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Human activities pose a major threat to tropical forest biodiversity and ecosystem services. Although the impacts of deforestation are well studied, multiple land-use and land-cover transitions (LULCTs) occur in tropical landscapes, and we do not know how LULCTs differ in their rates or impacts on key ecosystem components. Here, we quantified the impacts of 18 LULCTs on three ecosystem components (biodiversity, carbon, and soil), based on 18 variables collected from 310 sites in the Brazilian Amazon. Across all LULCTs, biodiversity was the most affected ecosystem component, followed by carbon stocks, but the magnitude of change differed widely among LULCTs and individual variables. Forest clearance for pasture was the most prevalent and high-impact transition, but we also identified other LULCTs with high impact but lower prevalence (e.g., forest to agriculture). Our study demonstrates the importance of considering multiple ecosystem components and LULCTs to understand the consequences of human activities in tropical landscapes.
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Efeitos Antropogênicos , Biodiversidade , Conservação dos Recursos Naturais , Floresta Úmida , Agricultura , Brasil , Carbono , HumanosRESUMO
Concerted political attention has focused on reducing deforestation, and this remains the cornerstone of most biodiversity conservation strategies. However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes. These disturbances occur both within forests, including selective logging and wildfires, and at the landscape level, through edge, area and isolation effects. Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Pará. Catchments retaining more than 6980% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil's Forest Code, resulted in a 3954% loss of conservation value: 96171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará's strictly protected areas is equivalent to the loss of 92,000139,000 km2 of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems.
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Biodiversidade , Conservação dos Recursos Naturais/métodos , Conservação dos Recursos Naturais/estatística & dados numéricos , Florestas , Atividades Humanas , Clima Tropical , Animais , Aves/fisiologia , Brasil , Besouros/fisiologia , Incêndios/estatística & dados numéricos , Agricultura Florestal/estatística & dados numéricos , PlantasRESUMO
Ecological knowledge plays a significant role in ensuring efficient ecological restoration. We conducted a systematic review to assess if sufficient ecological knowledge has been accumulated to aid restoration practices for the Cerrado, a Brazilian biome dominated by savanna ecosystems and threatened by anthropogenic disturbances. Most Cerrado restoration studies were performed by few research groups and focused primarily on two vegetation types: cerrado sensu stricto (typical savanna) and riparian forest. We also found that defining reference ecosystems and selecting plant species for restoration programs is neglected, mostly disregarding their original occurrence and proportion of plant growth forms. Furthermore, studies lacked standardized and systematic evaluation of restoration outcomes. Hence, we argue that current ecological knowledge is insufficient to guarantee the success of large-scale ecological restoration of the Cerrado. We strengthen the need to explicitly define the reference ecosystem for each Cerrado ecosystem and use its structure and composition as guidance for ecological restoration research, which should be based on a scientific approach. We encourage investigations into ecological dynamics and natural regeneration of the different vegetation types of the Cerrado and highlight the importance of integrating such knowledge with environmental laws, societal engagement and cost-effective techniques to advance Cerrado ecological restoration.
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Biodiversidade , Ecossistema , Efeitos Antropogênicos , Brasil , Florestas , PlantasRESUMO
Cocoa beans used for chocolate production are fermented seeds of Theobroma cacao obtained by a natural fermentation process. The flavors and chemical compounds produced during the fermentation process make this step one of the most important in fine chocolate production. Herein, an integrative analysis of the variation of microbial community structure, using a shotgun metagenomics approach and associated physicochemical features, was performed during fermentation of fine cocoa beans. Samples of Forastero variety (FOR) and a mixture of two hybrids (PS1319 and CCN51) (MIX) from Bahia, Brazil, were analyzed at 7 different times. In the beginning (0 h), the structures of microbial communities were very different between FOR and MIX, reflecting the original plant-associated microbiomes. The highest change in microbial community structures occurred at the first 24 h of fermentation, with a marked increase in temperature and acetic acid concentration, and pH decrease. At 24-48 h both microbial community structures were quite homogenous regarding temperature, acetic acid, succinic acid, pH, soluble proteins and total phenols. During 72-96 h, the community structure resembles an acidic and warmer environment, prevailing few acetic acid bacteria. Taxonomic richness and abundance at 72-144 h exhibited significant correlation with temperature, reducing sugars, succinic, and acetic acids. Finally, we recommend that dominant microbial species of spontaneous fine cocoa fermentations should be considered as inoculum in accordance with the farm/region and GMP to maintain a differential organoleptic feature for production of fine chocolate. In our study, a starter inoculum composed of Acetobacter pausterianus and Hanseniaspora opuntiae strains is indicated.
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Cacau/microbiologia , Fermentação , Alimentos Fermentados , Microbiologia de Alimentos , Metagenômica/métodos , Ácido Acético/metabolismo , Acetobacter/metabolismo , Bactérias/metabolismo , Brasil , Chocolate , Aromatizantes , Hanseniaspora/genética , Hanseniaspora/metabolismo , Microbiota/genética , Sementes/microbiologiaRESUMO
Myrmecochory (seed dispersal by ants) is a unique seed dispersal syndrome among invertebrates. It comprises three main phases: seed removal, seed manipulation, and seed deposition. However, the contribution of each phase to seed and seedling fate remains unclear. Here, we experimentally quantified the effects of each phase of myrmecochory on seed germination and seedling establishment, the two most critical life history stages involved in plant recruitment. We established 30 sample points, and each included an adult Mabea fistulifera tree, an Atta sexdens nest entrance, and six seed depots. We monitored the germination of M. fistulifera seeds for 3 months and subsequently followed the growth and mortality of the resulting seedlings for 12 months. Only the dispersal distance influenced plant establishment, reducing seed germination and increasing seedling growth, but with no effect of seed manipulation and deposition site. Despite the contrasting effects of distance on seed germination and seedling growth, the positive effect of dispersal distance on seedling growth was ten times greater than the negative effect on seed germination. Moreover, A. sexdens behaved neither as granivore nor as herbivore of M. fistulifera seeds or seedlings, which suggests that seed dispersal by A. sexdens is advantageous to M. fistulifera. Thus, the joint occurrence of these two species in disturbed areas could have a positive effect on this pioneer plant population, which might promote forest regeneration.
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Formigas , Dispersão de Sementes , Animais , Germinação , Plantas , Plântula , SementesRESUMO
PREMISE: Fog is a frequent event in Brazilian rupestrian field and plays an important role in the physiology of several plant species. Foliar water uptake (FWU) of fog may be fast or slow depending on the species. However, fog water may negatively affect CO2 assimilation. Thus, the interference in the water and carbon balance as a result of different strategies of FWU was evaluated to verify whether fog may mitigate possible water deficit in leaves. METHODS: Four plant species with different FWU strategies were studied in a ferruginous rupestrian field with frequent fog. Gas exchange and water potential were measured before dawn and at midday during the dry and rainy seasons, separating foggy from non-foggy days during the dry season. RESULTS: The FWU speed negatively influences CO2 assimilation in the dry season, possibly because of its negative relationship with stomatal conductance, since reduced stomatal aperture impairs carbon entrance. Fog presence increased leaf water potential both in early morning and midday during the dry season. However, during the rainy season, the values of leaf water potential were lower at midday, than during the dry season with fog at midday, which favors leaf gas exchanges. CONCLUSIONS: FWU interferes negatively, but briefly with CO2 assimilation. Nevertheless, FWU prevents water loss through transpiration and increases the water status of plants in the dry season. That is, FWU results in a compensation between CO2 assimilation and foliar hydration, which, in fact, is beneficial to the plants of this ecosystem.
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Ecossistema , Folhas de Planta/fisiologia , Água/fisiologia , Dióxido de Carbono/metabolismoRESUMO
Resource-ratio theory predicts that consumers should achieve optimal ratios of complementary nutrients. Accordingly, different trophic groups are expected to vary in their N-limitation depending on the extent to which they feed primarily on carbohydrate (CHO) or protein. Among arboreal ants, N-limitation ranges from high (for trophobiont tenders), intermediate (leaf foragers) and low (predators). We report results from a manipulative field experiment in a Brazilian savanna that tests the differential attractiveness of nitrogen and CHO to arboreal ants, as well as experimentally examines changes in broader ant foraging patterns in response to protein and CHO supplementation. Every tree within 32 20 × 20 m plots were supplemented with either protein, CHO; protein + CHO or a water control (n = 8 in each case) for a 7-day period in each of the wet and dry seasons. As predicted, different trophic groups responded differentially to supplementation treatment according to the extent of their N-limitation. The richness and abundance of the most N-limited group (trophobiont tenders) was highest at protein supplements, whereas less N-limited trophic groups showed highest species richness (leaf foragers) or abundance (predators) at CHO supplements. Protein supplementation markedly increased the general foraging abundance of trophobiont tenders, but decreased the abundance of leaf foragers. We attribute the latter to increased competition from behaviorally dominant trophobiont tenders. Our study provides experimental evidence that nutrient availability is a major factor influencing arboreal ant communities, both directly through the provision of different resources, and indirectly through increased competitive pressure.
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Formigas , Animais , Brasil , Suplementos Nutricionais , Pradaria , ÁrvoresRESUMO
Secondary forests (SFs) regenerating on previously deforested land account for large, expanding areas of tropical forest cover. Given that tropical forests rank among Earth's most important reservoirs of carbon and biodiversity, SFs play an increasingly pivotal role in the carbon cycle and as potential habitat for forest biota. Nevertheless, their capacity to regain the biotic attributes of undisturbed primary forests (UPFs) remains poorly understood. Here, we provide a comprehensive assessment of SF recovery, using extensive tropical biodiversity, biomass, and environmental datasets. These data, collected in 59 naturally regenerating SFs and 30 co-located UPFs in the eastern Amazon, cover >1,600 large- and small-stemmed plant, bird, and dung beetles species and a suite of forest structure, landscape context, and topoedaphic predictors. After up to 40 years of regeneration, the SFs we surveyed showed a high degree of biodiversity resilience, recovering, on average among taxa, 88% and 85% mean UPF species richness and composition, respectively. Across the first 20 years of succession, the period for which we have accurate SF age data, biomass recovered at 1.2% per year, equivalent to a carbon uptake rate of 2.25 Mg/ha per year, while, on average, species richness and composition recovered at 2.6% and 2.3% per year, respectively. For all taxonomic groups, biomass was strongly associated with SF species distributions. However, other variables describing habitat complexity-canopy cover and understory stem density-were equally important occurrence predictors for most taxa. Species responses to biomass revealed a successional transition at approximately 75 Mg/ha, marking the influx of high-conservation-value forest species. Overall, our results show that naturally regenerating SFs can accumulate substantial amounts of carbon and support many forest species. However, given that the surveyed SFs failed to return to a typical UPF state, SFs are not substitutes for UPFs.
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Biodiversidade , Biomassa , Florestas , Animais , Aves/fisiologia , Ciclo do Carbono , Besouros/fisiologia , Conservação dos Recursos Naturais , Conjuntos de Dados como Assunto , Ecossistema , Árvores , Clima TropicalRESUMO
Several techniques have been used to model the area covered by biomes or species. However, most models allow little freedom of choice of response variables and are conditioned to the use of climate predictors. This major restriction of the models has generated distributions of low accuracy or inconsistent with the actual cover. Our objective was to characterize the environmental space of the most representative biomes of Brazil and predict their cover, using climate and soil-related predictors. As sample units, we used 500 cells of 100 km2 for ten biomes, derived from the official vegetation map of Brazil (IBGE 2004). With a total of 38 (climatic and soil-related) predictors, an a priori model was run with the random forest classifier. Each biome was calibrated with 75% of the samples. The final model was based on four climate and six soil-related predictors, the most important variables for the a priori model, without collinearity. The model reached a kappa value of 0.82, generating a highly consistent prediction with the actual cover of the country. We showed here that the richness of biomes should not be underestimated, and that in spite of the complex relationship, highly accurate modeling based on climatic and soil-related predictors is possible. These predictors are complementary, for covering different parts of the multidimensional niche. Thus, a single biome can cover a wide range of climatic space, versus a narrow range of soil types, so that its prediction is best adjusted by soil-related variables, or vice versa.
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Clima , Ecossistema , Modelos Teóricos , Solo/química , BrasilRESUMO
The widespread clearing of tropical forests causes lower tree cover, drier microclimate, and higher and drier fuel loads of forest edges, increasing the risk of fire occurrence and its intensity. We used a manipulative field experiment to investigate the influence of fire and fuel loads on ant communities and their interactions with myrmecochorous seeds in the southern Amazon, a region currently undergoing extreme land-use intensification. Experimental fires and fuel addition were applied to 40 × 40-m plots in six replicated blocks, and ants were sampled between 15 and 30 days after fires in four strata: subterranean, litter, epigaeic, and arboreal. Fire had extensive negative effects on ant communities. Highly specialized cryptobiotic and predator species of the litter layer and epigaeic specialist predators were among the most sensitive, but we did not find evidence of overall biotic homogenization following fire. Fire reduced rates of location and transport of myrmecochorous seeds, and therefore the effectiveness of a key ecosystem service provided by ants, which we attribute to lower ant abundance and increased thermal stress. Experimental fuel addition had only minor effects on attributes of fire severity, and limited effects on ant responses to fire. Our findings indicate that enhanced fuel loads will not decrease ant diversity and ecosystem services through increased fire severity, at least in wetter years. However, higher fuel loads can still have a significant effect on ants from Amazonian rainforests because they increase the risk of fire occurrence, which has a detrimental impact on ant communities and a key ecosystem service they provide.
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Formigas , Incêndios , Animais , Ecossistema , Sementes , ÁrvoresRESUMO
Land-cover change and ecosystem degradation may lead to biotic homogenization, yet our understanding of this phenomenon over large spatial scales and different biotic groups remains weak. We used a multi-taxa dataset from 335 sites and 36 heterogeneous landscapes in the Brazilian Amazon to examine the potential for landscape-scale processes to modulate the cumulative effects of local disturbances. Biotic homogenization was high in production areas but much less in disturbed and regenerating forests, where high levels of among-site and among-landscape ß-diversity appeared to attenuate species loss at larger scales. We found consistently high levels of ß-diversity among landscapes for all land cover classes, providing support for landscape-scale divergence in species composition. Our findings support concerns that ß-diversity has been underestimated as a driver of biodiversity change and underscore the importance of maintaining a distributed network of reserves, including remaining areas of undisturbed primary forest, but also disturbed and regenerating forests, to conserve regional biota.
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Biodiversidade , Florestas , Clima Tropical , Agricultura , Animais , Aves , Brasil , Conservação dos Recursos Naturais , InsetosRESUMO
Scavenging is a key process for the cycling of nutrients in ecosystems, yet it is still neglected in the ecological literature. Apart from the importance of specific groups of animals in scavenging, there have been few ecological studies that compare them. Furthermore, the ecological studies on scavenging have mainly focused on vertebrates despite the crucial importance of invertebrates in this process. Here, we performed a large-scale ant suppression and vertebrate exclusion experiment to quantify the relative contribution of ants, non-ant invertebrates and vertebrates in scavenging nitrogen-rich (insect carcasses) and carbon-rich (seeds) baits in two contrasting mountainous habitats in Brazil (grasslands and forests). Overall, bait removal was 23.2% higher in forests than in grasslands. Ants were the primary scavengers in grasslands, responsible for more than 57% of dead insect larvae and seed removal, while, in forests, non-ant invertebrates dominated, removing nearly 65% of all baits. Vertebrates had a minor role in scavenging dead insect larvae and seeds in both habitats, with <4% of removals. Furthermore, our results show that animal-based baits were more consumed in forests than seeds, and both resources were equally consumed in grasslands. Therefore, we demonstrate the superiority of invertebrates in this process, with a particular emphasis on the irreplaceable role of ants, especially in this grassland ecosystem. As such, we further advance our knowledge of a key ecosystem process, showing the relative importance of three major groups in scavenging and the differences in ecosystems functioning between two contrasting tropical habitats.
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Formigas , Florestas , Pradaria , Invertebrados , Animais , Formigas/fisiologia , Invertebrados/fisiologia , Brasil , Comportamento Alimentar/fisiologia , Ecossistema , Insetos/fisiologiaRESUMO
Myrmecochory-seed dispersal by ants-is a mutualistic interaction in which ants attracted by seed appendices take them away from the parental plant location, where seeds usually have better development odds. Not all ant species benefit plants, and the mechanisms of those divergent outcomes are still unclear, especially from the perspective of microbial third parties. Here, we explore the effects of seed manipulation on fungi communities promoted by two ant species with contrasting effects on seed germination and antimicrobial cleaning strategies. We hypothesize that: i) fungi richness is higher in seeds manipulated by Acromyrmex subterraneus (species that negatively affect seed germination), followed by unmanipulated seeds and seeds manipulated by Atta sexdens (ant species that increase seed germination) and ii) seeds manipulated by A. sexdens, Ac. subterraneus and unmanipulated seeds present dissimilar fungi compositions. We identified fungal morphotypes in three groups of seeds: i) manipulated by A. sexdens; ii) manipulated by Ac. subterraneus; iii) unmanipulated. Seeds manipulated by Ac. subterraneus exhibited higher fungal richness than those manipulated by A. sexdens and unmanipulated seeds, indicating that the ant species known to impair germination increases the fungal load on seeds. Additionally, we found that A. sexdens ants were unable to reduce fungal richness compared to unmanipulated seeds. Furthermore, fungal composition differed among all three treatments. Our results underscore the significance of ant species identity in shaping the fungal communities associated with myrmecochorous seeds. Given the potential influence of microbial infection on seed fate, we suggest considering manipulation strategies when evaluating the overall quality of an ant as a seed disperser.
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Formigas , Dispersão de Sementes , Animais , Sementes , Plantas , Germinação , FungosRESUMO
Global changes increasingly worry researchers and policymakers and may have irreversible impacts on Earth's biodiversity. Similar to other phytophysiognomies, natural grasslands suffer from the effects of land use changes and rising temperatures, threatening animal and plant communities. Birds, being very sensitive to these changes, are widely studied and fundamental to understand the dynamics of ecosystems in relation to climate and land use changes. The Campo Miner Geositta poeciloptera is a grassland bird endemic to the Brazilian Cerrado and threatened with extinction that has been widely studied in recent years. We analyze the decrease in its extent of occurrence (EOO) and the effects of climate and land use change to understand the environmental suitability of the species in current and future scenarios. We used 5 common algorithms to produce ecological niche models. For future predictions, we use two general circulation models for two different greenhouse gas emission scenarios with different climate policies, an optimistic (ssp245) and a pessimistic (ssp585), plus two land use models focusing on increasing farmlands and reducing native grasslands. The current EOO represents ~45% of that presented by the IUCN EOO. The models generated for the present were satisfactory (TSS = 0.77 and ROC = 0.90) and showed high environmental suitability in areas where the species is currently found and low suitability where it is already extinct. All future scenarios have reduced suitable areas for the species, and the models of a greater increase in temperature and increase in farmlands and a greater decrease in grasslands were the worse. Our results reinforce the need to care about biome awareness disparity and the importance of actively preserving grassy-shrub areas. Apparently, the state of Minas Gerais will be the only stronghold of the species in the coming years; however, the lack of protected areas that guarantee its survival needs attention.
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Research findings in natural sciences need to be comparable and reproducible to effectively improve our understanding of ecological and behavioural patterns. In this sense, knowledge frontiers in biodiversity studies are directly tied to taxonomic research, especially in species-rich tropical regions. Here we analysed the taxonomic information available in 470 studies on Brazilian ant diversity published in the last 50 years. We aimed to quantify the proportion of studies that provide enough data to validate taxonomic identification, explore the frequency of studies that properly acknowledge their taxonomic background, and investigate the primary resources for ant identification in Brazil. We found that most studies on Brazilian ant diversity (73.6%) explicitly stated the methods used to identify their specimens. However, the proportion of papers that provide complete data for the repository institutions and vouchered specimens is vanishingly small (5.8%). Additionally, only 40.0% of the studies consistently presented taxon authorities and years of description, rarely referencing taxonomic publications correctly. In turn, the number of specialists and institutions consulted for ant identification in Brazil has increased in the last years, along with the number of studies that explicitly provide their taxonomic procedures for ant identification. Our findings highlight a shift between generations regarding the recognition of taxonomy as fundamental science, deepening our understanding of biodiversity.
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Cocoa beans fermentation is a spontaneous process, essential for the generation of quality starting material for fine chocolate production. The understanding of this process has been studied by the application of high-throughput sequencing technologies, which grants a better assessment of the different microbial taxa and their genes involved in this microbial succession. The present study used shotgun metagenomics to determine the enzyme-coding genes of the microbiota found in two different groups of cocoa beans varieties during the fermentation process. The statistical evaluation of the most abundant genes in each group and time studied allowed us to identify the potential metabolic pathways involved in the success of the different microorganisms. The results showed that, albeit the distinction between the initial (0 h) microbiota of each varietal group was clear, throughout fermentation (24-144 h) this difference disappeared, indicating the existence of selection pressures. Changes in the microbiota enzyme-coding genes over time pointed to the distinct ordering of fermentation at 24-48 h (T1), 72-96 h (T2), and 120-144 h (T3). At T1, the significantly more abundant enzyme-coding genes were related to threonine metabolism and those genes related to the glycolytic pathway, explained by the abundance of sugars in the medium. At T2, the genes linked to the metabolism of ceramides and hopanoids lipids were clearly dominant, which are associated with the resistance of microbial species to extreme temperatures and pH values. In T3, genes linked to trehalose metabolism, related to the response to heat stress, dominated. The results obtained in this study provided insights into the potential functionality of microbial community succession correlated to gene function, which could improve cocoa processing practices to ensure the production of more stable quality end products.
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Over 70% of the total channel length in all river basins is formed by low order streams, many of which originate on mountaintops. Headwater streams play fundamental roles in processing and transporting terrestrial and aquatic organic matter, often harboring high biodiversity in bottom leaf patches deposited from riparian vegetation. The objective of this study was to assess the variation in taxonomic composition (measured by beta diversity of aquatic macroinvertebrates) among stream sites located in the Espinhaço Meridional Mountain Range, part of a UNESCO Biosphere Reserve in eastern Brazil. We tested two hypotheses. (a) Taxa turnover is the main reason for differences in aquatic insect assemblages within stream sites; we predicted that turnover would be higher than nestedness in all stream sites. (b) Stream site altitude and catchment elevation range are the main explanatory variables for the differences in beta diversity; we predicted that local stream site variables would account for only minor amounts of variation. In both dry and wet seasons, we sampled twice in two habitat types (five leaf patches in pools and five in riffles) in each of nine stream sites distributed in three different river basins. We computed average pairwise beta diversity among sampling stations and seasons in each stream site by using Jaccard and Bray-Curtis indices, and calculated the percentages of diversity resulting from turnover and nestedness. Finally, we tested the degree that local- or catchment-level predictor variables explained beta diversity. We found that turnover was the main component of beta diversity and that both dissolved oxygen and elevation range best explained Bray-Curtis beta diversity. These results reinforce the importance of leaf patches in montane (sky islands) Neotropical savanna streams as biodiversity hotbeds for macroinvertebrates, and that both local and landscape variables explained beta diversity.
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AbstractTestosterone (T) is a sexual hormone capable of modulating several traits in birds, including aggressiveness and reproductive behavior. Although variation in T-related traits is well-known for temperate zone birds, this variation has not been extensively studied in tropical species. The campo miner (Geositta poeciloptera) is a threatened bird endemic to the grasslands of the South American Cerrado. We investigated the seasonal variation in plasma T levels and associated behavior in the campo miner, addressing the following questions: (1) Does the species exhibit seasonal variation in T profile? (2) Do males have higher plasma T levels than females, irrespective of season? (3) Are males with higher plasma T levels more aggressive than males with lower T levels? (4) Do males' plasma T levels decrease after females lay eggs? We found that T levels are higher during the breeding season than during the nonbreeding season and that males present higher T levels than females throughout the year. Such high T levels are associated with a higher probability to engage in aggressive behavior; however, T levels decline toward the egg-laying date and keep decreasing afterward. Higher T levels before egg laying are apparently related to territorial defense against invaders and extrapair copulations. With the beginning of parental care, T levels decrease, which is in line with previous observations that the species becomes less aggressive after egg laying. This study contributes to the understanding of environmental endocrinology of tropical birds, filling some knowledge gaps about the diverse Neotropical avifauna.
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Ecossistema , Passeriformes/sangue , Passeriformes/fisiologia , Estações do Ano , Testosterona/sangue , Clima Tropical , Animais , Espécies em Perigo de Extinção , Feminino , Masculino , Fatores SexuaisRESUMO
Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant-herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species. Thus, when compared to the most recent comprehensive review of insect herbivory (Kozlov et al.), our data set has increased the base of available data for the tropical plants more than 460% (from 33 to 152 species) and the Brazilian sampling was increased 7,300% (from 2 to 146 species). Data on precise levels of herbivory are presented for more than 57,000 leaves worldwide. There are no copyright restrictions. Please cite this paper when using the current data in publications; the authors request to be informed how the data is used in the publications.
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Conservation initiatives overwhelmingly focus on terrestrial biodiversity, and little is known about the freshwater cobenefits of terrestrial conservation actions. We sampled more than 1500 terrestrial and freshwater species in the Amazon and simulated conservation for species from both realms. Prioritizations based on terrestrial species yielded on average just 22% of the freshwater benefits achieved through freshwater-focused conservation. However, by using integrated cross-realm planning, freshwater benefits could be increased by up to 600% for a 1% reduction in terrestrial benefits. Where freshwater biodiversity data are unavailable but aquatic connectivity is accounted for, freshwater benefits could still be doubled for negligible losses of terrestrial coverage. Conservation actions are urgently needed to improve the status of freshwater species globally. Our results suggest that such gains can be achieved without compromising terrestrial conservation goals.