682 resultados para Biotic communities.


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The Pernambuco Center of Endemism (PCE) in northeastern Brazil is highly fragmented and degraded. Despite its potential conservation importance the bird fauna in this area is still relatively unknown and there are many remnant fragments that have not been systematically surveyed. Here, we report the results of bird surveys in five forest fragments (one pioneer, two ombrophilous and two seasonal). In total, 162 taxa were recorded, 12 of which are endemic to the PCE. The frequency of endangered species was lower than what has been reported in studies from the same area and most of the taxa considered to be at risk of extinction were sub-species of uncertain taxonomic validity. The comparatively low number of endemic/threatened species may be due to the small size of the fragments in the present study - a consequence of the high levels of habitat loss in this region. Analysis of species richness patterns indicates that ombrophilous forest fragments are acting as refuges for those bird species that are most sensitive to environmental degradation.

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The zooplankton community presents stochastic temporal fluctuation and heterogeneous spatial variation determined by the relationships among the organisms and environmental conditions. We predicted that the temporal and spatial zooplankton distribution is heterogeneous and discrete, respectively, and that the daily variation of most abundant species is related to environmental conditions, specifically the availability of resources. Zooplankton samples were collected daily at three sampling stations in a lateral arm of the Rosana Reservoir (SP/PR). The zooplankton did not present significant differences in abundance and evenness among sampling stations, but the temporal variation of these attributes was significant. Abiotic variables and algal resource availability have significantly explained the daily variation of the most abundant species (p<0.001), however, the species distribution makes inferences on biotic relationships between them. Thus, not only the food resource availability is influential on the abundance of principal zooplankton species, but rather a set of factors (abiotic variables and biotic relationships).

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The objectives of Participant 4 were: - Establishment and maintenance of a representative collection of AM fungal species in vivo on trap plant cultures. - Study of the effects of early mycorrhizal inoculation in the growth and health of in vitro plantlets and their subsequent behaviour in the nursery. - Effect of the mycorrhization of in vitro produced bananas and plantains on plant growth and health, under biotic stress conditions (nematode and fungi)

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When we ask ourselves about a concrete definition of “Natural Capital” we can find a large and wide range of conceptions, which are attached to it. These can turn out to be confusing and contradictory in some cases. In theory, through books and different studies we know natural resources are composed by all the natural actives originated by the nature itself. Besides, these conform a patrimony for society as them are translated into a path towards economy: The Natural Capital. May not the Natural Capital be an easy conception to put in terms of economy it turns out to be an important capacitor for economy growth in most countries. In any case, we can clearly distinguish two ways as Natural Capital can be seen. One may elaborate a definition about it by reading what others have previously written, those who usually are quite far from the direct use of natural resources. On the other hand it would also be interesting to conform a definition of it by asking people who are constantly in contact with natural resources and consequently contribute to form the Natural Capital.

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Arbuscular mycorrhizal fungi (AMF) are symbiotic soil fungi that are intimately associated with the roots of the majority of land plants. They colonise the interior of the roots and the hyphae extend into the soil. It is well known that bacterial colonisation of the rhizosphere can be crucial for many pathogenic as well as symbiotic plant-microbe interactions. However, although bacteria colonising the extraradical AMF hyphae (the hyphosphere) might be equally important for AMF symbiosis, little is known regarding which bacterial species would colonise AMF hyphae. In this study, we investigated which bacterial communities might be associated with AMF hyphae. As bacterial-hyphal attachment is extremely difficult to study in situ, we designed a system to grow AMF hyphae of Glomus intraradices and Glomus proliferum and studied which bacteria separated from an agricultural soil specifically attach to the hyphae. Characterisation of attached and non-attached bacterial communities was performed using terminal restriction fragment length polymorphism and clone library sequencing of 16S ribosomal RNA (rRNA) gene fragments. For all experiments, the composition of hyphal attached bacterial communities was different from the non-attached communities, and was also different from bacterial communities that had attached to glass wool (a non-living substratum). Analysis of amplified 16S rRNA genes indicated that in particular bacteria from the family of Oxalobacteraceae were highly abundant on AMF hyphae, suggesting that they may have developed specific interactions with the fungi.

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Dissecting drivers of plant defence investment remains central for understanding the assemblage of communities across different habitats. There is increasing evidence that direct defence strategies against herbivores, including secondary metabolites production, differ along ecological gradients in response to variation in biotic and abiotic conditions. In contrast, intraspecific variation in indirect defences remains unexplored. Here, we investigated variation in herbivory rate, resistance to herbivores, and indirect defences in ant-attracting Vicia species along the elevation gradient of the Alps. Specifically, we compared volatile organic compounds (VOCs) and ant attraction in high and low elevation ecotypes. Consistent with adaptation to the lower herbivory conditions that we detected at higher elevations in the field, high elevation plants were visited by fewer ants and were more susceptible to herbivore attack. In parallel, constitutive volatile organic compound production and subsequent ant attraction were lower in the high elevation ecotypes. We observed an elevation-driven trade-off between constitutive and inducible production of VOCs and ant attraction along the environmental cline. At higher elevations, inducible defences increased, while constitutive defence decreased, suggesting that the high elevation ecotypes compensate for lower indirect constitutive defences only after herbivore attack. Synthesis. Overall, direct and indirect defences of plants vary along elevation gradients. Our findings show that plant allocation to defences are subject to trade-offs depending on local conditions, and point to a feedback mechanism linking local herbivore pressure, predator abundance and the defence investment of plants.

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Community studies of non-hospitalized children are essential to obtain a more thorough understanding of acute respiratory infections (ARI) and provide important information for public health authorities. This study identified a total ARI incidence rate (IR) of 4.5 per 100 child-weeks at risk and 0.78 for lower respiratory tract infections (LRI). Disease duration averaged less than one week and produced a total time ill with ARI of 5.8% and for LRI 1.2%. No clear seasonal variation was observed, the sex-specific IR showed a higher proportion of boys becoming ill with ARI and LRI and the peak age-specific IR occurred in infants of 6-11 months. Correlation with risk factors of the child (breastfeeding, vaccination, diarrheal disease, undernourishment) and the environment (crowding, living conditions, maternal age and education) showed marginal increases in the rate ratios, making it difficult to propose clear-cuts targets for action to lower the ARI and LRI morbidity. The importance of an integral maternal-child health care program and public education in the early recognition of LRI is discussed.

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Chrysomya albiceps specimens were derived from colonies kept under laboratory conditions. The oviposition period, total number of eggs-mass and the weight of the eggs-mass (average/female) presented significant differences between colonies regarding the sexual ratio of 1male/1female (situation I), when compared to the other ratios (1male/3female, situation II), (1male/5female, situation III), (3male/1female, situation IV) and (5 male/1female, situation V). It was ascertained that the increase in the proportion of females, resulted in higher weight and greater number of ovipositions and lenghtening of the period of oviposition, leads to a decrease in their lifespan.

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A better understanding of the factors that mould ecological community structure is required to accurately predict community composition and to anticipate threats to ecosystems due to global changes. We tested how well stacked climate-based species distribution models (S-SDMs) could predict butterfly communities in a mountain region. It has been suggested that climate is the main force driving butterfly distribution and community structure in mountain environments, and that, as a consequence, climate-based S-SDMs should yield unbiased predictions. In contrast to this expectation, at lower altitudes, climate-based S-SDMs overpredicted butterfly species richness at sites with low plant species richness and underpredicted species richness at sites with high plant species richness. According to two indices of composition accuracy, the Sorensen index and a matching coefficient considering both absences and presences, S-SDMs were more accurate in plant-rich grasslands. Butterflies display strong and often specialised trophic interactions with plants. At lower altitudes, where land use is more intense, considering climate alone without accounting for land use influences on grassland plant richness leads to erroneous predictions of butterfly presences and absences. In contrast, at higher altitudes, where climate is the main force filtering communities, there were fewer differences between observed and predicted butterfly richness. At high altitudes, even if stochastic processes decrease the accuracy of predictions of presence, climate-based S-SDMs are able to better filter out butterfly species that are unable to cope with severe climatic conditions, providing more accurate predictions of absences. Our results suggest that predictions should account for plants in disturbed habitats at lower altitudes but that stochastic processes and heterogeneity at high altitudes may limit prediction success of climate-based S-SDMs.

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The HIA Forum provides an opportunity for those with an interest in HIA to meet, share experiences, hear about new developments and consider how to progress HIA. 2009 HIA Forum events focused on how HIA can and is being used to support healthier communties.

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Presentation which considers how HIA can be used as a tool to support healthier communities

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Between January and March 1998, a cross-sectional survey was carried out in four rural communities in Honduras, Central America. We examined the prevalence and intensity of Ascaris lumbricoides and Trichuris trichiura infections among 240 fecal specimens, and the association between selected socio-demographic variables and infection for 62 households. The overall prevalence of A. lumbricoides and T. trichiura was 45% (95% CI 39.0-51.9) and 38% (95% CI 31.8-44.4) respectively. The most intense infections for Ascaris and Trichuris were found in children aged 2-12 years old. By univariate analysis variables associated with infections of A. lumbricoides were: number of children 2-5 years old (p=0.001), level of formal education of respondents (p=0.01), reported site of defecation of children in households (p=0.02), households with children who had a recent history of diarrhea (p=0.002), and the location of households (p=0.03). Variables associated with both A. lumbricoides and T. trichiura infection included: number of children 6-14 years old (p=0.01, p=0.04, respectively), ownership of a latrine (p=0.04, p=0.03, respectively) and coinfection with either helminth (p=0.001, p=0.001, respectively). By multivariate analysis the number of children 2-5 years living in the household, (p=0.01, odds ratio (OR)=22.2), children with a recent history of diarrhea (p=0.0, OR=39.8), and infection of household members with T. trichiura (p=0.02, OR=16.0) were associated with A. lumbricoides infection. The number of children 6-14 years old in the household was associated with both A. lumbricoides and T. trichiura infection (p=0.04, p=0.01, OR=19.2, OR=5.2, respectively).

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The western region of the Brazilian Amazon Basin has long been shown to be a highly endemic area for hepatitis B and hepatitis D viruses. Data concerning the prevalence of hepatitis C and E viruses in this region are still scarce. In this study we investigated the presence of hepatitis A, B, C, D and E viruses infection in communities that live along the Purus and Acre rivers in the states of Acre and Amazonas within the Amazon Basin. A total of 349 blood samples were collected and tested for hepatitis A-E serological markers (antibodies and/or antigens) using commercial enzyme linked immunosorbent assays. Anti-HCV positive sera were further assayed by an immunoblot. HBsAg positive sera were subtyped by immunodifusion. The overall prevalence for hepatitis A, B, C, and E were 93.7%, 66.1%, 1.7%, and 4%, respectively. A very high prevalence of delta hepatitis (66.6%) was found among HBsAg positive subjects. Hepatitis A, B and D viruses were shown to be largely disseminated in this population, while hepatitis C and E viruses infection presented low prevalence rates in this region. The analysis of risk factors for HBV infection demonstrated that transmission was closely associated with sexual activity.

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The purpose of this study was the evaluation of Helicobacter pylori infections in children and adults from two indigenous communities of Delta Amacuro State, Venezuela, that differ in hygienic conditions of the housing. The evaluation was performed in 98 children (mean age 7 ± 3.37 years) and their mothers (33.96 ± 13.77 years) from two communities of Warao lineage. Anti-H. pylori serum IgG and secretory anti-H. pylori IgA antibodies were de-termined, as well as total secretory IgA and H. pylori antigens in feces. Serological prevalence of H. pylori infection was 38% in children and 84% their in mothers. Children from the community that had the most deficient sanitary and hygienic conditions had significantly lower titers of specific IgG antibodies and total secretory IgA (P < 0.0001) and a high percentage of them had H. pylori antigens in their feces (P < 0.0001). The levels of specific IgA were similar in both groups. The results indicate that in these populations there is a high prevalence of H. pylori infection and that poor hygienic conditions can increase the risk of infection and damage to the gastrointestinal tract.