Showing papers by "Luis Mauricio Bini published in 2017"
TL;DR: In this paper, the authors studied the key mechanisms affecting the distribution of individuals, populations, and communities in nature and found that dispersal is one of the key factors affecting individuals and populations in nature.
Abstract: Dispersal is one of the key mechanisms affecting the distribution of individuals, populations, and communities in nature. Despite advances in the study of single species, it has been notoriously di...
84 citations
TL;DR: These findings suggest that particular fish traits are selected for across reservoir cascades, and found evidence of an association between reservoir age and the domination of fish communities by small-sized species with parental care, external fecundation, and benthic habits.
Abstract: Dam construction alters flow regimes and can change the composition of aquatic communities. Using data from three Brazilian hydrographic basins, we tested the hypothesis that reservoir cascades act as environmental filters for fish traits. This dataset included information on different environmental variables and fish traits (diet, migration, fecundation, parental care, position in the water column, and body size), and we used multivariate analysis (partial RLQ) to quantify the relationships between environmental variables, species abundance and traits. We found that the abundance of migratory species declined towards downstream reservoirs, which tend to be smaller and less turbid with a shorter water residence time than upstream reservoirs. We also found evidence of an association between reservoir age and the domination of fish communities by small-sized species with parental care, external fecundation, and benthic habits. Our findings suggest that particular fish traits are selected for across reservoir cascades.
62 citations
TL;DR: In this paper, the authors conducted a meta-analysis on 44 published studies of river biodiversity that had replicated data and applied random effects models to the data to obtain weighted mean effect sizes for differences between rivers and their confidence intervals, by first considering all studies and then by splitting studies into groups on the basis of the above factors.
Abstract: Comprehensive knowledge of the effects of disturbances on biodiversity is crucial for conservation and management, not least because ecosystems with low biodiversity may be the most vulnerable. In rivers, the role of disturbance in shaping aquatic biodiversity has mainly focused on floods. Perennial rivers (PRs) often flood, whereas intermittent rivers (IRs) flood, stop flowing and dry. Despite the recent and significant increase in research on IRs, controversy remains about whether they are more or less biodiverse than PRs. Our aim was to determine (Q1) if PRs and IRs differ in biodiversity and (Q2) if the direction and magnitude of the differences (effect sizes) are related to environmental (climate, season, habitat, longitudinal zonation and anthropogenic disturbance) and/or biological factors (taxonomic group). We conducted a meta-analysis on 44 published studies of PR and IR biodiversity that had replicated data. We applied random effects models to the data to obtain weighted mean effect sizes for differences between PRs and IRs, and their confidence intervals, by first considering all studies and then by splitting studies into groups on the basis of the above factors. We found that biodiversity was significantly higher in PRs than in IRs (Q1). We also detected significant differences (PRs> IRs) in studies of macroinvertebrates, in those conducted within arid and temperate climates, dry and wet sampling seasons, headwaters, and regions subject to different levels of anthropogenic disturbance (Q2). Our meta-analysis suggests that the expected increase in the prevalence of IRs in certain regions of the world due to global change could result in a decrease in freshwater biodiversity. To better manage and preserve aquatic biodiversity under future global change scenarios and to avoid potential ecosystem consequences of biodiversity loss, conservation efforts should be targeted towards those environmental conditions or taxonomic groups with significant differences (PRs > IRs).
62 citations
TL;DR: The results suggest that eutrophication control is essential to prevent biotic homogenisation, at least in the study system, and highlight that metacommunity patterns detected in snapshot surveys should not be extrapolated temporally.
Abstract: Summary
Analysing the beta diversity components and spatial patterns of species distribution may provide key insights into how local communities respond to human-induced environmental changes. Indeed, analysing temporal variation in spatial patterns of species distribution may reveal trends of biotic homogenisation and its likely causes.
We used an eight-year phytoplankton data set generated from to 17 reservoirs in Brazil to analyse the temporal variability in beta diversity and its turnover and nestedness components. This data set was also used to determine metacommunity structures across these subtropical reservoirs. We tested whether there was any long-term temporal trend in beta diversity that might be indicative of biotic homogenisation or differentiation. We also tested how temporal variation was related to climatic conditions, environmental heterogeneity, productivity and cyanobacterial dominance. Lastly, we verified whether the phytoplankton metacommunity showed non-random structure.
We did not find supporting evidence for biotic homogenisation among the reservoirs. Rather, we did find that nestedness decreased during the study. Environmental heterogeneity was the main variable positively related to phytoplankton beta diversity, while high ammonium concentration and cyanobacterial abundance were negatively correlated with spatial variation among the reservoirs. Despite the noticeable temporal variation in metacommunity structures, the phytoplankton species responded similar to latent environmental gradients. Clementsian patterns found mainly in fall and winter were consistent with differences in species composition between sites, reinforcing the role of environmental filtering in driving changes in these metacommunities.
Our results suggest that eutrophication control is essential to prevent biotic homogenisation, at least in our study system. We also highlight that metacommunity patterns detected in snapshot surveys should not be extrapolated temporally.
60 citations
TL;DR: It is suggested that the conservation of insect biodiversity in urban pond should consider the surroundings of the ponds, and that high-richness ponds are not necessarily those that require most attention because they are not ecologically the most unique.
56 citations
TL;DR: Environmental heterogeneity and dispersal limitation were likely the main factors that determined diatom beta diversity in tropical reservoirs, and a strong relationship between beta diversity and environmental heterogeneity, productivity and spatial extent is suggested.
Abstract: Simultaneous effects of productivity, environmental heterogeneity and spatial extent on beta diversity of microbial communities have seldom been investigated. Here, we evaluated how these components are related to diatom beta diversity in tropical reservoirs. We hypothesised positive relationships between diatom beta diversity and environmental heterogeneity, productivity and spatial extent. Regression models were used to model beta diversity as a function of different measures of abiotic environmental heterogeneity, productivity, reservoir morphology, spatial extent, and habitat heterogeneity. Our results suggest a strong relationship between beta diversity and environmental heterogeneity, productivity and spatial extent. However, contrary to our hypothesis, productivity was negatively related to beta diversity. We speculate that artificial eutrophication can lead to decreased beta diversity (biotic homogenisation). Furthermore, the relationship between beta diversity and abiotic environmental heterogeneity depends how this component was measured. In conclusion, environmental heterogeneity and dispersal limitation were likely the main factors that determined diatom beta diversity in tropical reservoirs.
46 citations
TL;DR: In this paper, the authors evaluated how planktonic and surface-sediment diatom communities, including trait-based communities, were structured by environmental, spatial and land-use variables in tropical reservoirs.
Abstract: A metacommunity is defined as a set of local communities that are connected by dispersal and are controlled by environmental drivers operating at different spatial and temporal scales. Although diatom ecology has been studied extensively in temperate and lotic ecosystems, knowledge of tropical lentic systems is more limited.
We evaluated how planktonic and surface-sediment diatom communities, including trait-based communities, were structured by environmental, spatial and land-use variables in tropical reservoirs. Diatoms were sampled in seven reservoirs (31 sites in total) in south-east Brazil, from the surface sediment and the plankton in summer and winter.
Diatom communities responded primarily to a trophic gradient and secondarily to a light-availability gradient. Connectivity was also a strong predictor, whereas land use had a weaker influence on community variation. Our results further suggested that surface-sediment and planktonic diatom groups were structured by similar environmental variables. Trait-based analysis also indicated that these communities were related to environmental and spatial factors.
We conclude that (1) trophic state, light availability and connectivity were the main drivers of diatoms in this set of tropical reservoirs, resulting in spatially structured communities; (2) patterns for surface-sediment diatoms resembled both summer and winter diatom communities in the plankton; and (3) the effects of the explanatory variables (local environment, connectivity and land use) varied among the different biological datasets (i.e. when organised taxonomically, or according to growth morphology, cell size or trophic preference). We emphasize that studies in tropical reservoirs should take spatial variables into account, due to the connectivity of the sites.
37 citations
TL;DR: Habitat heterogeneity (as proxied by aquatic macrophytes richness) is important for maintaining periphyton species richness in floodplain environments, but other factors played a role, suggesting that the analysis of species richness of different trait-based groups unveils relationships that were not detectable when the entire community was analysed together.
Abstract: Periphytic algae are important components of aquatic ecosystems. However, the factors driving periphyton species richness variation remain largely unexplored. Here, we used data from a subtropical floodplain (Upper Parana River floodplain, Brazil) to quantify the influence of environmental variables (total suspended matter, temperature, conductivity, nutrient concentrations, hydrology, phytoplankton biomass, phytoplankton species richness, aquatic macrophyte species richness and zooplankton density) on overall periphytic algal species richness and on the richness of different algal groups defined by morphological traits (cell size and adherence strategy). We expected that the coefficients of determination of the models estimated for different trait-based groups would be higher than the model coefficient of determination of the entire algal community. We also expected that the relative importance of explanatory variables in predicting species richness would differ among algal groups. The coefficient of determination for the model used to predict overall periphytic algal species richness was higher than the ones obtained for models used to predict the species richness of the different groups. Thus, our first prediction was not supported. Species richness of aquatic macrophytes was the main predictor of periphyton species richness of the entire community and a significant predictor of the species richness of small mobile, large mobile and small-loosely attached algae. Abiotic variables, phytoplankton species richness, chlorophyll-a concentration, and hydrology were also significant predictors, depending on the group. These results suggest that habitat heterogeneity (as proxied by aquatic macrophytes richness) is important for maintaining periphyton species richness in floodplain environments. However, other factors played a role, suggesting that the analysis of species richness of different trait-based groups unveils relationships that were not detectable when the entire community was analysed together.
25 citations
TL;DR: Beta diversity declined over time, which is consistent with the process of biotic homogenization, a worldwide cause of concern.
Abstract: Beta diversity, the spatial variation in species composition, has been related to different explanatory variables, including environmental heterogeneity, productivity and connectivity. Using a long-term time series of zooplankton data collected over 62 months in a tropical reservoir (Ribeirao das Lajes Reservoir, Rio de Janeiro State, Brazil), we tested whether beta diversity (as measured across six sites distributed along the main axis of the reservoir) was correlated with environmental heterogeneity (spatial environmental variation in a given month), chlorophyll-a concentration (a surrogate for productivity) and water level. We did not found evidence for the role of these predictors, suggesting the need to reevaluate predictions or at least to search for better surrogates of the processes that hypothetically control beta diversity variation. However, beta diversity declined over time, which is consistent with the process of biotic homogenization, a worldwide cause of concern.
24 citations
TL;DR: Using a phytoplankton dataset from 17 reservoirs in Southern Brazil, sampled seasonally over eight years, the hypothesis that the explanatory power of multivariate models would be higher when the analyses were based on functional groups than when based on a taxonomic approach was tested.
Abstract: Recent studies have found that the relative importance of predictors of metacommunity structure is dependent on different factors. Low explanatory power of multivariate models is a frequent result. To increase this power, ecologists have suggested different strategies, including the use of functional approaches. Using a phytoplankton dataset from 17 reservoirs in Southern Brazil, sampled seasonally over eight years, we tested the hypothesis that the explanatory power of multivariate models would be higher when the analyses were based on functional groups than when based on a taxonomic approach. We also modeled the temporal variation in the strength of species sorting (as given by the adjusted coefficient of determination derived from environmental variables). We found high temporal variability in the strength of species sorting, indicating that results from snapshot surveys should be interpreted cautiously. When compared to the taxonomic approach, we did not find an increase in the explanatory power of multivariate models when the analyses were based on a functional approach. The main correlates of the temporal variation in the strength of species sorting were insolation, water temperature, and environmental heterogeneity, suggesting that conditions related to productivity and heterogeneity are important in determining the role of species sorting in phytoplankton communities.
22 citations
TL;DR: This article found that common ciliates were more associated with environmental gradients and rare species were more related to spatial variables; however, this pattern seemed to change depending on the temporal and spatial scales considered.
Abstract: After much discussion about the cosmopolitan nature of microbes, the great issue nowadays is to identify at which spatial extent microorganisms may display biogeographic patterns and if temporal variation is important in altering those patterns. Here, planktonic ciliates were sampled from shallow lakes of four Neotropical floodplains, distributed over a spatial extent of ca. 3000 km, during high and low water periods, along with several abiotic and biotic variables potentially affecting the ciliate community. We found that common ciliate species were more associated with environmental gradients and rare species were more related to spatial variables; however, this pattern seemed to change depending on the temporal and spatial scales considered. Environmental gradients were more important in the high waters for both common and rare species. In low waters, common species continued to be mainly driven by environmental conditions, but rare species were more associated with the spatial component, suggesting dispersal limitation likely due to differences in dispersal ability and ecological tolerance of species. We also found that common and rare species were related to different environmental variables, suggesting different ecological niches. At the largest spatial extents, rare species showed clear biogeographic patterns.
TL;DR: It is suggested that eutrophication enhanced the resistance offered by the native community and thereby reduced the establishment of invaders, underscoring the importance of native communities as biotic filters to invasion, especially in environments that are subjected to anthropogenic impacts such as nutrient enrichment.
Abstract: Summary
Biotic resistance theory predicts that the presence of a species-rich native community is able to inhibit the establishment of invasive species. On the other hand, disturbed environments, for example, through eutrophication, tend to be more easily invaded.
We investigated the effect of biotic resistance on the establishment success of the aquatic grass Urochloa arrecta in nutrient-enriched and non-enriched mesocosms so as to test the hypothesis that the effects of biotic resistance on invader success depend on ecosystem trophic state.
Invader success, measured as plant biomass and length, increased with nutrient enrichment in treatments without biotic resistance, whereas there was no difference between the success of the invader in enriched or non-enriched mesocosms in the presence of biotic resistance.
Our results suggest that eutrophication enhanced the resistance offered by the native community and thereby reduced the establishment of invaders. The results underscore the importance of native communities as biotic filters to invasion, especially in environments that are subjected to anthropogenic impacts such as nutrient enrichment.
TL;DR: The use of zooplankton genera and presence/absence data may be a reliable strategy to monitor reservoirs, however, the results highlight the need to monitor different zoop lankton groups, as the ordination patterns depicted by a given group were poorly related to those generated by a second zoopLankton group.
TL;DR: It is found that, in comparison with species-level data, genus-level identification was sufficient to detect the effects of the environmental changes caused by floods, to retrieve the ordination patterns generated during each hydrological period and to detect relationships with environmental and spatial gradients.
Journal Article•
TL;DR: Pterosaurian body size did not follow Bergmann’s rule during the TriassicJurassic, but a converse Bergmann's rule may have been present during the Cretaceous and seems to be a mechanistically independent macroevolutionary pattern.
Abstract: Background: Little is known about the existence or validity of ecogeographical rules – spatial patterns in biological traits – over geological time scales and in extinct clades. Some have claimed that pterosaurs, a Mesozoic clade of flying reptiles, follow Cope’s rule – the trend of increasing body size through time – yet no conclusive explanations for this rule have been provided and some explanations even converge with those about Bergmann’s rule: the tendency of species to be larger in colder environments. Goals: Determine whether Bergmann’s rule exists in pterosaur reptiles over their evolutionary history, and discuss its potential association with Cope’s rule. Data: Previously published morphological, phylogenetic, and geographic occurrence data of Pterosauria. Search methods: We applied cross-species and assemblage-based approaches along with phylogenetic comparative methods as well as sister-pair comparisons to evaluate the validity of Bergmann’s rule in Pterosauria. Conclusions: Pterosaurian body size did not follow Bergmann’s rule during the TriassicJurassic. But a converse Bergmann’s rule may have been present during the Cretaceous. There is no strong evidence to support an influence of Bergmann’s rule in the evolution of pterosaurian body size. Therefore, Cope’s rule in Pterosauria seems to be a mechanistically independent macroevolutionary pattern.
TL;DR: The results indicate that aquatic species that follow a metapopulation dynamic and depend on dispersal among sites to recover may be severely affected in a future climate change scenario, in which extreme events (including droughts) will tend to be more frequent.
TL;DR: In this article, the authors focus on determining how many samples are needed to effectively assess the species richness of a community, and they find that using a single sampling unit per lake would not be sufficient to accurately estimate their diversity.
Abstract: This study focuses on determining how many samples are needed to effectively assess the species richness of a community. Zooplankton samples at 40 sampling sites distributed among four lakes in the floodplain of the middle Araguaia River (Central-West region of Brazil) were evaluated to determine the effect of the accumulation of collecting points by lake on species richness estimates. The results indicated the zooplankton community has high spatial heterogeneity. Thus, using a single sampling unit per lake would not be sufficient to accurately estimate their diversity (i.e. the zooplankton composition in these cases would be represented mainly by abundant species). Sampling designs that include a minimum of seven sampling sites in each lake are needed to record 70% of the total species richness. It is recommended, therefore, that researchers use a larger number of sampling sites per lake or, alternatively, that the water obtained and filtered through plankton nets is extracted from a wide area and in different lake compartments, rather than from a single site.