Ecologia trófica em uma taxocenose de anfíbios: estrutura, filogenia e especialização individual

Historically, ever since the pre-Darwinian naturalists interspecific competition was considered the main force responsible for structuring ecological communities. This interpretation lost strength in the late 70s and throughout the 80s giving room for other views, which consider other factors such as predation, parasitism and the phylogenetic inertia more important. Studies on changes in the trophic niche of a species are still uncommon in general and especially in amphibians. Species considered generalist might actually be a group of individual specialists, or individuals that specialize in a particular category of prey during a period of scarcity of resources, thus reducing intraspecific competition. This work studied the community structure of litter amphibians and trophic variation along the dry and rainy seasons in a population of Leptodactylus macrosternum. Sixteen-litter frog species were studied for their diet. Two central assumptions were tested: 1a) if the community is structured in the niche trophic level, and 1b) if there is a significant difference in the use of food resources by different species (i.e. if the community is structured), the observed structure is the result of ecological interactions or just the current phylogenetic inertia of species. Finally, 2) if there is variation in food resource use between seasons for L. macrosternum. The community showed a structure with respect to the use of food resources, and this structure persisted after taking into account the phylogenetic relationships among species. The diet of Leptodactylus macrosternum varied with the seasons, with a significant degree of individual specialization for the dry season. Patterns of a local community are important to understand its dynamics, and this may play a role in larger- scale processes. Therefore, the studies in community ecology are fundamental to understand and eventually restoring degraded areas

Ecologia trófica de anfíbios anuros: relações filogenéticas em diferentes escalas

Understand the origin, maintenance and the mechanisms that operate in the current biodiversity is the major goal of ecology. Species ecology can be influenced by different factors at different scales. There are three approaches about the ecological differences between species: the first brings that differences result from current processes on niche characteristics (e.g. diet, time, space); the second that species differences are explained by random patterns of speciation, extinction and dispersion, the third that historical events explain the formation and composition of species in communities. This study aims to evaluate the influence of phylogenetic relationships in determining ecological characteristics in amphibians (globally) and test with that, if ecological differences between species of frogs are the result of ancient pre-existing differences or as result of current interactions. Another objective of this study is to verify if ecological, historical or current characteristics determine the size of species geographical distribution. The diet data for analysis of trophic ecology were collected from published literature. We performed a non-parametric MANOVA to test the existence of phylogenetic effects in diet shifts on frogs history. Thus, it is expected to know the main factors that allow the coexistence of anuran species. We performed a phylogenetic regression to analyze if niche breadth, body size and evolutionary age variables determine the size of the geographical distribution of amphibians in the Amazon. In the present study, new contributions to knowledge of major ecological patterns of anurans are discussed under a phylogenetic perspective

Morfologia larval e sua importância para a sistemática e taxonomia de anfíbios anuros

Os anfíbios anuros formam um grupo comprovadamente monofilético e apresentam várias características em comum que estão relacionadas, principalmente, a adaptação das espécies à ambientes úmidos, aonde estas se desenvolvem e reproduzem. Apesar da restrição do ambiente de reprodução, as espécies de anfíbios anuros apresentam grande diversidade morfológica, como também a maior diversidade de modos reprodutivos relatados para todos os grupos de tretápodas atuais. O Brasil é o país com maior riqueza de anfíbios anuros com, aproximadamente, 950 espécies descritas até o momento. A maioria das espécies do território brasileiro apresentam uma fase larval que, na maioria dos casos, se desenvolve no ambiente aquático e não apresenta qualquer semelhança com a sua forma adulta, seja na sua morfologia ou no nicho ecológico que ocupa. As larvas de anfíbios anuros são comumente utilizadas em estudos taxonômicos e fornecem informações importantes que auxiliam na classificação das espécies. Além disso, a identificação das espécies baseadas na forma larvária facilitam estudos de ecologia de populações e comunidades, como também, tornam mais precisos inventários faunísticos. Apesar disso, aproximadamente 50% dos girinos das espécies de anuro que ocorrem no território brasileiro não são conhecidas e existem poucos trabalhos com foco na variação dos caracteres larvais ao longo de várias populações, o que dificulta a avaliação da sua utilidade em estudos taxonômicos e pode contribuir, por exemplo, para a existência de espécies crípticas. Além disso, existem poucos trabalhos que descrevem a diversidade morfológica larval com enfoque em regiões específicas e, no Brasil, exsitem, apenas, três chaves de identificação de espécies com base nos caracteres larvais. A falta de descrições afeta diretamente trabalhos sobre anurofauna no país, e dificultam o desenvolvimento de trabalhos experimentais ou de interações ecológicas, por exemplo. Logo, descrições de girinos são necessários para tornar mais completo o conhecimento sobre a anurofauna das espécies que ocorrem no território brasileiro. Com isso, este trabalho teve como objetivo fornecer dados que complementam o conhecimento existente sobre as formas larvais no território brasileiro, com foco na anurofauna da região sudeste do Estado do Rio Grande do Norte. Neste trabalho, são descritos os girinos de cinco espécies cuja forma larval ainda não era conhecida, como também, elaboro uma chave de identificação dicotômica baseada em caracteres larvais para a região sudeste do Estado do Rio Grande do Norte e comento sobre a utilidade dos caracteres larvais para a taxonomia e sistemática dos diversos grupos de anfíbios anuros abordados neste trabalho. Além disso, uma nova espécie do gênero Pseudopaludicola é descrita e os caracteres larvais auxiliaram em sua diagnose e na diferenciação de congeneros. Os resultados gerados aqui poderão ser úteis ou auxiliar em trabalhos futuros que necessitem da identificação das formas larvais de anfíbios anuros, principalmente, no Estado do Rio Grande do Norte.

Ecologia de comunidades e comportamento reprodutivo de anfíbios anuros em savana amazônica

The Amazon savannas occur as isolated patches throughout extensive areas of forest in the states of Amapá, Amazonas, Pará, and Roraima. There is a considerable variation in the composition of anuran assemblages in the localities and phytophysiognomies of Amazon savannas and given the absence of studies on reproductive behavior, a systematic and geographically wide sampling has been carried out in the Amapá savanna, located in the Eastern Amazon. The study was conducted in a savanna area in the state of Amapá to examine the composition, ecology, and reproductive behavior of anuran amphibians. We carried out 24 field trips in each phytophysiognomy (gramineous-woody savana, gramineous-herbaceous-woody savana, park savana, and arboreal savanna); for analysis of reproductive behavior observations were made during the period January to December 2013, lasting four consecutive days. Samples were collected by active and acoustic search along 20 plots of 100x50 meters. Twenty-one anuran species were recorded, of which four are new records for the state of Amapá: Dendropsophus walfordi, Scinax fuscomarginatus, Pseudopaludicola boliviana e Elachistocleis helianneae. The KruskalWallis ANOVA revealed significant differences between richness and species diversity in the phytophysiognomies (p < 0.05). The Bray-Curtis similarity coefficient divided the phytophysiognomies into three groups: arboreal savana, gramineous-woody savanna and gramineous-herbaceous-woody savanna, and park savanna. According to the non-metric multidimensional scaling, the structure of the anuran community resulted in a separation into three phytophysiognomies, with significant differences in the structure of communities (ANOSIM, R = 0.823; p < 0.001). In the study of community ecology, the results obtained for spatial, temporal, and trophic niche breadth suggest that the assemblage of anurans of the Amapá savanna is not composed of predominantly generalist species. Also, the presence of other specialist anurans may explain the processes of speciation associated with the isolation of habitats, resulting in heterogeneity and spatial discontinuity in the phytophysiognomies with open formations. The null model analysis revealed that the community is structured based on temporal and trophic niche, indicating a significant influence of contemporary ecological factors on the assemblage. The absence of structure based on spatial niche might be explained by the spatial segregation in the distribution and occupation of anurans in the different phytophysiognomies of the Amapá savanna. Regarding the reproductive behavior of anurans, 11 species were classified as having a long breeding season, intrinsically associated with the rainy season and the reproductive mode of most species that lay egg clutches in lentic water bodies. Six reproductive modes were recorded and parental care was observed in Leptodactylus macrosternum and L. podicipinus, whose reproductive mode is characterized by foam nests. Regarding behavioral reproductive strategies, calling males were observed in all species of anurans, satellite males were recorded only for D. walfordi, Hypsiboas multifasciatus, S. nebulosus and S. fuscomarginatus; active search for females was observed for Phyllomedusa hypochondrialis and L. fuscus, and male displacement was recorded only for Rhinella major and R. margaritifera. Of the reproductive behaviors observed, throat and vocal sac display is associated with courtship and territorial behavior exhibited by males. In addition to courtship behavior, visual signals associated with courtship strategies were recorded for the anurans of the Amapá savanna.

Diversidade de espécies e ecologia da comunidade de lagartos de um fragmento de Mata Atlântica no nordeste do Brasil

Neste estudo foram investigadas a diversidade, a composição, e as diferenças no uso do espaço (hábitat e microhábitat) e do alimento em uma comunidade de lagartos habitantes da serapilheira de um fragmento de Mata Atlântica, do Estado de Alagoas, Brasil. Para a observação e/ou coleta dos espécimes, foram utilizados os métodos de busca ativa e armadilhas de queda (pit-fall traps) sem cerca-guia. Para análises de diversidade e da existência de diferenças de diversidade entre os hábitats e microhábitats, utilizou-se o índice de Shannon. A largura dos nichos espacial (hábitat e microhábitat) e alimentar foi avaliada, utilizando-se o índice de diversidade de Simpson. A similaridade entre as áreas foi averiguada utilizando-se o índice de Jaccard. Para avaliar o grau de sobreposição quanto ao uso do espaço (hábitats e microhábitats) e do alimento pelas espécies, foi utilizada uma versão da equação de MarcArthur & Levis. Foram obtidas vinte e três espécies de lagartos, pertencentes a nove famílias; destas, dezenove foram obtidas no interior da mata e nove na borda. Para o interior da mata as espécies mais abundantes foram Kentropyx calcarata, Dryadosaura nordestina, Enyalius catenatus e Gymnodactylus darwinii. Na borda da mata as espécies mais abundantes foram Tropidurus hispidus, T. semitaeniatus, Ophiodes striatus e Ameiva ameiva. Quanto à utilização dos recursos, os resultados mostraram que espécies filogeneticamente próximas nem sempre utilizam de maneira semelhante os recursos disponíveis. A dieta em geral foi composta por artrópodes. Tropidurus hispidus e T. semitaeniatus se mostraram especialistas no consumo de Himenoptera (Formicidae), que estiverem presentes em 100% dos seus estômagos. Ophiodes striatus teve como principal alimento caramujos (Gastropoda) e aranhas com 60% cada; sendo Gastropoda mais abundante para esta espécie

Determinantes locais da decomposição foliar e de raízes finais em um ecossistema semiárido do nordeste brasileiro

The decomposition process exercises an extensive control over the carbon cycle, affecting its availability and nutrient cycling in terrestrial ecosystems. The understanding of leaf decomposition patterns above the soil and fine roots decomposition below the soil is necessary and essential to identify and quantify more accurately the flow of energy and matter in forest systems. There is still a lack of studies and a large gap in the knowledge about what environmental variables act as local determinants over decomposition drivers. The knowledge about the decomposition process is still immature for Brazilian semiarid region. The aim of this study was to analyze the decomposition process (on leaves and fine roots) of a mixture of three native species for 12 months in a semiarid ecosystem in Northeast Brazil. We also examined whether the rate of decomposition can be explained by local environmental factors, specifically plant species richness, plant density and biomass, soil macro-arthropods species richness and abundance, amount of litterfall and fine root stock. Thirty sampling points were randomly distributed within an area of 2000 m x 500 m. To determine the decomposition rate, the litterbag technique was used and the data analysis were made with multiple regressions. There was a high degradation of dead organic matter along the experiment. Above ground plant biomass was the only environmental local factor significantly related to leaf decomposition. The density of vegetation and litter production were positively and negatively related to decay rates of fine roots, respectively. The results suggest that Caatinga spatial heterogeneity may exert strong influences over the decomposition process, taking into account the action of environmental factors related to organic matter exposure of and the consequent action of solar radiation as the decomposition process main controller in this region

Variabilidade acústica e respostas evolutivas a diferentes pressões seletivas no canto de anúncio de anfíbios

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Borboletas no semiárido: sazonalidade e padrões de diversidade de borboletas frugívoras em um ambiente extremo

The spatial and temporal distribution of the population reflects the adjustment of their biological characteristics to environmental conditions and biotic interactions as adaptive and phylogenetic precursors elements. The habitat’s heterogeneity and alternating seasons tend to cause patterns of activity of organisms and species diversity. However, these seasonal and spatial patterns in butterfly communities in dry environments are not yet clear. We studied a community of frugivorous butterflies in ESEC Seridó, in northeastern Brazil, aiming to characterize the guild in semiarid and check the relative contribution of climate and vegetation variables on its composition, diversity and phenofaunistic. The butterflies were sampled monthly during one year, and the distribution of species was associated with structural characteristics of three vegetation types (eg. richness and abundance of tree and shrub species, canopy cover, herbaceous cover, litter) and climatological data (temperature, rainfall and humidity). We captured 9580 individuals of 16 species of butterflies belonging to four subfamilies (Biblidinae, Charaxinae, Nymphalinae and Satyrinae). The richness, abundance and diversity varied in different scales, especially in time, being higher in the rainy season, while the β-diversity and turnover was higher in the dry. The distribution of species mainly followed the changes in humidity, rainfall and vegetation phenology, with no defined boundaries between habitats. The flight period was shared within subfamilies, which should have distinct response to environmental stimuli, as well as respond to the phenology of host plants and have different reproductive strategies. There is even evidence of physiological and behavioral adaptations as seasonal reproduction and aestivation. So there was environmental control over the distribution and diversity of species, with the key role climate Association and vegetation structure in the community of differentiation in the seasons, and the availability and quality of resources on the variation of species abundance in small scales. These results may support the biomonitoring and conservation preserved areas, particularly in environments under human pressure and extreme environmental conditions such as semi-arid.