonization processes may be performed by different species, which may affect the metacommunity dynamics. We address this issue by developing a discrete-time framework that describes these kinds of metacommunity interactions, and we consider different colonization dynamics. To understand potential dynamics, we consider specific functional forms that characterize the colonization and extinction processes of metapopulations competing for space as their limiting factor. We then provide a mathematical analysis of the models generated by this framework, and we compare these results to what is seen in nature and in previous models. [ABSTRACT FROM AUTHOR]

Running the gauntlet of predators consumes critical time and energy resources, as all species are vulnerable to one or, typically, more predators at some life stage. Prey employ a vast array of mechanisms to avoid predation, and predators, likewise, come in a bewildering variety. Thus, defensive adaptations are rarely one size fits all. Considerable work has addressed multi‐predator consumptive effects, but we now know that non‐consumptive effects of predators can dramatically impact individuals, (meta)populations, and (meta)communities. However, little is known regarding the community‐wide dynamics of non‐consumptive effects generated by multiple predators. Predator avoidance by choosing a patch that is free of a particular predator or predators can be the most effective strategy if conditions at colonization are a reliable predictor of absence, which is often true for fish in freshwater systems. We experimentally manipulated composition of the predator assemblage in aquatic mesocosms in a substitutive design, with zero, one, two, or three caged predatory fish species (one benthic, one pelagic, and one surface fish) at constant density and biomass, and assayed responses of naturally colonizing aquatic insects. We addressed three related questions; first, how do members of a diverse assemblage of colonizing aquatic insects respond to this variation in species and species combinations, second, do individual species (and higher taxa), respond differently to single vs. multiple predator species (species richness), and third how do any responses to fish species and species combinations, and effects on species richness, translate into community‐wide changes in the composition of colonists. Prey had varied responses to specific predators or combinations of predators, resulting in distinct community composition across treatments and higher β‐diversity with predators. Prey showed emergent multi‐predator effects, where certain species only responded to predator species combinations, but not to any individual predator, and stronger effects of multiple predator vs. single‐predator treatments, despite strong responses to individual predators in many taxa. Habitat selection effects can range from the individual to the metacommunity, and the dynamics of habitat selection in response to predators is a complex function of predator identity, density, richness, species composition, and patch spatial context. [ABSTRACT FROM AUTHOR]

Eco‐evolutionary dynamics can mediate species and community responses to habitat warming and fragmentation, two of the largest threats to biodiversity and ecosystems. The eco‐evolutionary consequences of warming and fragmentation are typically studied independently, hindering our understanding of their simultaneous impacts. Here, we provide a new perspective rooted in trade‐offs among traits for understanding their eco‐evolutionary consequences. On the one hand, temperature influences traits related to metabolism, such as resource acquisition and activity levels. Such traits are also likely to have trade‐offs with other energetically costly traits, like antipredator defences or dispersal. On the other hand, fragmentation can influence a variety of traits (e.g. dispersal) through its effects on the spatial environment experienced by individuals, as well as properties of populations, such as genetic structure. The combined effects of warming and fragmentation on communities should thus reflect their collective impact on traits of individuals and populations, as well as trade‐offs at multiple trophic levels, leading to unexpected dynamics when effects are not additive and when evolutionary responses modulate them. Here, we provide a road map to navigate this complexity. First, we review single‐species responses to warming and fragmentation. Second, we focus on consumer–resource interactions, considering how eco‐evolutionary dynamics can arise in response to warming, fragmentation, and their interaction. Third, we illustrate our perspective with several example scenarios in which trait trade‐offs could result in significant eco‐evolutionary dynamics. Specifically, we consider the possible eco‐evolutionary consequences of (i) evolution in thermal performance of a species involved in a consumer–resource interaction, (ii) ecological or evolutionary changes to encounter and attack rates of consumers, and (iii) changes to top consumer body size in tri‐trophic food chains. In these scenarios, we present a number of novel, sometimes counter‐intuitive, potential outcomes. Some of these expectations contrast with those solely based on ecological dynamics, for example, evolutionary responses in unexpected directions for resource species or unanticipated population declines in top consumers. Finally, we identify several unanswered questions about the conditions most likely to yield strong eco‐evolutionary dynamics, how better to incorporate the role of trade‐offs among traits, and the role of eco‐evolutionary dynamics in governing responses to warming in fragmented communities. [ABSTRACT FROM AUTHOR]

Ecological connectivity among protected Natura 2000 sites is a priority for conservation in Europe due to the increasing pressure on biodiversity from human activities and climate change. Drove roads, the traditional paths used to move livestock through the territory, have been proposed as potential ecological corridors due to their large extent, continuous nature and centennial protection from ploughing and urbanization, which allows the persistence of some tree cover and natural habitats in them. Bird communities were sampled during the reproductive season along 19 drove road transects in agrarian landscapes between Natura 2000 sites, all of them around the conurbation of Madrid (Madrid Region, Spain). Bird community nestedness was assessed by NODF computation followed by significance estimation by aleatorization, and factors explaining species richness and bird abundance were analyzed through General Linear Models fitted with environmental variables measured on official vegetation maps and orthophotos. Bird communities in drove roads were significantly nested, showing high predictability in the order of species loss from better preserved sites to those under stronger environmental pressures. Accordingly, Poisson regression showed bird richness to decrease strongly with distance from the closest Natura 2000 site and to increase with forest cover at the landscape and at the drove road scales. Bird abundance increased strongly with distance from urban areas and motorways, and it was slightly higher in areas with more forest cover and in transects with less bare ground. These results, and the higher relevance detected for landscape scale variables (500 m around transects) than for those at the drove road (50 m) scale, show that (i) they can only play a secondary role as habitat for nesting birds but (ii) they may add to the Green Infrastructure strategy as facilitators or stepping stones for bird communities if the surrounding landscape is favorable for them. [ABSTRACT FROM AUTHOR]

Agricultural intensification has been associated with biodiversity declines, habitat fragmentation and loss in a number of organisms. Given the prevalence of this process, there is a need for studies clarifying the effects of changes in agricultural practices on local biological communities; for instance, the transformation of traditional rainfed agriculture into intensively irrigated agriculture. We focused on pond-breeding amphibians as model organisms to assess the ecological effects of agricultural intensification because they are sensitive to changes in habitat quality at both local and landscape scales. We applied a metacommunity approach to characterize amphibian communities breeding in a network of ponds embedded in a terrestrial habitat matrix that was partly converted from rainfed crops to intensive irrigated agriculture in the 1990s. Specifically, we compared alpha and beta diversity, species occupancy and abundance, and metacommunity structure between irrigated and rainfed areas. We found strong differences in patterns of species occurrence, community structure and pairwise beta diversity between agricultural management groups, with a marked community structure in rainfed ponds associated with local features and the presence of some rare species that were nearly absent in the irrigated area, which was characterized by a random community structure. Natural vegetation cover at the landscape scale, significantly lower on the irrigated area, was an important predictor of species occurrences. Our results suggest that maintaining both local and landscape heterogeneity is key to preserving diverse amphibian communities in Mediterranean agricultural landscapes. [ABSTRACT FROM AUTHOR]

Biodiversity is structured in space and time, yet our understanding about the temporal variation of biological communities is still limited. Recent work suggests that temporal β diversity should be lowest in unpredictable systems with low seasonality, as expected for tropical ecosystems. However, this hypothesis remains largely unexplored.Here, we analysed the temporal dynamics of Atlantic Forest coastal stream caddisfly assemblages sampled simultaneously along four years, resulting in 99 unique site‐time combinations. Given that the region we studied is expected to have low climatic seasonality and low environmental harshness, we expected to find: (1) unseasonal variation in community composition; (2) equal contribution of nestedness and turnover to β diversity; (3) weak correlation between variation in community composition and in environmental variables; and (4) temporal β diversity similar to that expected by neutral dynamics.Using wavelet analysis we found that, in spite of general temperature stability, precipitation was highly seasonal but unpredictable at the monthly scale. We found high temporal β diversity, with a larger contribution of nestedness due to an overall decrease in abundance and diversity during months characterised by heavy rain events. We also found that community composition was moderately structured in space, suggesting that both local in‐stream characteristics and dispersal limitation drive community reassembly after heavy rain events.Null model analysis indicated that observed short‐term β diversity was not distinct from that expected by chance (i.e. produced by null simulations). This suggests an important role of stochastic colonisation and dispersal limitation in the temporal organisation of Atlantic Forest stream assemblages.Since heavy rain events strongly disassemble communities that are then randomly recolonised, and considering the current scenario of climate change, increased extreme events of precipitation could lead to unpredictable changes in biodiversity in tropical regions. [ABSTRACT FROM AUTHOR]

Due to the difficulty of tracking microbial dispersal, it is rarely possible to disentangle the relative importance of dispersal and species sorting for microbial community assembly. Here, we leverage a detailed multilevel network to examine drivers of bacterial community assembly within flowers. We observed flower visitors to 20 focal plant species in a coflowering community in the Sierra Nevada, revealing 289 species of arthropods. We also analyzed bacterial communities on flowers of each species. We found that plant species with similar visitor communities tend to have similar bacterial communities, and visitor identity to be more important than plant relatedness in structuring floral bacterial communities. However, plant species that were hubs of arthropod visitation were not necessarily hubs of floral bacteria, suggesting an important role for species sorting. Across plant species, the composition of flower‐visiting Diptera (flies), bees and non‐bee Hymenoptera best predicted bacterial species composition on flowers. Taken together, our analyses suggest dispersal is important in determining similarity in microbial communities across plant species, but not as important in determining the overall macrostructure (nestedness, modularity) and microstructure (connectedness based on shared interactors) of the floral bacterial network. A multilevel network approach thus allows us to address features of community assembly that cannot be considered when viewing networks as separate entities. [ABSTRACT FROM AUTHOR]