81 resultados para correspondence analysis


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Brazilian cerrado is a biologically-rich, poorly understood, yet rapidly disappearing habitat. Composition of the spider assemblages from areas of cerrado from three separate sites in the State of São Paulo, Brazil were sampled by beating the canopies and adjacent shrubs of three Myrcia (Myrtaceae; "myrtle") tree species. These produced a total of 859 spiders 'belonging to 21 families and 75 species. The most undisturbed and densest cerrado habitat had the largest number and greatest diversity of spider species, encompassing stalkers, ambushers, space web-weavers, and foliage runners. The other two areas were dominated by foliage runners. Spider distribution in this natural and complex habitat was evaluated by classifying the samples into 12 habitat/microhabitat groups according to local of the patch, tree species, and microhabitat (target tree or adjacent shrub). Correspondence analysis was used for ordination of species and groups based on their abundance. Environmental factors such as patches type (p=0.027) and plant species (p=0.046) had significant effects in explaining the ordination. Canonical correspondence analysis was applied for relating the patterns in species richness and/or abundance to the significant environmental factors. A comparison of the results showed that the family composition among the patches is rather similar, and there is a tendency of spiders species overlap an interregional level (patches effect, p=0.027). However, the most similar spider assemblages living on woody vegetation occurred in Myrcia venulosa and Myrcia guianensis at São Carlos and Pirassununga, demonstrating an interregional similarity (plant species effect, p=0.046) that indicates an association between spiders and particular vegetation.

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In this study, it was examined, during the period from March to December 2006, the effects of human disturbance on themacroinvertebrates that live near macrophytes in Guare River, São Paulo State - Brazil. It was questioned if the high conductivityrecorded in Guare River affected the distribution of the macroinvertebrates and what were the most important variables thataffect macroinvertebrates in a river with a strong nutrient concentration. The objective of this study was to investigate theeffects of environmental variables on densities and composition of the macroinvertebrates. Three stands of aquatic plantswere sampled with with 0.25 mm mesh net on a 0.07 m2 square metal frame. Air and water temperature, depth, pH, electricalconductivity, suspended solids, dissolved oxygen and macrophyte biomass were measured. A canonical correspondence analysis(CCA) was performed using the density of the macroinvertebrates and environmental variables. Chironomidae, Culicidae,Acanthagrion, Coryphaeschna, Erythrodiplax, Miathyria marcella, Micrathyria, Gastropoda, Ostracoda and Hemiptera werethe only taxa that showed significant correlation with the axes. From the results, we can conclude that the high conductivity recordedin Guare River due to the high amount of organic matter released during its course did not significantly affected thedistribution of the macroinvertebrates during the studied period. However, the ACC recorded that oxygen was the most significantenvironmental factor for the density variance of the macroinvertebrates, especially larval Odonata.

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Meat, flour and sugar baits were used on the soil surface and buried to examine species composition of the ant fauna in three separate tropical forests in Brazil, and to control for the effect of the regional faunal pool. Compositional mosaic diversities were comparable among areas, bait types and foraging strata. Mosaic diversity was independent of mean assemblage size. The number of unique species per sampling unit was correlated with mean assemblage size. Canonical correspondence analysis ordered species first by foraging substrate, second by geographic location, and third by diet. The first axis was significantly correlated with mean similarity and affinity. Mean Mahanalobis distances between centroids of groups based upon foraging strata were significantly larger than between localities, indicating local ecological pressures stronger than regional species pool constraints. As most. species foraged in only one stratum in one geographical position and were not omnivorous, the response of species to environmental gradients (continuums) showed a lower coherency with these patterns than did communities, structured around guilds based upon foraging strata and diet.

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We examined the relationships between topography, soil properties and tree species composition in a Neotropical swamp forest in southeastern Brazil. Plots were sampled in the forest, encompassing three different soil ground water regimes along the topographical declivity. All non-climbing plant individuals with trunk height >1.3 m were sampled. A canonical correspondence analysis-CCA-of the species-environmental relationships grouped tree species according to drainage and chemical soil conditions. A total of 86 species were found, being 77 species in the inferior, 40 species in the intermediate and 35 species in the superior topographic section. Some species were among the 10 most abundant ones, both in the overall sampled area and in each topographical section, with alternation events occurring only with their abundance position. However, substantial differences in floristic composition between sections were detected in a fine spatial scale, due to higher number of species, diversity index (H′) and species unique (exclusives) in the inferior topographic section. These higher values can be attributed to its higher spatial heterogeneity that included better drained and seasonally waterlogged soils, higher soil fertility and lower acidity. The increase of the soil water saturation and the uniform conditions derived from the superficial water layer has led to a lower number of species and an increase on the palm trees abundance in the intermediate and superior sections. Our results showed that at a small spatial scale niche differentiation must be an important factor related to the increase of the local diversity. The wide distribution of the most abundant species in the studied area and the increase of local diversity corroborate the pattern of distribution of species in larger scales of swamp forests, in which the most abundant species repeat themselves in high densities in different remnants. However, the floristic composition of each remnant is strongly variable, contributing to the increase of regional diversity. © 2008 Springer Science+Business Media B.V.

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Planktonic rotifers and cyclopoid copepods were studied in two reservoirs of different trophic states (eutrophic and oligo/mesoeutrophic) in the south of Brazil. During a year, monthly samplings were carried out in three stations in each reservoir. Species richness, frequency and abundance were used to find out useful and indicatives trends of water quality based on these organisms, reinforced by literature data. Species that showed higher differences between reservoirs were chosen. For Rotifera, richness, frequency and abundance of Brachionus were higher in the eutrophic reservoir, but Plationus patulus occurred only in the oligo/mesotrophic reservoir. For copepods, Tropocyclops prasinus dominated in the eutrophic reservoir, but Thermocyclops decipiens, T. minutus, T. inversus and Microcyclops anceps were dominants in the oligo/mesotrophic reservoir. In the canonical correspondence analysis, these species were indicators of the trophic state and were related with chlorophyll-a, total phytoplankton and total phosphorus. The use of these species can be efficient in the studied regions (subtropical/temperate), but comparing with other Brazilian reservoirs of tropical climate, the results could be different. Despite the dominance of T. decipiens over T. minutus, T. inversus has been widely used in Brazil as an indicator of eutrophic waters; in those cases of excessive eutrophication, other species, more rustic, commonly dominate. In the present study, Thermocyclops was dominant in the oligo/mesotrophic reservoir. The dominance of Brachionus for rotifers and Tropocyclops prasinus and Acanthocyclops robustus for copepods were indicative of eutrophic conditions.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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It is well established in the literature that musculoskeletal injuries are important compromising agents in the performance of Thoroughbred horses. In Brazil, there are no studies on the interrelation between lay-up period post-injury and retirement of racehorses due to musculoskeletal injures. The aim of this study is to determine the relationship between rehabilitation times of track injures and variables of prior race performance and later return to competitions. The radiographic reports and athletic history of 416 thoroughbreds during the period between 2003 and 2006 were examined; they were selected based on continued presentations after injury diagnosis. The temporal variables (post-injury rehabilitation time) and performance variables (race score before and after injury) were evaluated by multivariate correspondence analysis of the data and represented in perceptual maps. Correspondence was observed between most of the animals that had a short lay-up post-injury and variables that denote decline in subsequent performance. Considering the integrity of the bone healing process as crucial for the horse to be able to handle later training routines and competitions, shortening this period could lead to an imbalance of the bone repair metabolism, thus resulting in performance decline and compromise of the horse athletic career.

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Correspondence Analysis was adopted as tool for investigating the statistical structure of hydrochemical and weathering datasets of groundwater samples, with the main purpose of identifying impacts on mineral weathering caused by anthropogenic activities, namely fertilizing of farmlands. The hydrochemical dataset comprised measured concentrations of major inorganic compounds dissolved in groundwater, namely bicarbonate, silica (usually by-products of chemical weathering), chloride, sulphate and nitrate (typically atmospheric plus anthropogenic inputs). The weathering dataset consisted of calculated mass transfers of minerals being dissolved in loess sediments of a region located in SW Hungary (Szigetvár area), namely Na-plagioclase, calcite and dolomite, and of pollution-related concentrations of sodium, magnesium and calcium. A first run of Correspondence Analysis described groundwater composition in the study area as a system of triple influence, where spots of domestic effluents-dominated chemistries are surrounded by areas with agriculture-dominated chemistries, both imprinted over large regions of weathering dominated chemistries. A second run revealed that nitrification of N-fertilizers is promoting mineral weathering by the nitric acid reaction (anthropogenic pathway), in concurrence with the retreating of weathering by carbonic acid (natural pathway). It also indicated that dolomite and calcite are being players in a dedolomitization process driven by dissolution of gypsum fertilizers and nitrification of N-fertilizers. © 2013 Elsevier Ltd.

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Pós-graduação em Ciências Cartográficas - FCT

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)