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Prey availability and temporal partitioning modulate felid coexistence in Neotropical forests
Get PDFCarnivores have long been used as model organisms to examine mechanisms that allow coexistence among ecologically similar species. Interactions between carnivores, including competition and predation, comprise important processes regulating local community structure and diversity. We use data from an intensive camera-trapping monitoring program across eight Neotropical forest sites to describe the patterns of spatiotemporal organization of a guild of five sympatric cat species: jaguar (Panthera onca), puma (Puma concolor), ocelot (Leopardus pardalis), jaguarundi (Herpailurus yagouaroundi) and margay (Leopardus wiedii). For the three largest cat species, we developed multi-stage occupancy models accounting for habitat characteristics (landscape complexity and prey availability) and models accounting for species interactions (occupancy estimates of potential competitor cat species). Patterns of habitat-use were best explained by prey availability, rather than habitat structure or species interactions, with no evidence of negative associations of jaguar on puma and ocelot occupancy or puma on ocelot occupancy. We further explore temporal activity patterns and overlap of all five felid species. We observed a moderate temporal overlap between jaguar, puma and ocelot, with differences in their activity peaks, whereas higher temporal partitioning was observed between jaguarundi and both ocelot and margay. Lastly, we conducted temporal overlap analysis and calculated species activity levels across study sites to explore if shifts in daily activity within species can be explained by varying levels of local competition pressure. Activity patterns of ocelots, jaguarundis and margays were similarly bimodal across sites, but pumas exhibited irregular activity patterns, most likely as a response to jaguar activity. Activity levels were similar among sites and observed differences were unrelated to competition or intraguild killing risk. Our study reveals apparent spatial and temporal partitioning for most of the species pairs analyzed, with prey abundance being more important than species interactions in governing the local occurrence and spatial distribution of Neotropical forest felids. © 2019 Santos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
O papel de características funcionais e competição por luz na variação intraannual do diâmetro de oito espécies arbóreas sob efeito de fragmentação na Amazônia Central
Get PDFThere are microclimatic variations in continuous and fragmented mature forests, modulated by climatic seasonality. However, we do not know how species that persist in fragmented habitats differ in functional strategy and growth. The slow annual growth of some tropical tree species may be due to stagnation and seasonal shrinkage of the stem, but the literature is not consistent about which intrinsic and extrinsic
factors are linked to shrinkage. We investigated the variation in diameter of 146 individuals of eight abundant tree species in mature forest and remnants of forest fragments isolated for almost 40 years in the Brazilian Central Amazon. The availability of light, variations in precipitation, soil water volume and temperature, as well as several tree functional traits, were evaluated as predictors of diametric increase and shrinkage. We used paired t-tests to evaluate whether the absolute (GR) and relative (RGR) annual growth rate, annual and seasonal (bimonthly dendrometric bands data), of 146 individuals varies according to climatic seasonality along two years, and if there is evidence of acclimatization in the functional traits of the individuals in the two habitats (continuous forest and forest fragment). We also tested which variables are best predictors of diametric increase and shrinkage. There was greater annual GR of trees in the continuous forest, due to the larger average size of the trees in this habitat, but no differences in annual RGR. Seasonal RGR was higher in the rainier periods, with no differences among habitats, except in the rainiest period of 2018, where values were higher in individuals from the continuous forest. Individuals in the forest fragments had SAP almost 20% and SLA more than 25% larger in relation to individuals in the continuous forest. Some functional traits and climatic variables had different relationships between habitats and were the most important factors in explaining the variation of tree diameter increase and shrinkage. The availability of light had no relation with increase and shrinkage.A fragmentação pode alterar a estrutura e funcionalidade de florestas tropicais, mas não sabemos como espécies arbóreas que persistem nos habitats fragmentados diferem no crescimento e na estratégia funcional de coespecíficas em florestas contínuas. Aqui investigamos se há diferenças no crescimento, na estratégia funcional e na variação diâmétrica de espécies arbóreas coespecíficas em floresta contínua madura e em
fragmentos florestais na Amazônia central. Para isso, selecionamos 146 indivíduos de oito espécies arbóreas abundantes em floresta contínua madura e remanescentes em fragmentos florestais, que se distribuem ao longo do espectro de economia da madeira e ocupam desde o sub-bosque até o dossel superior da floresta. Usamos testes t pareados para investigar se os habitats selecionam diferenças nas taxas de crescimento diamétrico sazonais e anuais e na estratégia funcional. A identidade das árvores, determinadas características funcionais, variações na precipitação, volume de água no solo, na temperatura do ar e na disponibilidade de luz foram testadas como preditores de incrementos e encolhimentos diamétricos. Árvores nos fragmentos florestais tiveram menores taxas de crescimento absoluto anual, moldada pelo menor tamanho médio das árvores neste habitat. Quando tiramos o efeito do tamanho, mostramos que não há diferenças nas taxas de crescimento relativo anual e sazonal entre habitats, exceto no período mais chuvoso de 2018, onde os indivíduos da floresta contínua cresceram mais. Apesar de não haver diferença de crescimento entre os habitats, os indivíduos nos fragmentos florestais tiveram proporção de xilema ativo (em relação a área basal) quase 20 % e área foliar específica mais de 25 % maiores em relação aos indivíduos na floresta contínua. A identidade das árvores explicou a maior parte dos incrementos diamétricos, enquanto algumas características funcionais e variáveis climáticas foram os fatores mais importantes na explicação dos encolhimentos no diâmetro das árvores. Esse é um dos primeiros estudos que inferem sobre a resiliência das árvores que
persistem frente às mudanças ambientais causadas pela fragmentação. Mostramos que mesmo tendo variação nas estratégias funcionais e ocupando diferentes estratos verticais no dossel, algumas espécies arbóreas podem manter o ritmo de crescimento após a fragmentação através da aclimatação das características funcionais em direção à aquisição de recursos
Urban pollution greatly enhances formation of natural aerosols over the Amazon rainforest
Get PDFOne of the least understood aspects in atmospheric chemistry is how urban emissions influence the formation of natural organic aerosols, which affect Earth’s energy budget. The Amazon rainforest, during its wet season, is one of the few remaining places on Earth where atmospheric chemistry transitions between preindustrial and urban-influenced conditions. Here, we integrate insights from several laboratory measurements and simulate the formation of secondary organic aerosols (SOA) in the Amazon using a high-resolution chemical transport model. Simulations show that emissions of nitrogen-oxides from Manaus, a city of ~2 million people, greatly enhance production of biogenic SOA by 60–200% on average with peak enhancements of 400%, through the increased oxidation of gas-phase organic carbon emitted by the forests. Simulated enhancements agree with aircraft measurements, and are much larger than those reported over other locations. The implication is that increasing anthropogenic emissions in the future might substantially enhance biogenic SOA in pristine locations like the Amazon. © 2019, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply
Ecophysiology, genotoxicity, histopathology, and gene responses of naphthalene injected colossoma macropomum (Cuvier, 1818) exposed to hypoxia
Get PDFThe present study aimed to evaluate the biological responses of Colossoma macropomum to naphthalene injection and subsequent hypoxia exposure, emphasizing the expression of the tumor suppressor gene tp53. Tambaquis were intraperitoneally injected with naphthalene (50 mg/kg) and, after 96 hours, the fish were transferred to respirometry chambers and, submitted to progressive hypoxia for the determination of critical PO2. In a subsequent experiment, the fish received an intraperitoneal injection of naphthalene and were kept for 96 hours under normoxia. Successively, fish were challenged with acute hypoxia (PO2 <PO2 crit) during 6 hours. We observed that the PO2 crit was not affected by naphthalene injection. Moreover, hematological parameters were modulated only in response to hypoxia. Fish with naphthalene injection plus hypoxia exposure presented altered activity of the GST and CAT enzymes. Exposure to naphthalene also resulted in DNA damages, which was not influenced by hypoxia. Hypoxia accentuated the hepatic lesions caused by naphthalene, as well as it also impaired the transcription of tp53 in naphtalene injected fish, demonstrating the risks of contaminating aquatic environments, especially environments where hypoxic conditions are common and occur on a daily or on seasonal basis, as in the Amazon basin. © 2019, Sociedade Brasileira de Genética
Five different foods in initial development of siamese fighting fish (Betta splendens)
No full textThe aim of this study was to test the use of five different foods for the initial growth of the Betta splendens. The experiment was performed in randomized design with five treatments and five replications, 125 animals with average initial weight of 0.0013±0.0003 g and length averaging 0.56±0.04 cm. The treatments were: T1-Artemia nauplii, T2-egg yolk, T3-feed powder, T4-Daphnia and T5-plankton, provided for 30 days. At the end, we measured the standard length, total length, height, weight, specific growth rate, specific development rate and survival. Statistical difference was observed at 5% for survival and the level of 5% for other variables by the Tukey test, being the Artemia nauplii the food with best results for all variables, following then the egg yolk and feed powder that did not differ statistically. © 2019, BIOFLUX SRL. All rights reserved
Molecular-genetic analysis for validation of peach palm (Bactris gasipaes Kunt) landraces using RAPD markers
Get PDFNumerous landraces of peach palm (Bactris gasipaes var. gasipaes) have been described in the Neotropics and are conserved in a genebank of INPA. We used RAPD markers to analyze the genetic diversity of eight peach palm landraces and two wild populations. Eight primers generated 124 markers; 101 markers were polymorphic (81.5 %). Observed heterozygosity was 0.38 and polymorphism was 93 %, both slightly higher than in previous studies. Amazonian landraces presented high heterozygosity (0.30) and a percentage of polymorphism (87,8 %) similar to Central American landraces (0.29 and 83,5 %, respectively), different from previous studies, which found Central American landraces to have lower values than Amazonian landraces. The structure of the dendrogram with Nei s genetic distance was similar to that of previous studies, with minor differences. The two wild populations were grouped far from the landraces, suggesting that they did not participate in the domestication of the cultivated populations. © 2019 Universidade Estadual Paulista - UNESP. All rights reserved
On the future of the giant South American river turtle Podocnemis expansa
Get PDFThere is a long history of exploitation of the South American river turtle Podocnemis expansa. Conservation efforts for this species started in the 1960s but best practices were not established, and population trends and the number of nesting females protected remained unknown. In 2014 we formed a working group to discuss conservation strategies and to compile population data across the species' range. We analysed the spatial pattern of its abundance in relation to human and natural factors using multiple regression analyses. We found that > 85 conservation programmes are protecting 147,000 nesting females, primarily in Brazil. The top six sites harbour > 100,000 females and should be prioritized for conservation action. Abundance declines with latitude and we found no evidence of human pressure on current turtle abundance patterns. It is presently not possible to estimate the global population trend because the species is not monitored continuously across the Amazon basin. The number of females is increasing at some localities and decreasing at others. However, the current size of the protected population is well below the historical population size estimated from past levels of human consumption, which demonstrates the need for concerted global conservation action. The data and management recommendations compiled here provide the basis for a regional monitoring programme among South American countries. © Fauna & Flora International 2019
New records of nocturnal Anomaloninae (Hymenoptera: Ichneumonidae) in South America
Get PDFWe report for the first time Aphanistes ruthae Alvarado, 2018 in Venezuela and Castrosion renei Gauld & Bradshaw, 1997 in South America (Venezuela and Brazil). Castrosion renei is associated with the amazon rainforest in the Amazonas and Maranhão, States of Brazil
Precipitation mediates sap flux sensitivity to evaporative demand in the neotropics
No full textTranspiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature