Correlates of Zooplankton Beta Diversity in Tropical Lake Systems

The changes in species composition between habitat patches (beta diversity) are likely related to a number of factors, including environmental heterogeneity, connectivity, disturbance and productivity. Here, we used data from aquatic environments in five Brazilian regions over two years and two seasons (rainy and dry seasons or high and low water level periods in floodplain lakes) in each year to test hypotheses underlying zooplankton beta diversity variation. The regions present different levels of hydrological connectivity, where three regions present lakes that are permanent and connected with the main river, while the water bodies of the other two regions consist of permanent lakes and temporary ponds, with no hydrological connections between them. We tested for relationships between zooplankton beta diversity and environmental heterogeneity, spatial extent, hydrological connectivity, seasonality, disturbance and productivity. Negative relationships were detected between zooplankton beta diversity and both hydrological connectivity and disturbance (periodic dry-outs). Hydrological connectivity is likely to affect beta diversity by facilitating dispersal between habitats. In addition, the harsh environmental filter imposed by disturbance selected for only a small portion of the species from the regional pool that were able to cope with periodic dry-outs (e.g., those with a high production of resting eggs). In summary, this study suggests that faunal exchange and disturbance play important roles in structuring local zooplankton communities.     

Disturbances due to increased salinity and the resilience of zooplankton communities: the potential role of the resting egg bank

When faced with disturbances such as increased salinity, aquatic communities inhabiting inland coastal systems change and may or may not be resilient after salinity decreases. The purpose of this study was to assess the potential role of the resting egg bank for zooplankton community resilience. We predicted that (1) hatching of resting eggs is inhibited by increased salinities and (2) resting eggs remain viable when exposed to salinity and hatch when returned to freshwater. At the community level, we evaluated the hatching responses and the short-term viability of resting eggs exposed to a salinity gradient. The hatching of resting eggs was inhibited at higher salinities (16.0 and 32.0 g l^?1). However, some resting eggs remained viable and hatched when returned to freshwater. Additionally, combining our experimental results to previously published field data, we observed that the pattern of hatching during exposure to salinity matches the temporal succession observed in the zooplankton community at our model system, after increased salinity. The recovery of zooplankton communities after disturbances involving increased salinity is likely facilitated by the presence of an egg bank. This finding has important implications for the recovery of zooplankton communities and the management of aquatic systems vulnerable to salinization worldwide.     

Evidence for positive selection in the gene <Emphasis Type="Italic">fruitless</Emphasis> in <Emphasis Type="Italic">Anastrepha</Emphasis>fruit flies

Background  

Many genes involved in the sex determining cascade have indicated signals of positive selection and rapid evolution across different species. Even though fruitless is an important gene involved mostly in several aspects of male courtship behavior, the few studies so far have explained its high rates of evolution by relaxed selective constraints. This would indicate that a large portion of this gene has evolved neutrally, contrary to what has been observed for other genes in the sex cascade.     

How ethnobotany can aid biodiversity conservation: reflections on investigations in the semi-arid region of NE Brazil

Ethnobotany is a relatively new discipline but its social and scientific roles are becoming more consistently defined and its importance as a tool for complimenting management and conservation strategies at local and regional levels is now well recognized by the scientific community throughout the world. In the present work we have collected information from four years of ethnobotanical study in an area of caatinga vegetation in the semi-arid region of northeastern Brazil with the goal of defining a model for conservation and management actions in the region. Drawing on ethnobotanical and ecological information obtained through traditional techniques of ethnobotanical and vegetation surveys, we discuss the uses of 166 native and exotic plant species and suggest specific actions and specific groups of species for conservation and sustainable use programs. We also discuss the limitations of our approach and indicate what information must still be collected in order to construct robust and workable plans of action.     

Trypanosoma evansi: Effect of experimental infection on the osmotic fragility, lipid peroxidation and calcium-ATPase activity of rat red blood cells

Trypanosoma evansi is the causative agent of equine trypanosomoses. The disease is characterized by fever, anemia, and cachexia. Peroxidative damage of the red blood cells caused by the parasite, may contribute to the pathogenesis of the anemia seen in trypanosomoses. Consequently, we evaluated the hematocrit, the osmotic fragility of the red blood cells, the level of lipid peroxidation and the activity of the Ca-ATPase of red blood cell ghosts from rats experimentally infected with T. evansi. After 72 h inoculation, the hematocrit decreased from 49.5% to 33%; the osmotic fragility of the red blood cells was approximately 40% higher as compared to the healthy animals; and the red blood cell ghosts showed a higher level of lipid peroxidation and a lower Ca-ATPase activity than the red cell ghosts from the healthy animals. In vitro incubations of red blood cells from healthy animals with T. evansi, produced also a significant increase of the osmotic fragility of the red blood cells.     

Immune response to the mumps component of the MMR vaccine in the routine of immunisation services in the Brazilian National Immunisation Program

A non-controlled longitudinal study was conducted to evaluate the combined vaccine against measles, mumps and rubella (MMR) immunogenicity in 150 children vaccinated in the routine of three health units in the city of Rio de Janeiro, Brazil, 2008-2009, without other vaccines administered during the period from 30 days before to 30 days after vaccination. A previous study conducted in Brazil in 2007, in 1,769 children ranging from 12-15 months of age vaccinated against yellow fever and MMR simultaneously or at intervals of 30 days or more between doses, had shown low seroconversion for mumps regardless of the interval between administration of the two vaccines. The current study showed 89.5% (95% confidence interval: 83.3; 94.0) seroconversion rate for mumps. All children seroconverted for measles and rubella. After revaccination, high antibody titres and seroconversion rates were achieved against mumps. The results of this study and others suggest that two MMR doses confer optimal immunoresponses for all three antigens and the possible need for additional doses should be studied taking into account not only serological, but also epidemiological data, as there is no serological correlate of protection for mumps.     

The role of native vegetation on infection rates of Calacarus heveae (Acari: Eriophyidae) by Hirsutella thompsonii (Ascomycota: Ophiocordycipitaceae)

Hirsutella thompsonii (Fischer) (Ascomycota: Ophiocordycipitaceae), a fungal pathogen, often causes high mortality in populations of Calacarus heveae Feres (Acari: Eriophyidae), an important pest mite in rubber tree plantations (Hevea brasiliensis Muell. Arg., Euphorbiaceae). However, the ecological and climatic factors regulating this host-pathogen system are poorly known. We compared fungal infections in agroforestry and traditional rubber plantations to evaluate the role of native vegetation and climatic factors on infection rates of C. heveae by H. thompsonii. While the prevalence of H. thompsonii was higher in managed rubber tree plantations, the abundance of C. heveae was about three times higher in traditional plantations. Abundance of C. heveae, agroecosystem management type and microclimatic variables were responsible for driving the infection rates of H. thompsonii. Native vegetation was a source for H. thompsonii and also modified the crop’s microclimate, which contributed to its maintenance in the crop fields. Therefore, appropriate management practices may enhance the effects of entomopathogens on conservative biological control of pest mites in agroforestry systems.     

Linking disturbances in neotropical landscapes with ecosystem functional traits: A preliminary assessment using epigaeic and leaf-litter ant communities

1. Environmental stressors and changes in land use have led to rapid and dramatic species losses and a reduction in associated ecosystem services.
2. Functional diversity has increasingly been suggested as an alternative for evaluating anthropogenic disturbances and restoration programs because it reflects different aspects of the relationship between biological diversity, ecosystem functioning and environmental constraints.
3. Ants are important components of terrestrial food webs and a key group associated with diverse interactions and ecosystem processes.
4. Additionally, their sensitiveness and rapid response to environmental changes pave the way for their use as informative metrics for monitoring several processes that threaten biodiversity and ecosystem services.
5. Consequently, ants' functional diversity might be considered leading edge indicators to assess ecosystem changes to ongoing anthropogenic disturbances.
6. The purpose of this study was to gauge the usefulness of epigaeic and leaf-litter ants' functional responses towards measuring ecosystem degradation (and/or restoration) in the Brazilian Amazon.
7. Our results demonstrate that functional traits exhibited sensitivity to ongoing changes, as well as different responses to specific environmental disturbances.
8. Communities supporting ants with specialised functional traits associated with pristine ecosystems suffered high species loss and were correlated with specific anthropogenic stressors.
9. The results obtained pinpoint the importance of pristine ecosystems for conserving unique functional attributes and biodiversity in neotropical forest landscapes.
10. We highlight the significance of further studies in this scope to guide environmental managers and practitioners in applying the best policies for integrated neotropical landscapes conservation, considering the competing interests of farmers, foresters and conservationists, but also the unpredictable effects of local and regional environmental changes.