RESUMO

Global demand for crops will continue increasing over the next few decades to cover both food and biofuel needs. This demand will put further pressure to expand arable land and replace natural habitats. However, we are only beginning to understand the combined effects of agrochemicals and land-use change on tropical freshwater biodiversity. In this study, we analyzed how pond-dwelling anuran larvae responded to pond characteristics, landscape composition, and agrochemical contamination in a sugarcane-dominated agroecosystem in Brazil. Then we used an information theoretical approach with generalized linear models to relate species richness and abundance to predictor variables. The variation in tadpole abundance was associated with both agrochemical concentration (e.g., ametryn, diuron, and malathion) and landscape variables (e.g., percentage of forest, percentage of agriculture, and distance to closest forest). The relationship between species abundance and agrochemicals was species-specific. For example, the abundances of Scinax fuscovarius and Physalaemus nattereri were negatively associated with ametryn, and Dendropsophus nanus was negatively associated with tebuthiuron, whereas that of Leptodactylus fuscus was positively associated with malathion. Conversely, species richness was associated with distance to forest fragments and aquatic vegetation heterogeneity, but not agrochemicals. Although we were unable to assign a specific mechanism to the variation in tadpole abundance based on field observations, the lower abundance of three species in ponds with high concentrations of agrochemicals suggest they negatively impact some frog species inhabiting agroecosystems. We recommend conserving ponds near forest fragments, with abundant stratified vegetation, and far from agrochemical runoffs to safeguard more sensitive pond-breeding species.

Assuntos

RESUMO

Abstract Here, we summarize examples of significant advances in amphibian research supported by the São Paulo Research Foundation (FAPESP), focusing on recent discoveries in the fields of community ecology, habitat change, infection diseases, and multipurpose DNA sequencing. We demonstrated that FAPESP has been fundamental not only by directly funding research projects and scholarships, but also through its science training policy, fostering international collaborations with world-class research institutions, improving and consolidating new lines of research that often depended on a synergetic combination of different knowledge and complex tools. We emphasized that future studies will continue to focus on basic questions, such as description of new species, as well as taxonomic and systematic corrections. Furthermore, we also expect that there will be a strong integration among different disciplines using novel bioinformatics tools and modeling approaches, such as machine learning. These new approaches will be critical to further develop our understanding of foundational questions of amphibian life-history trait variation, disease transmission, community assembly, biogeography, and population forecasts under different global change scenarios such as agricultural expansion, agrochemical use, habitat loss, and climate change.

Resumo No presente estudo apresentamos exemplos de avanços significativos nas pesquisas com anfíbios financiadas pela Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), focando em descobertas recentes nos campos de ecologia de comunidades, modificação do habitat, doenças infecciosas e o sequenciamento de DNA com múltiplos propósitos. Demonstramos que a FAPESP tem sido fundamental não somente pelo financiamento direto de projetos de pesquisa e bolsas de estudo, mas também através de sua política de formação científica, fomentando colaborações internacionais com instituições de pesquisa de excelência mundial, melhorando e consolidando novas linhas de pesquisa que frequentemente dependem da combinação sinérgica entre diferentes linhas de conhecimento e ferramentas complexas. Enfatizamos que futuros estudos continuem com foco em questões básicas, como a descrição de novas espécies, bem como correções taxonômicas e sistemáticas. Além disso, esperamos uma forte integração entre diferentes disciplinas usando novas ferramentas de bioinformática e abordagens de modelagem, como o aprendizado de máquina. Essas novas abordagens serão críticas para desenvolver ainda mais nossa compreensão a respeito de questões fundamentais sobre as características da história de vida dos anfíbios, transmissão de doenças, estrutura de comunidades, biogeografia e previsões populacionais em diferentes cenários de mudanças globais, como a expansão da agricultura, uso de agrotóxicos, perda de habitat e mudanças climáticas.

RESUMO

We partitioned the total beta diversity in the species composition of anuran tadpoles to evaluate if species replacement and nestedness components are congruent at different spatial resolutions in the Brazilian Atlantic Forest. We alternated the sampling grain and extent of the study area (among ponds at a site, among ponds within regions, among sites within regions, and among sites within regions pooled together) to assess the importance of anuran beta diversity components. We then performed variation partitioning to evaluate the congruence of environmental descriptors and geographical distance in explaining the spatial distribution of the species replacement and nestedness components. We found that species replacement was the main component of beta diversity, independent of the sampling grain and extent. Furthermore, when considering the same sampling grain and increasing the extent, the values of species replacement increased. On the other hand, when considering the same extent and increasing the sampling grain, the values of species replacement decreased. At the smallest sampling grain and extent, the environmental descriptors and geographic distance were not congruent and alternated in the percentage of variation explaining the spatial distribution of species replacement and nestedness. At the largest spatial scales (SSs), the biogeographical regions showed higher values of the percentage explaining the variation in the beta diversity components. We found high values of species replacement independently of the spatial resolution, but the processes driving community assembly seem to be dependent on the SS. At small scales, both stochastic and deterministic factors might be important processes structuring anuran tadpole assemblages. On the other hand, at a large spatial grain and extent, the processes restricting species distributions might be more effective for drawing inferences regarding the variation in anuran beta diversity in different regions of the Brazilian Atlantic Forest.

RESUMO

Anurans are a highly diverse group in the Atlantic Forest hotspot (AF), yet distribution patterns and species richness gradients are not randomly distributed throughout the biome. Thus, we explore how anuran species are distributed in this complex and biodiverse hotspot, and hypothesize that this group can be distinguished by different cohesive regions. We used range maps of 497 species to obtain a presence/absence data grid, resolved to 50×50 km grain size, which was submitted to k-means clustering with v-fold cross-validation to determine the biogeographic regions. We also explored the extent to which current environmental variables, topography, and floristic structure of the AF are expected to identify the cluster patterns recognized by the k-means clustering. The biogeographic patterns found for amphibians are broadly congruent with ecoregions identified in the AF, but their edges, and sometimes the whole extent of some clusters, present much less resolved pattern compared to previous classification. We also identified that climate, topography, and vegetation structure of the AF explained a high percentage of variance of the cluster patterns identified, but the magnitude of the regression coefficients shifted regarding their importance in explaining the variance for each cluster. Specifically, we propose that the anuran fauna of the AF can be split into four biogeographic regions: a) less diverse and widely-ranged species that predominantly occur in the inland semideciduous forests; b) northern small-ranged species that presumably evolved within the Pleistocene forest refugia; c) highly diverse and small-ranged species from the southeastern Brazilian mountain chain and its adjacent semideciduous forest; and d) southern species from the Araucaria forest. Finally, the high congruence among the cluster patterns and previous eco-regions identified for the AF suggests that preserving the underlying habitat structure helps to preserve the historical and ecological signals that underlie the geographic distribution of AF anurans.

Assuntos

RESUMO

Tetranychus evansi is an important pest of tomato in several countries. The predatory mite Phytoseiulus longipes has been found in association with it in Uruguaiana, State of Rio Grande do Sul, Brazil. The objective of this study was to evaluate the distribution of those two species in Uruguaiana region. Bi-weekly samples of plant parts were taken between January 28 and April 30, 2007 in Uruguaiana and five neighboring counties. Tetranychus evansi was found in all counties, but P. longipes was only found in Uruguaiana, mainly in the urban area. It is conceivable that such restricted distribution of P. longipes is due to its recent introduction to the region. Alternatively, unfavorable winter conditions could prevent its persistence, except in protected places. Buildings and vegetation characteristics of the urban area of Uruguaiana could moderate strong winds, intense rainfall and low temperatures that commonly occur in the area.

Assuntos