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Aim: Understanding the distance–decay relationship (DDR) has been considered important because it reflects a combination of several ecological processes such as dispersal limitation and environmental sorting. However, effects of human disturbances on DDR are poorly known, especially in freshwater lakes. This study is aimed to examine how anthropogenic eutrophication modified the relationships between three facets (taxonomic, functional and phylogenetic) of macroinvertebrate beta diversity and geographic and environmental distances across 30 freshwater lakes. Location: The Yangtze River floodplain, China. Methods: We used Mantel tests to examine the relationships between multiple facets of assemblage dissimilarities (overall beta diversity, replacement and richness difference components) and geographic and environmental distances. Distance‐based redundancy analysis (dbRDA) and associated variation partitioning procedures were applied to explore the relative contributions of environmental and spatial factors on the three facets of beta diversity. Results: We found that none of the three beta diversity facets was related to geographic distance, but all were significantly related to environmental distance, mainly mirroring eutrophication‐related variables. Based on the variation partitioning approach, the macroinvertebrate assemblages examined were almost exclusively structured by environmental factors associated with eutrophication, while spatial variables had a negligible effect. Nevertheless, the different facets of beta diversity did not decrease (i.e., no homogenization trend) in lake groups showing the highest eutrophication levels, implying complex influences of anthropogenic disturbances in driving homogenization or differentiation in assemblage compositional dissimilarity. Main Conclusions: Our findings suggested that the high degrees of eutrophication acted as an environmental filter to significantly modify the spatial distance–decay relationships, possibly via decreasing the importance of dispersal limitation in shaping macroinvertebrate assemblages in the studied lakes. Given the sensitivity of beta diversity patterns to eutrophication we found in this study, we recommend that the role of anthropogenic disturbances should be incorporated into research on general ecological patterns like the DDR. [ABSTRACT FROM AUTHOR]

Aim: Analysing the spatio‐temporal patterns and dynamics of non‐native species is essential to understanding the mechanisms underlying successful invasions and developing effective management strategies. Yet, such analyses generally neglect the influence of receiving ecosystem types and non‐native species sources (i.e. alien species, non‐natives originating outside the concerned region; translocated species, non‐natives introduced to locations outside their historical range within the concerned region). Location: Yunnan, China. Methods: We analysed long‐term (1950–2022) spatio‐temporal patterns and potential underlying dynamics of non‐native fishes in a biodiversity hotspot (Yunnan, China), paying special attention to waterbody types receiving non‐native species and comparing alien and translocated species. We did this through compiling a highly comprehensive occurrence dataset of native and non‐native fishes. Results: We recorded 783 native species and 94 non‐native species (49 alien species and 45 translocated species), which mainly belonged to the order Cypriniformes (52 species) and were introduced via purposes for advancing aquaculture. Most frequently encountered non‐native species were either intentionally introduced aquaculture species or small‐bodied fish unintentionally introduced via aquaculture activities. The richness and spatial ranges of non‐native fishes increased consistently since the 1950s and demonstrated a pronounced change after the 2000s, with densely populated areas and the middle to lower reaches of large rivers being more profoundly affected. The number of records of translocated species exceeded the number of records of alien species after the 2000s. Lakes and reservoirs are hotspots for both alien and translocated species introductions, and watersheds with large areas in Yunnan (e.g. the Jinsha‐Yangtze and Lancang‐Mekong basins) contained more non‐native fish. Main Conclusions: Our study highlights the need to consider invasion sensitivities of receiving ecosystems and pay special attention to intra‐regional species translocations when developing prevention and management strategies against invasions of alien species, particularly in important biodiversity hotspots around the world. [ABSTRACT FROM AUTHOR]

Aim: We propose a novel approach that considers taxonomic uniqueness, functional uniqueness and environmental uniqueness and show how it can be used in guiding conservation planning. We illustrate the approach using data for lake biota and environment. Location: Lake Puruvesi, Finland. Methods: We sampled macrophytes and macroinvertebrates from the same 18 littoral sites. By adapting the original "ecological uniqueness" approach, we used distance‐based methods to calculate measures of taxonomic (LCBD–t), functional (LCBD–f) and environmental (LCEH) uniqueness for each site. We also considered the numbers and locations of the sites needed to protect up to 70% of total variation in taxonomic, functional or environmental features in the studied part of the lake. Results: Relationships between taxonomic (LCBD–t), functional (LCBD–f) and environmental (LCEH) uniqueness were generally weak, and only the relationship between macrophyte LCBD–t and LCBD–f was statistically significant. Overall, however, if the whole biotic dataset was considered, macroinvertebrate LCBD–f values showed a consistent positive relationship with macrophyte LCBD–f. Depending on the measure of site uniqueness, between one‐third to one half of the sites could help protect up to 70% of the ecological uniqueness of the studied part of Lake Puruvesi. Main conclusions: Although the dataset examined originated from a large lake system, the approach we proposed here can be applied in different ecosystems and at various spatial scales. An important consideration is that a set of sites has been sampled using the same methods, resulting in species and environmental matrices that can be analysed using the methodological approach proposed here. This framework can be easily applied to grid‐based data, sets of islands or sets of forest fragments. We suggest that the approach based on taxonomic, functional and environmental uniqueness will be a useful tool in guiding nature conservation and ecosystem management, especially if associated with meta‐system ideas or network thinking. [ABSTRACT FROM AUTHOR]

Aim: We aimed to test whether contributions of individual species (SCBD) and contributions of single sites (LCBD) to overall beta diversity can be predicted by species metrics and species characteristics and also by community metrics and ecological variables, respectively. Location: A mainland‐island landscape in the southern Brazilian Atlantic Forest domain. Methods: Dung beetles were sampled along 100 sampling units within four large forest fragments. We partitioned beta diversity into SCBD and LCBD aiming to explore their relationships to species and site characteristics, respectively. We then used a combination of multivariate methods and beta regression analyses to examine patterns in SCBD and LCBD. The occupancy, total abundance, niche position, niche breadth and biological traits of species were used as predictor variables for SCBD values. Community metrics, environmental and spatial variables, and temporal patterns in the beta diversity components of turnover and nestedness were used as predictor variables for LCDB values. Results: We found that SCBD was strongly related to various species characteristics, such as occupancy, abundance and niche position, but was not related to biological traits of species and niche breadth. In particular, occupancy and its quadratic term showed a very strong unimodal relationship with SCBD, suggesting that intermediate species in terms of site occupancy contribute most to beta diversity. LCBD was mostly explained by variation in species richness, with a negative relationship being detected. Litter height and large‐scale spatial variables were also important in explaining variation in LCBD. Main conclusions: SCBD and LCBD were highly predictably related to species occupancy and species richness, respectively. Environmental conditions and large‐scale spatial variables also correlated with LCBD values. Understanding the determinants of SCBD and LCBD may thus hold a key to various general ecological, bioassessment and conservation issues. Protecting sites with high LCBD values may be a suitable approach to practical biodiversity conservation. [ABSTRACT FROM AUTHOR]

Abstract: Aim: We analysed beta‐diversity patterns of various biological groups simultaneously, from the perspective of site ecological uniqueness. We also investigated whether ecological uniqueness variation could be explained by variations in environmental conditions and spatial variables. Data: Central Amazonia. Methods: We estimated the total beta diversity and ecological uniqueness for 14 biological groups, including plants and animals, sampled at the same sites on a mesoscale in central Amazonia, Brazil. The uniqueness values for all biological groups were combined in a single matrix (multi‐taxa matrix of site uniqueness), which was then used as a response variable matrix in a partial redundancy analysis. We also investigated differences in the uniqueness patterns between plant and animal groups. Results: In general, plants showed higher total beta diversity than animals. For plants, uniqueness was explained mainly by environmental conditions, while for animals, uniqueness was also related to spatial variables. Although variation in uniqueness was mainly related to soil clay content, it is difficult to determine a single major environmental variable underlying the variation in uniqueness because the topographical gradient influences many of them, including soil clay content. Main Conclusion: The uniqueness values were higher in low‐lying areas, indicating that near‐stream sites were more ecologically unique. Despite the lower number of species in the lowlands, their unique biota contributed strongly to the maintenance of the total beta diversity of the area. This finding should be considered in conservation plans that aim to represent and preserve the regional biota. Our approach proved to be useful to analyse and compare the ecological uniqueness of multiple taxa. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Large‐scale diversity patterns are generated by different but not mutually exclusive mechanisms. However, understanding of multiple facets of diversity and their determinants in the freshwater realm remains limited. Here, we characterized the geographical gradients, hotspots and spatial congruence of three facets of freshwater molluscan diversity and evaluated the relative importance of three different underlying mechanisms related to the energy, area/environmental heterogeneity and dispersal/historical hypotheses. Location: China. Methods: Species richness (SR), functional richness (FR) and taxonomic distinctness (TD, a proxy of phylogenetic diversity) were calculated for 212 drainage basins with a total of 313 molluscan species. Spatial congruence between the diversity facets was evaluated with Pearson correlation coefficient and overlap among hotspots. Multiple linear regression models and variation partitioning were used to assess the relative importance of different mechanisms. Results: Hotspots of SR and FR were mainly concentrated in the Yangtze River and Huai River basins, while high TD values were patchily distributed across China. We found extremely low spatial congruence between TD and both SR and FR, while there was relatively high concordance between SR and FR. All diversity facets were best explained by the dispersal/historical hypothesis with strong unique effects, followed by the factors related to the energy hypothesis. The area/ environmental heterogeneity hypothesis was only weakly supported. Main conclusions: We found a potentially strong influence of dispersal limitation and evolutionary history on the geographical diversity gradients of Chinese molluscs. This finding contrasts with the general finding that energy‐related factors are the strongest correlates of diversity patterns at large spatial scales. Moreover, our results do not support the idea that using any one diversity component as a surrogate of the others in developing conservation strategies. Instead, an integrative approach embracing multiple facets of diversity should be adopted in the conservation of freshwater biodiversity. [ABSTRACT FROM AUTHOR]

Aim To discover whether lake and stream diatom communities show different patterns in species richness and in their local ( LCBD) and species ( SCBD) contributions to beta diversity in relation to macroscale environmental characteristics. Location Finland. Methods As biological data, we used diatom samples collected from Finnish stream ( n = 492) and lake ( n = 290) sites. As explanatory variable data, we used information on macroscale environmental and historical aspects, such as bedrock, soil and post-glacial highest shoreline. We also accounted for catchment areas, different levels of isolation and relative centrality of the study sites. We ran multiple linear models and selected best models based on AICc values. Results We found that macroscale factors affecting diatom richness and ecological uniqueness differed clearly between streams and lakes. LCBD and species richness of stream communities were more affected by regional environmental characteristics, whereas LCBD and species richness of lake communities were more often driven by spatial measures. The measures of LCBD and species richness showed a slightly negative relationship in streams, but no such relationship was detected in lakes. Also, we showed that, for both streams and lakes, SCBD was strongly determined by the number of sites occupied by a species and the overall abundance of a species. Main conclusions Our findings related to the distinction between the determinants of lake and stream species richness or LCBD may be tied to the different hydrological connectivity levels occurring in freshwater lotic and lentic systems. Also, in streams, sites with exceptional ecological uniqueness seem to have a rather low number of species. Our findings may be applied to biological conservation and monitoring planning, emphasizing that not only species-rich but also unique low-richness sites may be valuable conservation goals. [ABSTRACT FROM AUTHOR]

Aims The nested subset pattern has been widely studied in the last 20 years, and recent syntheses have challenged the prevalence of this pattern in nature. We examined the degree of nestedness, its temporal variability and its environmental correlates in stream insects of a boreal drainage system. We also examined differences between nested and idiosyncratic species in site occupancy, niche position and niche breadth. Location Koutajoki drainage basin in northern Finland. Methods We used (i) nestedness analyses with three null models for testing the significance of nestedness; (ii) Spearman rank correlation to examine the correlates of nestedness; (iii) outlying mean index analysis to analyse the niche characteristics of species; (iv) and t-test to examine differences in niche breadth, niche position and site occupancy of idiosyncratic and other nested species. Results Stream insect assemblages were significantly nested in each of the three study years. The maximally packed matrices were significantly nested according to the nestedness calculator based on null models I (species frequencies and site richness equiprobable) and II (species frequencies fixed and site richness equiprobable), but non-significant based on a conservative null model III (species frequencies and site richness fixed to those of the observed matrix). The most important correlate of nestedness was stream size, whereas isolation, productivity (total phosphorus) and habitat heterogeneity exhibited non-significant relationship with nestedness. Idiosyncratic species occurred, on average, at more sites than nested species, mirroring the restricted distributions of several nested species that were inclined towards species-rich sites. Idiosyncratic and nested species also differed in niche position and niche breadth, with idiosyncratic species having, on average, less marginal niche positions and wider niches than nested species. Main conclusions Stream size correlated with nestedness, possibly because small streams were inhabited only by species able to persist under, or colonize shortly after, disturbances, while most species could occur at larger sites where disturbances are less severe. From the conservation perspective, our findings suggest that stream size really matters, given that sites with high species richness and many rare species are more likely to occur in larger streams. However, also the requirements of idiosyncratic species should be accommodated in conservation planning. [ABSTRACT FROM AUTHOR]