Browsing by Subject "biotic communities"

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  • Camarena‐Gómez, María Teresa; Ruiz‐González, Clara; Piiparinen, Jonna; Lipsewers, Tobias; Sobrino, Cristina; Logares, Ramiro; Spilling, Kristian (American Society of Limnology and Oceanography, 2021)
    Limnology and Oceanography 66: 1, 255-271
    In parts of the Baltic Sea, the phytoplankton spring bloom communities, commonly dominated by diatoms, are shifting toward the co-occurrence of diatoms and dinoflagellates. Although phytoplankton are known to shape the composition and function of associated bacterioplankton communities, the potential bacterial responses to such a decrease of diatoms are unknown. Here we explored the changes in bacterial communities and heterotrophic production during the spring bloom in four consecutive spring blooms across several sub-basins of the Baltic Sea and related them to changes in environmental variables and in phytoplankton community structure. The taxonomic structure of bacterioplankton assemblages was partially explained by salinity and temperature but also linked to the phytoplankton community. Higher carbon biomass of the diatoms Achnanthes taeniata, Skeletonema marinoi, Thalassiosira levanderi, and Chaetoceros spp. was associated with more diverse bacterial communities dominated by copiotrophic bacteria (Flavobacteriia, Gammaproteobacteria, and Betaproteobacteria) and higher bacterial production. During dinoflagellate dominance, bacterial production was low and bacterial communities were dominated by Alphaproteobacteria, mainly SAR11. Our results suggest that increases in dinoflagellate abundance during the spring bloom will largely affect the structuring and functioning of the associated bacterial communities. This could decrease pelagic remineralization of organic matter and possibly affect the bacterial grazers communities.
  • García-Girón, Jorge; Heino, Jani; García-Criado, Francisco; Fernández-Aláez, Camino; Alahuhta, Janne (Wiley Online Library, 2020)
    Ecography 43 8 (2020)
    Biotic interactions are fundamental drivers governing biodiversity locally, yet their effects on geographical variation in community composition (i.e. incidence-based) and community structure (i.e. abundance-based) at regional scales remain controversial. Ecologists have only recently started to integrate different types of biotic interactions into community assembly in a spatial context, a theme that merits further empirical quantification. Here, we applied partial correlation networks to infer the strength of spatial dependencies between pairs of organismal groups and mapped the imprints of biotic interactions on the assembly of pond metacommunities. To do this, we used a comprehensive empirical dataset from Mediterranean landscapes and adopted the perspective that community assembly is best represented as a network of interacting organismal groups. Our results revealed that the co-variation among the beta diversities of multiple organismal groups is primarily driven by biotic interactions and, to a lesser extent, by the abiotic environment. These results suggest that ignoring biotic interactions may undermine our understanding of assembly mechanisms in spatially extensive areas and decrease the accuracy and performance of predictive models. We further found strong spatial dependencies in our analyses which can be interpreted as functional relationships among several pairs of organismal groups (e.g. macrophytes–macroinvertebrates, fish–zooplankton). Perhaps more importantly, our results support the notion that biotic interactions make crucial contributions to the species sorting paradigm of metacommunity theory and raise the question of whether these biologically-driven signals have been equally underappreciated in other aquatic and terrestrial ecosystems. Although more research is still required to empirically capture the importance of biotic interactions across ecosystems and at different spatial resolutions and extents, our findings may allow decision makers to better foresee the main consequences of human-driven impacts on inland waters, particularly those associated with the addition or removal of key species.
  • Niittynen, Pekka; Heikkinen, Risto K.; Luoto, Miska (2020)
    Proceedings of the National Academy of Sciences of the United States of America 117: 35, 21480-21487
    The Arctic is one of the least human-impacted parts of the world, but, in turn, tundra biome is facing the most rapid climate change on Earth. These perturbations may cause major reshuffling of Arctic species compositions and functional trait profiles and diversity, thereby affecting ecosystem processes of the whole tundra region. Earlier research has detected important drivers of the change in plant functional traits under warming climate, but studies on one key factor, snow cover, are almost totally lacking. Here we integrate plot-scale vegetation data with detailed climate and snow information using machine learning methods to model the responsiveness of tundra communities to different scenarios of warming and snow cover duration. Our results show that decreasing snow cover, together with warming temperatures, can substantially modify biotic communities and their trait compositions, with future plant communities projected to be occupied by taller plants with larger leaves and faster resource acquisition strategies. As another finding, we show that, while the local functional diversity may increase, simultaneous biotic homogenization across tundra communities is likely to occur. The manifestation of climate warming on tundra vegetation is highly dependent on the evolution of snow conditions. Given this, realistic assessments of future ecosystem functioning require acknowledging the role of snow in tundra vegetation models.
  • Li, Zhengfei; Wang, Jun; Liu, Zhenyuan; Meng, Xingliang; Heino, Jani; Jiang, Xuankong; Xiong, Xiong; Jiang, Xiaoming; Xie, Zhicai (2019)
    Science of the Total Environment 655:1288-1300
    Examining the relative contribution of local environmental stressors and regional factors in structuring biological communities is essential for biodiversity conservation and environmental assessment, yet their relative roles for different community characterizations remain elusive. Here, we examined the responses of taxonomic and functional structures of stream macroinvertebrate communities to local and regional factors across a human-induced environmental gradient in the Han River Basin, one subtropical biodiversity hotspot in China. Our objectives were: 1) to examine the responses of traditional taxonomic measures and functional traits to anthropogenic disturbances; 2) to compare the relative importance of environmental versus spatial variables and catchment-scale versus reach-scale variables for the two community characterizations. We found that both species and trait compositions performed well in differentiating anthropogenic disturbances, indicating that both taxonomic and functional structures of macroinvertebrate communities were strongly altered by human activities. Particularly, some traits related to life history (e.g., voltinism), resilience and resistance (e.g., adult flying ability) are well suited for predicting changes of communities towards anthropogenic disturbances owing to their mechanistic relationship with environmental gradients. We found that environmental variables played more important roles than spatial effects in structuring both taxonomic and functional facets of macroinvertebrate communities. Environmental filtering was more important in determining functional than taxonomic structure, and the opposite was true for spatial effects. In terms of environmental variables, catchment land-uses played the primary role in determining taxonomic composition, whereas reach-scale variables related to local habitat heterogeneity were more influential for functional structure. Our study highlights the importance of employing metacommunity perspectives and different community characterizations in both theoretical and applied research. For stream bioassessment and management, we argue that the combination of taxonomic and functional characterizations of community should be implemented, as different facets of biological communities responded to different types of anthropogenic disturbances.
  • Li, Zhengfei; Wang, Jun; Meng, Xingliang; Heino, Jani; Sun, Meiqin; Jiang, Xiaoming; Xie, Zhicai (2019)
    Freshwater Science 38 (1): 170-182
    Disentangling the effects of dispersal mode on the environmental and spatial processes structuring biological assemblages is essential to understanding the mechanisms of species coexistence and maintenance. Here, we use field investigations to link dispersal mode with environmental and spatial processes that control stream macroinvertebrate assemblage structure across the Yarlung Zangbo Grand Canyon of Tibet (Tibetan Plateau). We sampled macroinvertebrates in streams that occur in 4 distinct regions. Each of these regions has a steep elevational gradient but different altitude ranges, climate types, and water replenishment sources. We classified macroinvertebrate taxa into passive and active dispersal mode groups to test whether macroinvertebrates with different dispersal modes responded differently to environmental and spatial processes. Our results showed that the assemblage structure of active dispersal groups was more strongly determined by environmental variables (habitat filtering/species sorting) than spatial factors both within and across regions. In contrast, the structure of passive dispersers was more strongly associated with spatial factors than environmental filtering in the entire study area and within lower canyon regions. However, spatial effects were not important for either type of dispersal group in the upper canyon regions, especially in the region with glacier-fed streams, indicating the predominance of species sorting processes in these harsh environments. Furthermore, the spatial structuring of assemblages became stronger as habitat filtering declined, which indicates a reduction in species sorting processes in less harsh environments. Our findings demonstrate diverse responses of macroinvertebrate assemblages to environmental and spatial processes across this poorly-known highland river system, and imply that dispersal mode influences the underlying mechanisms of community variation.
  • Tolonen, Kimmo T.; Karjalainen, Juha; Hämäläinen, Heikki; Nyholm, Kristiina; Rahkola-Sorsa, Minna; Cai, Yongjiu; Heino, Jani (Springer Link, 2020)
    Aquatic Ecology 54 3 (2020)
    Lake littoral environments are heterogeneous, and different organisms typically show specific responses to this environmental variation. We examined local environmental and spatial factors affecting lake littoral biodiversity and the structuring of assemblages of phytoplankton, zooplankton and macroinvertebrates within and among three basins of a large lake system. We explored congruence of species composition and species richness among the studied organism groups to evaluate their general indicator potential to represent spatial variation in other groups. We expected that effects of water chemistry on plankton assemblages were stronger than effects of habitat characteristics. In contrast, we anticipated stronger effects of habitat on macroinvertebrates due to their mainly benthic mode of life. We also expected that within-basin spatial effects would be strongest on macroinvertebrates and weakest on phytoplankton. We predicted weak congruence in assemblage composition and species richness among the organism groups. Phytoplankton assemblages were mainly structured by the shared effects of water chemistry and large-scale spatial factors. In contrast to our expectations, habitat effects were stronger than water chemistry effects on zooplankton assemblages. However, as expected, macroinvertebrate species composition and richness were mainly affected by habitat conditions. Among-group congruence was weak for assemblage composition and insignificant for richness. Albeit weak, congruence was strongest between phytoplankton and zooplankton assemblages, as we expected. In summary, our analyses do not support the idea of using a single organism group as a wholesale biodiversity indicator.
  • Brittain, John E.; Heino, Jani; Friberg, Nikolai; Aroviita, Jukka; Kahlert, Maria; Karjalainen, Satu‐Maaria; Keck, François; Lento, Jennifer; Liljaniemi, Petri; Mykrä, Heikki; Schneider, Susanne C.; Ylikörkkö, Jukka (Blackwell Scientific, 2022)
    Freshwater Biology
    1. Arctic freshwaters support biota adapted to the harsh conditions at these latitudes, but the climate is changing rapidly and so are the underlying environmental filters. Currently, we have limited understanding of broad-scale patterns of Arctic riverine biodiversity and the correlates of α- and β-diversity. 2. Using information from a database set up within the scope of the Arctic Council's Conservation of Arctic Flora and Fauna Circumpolar Biodiversity Monitoring Plan, we analysed patterns and correlates of α- and β-diversity in benthic diatom and macroinvertebrate communities across northern Norway, Sweden, and Finland. We analysed variation in total β-diversity and its replacement and richness difference components in relation to location of the river reach and its drainage basin (Baltic Sea in the south, the Barents Sea in the east and the north, and the Norwegian Sea in the west), in addition to climate and environmental variables. 3. In both macroinvertebrates and diatoms, the replacement and richness difference components showed wide variation. For macroinvertebrates, the richness difference component was the more important, whereas for diatoms, the replacement component was the more important in contributing to variation in β-diversity. There was no significant difference in β-diversity between the three main drainage basins, but species composition differed among the drainage basins. 4. Based on the richness difference component of β-diversity, climate variables were most strongly associated with community variation in macroinvertebrates. In diatoms, both environmental and climate variables were strongly correlated with community compositional variation. In both groups, there were also significant differences in α-diversity among the three main drainage basins, and several taxa were significant indicators of one of these drainage basins. Alpha diversity was greater in areas with a continental climate, while the oceanic areas in the west harboured greatly reduced flora and fauna. 5. The correlates of biodiversity were relatively similar in macroinvertebrates and diatoms. Climate variables, in particular temperature, were the most strongly associated with biodiversity patterns in the Arctic rivers of Fennoscandia. Sedimentary geology may be associated with increased productivity and, to a lesser extent, with sensitivity to acidification. There was considerable variation in community composition across Arctic Fennoscandia, indicating the necessity of protecting several stream reaches or even whole catchments within each region to conserve total riverine biodiversity. Furthermore, it is likely that the predicted changes in temperature in Arctic areas will influence riverine diversity patterns across Fennoscandia.
  • Vilmi, A.; Zhao, W.; Picazo, F.; Li, M.; Heino, J.; Soininen, J.; Wang, J. (2019)
    Science of the Total Environment 702: 134974
    Understanding the role of climatic variation on biodiversity is of chief importance due to the ongoing biodiversity loss and climate change. Freshwaters, one of the most threatened ecosystems in the world, offer a valuable context to study biodiversity patterns of distinct organism groups in relation to climatic variation. In the Tibetan Plateau biodiversity hotspot - Hengduan Mountain region, we studied the effects of climate and local physico-chemical factors on stream microorganisms (i.e. bacteria) and macroorganisms (i.e. macroinvertebrates) in two parallel catchments with contrasting precipitation and temperature, that is, the Nujiang and Lancang Rivers. Diversities and community structures were better explained by climatic and local environmental variables in the drier and colder catchment and at higher elevations, than in the warmer and wetter conditions and at lower elevations. This suggests that communities may be more strongly assembled by deterministic processes in the former, comparatively harsher conditions, compared to the latter, more benign conditions. Macroinvertebrates were more strongly affected by climatic and local environmental factors compared to bacteria, but the diversities and community structures of the two groups showed spatially similar responses to overall abiotic variation, being especially evident with their community structures' responses to climate. Furthermore, bacterial and macroinvertebrate diversities were positively correlated in the drier and colder catchment, implying that these biologically and ecologically distinct organism groups are likely to be driven by similar processes in areas with such climatic conditions. We conclude that changes in climatic and local environmental conditions may affect the diversity of macroorganisms more strongly than that of microorganisms, at least in subtropical mountainous stream ecosystems studied here, but simultaneous responses of both groups to environmental changes can also be expected.
  • da Silva, Pedro Giovâni; Cañedo-Argüelles, Miguel; Bogoni, Juliano André; Heino, Jani (Frontiers Media S.A., 2021)
    Frontiers in Ecology and Evolution 9: 670212
    According to metacommunity theory (Leibold et al., 2004), the structure of local communities results from the interplay between local factors (e.g., environmental filtering, species interactions) and regional factors (e.g., dispersal rates, landscape configuration). The relative importance of these factors is highly dependent on the organisms’ biological traits, landscape connectivity, and the spatial and temporal scales considered (Heino et al., 2015; Tonkin et al., 2018; Viana and Chase, 2019; Almeida-Gomes et al., 2020; Cañedo-Argüelles et al., 2020; Lansac-Tôha et al., 2021). However, the differences in metacommunity assembly mechanisms found among studies are far from being fully understood. The evaluation of temporal dynamics of metacommunities has only emerged recently (Cañedo-Argüelles et al., 2020; Jabot et al., 2020; Li et al., 2020; Lindholm et al., 2021) and the application of the metacommunity theory in other fields, such as biomonitoring, conservation biology or ecosystem restoration, is yet to be fully explored (Bengtsson, 2010; Heino, 2013; Leibold and Chase, 2018; Chase et al., 2020; Cid et al., 2020; Heino et al., 2021). In this Research Topic, our aim was to invite researchers working in different biogeographic regions and ecological systems (Figure 1) to publish a number of innovative papers on metacommunity spatio-temporal dynamics. We expect to obtain a better understanding of how the factors and processes that structure metacommunities vary in space and time, as well as the implications of such dynamics for biodiversity conservation and ecosystem management.
  • Hill, Matthew J.; Heino, Jani; White, James C.; Ryves, David B.; Wood, Paul J. (2019)
    Biological Conservation 237: 348-357
    Understanding the spatial patterns and environmental drivers of freshwater diversity and community structure is a key challenge in biogeography and conservation biology. However, previous studies have focussed primarily on taxonomic diversity and have largely ignored the phylogenetic and functional facets resulting in an incomplete understanding of the community assembly. Here, we examine the influence of local environmental, hydrological proximity effects, land-use type and spatial structuring on taxonomic, functional and phylogenetic (using taxonomic relatedness as a proxy) alpha and beta diversity (including the turnover and nestedness-resultant components) of pond macroinvertebrate communities. Ninety-five ponds across urban and non-urban land-uses in Leicestershire, UK were examined. Functional and phylogenetic alpha diversity were negatively correlated with species richness. At the alpha scale, functional diversity and taxonomic richness were primarily determined by local environmental factors while phylogenetic alpha diversity was driven by spatial factors. Compositional variation (beta diversity) of the different facets and components of functional and phylogenetic diversity were largely determined by local environmental variables. Pond surface area, dry phase length and macrophyte cover were consistently important predictors of the different facets and components of alpha and beta diversity. Our results suggest that pond management activities aimed at improving biodiversity should focus on improving and/or restoring local environmental conditions. Quantifying alpha and beta diversity of the different biodiversity facets facilitates a more accurate assessment of patterns in diversity and community structure. Integrating taxonomic, phylogenetic and functional diversity into conservation strategies will increase their efficiency and effectiveness, and maximise biodiversity protection in human-modified landscapes.
  • Jyväsjärvi, Jussi; Lehosmaa, Kaisa; Aroviita, Jukka; Turunen, Jarno; Rajakallio, Maria; Marttila, Hannu; Tolkkinen, Mikko; Mykrä, Heikki; Muotka, Timo (Elsevier, 2021)
    Ecological Indicators 121 (2021), 106986
    Degradation of freshwater ecosystems requires efficient tools for assessing the ecological status of freshwater biota and identifying potential cause(s) for their biological degradation. While diatoms and macroinvertebrates are widely used in stream bioassessment, the potential utility of microbial communities has not been fully harnessed. Using data from 113 Finnish streams, we assessed the performance of aquatic leaf-associated fungal decomposers, relative to benthic macroinvertebrates and diatoms, in modelling-based bioassessment. We built multi-taxon niche -type predictive models for fungal assemblages by using genus-based and sequence-based identification levels. We then compared the models’ precision and accuracy in the prediction of reference conditions (number of native taxa) to corresponding models for macroinvertebrates and diatoms. Genus-based fungal model nearly equalled the accuracy and precision of our best model (macroinvertebrates), whereas the sequence-based model was less accurate and tended to overestimate the number of taxa. However, when the models were applied to streams disturbed by anthropogenic stressors (nutrient enrichment, sedimentation and acidification), alone or in combination, the sequence-based fungal assemblages were more sensitive than other taxonomic groups, especially when multiple stressors were present. Microbial leaf decomposition rates were elevated in sediment-stressed streams whereas decomposition attributable to leaf-shredding macroinvertebrates was accelerated by nutrients and decelerated by sedimentation. Comparison of leaf decomposition results to model output suggested that leaf decomposition rates do not detect effectively the presence of multiple simultaneous disturbances. The rapid development of global microbial database may soon enable species-level identification of leaf-associated fungi, facilitating a more precise and accurate modelling of reference conditions in streams using fungal communities. This development, combined with the sensitivity of aquatic fungi in detecting the presence of multiple human disturbances, makes leaf-associated fungal assemblages an indispensable addition in a stream ecologist’s toolbox.
  • Fourcade, Yoan; WallisDeVries, Michiel F.; Kuussaari, Mikko; Swaay, Chris A. M.; Heliölä, Janne; Öckinger, Erik (John Wiley & Sons Ltd, 2021)
    Ecology Letters 24: 5, 950-957
    Habitat fragmentation may present a major impediment to species range shifts caused by climate change, but how it affects local community dynamics in a changing climate has so far not been adequately investigated empirically. Using long-term monitoring data of butterfly assemblages, we tested the effects of the amount and distribution of semi-natural habitat (SNH), moderated by species traits, on climate-driven species turnover. We found that spatially dispersed SNH favoured the colonisation of warm-adapted and mobile species. In contrast, extinction risk of cold-adapted species increased in dispersed (as opposed to aggregated) habitats and when the amount of SNH was low. Strengthening habitat networks by maintaining or creating stepping-stone patches could thus allow warm-adapted species to expand their range, while increasing the area of natural habitat and its spatial cohesion may be important to aid the local persistence of species threatened by a warming climate.
  • Truchy, Amélie; Sarremejane, Romain; Muotka, Timo; Mykrä, Heikki; Angeler, David G.; Lehosmaa, Kaisa; Huusko, Ari; Johnson, Richard K.; Sponseller, Ryan A.; McKie, Brendan G. (Wiley, 2020)
    Global Change Biology 26 6 (2020)
    Ongoing climate change is increasing the occurrence and intensity of drought episodes worldwide, including in boreal regions not previously regarded as drought prone, and where the impacts of drought remain poorly understood. Ecological connectivity is one factor that might influence community structure and ecosystem functioning post-drought, by facilitating the recovery of sensitive species via dispersal at both local (e.g. a nearby habitat patch) and regional (from other systems within the same region) scales. In an outdoor mesocosm experiment, we investigated how impacts of drought on boreal stream ecosystems are altered by the spatial arrangement of local habitat patches within stream channels, and variation in ecological connectivity with a regional species pool. We measured basal ecosystem processes underlying carbon and nutrient cycling: (a) algal biomass accrual; (b) microbial respiration; and (c) decomposition of organic matter, and sampled communities of aquatic fungi and benthic invertebrates. An 8-day drought event had strong impacts on both community structure and ecosystem functioning, including algal accrual, leaf decomposition and microbial respiration, with many of these impacts persisting even after water levels had been restored for 3.5 weeks. Enhanced connectivity with the regional species pool and increased aggregation of habitat patches also affected multiple response variables, especially those associated with microbes, and in some cases reduced the effects of drought to a small extent. This indicates that spatial processes might play a role in the resilience of communities and ecosystem functioning, given enough time. These effects were however insufficient to facilitate significant recovery in algal growth before seasonal dieback began in autumn. The limited resilience of ecosystem functioning in our experiment suggests that even short-term droughts can have extended consequences for stream ecosystems in the world's vast boreal region, and especially on the ecosystem processes and services mediated by algal biofilms.
  • Cai, Yongjiu; Zhang, You; Hu, Zhixin; Deng, Jianming; Qin, Boqiang; Yin, Hongbin; Wang, Xiaolong; Gong, Zhijun; Heino, Jani (2019)
    Ecological Indicators 103: 713-721
    Metacommunity theory emphasizes that local communities are jointly affected by environmental filtering and spatial processes. However, the roles of spatial processes are often given insufficient attention in bioassessment practices, which may bias the assessments of ecological status based on biotic metrics. Here, we quantified the relative importance and the seasonal stability of spatial processes, natural conditions and human-induced factors in structuring variation in different bioassessment metrics based on macroinvertebrate communities. Our study systems were two extensively sampled large and shallow lakes with strong nutrient gradients related to human disturbance. The roles of different drivers were examined for three kinds of indicators: general diversity, trait-based and taxonomic distinctness metrics, and their performance in characterizing human disturbance was evaluated. Overall, human-induced and spatial factors were all important in explaining variation in the three types of bioassessment metrics. Contrary to our expectations, however, we found that the importance of spatial processes on bioassessment metrics can be comparable to the effects of local environmental conditions at the within-lake scale. Furthermore, the results showed substantial seasonal variability in the relative roles of different drivers, which might be linked to life-cycle seasonality of macroinvertebrates. As expected, trait-based metrics generally were best associated with human-induced variables in both lakes, whereas general diversity and taxonomic distinctness metrics performed poorly. The low effectiveness of taxonomic distinctness metrics might due to low species richness associated with high nutrient levels. To conclude, our results suggest that bioassessment cannot exclusively rely on the idea of environmental filtering even if we focus on fine spatial scales. We hence strongly urge that spatial processes, natural drivers and temporal variability should be better considered in combination in the development and application of bioassessment approaches. In addition, taxonomic distinctness measures should be used with caution, especially for the ecosystems and organism groups typically characterized by low species richness.
  • Zhang, You; Cheng, Long; Li, Kuanyi; Zhang, Lu; Cai, Yongjiu; Wang, Xiaolong; Heino, Jani (2019)
    Limnology and Oceanography 64 (3): 1047-1058
    Eutrophication alters the trophic dynamics in lakes and may result in biotic homogenization. How nutrient enrichment drives patterns of taxonomic and functional (i.e., trait‐based) homogenization of macroinvertebrate assemblages at within‐lake (local) and among‐lake (regional) scales is, however, not well understood. Taxonomic and functional compositions of macroinvertebrate assemblages in 41 lakes of the middle and lower reaches of the Yangtze River and Huaihe River were analyzed at within‐lake and among‐lake scales. Our results indicated that there was a significant difference in macroinvertebrate assemblages among lakes under different trophic status, and that total phosphorus was the major environmental factor that regulated both taxonomic and functional beta diversity of macroinvertebrate assemblages. That the abundances of pollution‐tolerant species (e.g., Limnodrilus hoffmeisteri and Microchironomus tabarui) increased with trophic state contributed the most to among‐lake dissimilarity. Functional beta diversity was significantly positively correlated with taxonomic beta diversity, while functional beta diversity was on average lower than taxonomic beta diversity. A combination of univariate and multivariate techniques revealed that nutrient enrichment homogenized taxonomic and functional diversity of benthic macroinvertebrate assemblages in shallow lakes at within‐lake and among‐lake scales, and that there was an overall trend toward taxonomic homogenization that exceeded the trend of functional homogenization. Thus, taxonomic and functional compositions should be considered simultaneously to improve understanding of the response of aquatic communities to anthropogenic disturbance, as the loss and gain of species may be influenced by species‐specific features, and functional composition may exhibit a relatively high correspondence with changes in environmental conditions.
  • García-Girón, Jorge; Heino, Jani; Iversen, Lars Lønsmann; Helm, Aveliina; Alahuhta, Janne (Elsevier, 2021)
    Science of The Total Environment 786 (2021), 147491
    Patterns of species rarity have long fascinated ecologists, yet most of what we know about the natural world stems from studies of common species. A large proportion of freshwater plant species has small range sizes and are therefore considered rare. However, little is known about the mechanisms and geographical distribution of rarity in the aquatic realm and to what extent diversity of rare species in freshwater plants follows their terrestrial counterparts. Here, we present the first in–depth analysis of geographical patterns, potential deterministic ecogeographical factors and projected scenarios of freshwater vascular plant rarity using 50 × 50 km grid cells across Europe (41°N–71°N) and North America (25°N–78°N). Our results suggest that diversity of rare species shows different patterns in relation to latitude on the two continents, and that hotspots of rarity concentrate in a relatively small proportion of the European and North American land surface, especially in mountainous as well as in climatically rare and stable areas. Interestingly, we found no differences among alternative rarity definitions and measures when delineating areas with notably high diversity of rare species. Our findings also indicate that few variables, namely a combination of current climate, Late Quaternary climate–change velocity and human footprint, are able to accurately predict the location of continental centers of rare species diversity. However, these relationships are not geographically homogeneous, and the underlying factors likely act synergistically. Perhaps more importantly, we provide empirical evidence that current centers of rare species diversity are characterized by higher anthropogenic impacts and might shrink disproportionately within this century as the climate changes. Our reported distributional patterns of species rarity align with the known trends in species richness of other freshwater organisms and may help conservation planners make informed decisions mitigating the effects of climate change and other anthropogenic impacts on biodiversity.
  • Benito, Xavier; Vilmi, Annika; Luethje, Melina; Carrevedo, Maria Laura; Lindholm, Marja; Fritz, Sherilyn C. (Frontiers Media S.A., 2020)
    Frontiers Ecology Evolution 8 (2020)
    High-elevation tropical lakes are excellent sentinels of global change impacts, such as climate warming, land-use change, and atmospheric deposition. These effects are often correlated with temporal and spatial beta diversity patterns, with some local communities contributing more than others, a phenomenon known as local contribution to beta diversity (LCBD) or ecological uniqueness. Microorganisms, such as diatoms, are considered whole-ecosystem indicators, but little is known about their sensitivity and specificity in beta diversity studies mostly because of the lack of large spatial and temporal datasets. To fill this gap, we used a tropical South American diatom database comprising modern (144 lakes) and paleolimnological (6 sediment cores) observations to quantify drivers of spatial and temporal beta diversity and evaluated implications for environmental change and regional biodiversity. We used methods of beta diversity partitioning (replacement and richness components) by determining contributions of local sites to these components (LCBDrepl and LCBDrich), and studied how they are related to environmental, geological, and historical human variables using Generalized Additive Models (GAM). Beta replacement time series were also analyzed with GAM to test whether there is widespread biotic homogenization across the tropical Andes. Modern lake ecological uniqueness was jointly explained by limnological (pH), climatic (mean annual precipitation), and historical human density. Local lake (conductivity) and regional geodiversity variables (terrain ruggedness, soil variability) were inversely correlated to replacement and richness components of LCBD, suggesting that not all lakes contributing to broad-scale diversity are targets for conservation actions. Over millennial time scales, decomposing temporal trends of beta diversity components showed different trajectories of lake diatom diversity as response of environmental change: i) increased hydroclimatic variability (as inferred by decreased temperature seasonality) mediating higher contribution of richness to local beta diversity patterns ca. 1000 years ago in Ecuador Andean lakes and ii) lake-specific temporal beta diversity trends for the last ca. 200 years, indicating that biotic homogenization is not widespread across the tropical Andes. Our approach for unifying diatom ecology, metacommunity, and paleolimnology can facilitate the understanding of future responses of tropical Andean lakes to global change impacts.
  • Roa-Fuentes, Camilo A.; Heino, Jani; Cianciaruso, Marcus V.; Ferraz, Silvio; Zeni, Jaquelini O.; Casatti, Lilian (2019)
    Freshwater Biology (2019) 64 (3): 447-460
    A multi‐faceted assessment of diversity is needed to improve our understanding of the mechanisms underlying biodiversity patterns and to reveal the impacts of land use alterations on β‐diversity. In this study, we analysed stream fish β‐diversity based on taxonomic, functional, and phylogenetic facets in an intensively cultivated tropical region. We sampled 43 stream reaches in the northwest of São Paulo State, south‐eastern Brazil. Each sampling site was characterised according to catchment‐scale features, landscape dynamic indicators, local‐scale features, and distance between stream reaches as network distance (a proxy for dispersal processes). As response variables, we considered taxonomic, functional, and phylogenetic β‐diversities coupled with a null‐model approach. For each β‐diversity metric, we calculated the mean overall value and tested whether the mean value was different from that expected by chance. To examine variation in β‐diversity for the three facets and determine the relative contributions of predictor variables, we used a distance‐based approach. Taxonomic and functional β‐diversities were higher from the expected value under a null model, suggesting that community assembly of these facets was dominated by deterministic processes. In contrast, phylogenetic β‐diversity was not different from that expected by chance, suggesting that the lineage composition of these assemblages was random. Furthermore, for all three facets, there was a positive environment‐β‐diversity relationship that was determined primarily by local‐scale features, whereas catchment features and landscape dynamic indicators were not important. In addition, none of the β‐diversity facets was correlated with stream network distance, indicating that dispersal processes were not strongly structuring fish assemblages. Our study suggested that although multiple facets of stream fish β‐diversity are ruled mainly by deterministic processes (e.g. species sorting), stochasticity is also important in community assembly. An interesting finding was the mismatch between phylogenetic versus taxonomic and functional β‐diversity. It is likely that the lack of non‐random structure in phylogenetic β‐diversity is due to the variation of phylogenetic signal in some functional traits. Given that landscape dynamic indicators were not correlated with measures of β‐diversity, we suggest that the recent sugarcane expansion in our study area probably has not critically affected stream fish β‐diversity. Also, it is possible that catchment variables presented little variability and did not overwhelm the effect of local environmental variables on β‐diversity. In conclusion, our study suggests that even highly disturbed tropical agroecosystems with a pool of species that is probably decimated, can still display a relatively high β‐diversity determined mainly by species sorting. These findings suggest key environmental features that must be considered in restoration or conservation of β‐diversity in agroecosystems. Specifically, since variation in β‐diversity was explained mainly by local‐scale environmental gradients, conservation schemes would ideally protect enough sites to capture this entire gradient. Overall, the knowledge of multiple facets can foment more effective conservation and restoration actions by providing a more comprehensive view of the structuring factors of assemblages.
  • Blanka, Gál; Szivák, ldikó; Heino, Jani; Schmera, Dénes (2019)
    Ecological Indicators 104: 357-364
    Understanding the effects of urbanization on the diversity of freshwater macroinvertebrates is an important topic of biodiversity research and has direct conservation relevance. The absence of evidence-based systematic overviews on this topic motivated us to perform meta-analyses and to synthetize the present state of knowledge. We observed significant heterogeneity among individual case studies, reporting negative, neutral and positive effects. As expected, urbanization had an overall negative effect on the diversity of freshwater macroinvertebrates. These results are based mainly on the study of lotic (stream and river) ecosystems because there are insufficient data available for lentic (pond and lake) ecosystems. Compared to individual case studies, the present review reports an evidence-based synthesis for the first time. We identified knowledge gaps regarding case studies reporting the effects of urbanization on pond and lake ecosystems, case studies examining the phylogenetic and functional facets of biodiversity, as well case studies investigating the effect of urbanization on the beta diversity component of macroinvertebrate communities. The identification of these knowledge gaps allowed us to make recommendations for future research: (1) report results on specific taxonomic groups and not only the entire macroinvertebrate community, (2) study the impacts of urbanization on macroinvertebrate diversity in different habitat types and understudied continents, (3) focus on the functional and phylogenetic facets of diversity and (4) examine community differentiation (e.g. beta diversity) in urban freshwater ecosystems. Our results also suggested that the analysis of diversity- environment relationships is crucial for developing macroinvertebrate indicators especially in the increasingly urbanized world.
  • Jiang, Xiaoming; Pan, Baozhu; Jiang, Wanxiang; Hou, Yiming; Yang, Haiqiang; Zhu, Penghui; Heino, Jani (Elsevier, 2021)
    Ecological Indicators 124 (2021), 107407
    There is a growing recognition that examining patterns of ecological communities and their underlying determinants is not only feasible based on taxonomic data, but also functional and phylogenetic approaches. This is because these additional facets can enhance the understanding of the relative contribution of multiple processes in shaping biodiversity. However, few studies have focused on multifaceted beta diversities in lotic macroinvertebrates, especially when considering driving factors operating at multiple spatial scales. Here, we examined the spatial patterns of multi-faceted (i.e., taxonomic, functional and phylogenetic) beta diversity and their components (i.e., turnover and nestedness) of macroinvertebrates in 50 sites in 10 streams situated in the north and south slope of the Qinling Mountains, the geographical dividing line of Northern and Southern China. We found that the streams draining the north slope showed significantly lower values of beta diversity based on all three facets than the streams draining the south slope. Such north-to-south increases of beta diversity were caused by the distinct climatic and local environmental conditions between the sides of the mountain range. Moreover, spatial variables generally played the most important role in structuring all facets and components of beta diversity, followed by local environmental and climatic variables, whereas catchment variables were less important. Despite the similar results of relative contribution of explanatory variables on each beta diversity facet, the details of community-environment relationships (e.g., important explanatory variables and explanatory power) were distinct among different diversity facets and their components. In conclusion, measuring functional and phylogenetic beta diversity provides complementary information to traditional taxonomic approach. Therefore, an integrative approach embracing multiple facets of diversity can better reveal the mechanisms shaping biodiversity, which is essential in assessing and valuing aquatic ecosystems for biodiversity management and conservation.