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The rapid climatic and environmental changes observed in the Arctic and across the globe in general call for reliable model projections. In recent years our understanding of ongoing and future changes through ecosystem modelling has increased tremendously. Yet, most ecosystem models do not consider many of the feedback loops at play in natural ecosystems. Particularly those influenced by biota, beyond vegetation and to some extent microbes, are often neglected. As a first step towards a better integration of biotic influences into ecosystem models, we provide a broad overview of the various ways biota may influence feedback loops between the high-latitude biosphere and the atmosphere. We focus specifically on three key feedback loops between tundra and atmosphere (carbon dynamics, albedo and permafrost thaw) and the influences of three key ecosystem compartments (vegetation, decomposers and herbivores) on these. The influences of biota on ecosystem feedback loops are multifaceted and may appear patchy in both space and time. However, biota may still play important roles in modulating ecosystem feedback loops, and by including these dynamics into ecosystem models, magnitude, accuracy and credibility of model projections are likely to improve. [ABSTRACT FROM AUTHOR]

Linking changes in taxon abundance to biotic and abiotic drivers over space and time is critical for understanding biodiversity responses to global change. Furthermore, deciphering temporal trends in relationships among taxa, including correlated abundance changes (e.g. synchrony), can facilitate predictions of future shifts. However, what drives these correlated changes over large scales are complex and understudied, impeding our ability to predict shifts in ecological communities. We used two global datasets containing abundance time‐series (BioTIME) and biotic interactions (GloBI) to quantify correlations among yearly changes in the abundance of pairs of geographically proximal taxa (genus pairs). We used a hierarchical linear model and cross‐validation to test the overall magnitude, direction and predictive accuracy of correlated abundance changes among genera at the global scale. We then tested how correlated abundance changes are influenced by latitude, biotic interactions, disturbance and time‐series length while accounting for differences among studies and taxonomic categories. We found that abundance changes between genus pairs are, on average, positively correlated over time, suggesting synchrony at the global scale. Furthermore, we found that abundance changes are more positively correlated with longer time‐series, with known biotic interactions and in disturbed habitats. However, the magnitude of these ecological drivers alone are relatively weak, with model predictive accuracy increasing approximately two‐fold with the inclusion of study identity and taxonomic category. This suggests that while patterns in abundance correlations are shaped by ecological drivers at the global scale, these drivers have limited utility in forecasting changes in abundances among unknown taxa or in the context of future global change. Our study indicates that including taxonomy and known ecological drivers can improve predictions of biodiversity loss over large spatial and temporal scales, but also that idiosyncrasies of different studies continue to weaken our ability to make global predictions. [ABSTRACT FROM AUTHOR]

While biotic interactions often impose selection, species and populations vary in whether they are locally adapted to biotic interactions. Evolutionary theory predicts that environmental conditions drive this variable local adaptation by altering the fitness impacts of species interactions. To investigate the influence of an environmental gradient on adaptation between a plant and its associated rhizosphere biota, we cross-combined teosinte (Zea mays ssp. mexicana) and rhizosphere biota collected across a gradient of decreasing temperature, precipitation, and nutrients in a greenhouse common garden experiment. We measured both fitness and phenotypes expected to be influenced by biota, including concentrations of nutrients in leaves. Independent, main effects of teosinte and biota source explained most variation in teosinte fitness and traits. For example, biota from warmer sites provided population-independent fitness benefits across teosinte hosts. Effects of biota that depended on teosinte genotype were often not specific to their local hosts, and most traits had similar relationships to fitness across biota treatments. However, we found weak patterns of local adaptation between teosinte and biota from colder sites, suggesting environmental gradients may alter the importance of local adaptation in teosinte–biota interactions, as evolutionary theory predicts. [ABSTRACT FROM AUTHOR]

Aim: 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. Location: Streams of the Lake Balaton catchment, Hungary. Methods: 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. Results: 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. Main Conclusions: 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]

Questions: Community assembly is envisaged as filters that preclude some species in the regional pool from invading local communities. We tested whether the large floristic differences between adjacent calcicole and calcifuge grasslands are explained by either of five filters: environment (soil) or positive or negative interactions with plants and with soil biota. Location: Southern Mexico. Methods: We conducted a reciprocal‐transplant experiment with 20 species that were introduced to both habitats under three conditions: intact local community, without plants, and in sterilized plots. Each of the five filters mentioned above predict unique patterns in the performance (survival and growth) of plants in the six treatments. Thus, we used multimodel inference to determine which filters (patterns) were consistent with the evidence. Results: We detected at least one filter operating on all but four species. Survival data showed frequent support for environmental filtering, with interactions (mostly positive) playing a secondary role; however negative interactions became as frequent as environmental filtering when growth was considered. Conclusions: The large physicochemical differences between the soils of both grasslands explain the high frequency of environmental filtering. Soils differed in nutrient availability, but also had toxic concentrations of different elements. Survival was strongly influenced by early mortality, while size was measured at the end of the experiment. It is thus likely that the differences between analyses based on survival and size reflect an ontogenetic change from positive to negative interactions. Other plants frequently facilitate seedlings, but this interaction often turns competitive over time. Soil mutualists provide nutrients that seedlings cannot access, but antagonists build up in the rhizosphere as plants age. Unlike studies that infer filters from extant plants in communities or from successful invasions, our approach provides direct evidence on which filters cause species to be absent from communities. [ABSTRACT FROM AUTHOR]

Anthropogenic climate warming affects plant communities by changing community structure and function. Studies on climate warming have primarily focused on individual effects of warming, but the interactive effects of warming with biotic factors could be at least as important in community responses to climate change. In addition, climate change experiments spanning multiple years are necessary to capture interannual variability and detect the influence of these effects within ecological communities. Our study explores the individual and interactive effects of warming and insect herbivory on plant traits and community responses within a 7‐year warming and herbivory manipulation experiment in two early successional plant communities in Michigan, USA. We find stronger support for the individual effects of both warming and herbivory on multiple plant morphological and phenological traits; only the timing of plant green‐up and seed set demonstrated an interactive effect between warming and herbivory. With herbivory, warming advanced green‐up, but with reduced herbivory, there was no significant effect of warming. In contrast, warming increased plant biomass, but the effect of warming on biomass did not depend upon the level of insect herbivores. We found that these treatments had stronger effects in some years than others, highlighting the need for multiyear experiments. This study demonstrates that warming and herbivory can have strong direct effects on plant communities, but that their interactive effects are limited in these early successional systems. Because the strength and direction of these effects can vary by ecological context, it is still advisable to include levels of biotic interactions, multiple traits and years, and community type when studying climate change effects on plants and their communities. [ABSTRACT FROM AUTHOR]

Alternative perspectives on the maintenance of biodiversity and the assembly of ecological communities suggest that both processes cannot be investigated simultaneously. In this concept and synthesis, we challenge this view by presenting major theoretical advances in structural stability and permanence theory. These advances, which provide complementary views, allow studying the short‐ and long‐term dynamics of ecological communities as changes in species richness, composition, and abundance. Here, the global attractor, technically named informational structure (IS), is the central element to construct from information of species' intrinsic growth rates and their strength and sign of interactions. The global attractor has four main properties: (1) It contains all the limits of what is feasible and unfeasible of the dynamical behavior of an ecological system, therefore, (2) it provides a thorough characterization of all combinations of species' richness and composition in which species can coexist (i.e., feasible and stable equilibrium), (3) as well as all connections (paths) of assembly between coexisting communities. Importantly, (4) such topology of coexisting communities and their connections changes when environmental (abiotic and biotic) variation affects the ability of species to grow and interact with others. Overall, these four properties allow switching from a traditional evaluation of species coexistence at equilibrium to a much more realistic nonequilibrium perspective where changes in the structure of the global attractor underlie the transient ecological dynamics. Several fields in ecology can benefit from the study of an IS. For instance, it can serve to evaluate community responses after the end of a perturbation, to design restoration trajectories, to study the consequences of biological invasions on the persistence of native species within communities, or to assess ecosystem health status. We illustrate this latter possibility with empirical observations of 7 years in Mediterranean annual grasslands. We document that extremely wet or dry years generate ISs supporting few coexisting communities and few assembly paths. The remaining communities distinguish winners from losers of ongoing climate change and indicate the limits to future community assembly opportunities. A fully tractable operational framework is readily available to understand and predict the assembly and dynamics of ecological communities in an ever‐changing world. [ABSTRACT FROM AUTHOR]

This account presents information on all aspects of the biology of Trapa natans L. (water caltrop and water chestnut) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the International Biological Flora: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, conservation and global heterogeneity.The water caltrop is an annual herbaceous hydrophyte rooted in the sediment of water bodies, forming flexuous underwater stems that create a buoyant, light‐capturing leaf rosette at the water surface. The submerged stem nodes additionally bear linear leaves. These are replaced by photosynthetically active, pinnately branched structures and unbranched adventitious roots early on, which complement previously established roots on the hypocotyl, altogether facilitating anchorage, nutrient and water absorption, aeration and capture of subsurface irradiance. Solitary flowers pollinated primarily through autogamy and incidentally through entomophily give rise to a fully developed edible single‐seeded drupe with two to four barbed horns. Fruits are dispersed with the help of hydrochory, epizoochory and anthropochory.Throughout its lowland, global temperate, subtropical and tropical distribution in Eurasia and Africa, the thermophilic macrophyte is found in shallow, sun‐exposed, nutrient‐rich freshwater bodies with low‐velocity flows and steady water levels. These offer slightly acidic to mildly basic conditions. The accompanying soft substrate is usually characterized by a high organic matter content. Regularly co‐occurring with other macrophytes, some of which are also of conservation concern, such as those in rare stands of the association Trapetum natantis in Europe, the water caltrop has at times been outcompeted, though it may form monodominant stands, due to several competitive features.Formerly widespread in Europe, T. natans is today recognized as a rare, strictly protected macrophyte. It has been introduced to Australia and North America; on the latter continent, its naturalization, spread and aggressive overgrowth have led to extensive control efforts. Having been used as a crop since Neolithic times, it is still exploited in Asia for means of food production, phytoremediation, ornamental purposes, medication and alternative uses. [ABSTRACT FROM AUTHOR]

Understanding biotic interactions is a crucial goal in community ecology and species distribution modelling, and large strides have been made towards improving multivariate computational methods with the aim of quantifying biotic interactions and improving predictions of species occurrence. Yet, while considerable attention has been given to computational approaches and the interpretation of these quantitative tools, the importance of sampling design to reveal these biotic interactions has received little consideration. This study explores the influential role of priority effects, that is, the order of habitat colonisation, in shaping our ability to detect biotic interactions. Using a simple set of simulations, we demonstrate that commonly used cross‐sectional co‐occurrence data alone cannot be used to make reliable inferences on asymmetric biotic interactions, even if they perform well in predicting the occurrence of species. We then show how sampling designs that consider priority effects can recover the asymmetric effects that are lost when priority effects are ignored. Based on these findings, we urge for caution when drawing inferences on biotic interactions from cross‐sectional binary co‐occurrence data, and provide guidance on sampling designs that may provide the necessary data to tackle this longstanding challenge. [ABSTRACT FROM AUTHOR]

Context-dependent dispersal allows organisms to seek and settle in habitats improving their fitness. Despite the importance of species interactions in determining fitness, a quantitative synthesis of how they affect dispersal is lacking. We present a meta-analysis asking (i) whether the interaction experienced and/or perceived by a focal species (detrimental interaction with predators, competitors, parasites or beneficial interaction with resources, hosts, mutualists) affects its dispersal; and (ii) how the species' ecological and biological background affects the direction and strength of this interaction-dependent dispersal. After a systematic search focusing on actively dispersing species, we extracted 397 effect sizes from 118 empirical studies encompassing 221 species pairs; arthropods were best represented, followed by vertebrates, protists and others. Detrimental species interactions increased the focal species' dispersal (adjusted effect: 0.33 [0.06, 0.60]), while beneficial interactions decreased it (−0.55 [−0.92, −0.17]). The effect depended on the dispersal phase, with detrimental interactors having opposite impacts on emigration and transience. Interaction-dependent dispersal was negatively related to species' interaction strength, and depended on the global community composition, with cues of presence having stronger effects than the presence of the interactor and the ecological complexity of the community. Our work demonstrates the importance of interspecific interactions on dispersal plasticity, with consequences for metacommunity dynamics. This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'. [ABSTRACT FROM AUTHOR]

The effects of species on one another sometimes depend on the order in which they arrive at a local site. This historical contingency, termed priority effects, can have a major influence on the assembly and functioning of ecological communities. Although historically studied within community ecology, phenomena consistent with priority effects appear in a variety of biological scenarios and across a wide range of spatial and temporal scales, but are referred to by many different but related terms. There exists a fragmented communication landscape between studies of priority effects across these disparate biological subfields, which is stifling a conceptual unification of how, when, and why priority effects occur. Our review provides a launchpad for developing a unified framework across a broad range of ecological contexts. Although primarily studied through the lens of community ecology, phenomena consistent with priority effects appear to be widespread across many different scenarios spanning a broad range of spatial, temporal, and biological scales. However, communication between these research fields is inconsistent and has resulted in a fragmented co-citation landscape, likely due to the diversity of terms used to refer to priority effects across these fields. We review these related terms, and the biological contexts in which they are used, to facilitate greater cross-disciplinary cohesion in research on priority effects. In breaking down these semantic barriers, we aim to provide a framework to better understand the conditions and mechanisms of priority effects, and their consequences across spatial and temporal scales. [ABSTRACT FROM AUTHOR]

Recent outbreaks of the West Nile virus have been reported in southern Spain, a region with important wetland habitats for migratory birds. Here, we analyzed the role of species association and abiotic parameters on the abundance of seven mosquito species in the Doñana National Park, Spain. We applied the Joint Species Distribution Models (JSDM), using the Hierarchical Modeling of Species Communities approach to simultaneously model the effect of habitat type, normalized difference vegetation index, hydroperiod, distance to rivers, land surface temperature, and the abundance of seven mosquito species. We created three models with varied parameters and evaluated the effects of abiotic parameters and species-to-species associations, which served as proxies for species interactions. Our models estimated the species-specific responses of the mosquito community to abiotic parameters. A positive association was identified within the Culex community with potential biotic interactions. However, Ochlerotatus caspius, Ochlerotatus detritus, and Anopheles atroparvus had no statistically significant association with each other and with the Culex species after accounting for the effect of abiotic parameters. We also found that the potential species associations estimated at particular sites and abiotic parameters influenced the model projection for the average abundance of mosquito species. The JSDM will allow spatial projection of the abundance of each mosquito species, which is an important parameter for epidemiological models. The JSDM inference of species association is important because predation, competition, and facilitation affect the distribution and abundance of different species. [ABSTRACT FROM AUTHOR]

Biotic interactions are widely recognised as the backbone of ecological communities, but how best to study them is a subject of intense debate, especially at macro‐ecological scales. While some researchers claim that biotic interactions need to be observed directly, others use proxies and statistical approaches to infer them. Despite this ambiguity, studying and predicting the influence of biotic interactions on biogeographic patterns is a thriving area of research with crucial implications for conservation. Three distinct approaches are currently being explored. The first approach involves empirical observation and measurement of biotic interactions' effects on species demography in laboratory or field settings. While these findings contribute to theory and to understanding species' demographies, they can be challenging to generalise on a larger scale. The second approach centers on inferring biotic associations from observed co‐occurrences in space and time. The goal is to distinguish the environmental and biotic effects on species distributions. The third approach constructs extensive potential interaction networks, known as metanetworks, by leveraging existing knowledge about species ecology and interactions. This approach analyses local realisations of these networks using occurrence data and allows understanding large distributions of multi‐taxa assemblages. In this piece, we appraise these three approaches, highlighting their respective strengths and limitations. Instead of seeing them as conflicting, we advocate for their integration to enhance our understanding and expand applications in the emerging field of interaction biogeography. This integration shows promise for ecosystem understanding and management in the Anthropocene era. [ABSTRACT FROM AUTHOR]

Communities worldwide are losing multiple species at an unprecedented rate, but how communities reassemble after these losses is often an open question. It is well established that the order and timing of species arrival during community assembly shapes forthcoming community composition and function. Yet, whether the order and timing of species losses can lead to divergent community trajectories remains largely unexplored. Here, we propose a novel framework that sets testable hypotheses on the effects of the order and timing of species losses—inverse priority effects—and suggests its integration into the study of community assembly. We propose that the order and timing of species losses within a community can generate alternative reassembly trajectories, and suggest mechanisms that may underlie these inverse priority effects. To formalize these concepts quantitatively, we used a three‐species Lotka‐Volterra competition model, enabling to investigate conditions in which the order of species losses can lead to divergent reassembly trajectories. The inverse priority effects framework proposed here promotes the systematic study of the dynamics of species losses from ecological communities, ultimately aimed to better understand community reassembly and guide management decisions in light of rapid global change. [ABSTRACT FROM AUTHOR]

Invasive predatory species may alter population dynamic processes of their prey and impact biological communities and ecosystem processes. Revealing biotic interactions, however, including the relationship between predator and prey, is a difficult task, in particular for species that are hard to monitor. Here, we present a case study that documents the utility of environmental DNA analysis (eDNA) to assess predator–prey interactions between two invasive fishes (Lepomis gibbosus, Pseudorasbora parva) and two potential amphibian prey species, (Triturus cristatus, Pelobates fuscus). We used species-specific TaqMan assays for quantitative assessment of eDNA concentrations from water samples collected from 89 sites across 31 ponds during three consecutive months from a local amphibian hotspot in Germany. We found a negative relationship between eDNA concentrations of the predators (fishes) and prey (amphibians) using Monte-Carlo tests. Our study highlights the potential of eDNA application to reveal predator–prey interactions and confirms the hypothesis that the observed local declines of amphibian species may be at least partly caused by recently introduced invasive fishes. Our findings have important consequences for local conservation management and highlight the usefulness of eDNA approaches to assess ecological interactions and guide targeted conservation action. [ABSTRACT FROM AUTHOR]

Theory posits that the persistence of species in ecological communities is shaped by their interactions within and across trophic guilds. However, we lack empirical evaluations of how the structure, strength and sign of biotic interactions drive the potential to coexist in diverse multi‐trophic communities. Here, we model community feasibility domains, a theoretically informed measure of multi‐species coexistence probability, from grassland communities comprising more than 45 species on average from three trophic guilds (plants, pollinators and herbivores). Contrary to our hypothesis, increasing community complexity, measured either as the number of guilds or community richness, did not decrease community feasibility. Rather, we observed that high degrees of species self‐regulation and niche partitioning allow for maintaining larger levels of community feasibility and higher species persistence in more diverse communities. Our results show that biotic interactions within and across guilds are not random in nature and both structures significantly contribute to maintaining multi‐trophic diversity. [ABSTRACT FROM AUTHOR]

Species shifting their ranges under climate change are a conservation dilemma. Range‐shifters may be threatened by climate change in their historic range. However, range‐shifters are likely to be generalist opportunists, which could mean they could harm aspects of biodiversity in their new ecosystems. Therefore, we need approaches to rapidly assess how range‐shifters may integrate into the community of historically resident species.The small red‐eyed damselfly (Erythromma viridulum) has shifted into the United Kingdom since 1999 and may affect resident Odonata via intraguild predation. We asked whether the damselfly's arrival is associated with a decline in resident Odonata.We harnessed the British Dragonfly Society's dataset, using records from 49,788 site visits between 2000 and 2015 to construct dynamic species occupancy models for 17 resident UK Odonata. We estimated the potential effect of E. viridulum presence on the probability that each species would persist at a given site, while controlling for potential effects of climate and recording effort.On average, dragonflies (Anisoptera) persisted more frequently at sites where E. viridulum had established, while damselflies (Zygoptera) showed no change in persistence. Nevertheless, two resident damselflies, including E. viridulum's congener, disappeared more frequently when the range‐shifter established.We suggest that E. viridulum poses minimal risk to most UK resident Odonata. Rather, E. viridulum may be differentially establishing in areas with good habitat quality, where many species of historically resident Odonata are also found. Therefore, high quality, biodiverse sites may become home to increasing numbers of range‐shifters in future. Our approach permits rapid detection of how range‐shifters are integrating into resident biota. [ABSTRACT FROM AUTHOR]

The stability and harmony of ecological niches rely on intricate interactions between their members. During evolution, organisms have developed the ability to thrive in different environments, taking advantage of each other. Among these organisms, microalgae are a highly diverse and widely distributed group of major primary producers whose interactions with other organisms play essential roles in their habitats. Understanding the basis of these interactions is crucial to control and exploit these communities for ecological and biotechnological applications. The green microalga Chlamydomonas reinhardtii, a well-established model, is emerging as a model organism for studying a wide variety of microbial interactions with ecological and economic significance. In this review, we unite and discuss current knowledge that points to C. reinhardtii as a model organism for studying microbial interactions. [ABSTRACT FROM AUTHOR]

Earth systems are nearing a global tipping point, beyond which the dynamics of biological communities will become unstable. One major driver of instability is species invasion, especially by organisms that act as "ecosystem engineers" through their modification of abiotic and biotic factors. To understand how native organisms respond to modified habitat, it is essential to examine biological communities within invaded and non‐invaded habitat, identifying compositional shifts in native and non‐native taxa as well as measuring how modification by ecosystem engineers has affected interactions among community members. Using dietary metabarcoding, our study examines the response of a native Hawaiian generalist predator (Araneae: Pagiopalus spp.) to habitat modification by comparing biotic interactions across metapopulations of spiders collected in native forest and sites invaded by kāhili ginger. Our study shows that, although there are shared components of the dietary community, spiders in invaded habitat are eating a less consistent and more diverse diet consisting of more non‐native arthropods which are rarely or entirely undetected in spiders collected from native forest. Additionally, the frequency of novel interactions with parasites was significantly higher in invaded sites, reflected by the frequency and diversity of non‐native Hymenoptera parasites and entomopathogenic fungi. The study highlights the role of habitat modification driven by an invasive plant in altering community structure and biotic interactions, threatening the stability of the ecosystem through significant changes to the biotic community. [ABSTRACT FROM AUTHOR]

Aim: Mutualistic interactions between plants and animals are fundamental for the maintenance of natural communities and the ecosystem services they provide. However, particularly in human‐dominated island ecosystems, introduced species may alter mutualistic interactions. Based on an extensive dataset of plant–frugivore interactions, we mapped and analysed a meta‐network across the Caribbean archipelago. Specifically, we searched for subcommunity structure (modularity) and identified the types of species facilitating the integration of introduced species in the Caribbean meta‐network. Location: Caribbean archipelago (Lucayan archipelago, Greater Antilles, Lesser Antilles). Methods: We reviewed published scientific literature, unpublished theses and other nonpeer‐reviewed sources to compile an extensive dataset of plant–frugivore interactions. We visualized spatial patterns and conducted a modularity analysis of the cross‐island meta‐network. We also examined which species were most likely to interact with introduced species: (1) endemic, nonendemic native or introduced species, and (2) generalized or specialized species. Results: We reported 3060 records of interactions between 486 plant and 178 frugivore species. The Caribbean meta‐network was organized in 13 modules, driven by a combination of functional or taxonomic (modules dominated by certain groups of frugivores) and biogeographical (island‐specific modules) mechanisms. Few introduced species or interaction pairs were shared across islands, suggesting little homogenization of the plant–frugivore meta‐network at the regional scale. However, we found evidence of "invader complexes," as introduced frugivores were more likely to interact with introduced plants than expected at random. Moreover, we found generalist species more likely to interact with introduced species than were specialized species. Main conclusions: These results demonstrate that generalist species and "invader complexes" may facilitate the incorporation of introduced species into plant–frugivore communities. Despite the influx of introduced species, the meta‐network was structured into modules related to biogeographical and functional or taxonomic affinities. These findings reveal how introduced species become an integral part of mutualistic systems on tropical islands. [ABSTRACT FROM AUTHOR]

Human habitat disturbance affects both species diversity and intraspecific genetic diversity, leading to correlations between these two components of biodiversity (termed species–genetic diversity correlation, SGDC). However, whether SGDC predictions extend to host‐associated communities, such as the intestinal parasite and gut microbial diversity, remains largely unexplored. Additionally, the role of dominant generalist species is often neglected despite their importance in shaping the environment experienced by other members of the ecological community, and their role as source, reservoir and vector of zoonotic diseases. New analytical approaches (e.g. structural equation modelling, SEM) can be used to assess SGDC relationships and distinguish among direct and indirect effects of habitat characteristics and disturbance on the various components of biodiversity.With six concrete and biologically sound models in mind, we collected habitat characteristics of 22 study sites from four distinct landscapes located in central Panama. Each landscape differed in the degree of human disturbance and fragmentation measured by several quantitative variables, such as canopy cover, canopy height and understorey density. In terms of biodiversity, we estimated on the one hand, (a) small mammal species diversity, and, on the other hand, (b) genome‐wide diversity, (c) intestinal parasite diversity and (d) gut microbial heterogeneity of the most dominant generalist species (Tome's spiny rat, Proechimys semispinosus). We used SEMs to assess the links between habitat characteristics and biological diversity measures.The best supported SEM suggested that habitat characteristics directly and positively affect the richness of small mammals, the genetic diversity of P. semispinosus and its gut microbial heterogeneity. Habitat characteristics did not, however, directly impact intestinal parasite diversity. We also detected indirect, positive effects of habitat characteristics on both host‐associated assemblages via small mammal richness. For microbes, this is likely linked to cross species transmission, particularly in shared and/or anthropogenically altered habitats, whereas host diversity mitigates parasite infections. The SEM revealed an additional indirect but negative effect on intestinal parasite diversity via host genetic diversity.Our study showcases that habitat alterations not only affect species diversity and host genetic diversity in parallel, but also species diversity of host‐associated assemblages. The impacts from human disturbance are therefore expected to ripple through entire ecosystems with far reaching effects felt even by generalist species. [ABSTRACT FROM AUTHOR]

The nitrogen (N) economics of plants are generally described in terms of functional traits and how these affect N availability in a given environment. However, recent studies have shown that plant symbionts play a crucial role in plant N economics. A plant together with its symbiont can be considered as a meta‐organism, the holobiont. Plant‐associated symbionts are shaped by the plant, thereby extending the plant's phenotype. Decomposers also play an important role in plant N economics, yet are usually not included in the plant holobiont.In this review, we show the important roles that both symbionts and decomposers play in plant N economics. We focus on how plants respond to fluctuating N availability in a complex interaction network, which includes the plant's strategies and its interactions and feedback loops with the soil biota and with neighbouring plants, through competition for N by exploitation and interference.Synthesis. Plant N economics and the outcome of plant–plant interactions in a community cannot be fully described solely through the functional traits of plant individuals. Properties emerging from the interaction network bring new insights into plant N economics. Further research is now needed to gain a deeper understanding of plant N economics and resource economics in plant communities by integrating a broader extended plant phenotype. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal (ECM) fungi form the interface between soil and tree roots, playing critical roles in biogeochemical cycling in terrestrial ecosystems. Forest types influence ECM fungal colonization and host preferences; however, limited knowledge exists about neighborhood effects of tree species combinations on ECM fungal diversity patterns, and the consequences for microbial-mediated soil organic matter decomposition. Here, we compared Quercus acutissima ectomycorrhizas in pure (PF), broadleaf mixed (QBF), and Pinus mixed (QPF) forests and explored the possible links between ECM fungi and the physiological traits of free-living microbial decomposers. Results showed that the presence of pine neighbors increased Shannon diversity but decreased community similarity and stochasticity of focal ECM fungi. The increased ECM fungal diversity alleviates nutrient limitations for soil microorganisms and thus reduces investments for nutrient acquisition (especially for P), which is associated with increased microbial growth yields and potentially increased soil carbon stocks. Moreover, keystone ECM fungal assemblies primarily composed of Lactarius, Tomentella , and Cortinarius were identified as the most significant predictors of soil microbial physiological adaptions. Further analysis showed that biotic factors, especially bacterial richness, played a comparatively more important role in regulating ECM fungal diversity and function than edaphic factors. Together, our findings describe the complex relationships between plant-root-associated ECM fungal community structure and functionality within the framework of trait-based ecology, having important implications for ECM-mediated C cycling. [ABSTRACT FROM AUTHOR]

• We reviewed the literature of the last decade on food web ecology. • The diversity of approaches, scales and study objectives prevent synthesis. • Progress requires theory refinement and standards for data and methods. • Geographically distributed empirical and experimental studies are also required. Food webs represent the energy fluxes and the nutrient cycling between interacting species that underpin several ecosystem functions. Whether and how interactions vary across environmental gradients is still largely unknown. We reviewed the literature searching for systematic relationships between structural food-web properties and environmental gradients. Temperature and biotic factors are amongst the most frequently addressed drivers of food-web structure. We also assessed the degree to which food-web ecology has accomplished a mechanistic understanding of ecosystem functioning. We found that most studies are one-off descriptions of local food webs making it difficult to achieve an understanding of the response to human or environmental gradients. The lack of a consistent theory predicting how food webs change across environmental gradients, the diversity of objectives in food-web studies, and the absence of a standardized methodology for analysing them severely limit progress in the field. Moving forward requires the establishment of a core set of testable predictions, agreed standards for data collection and analysis, and the development of geographically distributed experimental studies of food-web dynamics. [ABSTRACT FROM AUTHOR]

Over longer periods of time, aboveground herbivores may stimulate plant compensatory growth to some extent, which can itself promote further herbivory and increase the return of plant litter, in the form of debris or herbivore feces, to the soil. Herbivory, plant evolution, secondary metabolites, soil community, species interactions, biotic interactions, leaf herbivory, plant-soil feedback, root exudates Keywords: biotic interactions; herbivory; leaf herbivory; plant evolution; plant-soil feedback; root exudates; secondary metabolites; soil community; species interactions EN biotic interactions herbivory leaf herbivory plant evolution plant-soil feedback root exudates secondary metabolites soil community species interactions 672 675 4 06/01/22 20220501 NES 220501 "We were men once, though we've become trees." The second has focused on the mechanisms of such interactions and, more specifically, how plant physiological changes, such as plant defence strategies or the production of particular primary and secondary metabolites, mediate above- and belowground interactions between herbivores and higher trophic level organisms (Soler et al., 2005). [Extracted from the article]

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

Aim: Ecological communities are assembled by regional and local processes. These processes select species through their traits, which are tied to species' evolutionary history. A multifaceted approach, encompassing taxonomic, functional and phylogenetic diversity can thus help us to better understand community assembly. We asked what the relative importance of geography, climate and soil parameters is in driving taxonomic, functional and phylogenetic diversities at local (alpha) and larger scales (beta diversity). Location: Atlantic Europe. Taxon Plant communities of Violion caninae grasslands. Methods: Alpha and beta taxonomic, functional and phylogenetic diversities were calculated for 153 sites. Traits were obtained from the LEDA database and phylogeny from Daphne. We summarized climatic (CHELSA database) and soil variables using principal component analysis (PCA), and geographical distance using Moran's Eigenvector Maps (MEMs). To assess the importance of environment and space on all three facets, we performed redundancy and distance‐based redundancy analyses for alpha and beta diversity, respectively, using the PCA and MEM axes as predictors. Results: Compared to alpha diversity, beta diversity was relatively high in taxonomic diversity, but very low in functional and phylogenetic diversity. Geography and climate were relatively more important at larger scales, whereas soil conditions acted more strongly at the local scales, with alpha diversity of all facets decreasing towards richer and acidic soils. Main Conclusions: Considering multiple biodiversity facets along environmental and spatial gradients enables advancing both theoretical and applied aspects of community assembly. Accordingly, the observed turnover across the study area was mediated by species that share similar suites of traits and evolutionary history. Towards richer and acidic soils, exclusion of weaker competitors was an important filter at local scales. In summary, assessing multiple biodiversity facets and broad scale environmental gradients is key to understand the relative importance of multi‐scale processes driving the community assembly of European grasslands. [ABSTRACT FROM AUTHOR]

Extinctions stemming from environmental change often trigger trophic cascades and coextinctions. Bottom–up cascades occur when changes in the primary producers in a network elicit flow‐on effects to higher trophic levels. However, it remains unclear what determines a species' vulnerability to bottom–up cascades and whether such cascades were a large contributor to the megafauna extinctions that swept across several continents in the Late Pleistocene. The pathways to megafauna extinctions are particularly unclear for Sahul (landmass comprising Australia and New Guinea), where extinctions happened earlier than on other continents. We investigated the potential role of bottom–up trophic cascades in the megafauna extinctions in Late Pleistocene Sahul by first developing synthetic networks that varied in topology to identify how network position (trophic level, diet breadth, basal connections) influences vulnerability to bottom–up cascades. We then constructed pre‐extinction (~80 ka) network models of the ecological community of Naracoorte, south‐eastern Sahul, to assess whether the observed megafauna extinctions could be explained by bottom–up cascades. Synthetic networks showed that node vulnerability to bottom–up cascades decreased with increasing trophic level, diet breadth and basal connections. Extinct species in the Naracoorte community were more vulnerable overall to these cascades than were species that survived. The position of extinct species in the network – tending to be of low trophic level and therefore having relatively narrow diet breadths and fewer connections to plants – made them vulnerable. However, these species also tended to have few or no predators, a network‐position attribute that suggests they might have been particularly vulnerable to new predators. Together, these results suggest that trophic cascades and naivety to predators could have contributed to the megafauna extinction event in Sahul. [ABSTRACT FROM AUTHOR]

Species distribution and ecological niche models (SDMs and ENMs) are popular tools used in a wide variety of research and conservation applications. However, their use in understanding community‐level patterns and processes is an emerging and rapidly developing field. Here, we examine a set of important and challenging topics that are central to advancing the field of community ecology where we believe SDMs and ENMs can help in making progress. Topics examined in this review include the prediction of community attributes (e.g., species richness and composition), the detection and estimation of rare species, species abundance patterns, scale dependencies in species–environment relations, biotic interactions, and historical contingencies. We also describe how SDMs can be used to help construct regional species pools and community assembly models that can be used to help address important questions in novel and interesting ways. We expect that greater integration between theoretical advancements in community ecology, local field‐based experimental studies, and coarse‐scale species distribution modeling applications will become a highly productive avenue for moving the field of community ecology forward and for developing more predictive models of community assembly and dynamics. [ABSTRACT FROM AUTHOR]

Direct and indirect effects of habitat modification and changes in biotic interactions should be taken into consideration to understand the ecological consequences of forest anthropogenic disturbance on forest ecosystems. Few empirical studies assess indirect effects and consider multiple trophic levels, but recent statistical and theoretical advances provide new paths to do so. Here, we investigate direct and indirect effects of anthropogenic disturbances on multi-trophic soil communities in a boreal forest. We assessed the short term (2 years) abiotic and biotic responses to two anthropogenic disturbance intensities: conventional harvesting and harvesting followed by organic matter removal. We quantified the changes on eight groups of species, including vegetation and soil fauna, and their potential effects on leaf litter decomposition. We used a trait-based approach and structural equation modeling to quantify direct and indirect effects of disturbance intensity on environmental conditions, functional responses of the above and below ground biotic communities and leaf litter decomposition. Forest disturbance intensity was found to have a bottom-up effect on species community composition, from lower trophic levels (for example, detritivorous springtails) up to soil fauna top predators (for example, running spiders). Our results suggested some impacts of disturbance on leaf litter decomposition through changes in faunal communities. Our study shows that a multi-trophic assessment of disturbance impacts provides an integrative understanding of ecosystem responses to environmental change. [ABSTRACT FROM AUTHOR]

Across the globe, ecological communities are confronted with multiple global environmental change drivers, and they are responding in complex ways ranging from behavioral, physiological, and morphological changes within populations to changes in community composition and food web structure with consequences for ecosystem functioning. A better understanding of global change‐induced alterations of multitrophic biodiversity and the ecosystem‐level responses in terrestrial ecosystems requires holistic and integrative experimental approaches to manipulate and study complex communities and processes above and below the ground. We argue that mesocosm experiments fill a critical gap in this context, especially when based on ecological theory and coupled with microcosm experiments, field experiments, and observational studies of macroecological patterns. We describe the design and specifications of a novel terrestrial mesocosm facility, the iDiv Ecotron. It was developed to allow the setup and maintenance of complex communities and the manipulation of several abiotic factors in a near‐natural way, while simultaneously measuring multiple ecosystem functions. To demonstrate the capabilities of the facility, we provide a case study. This study shows that changes in aboveground multitrophic interactions caused by decreased predator densities can have cascading effects on the composition of belowground communities. The iDiv Ecotrons technical features, which allow for the assembly of an endless spectrum of ecosystem components, create the opportunity for collaboration among researchers with an equally broad spectrum of expertise. In the last part, we outline some of such components that will be implemented in future ecological experiments to be realized in the iDiv Ecotron. [ABSTRACT FROM AUTHOR]

Aim: The need to forecast range shifts under future climate change has motivated an increasing interest in better understanding the role of biotic interactions in driving diversity patterns. The contribution of biotic interactions to shaping broad‐scale species distributions is, however, still debated, partly due to the difficulty of detecting their effects. We aim to test whether spatial exclusion between potentially competing species can be detected at the species range scale, and whether this pattern relates to fine‐scale mechanisms of coexistence. Location: Western Palearctic. Methods: We develop and evaluate a measure of geographic avoidance that uses outputs of species distribution models to quantify geographic exclusion patterns expected if interspecific competition affects broad‐scale distributions. We apply the measure to 10 Palearctic bat species belonging to four morphologically similar cryptic groups in which competition is likely to occur. We compare outputs to null models based on pairs of virtual species and to expectations based on ecological similarity and fine‐scale coexistence mechanisms. We project changes in range suitability under climate change taking into account effects of geographic avoidance. Results: Values of geographic avoidance were above null expectations for two cryptic species pairs, suggesting that interspecific competition could have contributed to shaping their broad‐scale distributions. These two pairs showed highest levels of ecological similarity and no trophic or habitat partitioning. Considering the role of competition modified predictions of future range suitability. Main conclusions: Our results support the role of interspecific competition in limiting the geographic ranges of morphologically similar species in the absence of fine‐scale mechanisms of coexistence. This study highlights the importance of incorporating biotic interactions into predictive models of range shifts under climate change, and the need for further integration of community ecology with species distribution models to understand the role of competition in ecology and biogeography. [ABSTRACT FROM AUTHOR]

We investigated spatial heterogeneity and diel variations in bacterioplankton and pico-nanoeukaryote communities, and potential biotic interactions at the extinction stage of the Ulva prolifera bloom in the Jiaozhou Bay, Yellow Sea. It was found that the presence of Ulva canopies significantly promoted the cell abundance of heterotrophic bacteria, raised evenness, and altered the community structure of bacterioplankton. A diel pattern was solely significant for pico-nanoeukaryote community structure. >50 % of variation in the heterotrophic bacterial abundance was accounted for by the ratio of Bacteroidota to Firmicutes, and dissolved organic nitrogen effectively explained the variations in cell abundances of phytoplankton populations. The factors representing biotic interactions frequently contributed substantially more than environmental factors in explaining the variations in diversity and community structure of both bacterioplankton and pico-nanoeukaryotes. There were higher proportions of eukaryotic pathogens compared to other marine systems, suggesting a higher ecological risk associated with the Ulva blooms. [Display omitted] • Ulva altered the cell abundance and community structure of bacterioplankton. • Ratio of Bacteroidota to Firmicutes well explained the variations in bacterial abundance. • Diatoms and Fusobacteria correlated with bacterial and pico-nanoeukaryote richness, respectively. • Diel variations in community structure were significant in pico-nanoeukaryotes. • Biotic interaction matters in driving microbial diversity and community assembly. [ABSTRACT FROM AUTHOR]

In this remembrance, we have brought together some of Victor Rico‐Gray's friends and collaborators to recall his many contributions to tropical ecology and his influence on so many young scientists. Victor's research ranged from Mexican ethnobotany to the evolutionary ecology of complex interactions between ants and plants. His research was highly collaborative, forming strong bonds among those who shared his interests in how the web of life is organized. He inspired students through his mentoring in tropical ecology, mainly his lectures at the Instituto de Ecología AC (INECOL), and later at the Universidad Veracruzana (UV), his courses organized by the Organization for Tropical Studies (OTS), and his talks at meetings, including the Association of Tropical Biology and Conservation (ATBC). Victor's story is not over. It will continue to be traced through countless scientists who were inspired by Victor's life and work. [ABSTRACT FROM AUTHOR]

Explaining and modeling species communities is more than ever a central goal of ecology. Recently, joint species distribution models (JSDMs), which extend species distribution models (SDMs) by considering correlations among species, have been proposed to improve species community analyses and rare species predictions while potentially inferring species interactions. Here, we illustrate the mathematical links between SDMs and JSDMs and their ecological implications and demonstrate that JSDMs, just like SDMs, cannot separate environmental effects from biotic interactions. We provide a guide to the conditions under which JSDMs are (or are not) preferable to SDMs for species community modeling. More generally, we call for a better uptake and clarification of novel statistical developments in the field of biodiversity modeling. In an era of global changes, developing reliable biodiversity models has become an important research area. Species distribution models are the common tools to understand and predict the distributions of species across space and time. However, they fail to explicitly account for species interactions. To this aim, joint species distribution models were introduced to tease apart the effect of the environment from that of species interactions, to improve rare species modeling, to account for functional traits, and to improve the predictive power of biodiversity models. Nevertheless, most announced advantages have remained unfulfilled, and there is still a need to better integrate the effect of species interactions in the response of species to environmental change. [ABSTRACT FROM AUTHOR]

Understanding how long-term environmental variation and biotic interaction determine biological assemblages is critical for evaluating the response of biological communities to anthropogenic and climate changes. We sampled plankton and water quality from a man-made lake monthly from 2006 to 2015 for the period from after creation to 13-year old of the lake. We used correlation, variation partitioning, multivariate autoregressive state-space models, and dynamic factor analyses to disentangle interactions of biotic and abiotic factors in regulating the dynamics of plankton size groups. We found that annual average total abundances decreased 86% for phytoplankton and 78% for zooplankton, while concentrations increased 1.8 times for total nitrogen and 2.7 times for total phosphorus during the study period. We concluded that the decline of plankton abundance was largely attributed to the predation of zooplankton on phytoplankton, fish predation on both phytoplankton and zooplankton, and linkages with the decline of water salinity, pH, and the increase of clarity. The decline of plankton abundance was apparently not resulted from long-term change in nutrient concentrations. These conclusions were further supported by that abundances of nano-phytoplankton and micro-phytoplankton oscillated in opposite direction with extremely low density of Cladocera (< 1 individual/L) during the study period. Our conclusions were also supported by the strong interactions between Rotifera and macro-phytoplankton and between nano-phytoplankton and Copepoda, as well as by the describability of the six plankton size groups in a shared trend that was opposite to the trends of water clarity and planktivorous fish stock density. [ABSTRACT FROM AUTHOR]

It has been long assumed that abiotic factors (i.e., geography and climate) dominate the ecological and evolutionary processes underlying the distribution of species, lineages and genes at broad spatial scales and, as a result, the study of interspecific interactions has largely been overlooked in biogeography research and ignored entirely in phylogeographic inference. Here, we focus on plant–plant interactions and test whether their demographic consequences translate into broad‐scale patterns of genomic variation in two Californian oak species. With our process‐based analyses and statistical comparison of the likelihoods of alternative models, we show that spatial patterns of genomic variation are better explained by demographic scenarios incorporating interspecific interactions (including both competition and facilitation) than by null models that only consider heterogeneity of environmental suitability across the landscape. Collectively, our integrative approach supports the notion that the consequences of biotic interactions transcend much larger geographical and evolutionary scales than the traditional local focus. see also the Perspective by Eva Graciá. [ABSTRACT FROM AUTHOR]

Recent technological and methodological advances have revolutionized wildlife monitoring. Although most biodiversity monitoring initiatives are geared towards focal species of conservation concern, researchers are increasingly studying entire communities, specifically the spatiotemporal drivers of community size and structure and interactions among species. This has resulted in the emergence of multi‐species occupancy models (MSOMs) as a promising and efficient approach for the study of community ecology. Given the potential of MSOMs for conservation and management action, it is critical to know whether study design and model assumptions are consistent with inference objectives. This is especially true for studies that are designed for a focal species but can give insights about a community. Here, we review the recent literature on MSOMs, identify areas of improvement in the multi‐species study workflow, and provide a reference model for best practices for focal species and community monitoring study design. We reviewed 92 studies published between 2009 and early 2018, spanning 27 countries and a variety of taxa. There is a consistent under‐reporting of details that are central to determining the adequacy of designs for generating data that can be used to make inferences about community‐level patterns of occupancy, including the spatial and temporal extent, types of detectors used, covariates considered, and choice of field methods and statistical tools. This reporting bias could consequently result in skewed estimates, affecting conservation actions and management plans. On the other hand, comprehensive reporting is likely to help researchers working on MSOMs assess the robustness of inferences, in addition to making strides in terms of reproducibility and reusability of data. We use our literature review to inform a roadmap with best practices for MSOM studies, from simulations to design considerations and reporting, for the collection of new data as well as those involving existing datasets. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of the scale dependency of environmental filtering and biotic interactions influencing the local assembly of species is paramount to derive realistic forecasts of the future of biodiversity and efficiently manage ecological communities. A classical assumption is that environmental filters are more prevalent at coarser scales with diminishing effects towards the finest scales where biotic interactions become more decisive. Recently, a refinement was proposed stipulating that the scale dependency of biotic interactions should relate to the type of interaction. Specifically, the effect of negative interactions (e.g. competition) should diminish with coarsening scale, whereas positive interactions (i.e. facilitation) should be detected irrespective of the scale.We use multiple vascular plant species datasets sampled at nested spatial scales (plot size varying from 0.04 to 64 m2) and recently developed joint species distribution models to test the hypotheses.Our analyses indicate slightly stronger environmental filtering with increasing plot size. While the overall strength of biotic interactions did not vary consistently across scales, we found a tendency for negative interactions to fade away with increasing plot size slightly more than positive interactions.Synthesis. We provide partial, but not unambiguous, evidence of the scale dependency of ecological assembly rules. However, our correlative methodology only allows us to interpret the findings as indication of environmental filtering and biotic interactions. [ABSTRACT FROM AUTHOR]

Light is one of the most important environmental filters for forest understory grass communities. It is predicted that light can select species with the same light requirements, resulting in a decrease in species compositional dissimilarity among grass communities experiencing the same light intensity, and an increase in community dissimilarity under variable light intensities. However, these predictions have been questioned recently in light of modern coexistence theories, and evidence for them in natural communities is often indistinguishable from patterns created by dispersal limitation and biotic interactions. To help fill this gap, we sampled 48 understory grass communities that had regenerated from the same soil seed bank in Southern China. Plots were established under a light intensity gradient. Changes in species composition and neighborhood densities were monitored over a growing season. Our experimental setup controls for bias from dispersal limitation and is useful for detecting the effects of biotic interactions at different intensities of light. As expected, (1) compositional dissimilarity of grass communities increased between communities with different light intensities. The extent to which communities became more dissimilar was positively correlated with the difference in the light intensity. (2) No significant change in compositional dissimilarity was observed among communities experiencing the same light intensity. (3) Finally, relative neighborhood density significantly decreased in communities with moderate to high shading treatments. Our results clearly show that light can drive compositional divergence among communities under different light densities. However, the light may not lead to convergence among communities experiencing the same low light intensity, because intense competition induced by low light might enlarge species compositional differences, as shown with the neighborhood density analysis. Therefore, our study provides more convincing evidence for the importance of light on understory grass communities in subtropical forests and highlights the need to jointly consider biotic interactions when testing for evidence for environmental filtering. [ABSTRACT FROM AUTHOR]

Plant defense suppression is an offensive strategy of herbivores, in which they manipulate plant physiological processes to increase their performance. Paradoxically, defense suppression does not always benefit the defense‐suppressing herbivores, because lowered plant defenses can also enhance the performance of competing herbivores and can expose herbivores to increased predation. Suppression of plant defense may therefore entail considerable ecological costs depending on the presence of competitors and natural enemies in a community. Hence, we hypothesize that the optimal magnitude of suppression differs among locations. To investigate this, we studied defense suppression across populations of Tetranychus evansi spider mites, a herbivore from South America that is an invasive pest of solanaceous plants including cultivated tomato, Solanum lycopersicum, in other parts of the world. We measured the level of expression of defense marker genes in tomato plants after infestation with mites from eleven different T. evansi populations. These populations were chosen across a range of native (South American) and non‐native (other continents) environments and from different host plant species. We found significant variation at three out of four defense marker genes, demonstrating that T. evansi populations suppress jasmonic acid‐ and salicylic acid‐dependent plant signaling pathways to varying degrees. While we found no indication that this variation in defense suppression was explained by differences in host plant species, invasive populations tended to suppress plant defense to a smaller extent than native populations. This may reflect either the genetic lineage of T. evansi—as all invasive populations we studied belong to one linage and both native populations to another—or the absence of specialized natural enemies in invasive T. evansi populations. [ABSTRACT FROM AUTHOR]

Climate change is expected to have significant and complex impacts on ecological communities. In addition to direct effects of climate on species, there can also be indirect effects through an intermediary species, such as in host–plant interactions. Indirect effects are expected to be more pronounced in alpine environments because these ecosystems are sensitive to temperature changes and there are limited areas for migration of both species (i.e. closed systems), and because of simpler trophic interactions. We tested the hypothesis that climate change will reduce the range of an alpine butterfly (Parnassius smintheus) because of indirect effects through its host plant (Sedum sp.). To test for direct and indirect effects, we used the simulations of climate change to assess the distribution of P. smintheus with and without Sedum sp. We also compared the projected ranges of P. smintheus to four other butterfly species that are found in the alpine, but that are generalists feeding on many plant genera. We found that P. smintheus gained distributional area in climate‐only models, but these gains were significantly reduced with the inclusion of Sedum sp. and in dry‐climate scenarios which resulted in a reduction in net area. When compared to the more generalist butterfly species, P. smintheus exhibited the largest loss in suitable habitat. Our findings support the importance of including indirect effects in modelling species distributions in response to climate change. We highlight the potentially large and still neglected impacts climate change can have on the trophic structure of communities, which can lead to significant losses of biodiversity. In the future, communities will continue to favour species that are generalists as climate change induces asynchronies in the migration of species. [ABSTRACT FROM AUTHOR]

Whole microbial communities regularly merge with one another, often in tandem with their environments, in a process called community coalescence. Such events impose substantial changes: abiotic perturbation from environmental blending and biotic perturbation of community merging. We used an aquatic mixing experiment to unravel the effects of these perturbations on the whole microbiome response and on the success of individual taxa when distinct freshwater and marine communities coalesce. We found that an equal mix of freshwater and marine habitats and blended microbiomes resulted in strong convergence of the community structure toward that of the marine microbiome. The enzymatic potential of these blended microbiomes in mixed media also converged toward that of the marine, with strong correlations between the multivariate response patterns of the enzymes and of community structure. Exposing each endmember inocula to an axenic equal mix of their freshwater and marine source waters led to a 96% loss of taxa from our freshwater microbiomes and a 66% loss from our marine microbiomes. When both inocula were added together to this mixed environment, interactions amongst the communities led to a further loss of 29% and 49% of freshwater and marine taxa, respectively. Under both the axenic and competitive scenarios, the diversity lost was somewhat counterbalanced by increased abundance of microbial taxa that were too rare to detect in the initial inocula. Our study emphasizes the importance of the rare biosphere as a critical component of microbial community responses to community coalescence. [ABSTRACT FROM AUTHOR]

Human influence along the coastline is a significant threat to biodiversity and includes the alteration or replacement of natural habitat with artificial structures. Infrastructure such as docks and marinas are common throughout the world and typically have negative impacts on coastal flora and fauna. Impacts include the reduction of native biodiversity, the increase of introduced species, and the alteration of biotic interactions (e.g., predation). Many studies examine human disturbance on biotic interactions within a single habitat (i.e., docks or marinas) but what lacks are paired comparisons using standardized methods of biotic interactions between artificial and nearby natural habitats. In the current study, benthic fouling communities were allowed to develop, with and without predator access, in artificial and seagrass habitats. Cages were used to reduce predation and removed to expose communities to fish predators. Prior to exposure, communities were either left at their original site or transplanted to the opposite habitat and changes in the percent cover of species found were compared. Initially, community composition differed between habitats and when predation was reduced (caged vs. open). When developed communities within cages were exposed to predators, predation was strong but only in artificial habitats and regardless of where communities originated. In contrast, little predation occurred at seagrass sites on previously caged communities developed within seagrass beds or that were transplanted from artificial habitat. Taken together, results indicate that the strength of biotic interactions can differ depending on habitat, leading to changes in community composition. With the continuous expansion of artificial structures world-wide, it is becoming increasingly important to understand not only their effects on biotic interactions and biodiversity but also how these effects extend and compare to adjacent natural habitats. • A reciprocal transplant approach was used to examine differences in predator effects in fouling communities found in natural and artificial habitats. • Communities differed between habitats and when predators were excluded. • Exposure of communities to predators indicated that predation pressure was stronger on vulnerable taxa in artificial habitats as compared to seagrass beds regardless of where communities were originally developed. • The strength of biotic interactions can differ by habitat type, leading to changes in community composition. [ABSTRACT FROM AUTHOR]

Multiple stressors are increasingly affecting organisms and communities, thereby modifying ecosystems' state and functioning. Raising awareness about the threat from multiple stressors has increased the number of experimental and observational studies specifically addressing consequences of stressor interactions on biota. Most studies measure the direct effects of multiple stressors and their interactions on biological endpoints such as abundance, biomass, or diversity of target organisms. This yields invaluable information for the management and restoration of stressed ecosystems. However, as we argue in our perspective paper, this common approach ignores a fundamental characteristic of communities and ecosystems, i.e., that organisms in ecosystems are interlinked by biotic interactions in ecological networks. Examples from the literature show that biotic interactions can modify stressor effects, transfer stressor effects to distant groups of organisms, and create new stressor interactions. These examples also suggest that changes in biotic interactions can have effects of similar or greater magnitude than direct stressor effects. We provide a perspective on how to include network characteristics and biotic interactions into analyses of multiple-stressor effects on ecosystems. Our approach can also make use of biomonitoring data produced with established and intercalibrated methods, and can combine it with novel metrics used to describe the functioning of ecosystems, such as trait information or stable-isotope measurements. The insights on network-mediated effects gained via the approach we propose can substantially increase mechanistic understanding of multiple-stressor effects, and in turn, the efficiency of ecosystem management and restoration.

Ecological communities are shaped by a complex interplay between abiotic forcing, biotic regulation and demographic stochasticity. However, community dynamics modelers tend to focus on abiotic forcing overlooking biotic interactions, due to notorious challenges involved in modeling and quantifying inter-specific interactions, particularly for species-rich systems such as planktonic assemblages. Nevertheless, inclusive models with regard to the full range of plausible drivers are essential to characterizing and predicting community response to environmental changes. Here we develop a Bayesian model for identifying, from in-situ time series, the biotic, abiotic and stochastic factors underlying the dynamics of species-rich communities, focusing on the joint biomass dynamics of biologically meaningful groups. We parameterize a multivariate model of population co-variation with an explicit account for demographic stochasticity, density-dependent feedbacks, pairwise interactions, and abiotic stress mediated by changing environmental conditions and resource availability, and work out explicit formulae for partitioning the temporal variance of each group in its biotic, abiotic and stochastic components. We illustrate the methodology by analyzing the joint biomass dynamics of four major phytoplankton functional types namely, diatoms, dinoflagellates, coccolithophores and phytoflagellates at Station L4 in the Western English Channel using weekly biomass records and coincident measurements of environmental covariates describing water conditions and potentially limiting resources. Abiotic and biotic factors explain comparable amounts of temporal variance in log-biomass growth across functional types. Our results demonstrate that effective modelling of resource limitation and inter-specific interactions is critical for quantifying the relative importance of abiotic and biotic factors. [ABSTRACT FROM AUTHOR]

Climate is a powerful force shaping adaptation within species, yet adaptation to climate occurs against a biotic background: species interactions can filter fitness consequences of genetic variation by altering phenotypic expression of genotypes. We investigated this process using populations of teosinte, a wild annual grass related to maize (Zea mays ssp. mexicana), sampling plants from 10 sites along an elevational gradient as well as rhizosphere biota from three of those sites. We grew half‐sibling teosinte families in each biota to test whether trait divergence among teosinte populations reflects adaptation or drift, and whether rhizosphere biota affect expression of diverged traits. We further assayed the influence of rhizosphere biota on contemporary additive genetic variation. We found that adaptation across environment shaped divergence of some traits, particularly flowering time and root biomass. We also observed that different rhizosphere biota shifted expressed values of these traits within teosinte populations and families and altered within‐population genetic variance and covariance. In sum, our results imply that changes in trait expression and covariance elicited by rhizosphere communities could have played a historical role in teosinte adaptation to environments and that they are likely to play a role in the response to future selection. [ABSTRACT FROM AUTHOR]

Summary: The tendency of closely related plant species to share natural enemies has been suggested to limit their co‐occurrence and performance, but we lack a deep understanding on how mutualistic interactions such as the mycorrhizal symbiosis affect plant–plant interactions depending on the phylogenetic relatedness of the interacting plants. We hypothesise that the effect of the mycorrhizal symbiosis on plant−plant facilitative interactions depends on the phylogenetic distance between the nurse and facilitated plants.A recently published meta‐analysis compiled the strength of plant facilitative interactions in the presence or absence (or reduced abundance) of mycorrhizal fungi. We use phylogenetically informed Bayesian linear models to test whether the effect size is influenced by the phylogenetic distance between the plant species involved in each plant facilitative interaction.Conspecific facilitative interactions are more strongly enhanced by mycorrhizal fungi than interactions between closely related species. In heterospecific interactions, the effect of the mycorrhizal symbiosis on plant facilitation increases with the phylogenetic distance between the nurse and facilitated plant species.Our result showing that the effect of mycorrhizal symbiosis on the facilitation interactions between plants depends on their phylogenetic relatedness provides new mechanisms to understand how facilitation is assembling ecological communities. [ABSTRACT FROM AUTHOR]

Species' geographic distributions have already shifted during the Anthropocene. However, we often do not know what aspects of the environment drive range dynamics, much less which traits mediate organisms' responses to these environmental gradients. Most studies focus on possible climatic limits to species' distributions and have ignored the role of biotic interactions, despite theoretical support for their importance in setting distributional limits. We used field experiments and simulations to estimate contributions of mammalian herbivory to a range boundary in the Californian annual plant Clarkia xantiana ssp. xantiana. A steep gradient of increasing probability of herbivory occurred across the boundary, and a reanalysis of prior transplant experiments revealed that herbivory drove severalfold declines in lifetime fitness at and beyond the boundary. Simulations showed that populations could potentially persist beyond the range margin in the absence of herbivory. Using data from a narrowly sympatric subspecies, Clarkia xantiana parviflora , we also showed that delayed phenology is strongly associated with C. xantiana ssp. xantiana 's susceptibility to herbivory and low fitness beyond its border. Overall, our results provide some of the most comprehensive evidence to date of how the interplay of demography, traits, and spatial gradients in species interactions can produce a geographic range limit, and they lend empirical support to recent developments in range limits theory. [ABSTRACT FROM AUTHOR]