Addressing biodiversity loss requires knowing how different living beings are spatially distributed. For hyper-diverse groups such as spiders, biogeographic dispersal-related processes tend to be the main factor driving diversity patterns at large spatial scales, while the relevance of ecological filtering (species sorting) may increase at lower spatial scales. To determine how spider diversity and structure are shaped at local spatial scales, we sampled spider communities using a standardized optimized protocol and assessed habitat heterogeneity across 10 Mediterranean forest plots in the Northeastern Iberian Peninsula. We compared the spiders' composition and structure among forest types and across vegetation layers using generalized linear models and linear mixed models for assessing patterns of alpha-diversity and constrained ordination analyses for understanding beta-diversity patterns. Across forests, habitat heterogeneity was the only significant driver for structuring alpha- and beta-diversity, and the geographic and climate distance explained a low variance of the models. Pine forests were separated in the redundancy analyses from holm oak and deciduous forests because a lower vegetation cover characterized the latter. Lineal models of alpha-diversity at the microhabitat scale only showed significant negative tendencies for the rock cover. Beta-diversity across vegetation layers within a plot and across forests appears to be influenced primarily by habitat heterogeneity, particularly by the presence of herbaceous and low shrub cover. Our results highlight the importance of species sorting over biogeography and climatic variables in shaping spider diversity patterns at the local scale. They also indicate that a mosaic of habitat structure within and between forest types is a significant driver of spider diversity. These findings have implications for assessing spider assemblages-and likely other arthropods-suggesting that a combination of methods capturing microhabitat descriptors is crucial for effective monitoring schemes.

Temporary rivers (TRs) are dynamic ecosystems that alternate between hydrological phases (i.e., flowing, disconnected pools, and dry). They are conservation refugia for aquatic species during dry seasons but are often neglected in bioassessment programs. To assess the biological quality of these ecosystems, morphological methods can be invasive, disrupting communities and diminishing their function as refugia. Environmental DNA (eDNA) metabarcoding provides a minimally invasive method, gathering community information from eDNA in water or sediment. We tested the effectiveness of eDNA methods alongside bulk DNA metabarcoding to characterize the macroinvertebrate communities and assess the biological quality of disconnected pools in TRs, comparing them with morphological methods. Additionally, we tested how the community patterns evolve over time using eDNA and how community composition shifts during disconnection. Biological quality was determined through macroinvertebrate indices widely used in Spain (i.e., IBMWP, family richness, and IASPT). eDNA samples were collected biweekly from three TRs in Catalonia, NE Spain. Macroinvertebrates were sampled during the three hydrological phases (connected, disconnecting, and disconnected pools). Macroinvertebrate samples were used to identify organisms using morphology and to sequence bulk DNA. eDNA and bulk DNA samples were analysed via DNA metabarcoding targeting the mitochondrial COI gene. Although communities determined by sediment eDNA did not detect variations in biotic indices (i.e., IBMWP and family richness), the method was useful to detect the replacement of EPT (Ephemeroptera, Plecoptera, Trichoptera) by OCH (Odonata, Coleoptera, Heteroptera). Additionally, sediment eDNA revealed significant impacts of hydrological changes on meiofauna (Ostracoda, Cladocera, Copepoda), a group often overlooked in stream assessments. These results indicate that sediment eDNA metabarcoding can serve as a valuable tool for the bioassessment of TRs, capturing the transitions between hydrological phases while preserving ecosystem integrity.

Biological indicators constitute an essential part of the ecological assessment under the European Water Framework Directive. However, in temporary rivers (TRs), high hydrological variability decreases richness and drives rapid community turnover, limiting the ability of biological communities to respond to anthropogenic impacts. To overcome these limitations, molecular methods such as environmental DNA (eDNA) metabarcoding may offer a more sensitive and minimally invasive approach to detect community-level responses because of a higher number of indicator taxa assessed. We aimed to evaluate the effectiveness of sediment eDNA metabarcoding for characterizing invertebrate communities and assessing the ecological status of disconnected pools in TRs. We collected sediment samples from 52 pools in Catalonia (NE Spain) and analyzed them using COI eDNA metabarcoding. Morphology-based indices and metrics did not detect significant differences between natural and impacted categories. In contrast, multiple invertebrate Operational Taxonomic Units (OTUs) showed strong and consistent associations with anthropogenic impact affecting sampled TRs. These taxa primarily belonged to groups typically determined at higher taxonomic levels (e.g., Class, Order) in routine river biomonitoring but also included members of the Chironomidae, Oligochaeta, Cladocera, Copepoda, and Ostracoda. The broader taxonomic coverage and the fine-scale OTU-level resolution provided by sediment eDNA metabarcoding revealed ecological responses masked by conventional invertebrate-based family-level metrics. We demonstrated that this approach can infer anthropogenic pressures in TRs by using a wider range of macro- and meiofaunal invertebrate taxa. This represents a significant methodological advance for deriving biological metrics in TR monitoring and assessment.

AimSpecies have different distribution patterns across the globe and among biogeographical regions. The Nearctic and Palaearctic regions share lineages because of their parallel biogeographic histories and ecological conditions. As the number of phylogenetic studies increases, there are more insights into past exchange events between these two regions and their effects on the current distribution of diversity. However, several groups have not been tested and an overall generalization is still missing. Here, we analyse the biogeographic history across multiple genera of odonates to elucidate a general process of species exchange, vicariance and species divergence between these two regions.LocationThe Holarctic, including the entire Nearctic and the East and West Palaearctic.Taxon14 genera of Odonata (Insecta).MethodsWe reconstructed a time-calibrated phylogenetic tree for each genus to determine species relationships and divergence time using 3614 COI sequences of 259 species. Biogeographic ancestral range estimation was inferred for each phylogeny using BioGeoBEARS. Preferred habitat (lotic versus lentic) was established for each species.ResultsExchange events were not restricted in time, direction or either lentic habitat or lotic habitat. Most genera crossed between both regions only once, and it was mainly across the Beringia, while three diverse anisopteran genera revealed multiple exchanges. Recent exchanges during the Pleistocene were associated with cold-dwelling and lentic species.Main ConclusionsOur finding reveals the absence of a generalizable pattern of species exchange and divergence between the Nearctic and Palaearctic regions; instead, we found lineage-specific biogeographic patterns. This finding highlights the complexity of drivers and functional traits that shaped current diversity patterns. Moreover, it emphasizes that general conclusions cannot be formulated based on one single clade.

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Determining biological status of freshwater ecosystems is critical for ensuring ecosystem health and maintaining associated services to such ecosystems. Freshwater macroinvertebrates respond predictably to environmental disturbances and are widely used in biomonitoring programs. However, many freshwater species are difficult to capture and sort from debris or substrate and morphological identification is challenging, especially larval stages, damaged specimens, or hyperdiverse groups such as Diptera. The advent of high throughput sequencing technologies has enhanced DNA barcoding tools to automatise species identification for whole communities, as metabarcoding is increasingly used to monitor biodiversity. However, recent comparisons have revealed little congruence between morphological and molecular-based identifications. Using broad range universal primers for DNA barcode marker cox1, we compare community composition captured between morphological and molecular-based approaches from different sources — tissue-based (bulk benthic and bulk drift samples) and environmental DNA (eDNA, filtered water) metabarcoding — for samples collected along a gradient of anthropogenic disturbances. For comparability, metabarcoding taxonomic assignments were filtered by taxa included in the standardised national biological metric IBMWP. At the family level, bulk benthic metabarcoding showed the highest congruence with morphology, and the most abundant taxa were captured by all techniques. Richness captured by morphology and bulk benthic metabarcoding decreased along the gradient, whereas richness recorded by eDNA remained constant and increased downstream when sequencing bulk drift. Estimates of biological metrics were higher using molecular than morphological identification. At species level, diversity captured by bulk benthic samples were higher than the other techniques. Importantly, bulk benthic and eDNA metabarcoding captured different and complementary portions of the community — benthic versus water column, respectively — and their combined use is recommended. While bulk benthic metabarcoding can likely replace morphology using similar benthic biological indices, water eDNA will require new metrics because this technique sequences a different portion of the community.

The extent to which the sequence and timing of important events on Earth have influenced biological evolution through geological time is a matter of ongoing debate. In this context, the phylogenetic history of aquatic insects remains largely elusive, and our understanding of their chronology is fragmentary and incomplete at best. Here, after gathering a comprehensive data matrix of 3125 targeted rRNA and protein -coding gene sequences from nine independent gene portions, we built a well -supported time -calibrated phylogenetic tree comprising almost 1200 genera that represent a large proportion of extant families of dragonflies and damselflies (Odonata), mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera). We reviewed the main evolutionary and historical scenarios for each aquatic insect lineage as revealed by our best -scoring molecular tree topology, major ancient radiations, calibrated divergence estimates, and important events in geological history related to the spatial arrangement of land masses, continental drift, and mass extinctions. Molecular dating using the birth -death model of speciation, with a lognormal -relaxed model of sequence evolution informed by transcriptomic constraints, suggested that (i) dragonflies and damselflies first radiated approximately 220 million years (Ma) ago and most extant lineages thrived independently after the Triassic -Jurassic (Tr -J) extinction event; (ii) mayflies underwent bursts of diversification during the Cretaceous; (iii) ancestral divergence separating the stonefly suborders Arctoperlaria and Antarctoperlaria was consistent with geographical isolation after vicariant fragmentation and tectonic splitting of the supercontinent Pangaea around 170 Ma ago; and (iv) the most recent common ancestors of caddisflies extended back to the time of Pangaea, supporting the earliest offshoot of the 'retreat -making ' Annulipalpia and a sister relationship between the predatory free-living Rhyacophilidae and Hydrobiosidae. Our 'Tree of Life ' of aquatic insects also resolved shallow phylogenetic relationships related to key evolutionary innovations, such as the convergent evolution of exophytic oviposition in dragonflies or the Jurassic origins of the burrowing lifestyle in mayflies. In this study, we also illustrate how our time -calibrated phylogeny can help to integrate phylogenetic aspects in biogeographical and ecological research across the world. To do so, we used three empirical datasets of stream insects from subarctic Finland, northeastern Spain, and southeastern Tibet as exemplary cases. These examples of application tested ecogeographical mechanisms related to (i) the responses of size structural resemblances to phylogenetic constraints, and patterns of (ii) phylogenetic relatedness and (iii) phylogenetic uniqueness along elevational and flow -intermittence gradients, respectively. We emphasise how specific details capturing different aspects of phylogenetic variation are dependent on the geological, geographical, and environmental contexts in different drainage basins. We finally highlight potential venues for future research, including evaluations of geographical patterns of phylogenetic diversity in space and time, evolution of ecological characters in relation to palaeoclimatic variation, and development of complementary algorithms for conservation prioritisation of evolutionarily valuable bioregions for aquatic insects. Overall, we hope that this work will stimulate multidisciplinary research efforts among different areas of the biogeosciences towards safeguarding the phylogenetic heritage of extant aquatic insects across the world.

Temporary rivers, forming the majority of river networks worldwide, are key biodiversity hotspots. Despite their great value for maintaining biodiversity and ecosystem functioning, they are often neglected in biomonitoring programs due to several challenges, such as their variable hydromorphology and the difficulty of establishing reference conditions given their dynamic nature, resulting in highly variable communities. Disconnected pools often form in temporary rivers when flow ceases, providing refuge for aquatic taxa. Given their importance for biodiversity conservation, revising and adapting biotic indices are needed. Here, we evaluate the performance of current biological indices designed for perennial rivers (macroinvertebrates, diatoms) and functional metrics (macroinvertebrates) in assessing biological quality of disconnected pools. We sampled 55 disconnected pools in Catalonia, NE Spain, covering local (e.g., physico-chemical variables, water chemistry) and regional (e.g., human influence, hydrological variables at the water body level) natural and anthropogenic gradients. Only a few macroinvertebrate biotic indices (e.g., family richness, EPT/EPT + OCH and OCH) showed strong responses to anthropogenic predictors and were unaffected by natural predictors at both local and regional scales, making them suitable for biomonitoring. Of the newly adopted functional metrics of macroinvertebrate communities tested, only two (i.e., functional redundancy of predators and response diversity based on the total community) responded strongly to anthropogenic predictors. The rest showed varying responses to the interactive effect of anthropogenic and natural predictors, requiring calibration efforts. Models assessing these metrics explained <40 % of the total variation, likely due to the interplay of colonization/extinction dynamics and density-dependent trophic interactions governing community assemblages in disconnected pools. Although some existing biological metrics could potentially be used to monitor the ecological status of disconnected pools, we call for further development of biomonitoring tools specifically designed for these habitats since they will become more widespread with global change.

Understanding biodiversity patterns is crucial for prioritizing future conservation efforts and reducing the current rates of biodiversity loss. However, a large proportion of species remain undescribed (i.e. unknown biodiversity), hindering our ability to conduct this task. This phenomenon, known as the ‘Linnean shortfall’, is especially relevant in highly diverse, yet endangered, taxonomic groups, such as insects. Here we explore the distributions of recently described freshwater insect species in Europe to (1) infer the potential location of unknown biodiversity hotspots and (2) determine the variables that can anticipate the distribution of unknown biodiversity.

The following database contains information on recently described species of aquatic insects described between 2000 and 2020 in the European continent (including western Russia, Cyprus and Turkey).

Climate change has the potential to modify habitat characteristics and, consequently, induce species responses to ongoing environmental changes. Functional traits determine both if a species can persist and maintain stable population sizes in particular ecological conditions, and its capacity to disperse to more favourable habitats. Given that functional traits evolve over time, one could expect closely related species to show similar responses to climate change, which should identify vulnerable lineages. Alternatively, species‐specific functional traits may anticipate species responses to climate change, and therefore, trait composition should be a strong predictor. We compiled a comprehensive dataset of functional traits of 84 Iberian and Moroccan odonates species and built a phylogenetic tree to determine if dissimilarity of traits and phylogenetic relatedness are relevant to better discriminate species range‐shift responses to climate change. Modelling results for 66 species showed clear impacts of the increase in temperature and drought events on their potential distribution. The traits that best‐discriminated species that expanded their ranges were multivoltinism, short‐life cycles and preference for temporary habitats, whereas species with a reduced and displaced potential distribution were mostly semivoltine, with a short flying season, oviposition on gravel and restricted to permanent streams, small rivers or oligotrophic lakes. Trait conservatism was rejected and phylogenetic relatedness was a poor predictor of range shifts. Considering odonates as model organisms, traits such as voltinism, beginning and prolongation of flight period and preference of temporal habitats should be examined to anticipate range‐shift responses of freshwater insects to climate change.

The use of urban wastewater reclaimed water has recently increased across the globe to restore stream environmental flows and mitigate the effects of water scarcity. Reclaimed water is disinfected using different treatments, but their effects into the receiving rivers are little studied. Physiological bioassays and biomarkers can detect sub-lethal effects on target species, but do not provide information on changes in community structure. In contrast, official monitoring programs use community structure information but often at coarse taxonomic resolution level that may fail to detect species level impacts. Here, we combined commonly used biomonitoring approaches from organism physiology to community species composition to scan a broad range of effects of disinfection of reclaimed water by UV-light only and both UV/chlorine on the biota. We (1) performed bioassays in one laboratory species (water flea Daphnia magna) and measured biomarkers in two wild species (caddisfly Hydropsyche exocellata and the barbel Luciobarbus graellsii), (2) calculated standard indices of biotic quality (IBQ) for diatoms, benthic macroinvertebrates, and fishes, and (3) analysed community species composition of eukaryotes determined by Cytochrome Oxidase C subunit I (cox1) metabarcoding. Only the UV/chlorine treatment caused significant changes in feeding rates of D. magna and reduced antioxidant defenses, increased anaerobic metabolism and altered the levels of lipid peroxidiation in H. exocellata. However, inputs of reclaimed water were significantly associated with a greater proportion of circulating neutrophils and LG-PAS cells in L. graellsii. Despite IBQ did not discriminate between the two water treatments, metabarcoding data detected community composition changes upon exposure to UV/chlorine reclaimed water. Overall, despite the effects of UV/chlorine-treated water were transient, our study suggests that UV-light treated is less harmful for freshwater biota than UV/chlorine-treated reclaimed water, but those effects depend of the organizational level.

ABSTRACT The current rate of species loss calls for immediate actions to preserve biodiversity and ecosystem functioning. Cataloguing species richness and composition, and revealing how diversity is geographically distributed are the first steps towards designing efficient conservation strategies. Here, we aim to determine diversity patterns and potential drivers of taxonomic and genetic diversity and population structure of Iberian spiders. We used a community level perspective, analysing more than 3000 DNA barcode sequences representing ~370 spider species dwelling in white‐oak forest habitats across the Spanish National Park network. By combining and comparing morphological and DNA barcode‐based species delimitation methods, we assessed their performance and identified putative factors behind cases of incongruence. Our findings uncovered potential overlooked diversity as suggested by the geographic patterns of genetic variation and put a red flag on those taxa that may be undergoing overlooked evolutionary or ecological processes. Spider functional traits associated with foraging strategy, microhabitat preference, ballooning ability and circadian activity explained the observed patterns of population structure across species but did not explain variation in genetic diversity. Overall, our study represents a major step forward in the understanding of large‐scale diversity patterns in Iberian spiders at the community level and provides relevant information to guide future conservation strategies of the so‐far largely overlooked invertebrate diversity.

Aim Community assembly processes are difficult to observe in nature but can be inferred from species diversity patterns. However, taxonomic patterns may be consistent with multiple explanations, such as habitat filtering or biogeographical processes, which can also act differently across spatial scales. Here, we assessed multiple facets of diversity to determine the relative contributions of local versus regional processes and historical versus contemporary factors in establishing macroecological patterns. Location From the Mediterranean peninsulas to northern Scandinavia. Time period Species occurrence data gathered since c. 1980. Major organism group studied Trichoptera (Insecta). Methods Based on an extensive functional space and a phylogenetic tree including 197 and 509 species, respectively, and the composition of 180 communities, we assessed the distribution of taxonomic, functional and phylogenetic diversity within 18 ecoregions (local alpha- and beta-diversity) and among those ecoregions (regional gamma- and beta-diversity). Results Local estimates of taxonomic, functional and phylogenetic alpha- and beta-diversity were similar across Europe, which reveals that all streams have similar carrying capacity even though the local abiotic factors involved are likely different among ecoregions. In contrast, regional taxonomic and phylogenetic diversities decreased as latitude increased, whereas functional richness and functional dispersion displayed unimodal relationships. The position of species on the functional space was not conserved, while northern species pools were found to be phylogenetically clustered and southern ones overdispersed. The nestedness component mainly contributed to the taxonomic and phylogenetic beta-diversity among northern communities, whereas in southern latitudes the turnover was dominant. Main conclusions Decoupled latitudinal patterns of taxonomic, phylogenetic and functional diversity reveal the importance of regional environmental filtering over local factors in limiting species range and shaping the regional species pool. The biogeographical signature is still present; the northern recolonizations following the Pleistocene glaciations originated exclusively from central regions, instead of Mediterranean refugia, as was previously accepted.

Aim Assuming genetic variants are selectively neutral, estimates of intraspecific genetic diversity and population structure should increase simultaneously in parallel to coalescent time, population size and gene flow. However, other processes, such as genetic drift associated with demographic fluctuations, might cause a loss of genetic diversity while not affecting population structure. In this study, we assess large-scale patterns of estimates of intraspecific genetic variation across species to determine the roles of dispersal, biogeography, divergence time and demographic fluctuations in decoupling genetic diversity and population structure. Location Pristine first-order streams distributed in seven regions from Neotropical to boreal climate, covering a gradient of habitat persistence through major biogeographical changes (e.g., Pleistocene glaciations). Time period 2008-2010. Major taxa studied Freshwater insect lineages that differ in dispersal propensity. Methods Intraspecific nucleotide diversity (pi) and population structure (phi(ST)) were estimated for 33 species using 2,128 sequences of the cox1 gene. The correlation between pi and phi(ST) was tested using linear regression models. The geographical distribution of haplotypes was represented in networks. Phylogenetic trees were time calibrated to determine divergence time. Results At a global scale, a positive relationship between pi and phi(ST) was found. Neotropical species showed the highest values of pi and phi(ST), probably owing to historical environmental stability. Across Europe, the low estimates of pi and the wide array of phi(ST) values and haplotype networks found across species, lineages and latitude were contrary to the biogeographical and dispersal paradigms. Main conclusions Beyond the macroecological trend found, genetic trajectories of co-distributed temperate species were disassociated from their functional traits and probably caused by persistent demographic fluctuations associated with local-scale habitat instability. Overall, the idiosyncratic relationship between pi and phi(ST) across species prevents the establishment of conclusive global patterns and questions the phylogeographical patterns established when studying a reduced number of co-distributed species.

A fundamental question in macroecology is how contemporary and historical environments, species interactions and evolutionary processes contribute to determining community structure and shape current large-scale taxa distributions. We used a novel perspective simultaneously considering taxonomic, functional, and phylogenetic diversity to elucidate how these factors have shaped regional diversity patterns in composition of Trichoptera (Insecta) at the genus level among 62 mountain stream reaches located across six regions from Morocco to Sweden. The biogeographical range paradigm postulates declining diversity with latitude, but our results showed that taxonomic diversity was unrelated to latitude and local richness was similar in both previously glaciated and unglaciated southern regions. Also, taxonomic beta-diversity across regions was mostly driven by turnover rather than the expected nestedness component. High taxonomic diversity and several indicator genera (i.e. genera characteristic of any specific region) were found in Mediterranean regions, but also in the Carpathians and across central-eastern Europe. Functional traits revealed phylogenetic trait conservatism. Phylogenetic diversity and functional richness did not decrease with latitude. Phylogenetic structure of central and eastern communities was clustered (i.e. communities composed by closely related genera), whereas south-western communities were phylogenetically overdispersed (i.e. less closely related than expected by chance). Overall, latitudinal patterns of taxonomic turnover and variable phylogenetic community structure indicate an important role of contemporary ecological conditions in structuring community composition, probably by environmental filtering. However, the signature of biogeographical history is also relevant to understanding the large-scale distribution of taxa. The permanence of caddisfly communities in temperate regions during Pleistocene glaciations demonstrates the presence of refugia there and, therefore, broadens the spatial extent of refugia beyond Mediterranean areas. This contrasts with theories which placed refugia exclusively in Mediterranean areas.

Temporary rivers, characterized by shifts between flowing water, disconnected pools and dry periods, represent over 50% of the world’s river network and future climatic projections suggest their increase. These rivers are understudied, especially when only disconnected pools remain, because gauging stations or hydrological models do not inform of what happens after the cessation of flow. In addition, most of biological indicators for water quality are designed for flowing waters and their adequacy for temporary rivers is uncertain. The development of biological metrics adequate for the assessment of disconnected pools is difficult, because the high species replacement during and following flow cessation. For this reason, one hydrological variable of paramount importance for the assessment of ecological quality of disconected pools is the time since disconnection from the river flow. The objective of our work is to present a methodology to estimate the time since disconnection of pools from the river flow. This methodology, following the Gonfiantini (1986) model, is based on the sampling of water stable isotopes in disconnected pools. For pools disconnected from the groundwater, knowing the isotopic modification of the water in time due to evaporation, allows to estimate the relative volume of water evaporated since the pool has been disconnected. However, this approach gets complicated when pools have relevant rainfall inputs or exchanges with groundwater. Within the Vallcebre research area (42º12’N and 1º49’E), two artificial pools, one covered with a transparent lid to prevent the input of rainfall and another uncovered, were installed to validate this methodology in controlled conditions. From July to November 2020, water volume of these pools were weekly measured and sampled for isotopic analysis. In parallel, meteorological variables were monitored and rainfall was also sampled for water stable isotopes. To develop and validate an operational methodology for estimating the time since disconnection, we first calculated the relative amount of evaporated water based on the variations of isotopic composition of the covered pool samples, and estimated the time since disconnection (for a given natural pool) using the potential evaporation calculated from the meteorological data. For the uncovered pool, the information of amount and isotopic composition of rainfall was added in a mass balance model. Additionally, the same estimations were calculated with standard information (i.e. the meteorological data obtained from the National Meteorological Service and precipitation isotopes data from the Global Network of Isotopes in Precipitation (GNIP) of the International Atomic Energy Agency). Finally, measured volumes changes in pools, were used to assess the limitations of the operational methodology and the sensitivity of the results to meteorological conditions. Our approach suggests that changes in isotopic composition can be a reliable method to estimate time since disconnection of pools in temporary rivers to better assess their ecological quality.

Urbanisation is driving rapid declines in species richness and abundance worldwide, but the general implications for ecosystem function and services remain poorly understood. Here, we integrate global data on bird communities with comprehensive information on traits associated with ecological processes to show that assemblages in highly urbanised environments have substantially different functional composition and 20% less functional diversity on average than surrounding natural habitats. These changes occur without significant decreases in functional dissimilarity between species; instead, they are caused by a decrease in species richness and abundance evenness, leading to declines in functional redundancy. The reconfiguration and decline of native functional diversity in cities are not compensated by the presence of exotic species but are less severe under moderate levels of urbanisation. Thus, urbanisation has substantial negative impacts on functional diversity, potentially resulting in impaired provision of ecosystem services, but these impacts can be reduced by less intensive urbanisation practices.

Aim To analyse temporal metacommunity dynamics in river networks in relation to hydrological conditions and dispersal. Location Fifteen river reaches from the Llobregat, Besos and Foix catchments in the North-Eastern Iberian Peninsula. Taxon Aquatic macroinvertebrates belonging to 99 different families. Methods We sampled aquatic macroinvertebrate communities during spring in 20 consecutive years. We built two environmental distances (one related with water chemistry and another one with river flow regime) and two spatial distances (network distance and topographic distance). Then we used Mantel tests (accounting for spatial autocorrelation) to relate macroinvertebrate dissimilarity with environmental and spatial distances. Additionally, we determined the dry and wet years using the Standardized Precipitation Index (SPI) and we classified macroinvertebrate families based on their ability to fly and to drift. Finally, we ran a linear regression model including the correlation value (r) of each Mantel test as response variable and distance type (environmental or spatial), SPI, dispersal mode, their pairwise interactions and a three-way interaction as predictor variables. Results Metacommunity organization varied over time and it was significantly affected by precipitation, which can be related to river network connectivity. The environmental filters, mainly the flow regime, were generally more important than the spatial filters in explaining community dissimilarity over the study period. However, this depended on the dispersal abilities of the organisms. Network fragmentation due to flow intermittence during the dry years significantly reduced the dispersal capacity of strong aerial dispersers, leading to spatially structured metacommunities. For strong drift dispersers, community dissimilarity patterns were generally best explained by environmental filters regardless of SPI. Main conclusions A significant temporal variation in metacommunity organization can be expected in highly dynamic systems (e.g. Mediterranean rivers) and it might depend on the dispersal modes and abilities of the organisms, since they determine the response to changes in environmental and landscape filters.

Climate change is predicted to progressively shift habitat characteristics that will alter the distribution and eco‐physiological responses of organisms. High‐elevation stream insects without extensive dispersal are expected to be highly vulnerable if they are unable to track predicted shifts. Understanding dispersal is therefore crucial to implement practical solutions in conservation. The evolutionary history of the Palaearctic genus Annitella (Trichoptera), the population dynamics and habitat distribution (present and future) of two endemic species (A. esparraguera and A. iglesiasi) confined to Baetic Mountains (SE‐Iberian Peninsula) were assessed to gain fundamental insights into species responses to climate warming and to identify populations at risk. Diversification of Annitella was dated to the Pleistocene and was likely associated with southern and extra‐Mediterranean refugia located across Europe. The two endemic species belong to distant lineages that preferred similar cold headwater pristine habitats. The range of A. esparraguera was larger than that of A. iglesiasi. Both species showed low genetic diversity in cox1, but only A. esparraguera exhibit locally unique haplotypes, indicating limited gene flow. For A. esparraguera, modelled future habitat suitability showed 88.4% range contraction by 2050 (RCP scenario 8.5) and a displacement of 41.5% of the current potential distribution to higher elevations. Populations of A. esparraguera are predicted to be lost because of the reduction of optimal habitat and limited propensity for tracking future suitable conditions. Beyond the preservation of their current habitat, their conservation might require proactive measures (translocations). Similar predictions may apply to other Mediterranean endemic headwater specialist restricted to isolated high‐elevation streams.