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Aim: Evaluating the similarity of diversity patterns across micro‐ to macroevolutionary scales in natural communities, such as species–genetic diversity correlations (SGDCs), may inform on processes shaping community assembly. However, whether SGDCs not only hold across communities but also across lineages has never been explored so far. Here we investigated SGDCs across co‐distributed taxa for different spatial components (α, β, γ), and formally tested the influence of dispersal traits on β‐SGDCs. Location: Western Indian Ocean. Time period: 2016–2017. Major taxa studied: Tropical reef fish species with contrasting dispersal traits. Methods: Using double‐digest restriction‐site associated DNA sequencing (ddRADseq) Single Nucleotide Polymorphism data for 20 tropical reef fishes and distribution data of 2,446 species belonging to 12 families, we analysed the correlations between within‐species genetic diversity and within‐family species diversity (i.e., lineage diversity) for the three spatial components (α, β, γ‐SGDCs). We then related the strength of β‐SGDCs per species to proxies of larval dispersal abilities. Results: We detected positive and significant lineage‐based SGDC only for the β component, that is, the families showing the greatest level of species turnover among sites contain the species with the greatest levels of genetic differentiation. We showed that the Monsoon Drift mainly explained the β‐diversity patterns at both intraspecific and interspecific levels. Higher β‐SGDCs were found for species with short pelagic larval duration and weak larval swimming capacity. Main conclusions: Our study reveals a strong correlation between genetic and species β‐diversity, a result explained by the presence of a 'soft' barrier and mediated by larval dispersal processes. This suggests that vicariance and dispersal limitation are major processes shaping β‐diversity patterns from microevolutionary to macroevolutionary scales in tropical reef fishes. [ABSTRACT FROM AUTHOR]

Aim: While it is now well accepted that human activities are having pronounced effects on natural ecosystems, regional variation in the rate and magnitude of various human impacts is unclear. Moreover, the effects of land use change on natural aquatic communities have only relatively recently begun to be explored. Our goal was to understand how and where assemblages of a central food web component of freshwater lakes have changed over the course of industrialization in relation to land use. Location: Canada. Time period: Pre‐1880 AD to present. Major taxa studied: Cladoceran zooplankton. Methods: As part of the Natural Sciences and Engineering Research Council (NSERC) Canadian Lake Pulse Network, we selected 101 lakes across Canada along a gradient of human impact to analyse subfossil cladoceran assemblages from sediment cores. We examined relationships between taxonomic and functional indicators of cladoceran assemblage change among lakes and through time. Results: Contemporary assemblages were taxonomically and functionally less diverse locally relative to pre‐industrial assemblages (α‐diversity) and were structured by the degree of human impact in watersheds. Local α‐diversity losses were greatest in highly impacted lakes where agriculture and pasture are prevalent. While spatial homogenization (spatial β‐diversity) did not increase since pre‐industrial times as expected, temporal turnover (temporal β‐diversity) showed a non‐significant but increasing trend in highly impacted lakes, especially in urbanized watersheds. Main conclusions: Cladoceran assemblages have changed significantly over the course of the Industrial period, and especially in more highly impacted watersheds, underscoring the important role of watershed land use in shaping diversity. However, indicators of cladoceran function have remained relatively conserved over time and land use change showed little impact on β‐diversity, despite important environmental variation. Overall, this research furthers our understanding of the health status of Canadian lakes and the consequences of human activities, especially agriculture and urbanization, on lake zooplankton. [ABSTRACT FROM AUTHOR]

Aim: Understanding the variation in community composition and species abundances (i.e., β‐diversity) is at the heart of community ecology. A common approach to examine β‐diversity is to evaluate directional variation in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distance. We provide the first global synthesis of taxonomic and functional distance decay along spatial and environmental distance by analysing 148 datasets comprising different types of organisms and environments. Location: Global. Time period: 1990 to present. Major taxa studied: From diatoms to mammals. Method: We measured the strength of the decay using ranked Mantel tests (Mantel r) and the rate of distance decay as the slope of an exponential fit using generalized linear models. We used null models to test whether functional similarity decays faster or slower than expected given the taxonomic decay along the spatial and environmental distance. We also unveiled the factors driving the rate of decay across the datasets, including latitude, spatial extent, realm and organismal features. Results: Taxonomic distance decay was stronger than functional distance decay along both spatial and environmental distance. Functional distance decay was random given the taxonomic distance decay. The rate of taxonomic and functional spatial distance decay was fastest in the datasets from mid‐latitudes. Overall, datasets covering larger spatial extents showed a lower rate of decay along spatial distance but a higher rate of decay along environmental distance. Marine ecosystems had the slowest rate of decay along environmental distances. Main conclusions: In general, taxonomic distance decay is a useful tool for biogeographical research because it reflects dispersal‐related factors in addition to species responses to climatic and environmental variables. Moreover, functional distance decay might be a cost‐effective option for investigating community changes in heterogeneous environments. [ABSTRACT FROM AUTHOR]

Aim: Global declines in structurally complex habitats are reshaping both land‐ and seascapes in directions that affect the responses of biological communities to warming. Here, we test whether widespread loss of kelp habitats through sea urchin overgrazing systematically changes the sensitivity of fish communities to warming. Location: Global temperate latitudes. Time period: Modern. Major taxa studied: Fishes. Methods: Community shifts in thermal affinity related to habitat were assessed by simulating and comparing fish communities from 2271 surveys across 15 ecoregions. Results: We found that fishes in kelp and urchin barrens differed in realized thermal affinities and range sizes, but only in regions where species pools had high variability in the thermal affinities of species. Barrens on warm temperate reefs host relatively more warm‐affinity fish species than neighbouring kelp beds, highlighting the acceleration of tropicalization processes facilitated by urchin grazing. In contrast, proportionally more cool‐affinity fishes colonize barrens at high temperate latitudes, contributing to community lags with ocean warming in these regions. Main conclusions: Our findings implicate urchins as drivers of ecological change, in part by affecting ecological resilience to warming. [ABSTRACT FROM AUTHOR]

Aim: The aim was to identify the primary drivers of compositional change in breeding bird assemblages over a 40‐year period. Location: Britain. Time period: From 1970 to 2010. Major taxa studied: Birds. Methods: Using morphological trait measurements and a dataset of presence–absence data for British breeding birds surveyed in 10 km × 10 km hectads during two time periods, we calculated temporal taxonomic and functional beta diversity for each hectad alongside the change in species richness, mean nearest taxon distance (MNTD) and mean pairwise distance (MPD). We also estimated potential drivers of beta diversity, including climatic and land‐use and land‐cover (LULC) change variables, elevation and assemblage species richness in 1970 (1970rich). We used random forest regressions to test which variables best explained compositional change in the assemblages. We also assessed spatial taxonomic and functional change by analysing multiple‐site beta diversity and pairwise dissimilarities between time periods. Results: Initial (1970) species richness was the most important predictor (highest importance score) across all models, with areas characterized by higher initial richness experiencing less assemblage change overall. The coordinates included to capture spatial autocorrelation in the data were also important predictors of change. Most climate and LULC variables had relatively low explanatory power; elevation and average temperature were the most influential. All metrics increased slightly with increasing elevation, except for species richness change and MPD, which decreased. Main conclusions: The composition of British breeding bird assemblages changed substantially between 1970 and 2010. Spatial heterogeneity increased, both taxonomically and functionally. We show evidence that hectads with larger assemblages have been buffered from temporal diversity change and that those at higher elevations changed more in composition than those at lower elevations. Overall, coarse‐resolution climate and LULC explained only small to moderate amounts of variation, suggesting that stochastic assembly change or finer‐scale drivers might be drivers of temporal changes in assemblage composition. [ABSTRACT FROM AUTHOR]

Aim: A large body of ecological theory predicts that non‐indigenous species (NIS) are successful invaders if their niches overlap little with native taxa. Native–non‐indigenous trait dissimilarity, however, may also be observed if NIS have outcompeted ecologically similar native species. Discriminating these scenarios is essential for assessing invasion impacts but requires baseline assemblage data that are frequently unavailable. We overcome this impediment by analysing death assemblages – identifiable organism remains in the seafloor – which are natural community archives. Focusing on molluscs from the heavily invaded Eastern Mediterranean, we gain insights into the contentious role of competitive displacement by NIS as the primary driver of the massive regional declines of native populations, and their potential to alter ecosystem functioning. Location: Israel/Eastern Mediterranean. Time period: Pre‐Lessepsian invasion (pre‐1869) to contemporary. Major taxa studied: Mollusca. Methods: We sampled molluscan living and death assemblages from various substrates on the Israeli shelf and compiled trait information on all constituent species. We then compared the abundance‐weighted trait composition and functional diversity of native and non‐indigenous assemblage components. Death assemblage time‐coverage was quantified radiometrically. Results: Native and non‐indigenous assemblage components consistently differed in trait composition, both in present‐day (i.e., living) and historical (i.e., death) assemblages, irrespective of habitat conditions. Furthermore, present‐day non‐indigenous assemblage components had a different trait composition than historical native assemblages. These findings suggest that the increasing NIS dominance has considerably altered the functional properties of shallow‐water molluscan assemblages. Main conclusions: By utilizing death assemblages, we show that native and non‐indigenous assemblage components have differed in trait composition since the onset of the invasion, suggesting that competition was unlikely the primary driver of the regional‐scale native biodiversity loss. Our findings, however, also imply that NIS cannot functionally compensate for native species disappearance. Instead, the transition towards increasingly NIS‐dominated assemblages has profoundly altered ecosystem functioning, with unknown consequences. [ABSTRACT FROM AUTHOR]

Aim: In an age of increased anthropogenic changes, it is crucially important to understand how and why ecological communities change. Community assembly is governed by colonization and extinction processes, and the simplest model describing it is dynamic equilibrium (DE), which assumes that communities are shaped solely by stochastic colonization and extinction events. Deviations from this model can point to the role of species life histories, niches or human stressors acting on communities. Despite its potential to serve as a null model for community dynamics, there is currently no accepted methodology for identifying and measuring such deviations. Innovation: Here we propose a new, easily applicable methodology for testing and quantifying deviations of empirically observed time series of community dynamics from the predictions and assumptions of the classical DE model, in which assemblages of independent species undergo stochastic colonization–extinction dynamics with constant rates. The methodology consists of a novel randomization‐based null model to generate synthetic time series (PARIS) and a set of statistics that quantify and test how different facets of community dynamics deviate from DE. These statistics are designed to test the assumptions of the theory, namely species independence and constancy of colonization and extinction rates, and the predictions of the theory regarding the magnitude of changes in species richness and composition. Main conclusions: Tested against simulated data and a case study, the proposed methodology is shown to have good statistical properties: acceptable type I error rates, good statistical power and robustness against errors in the data. We discuss alternative methods and present guidelines for practical use of the methodology, hoping it will enhance the applicability of DE as a reference for studying changes in ecological communities. [ABSTRACT FROM AUTHOR]