Recognition of the main geobotanical features along the Bragança mangrove coast (Brazilian Amazon Region) from Landsat TM and RADARSAT-1 data

Orbital remote sensing data were assessedfor mapping of the main geomorphologicaland vegetation units of the Bragançapeninsula (North Brazil), which belongs toa vast though sparsely mapped mangrovecoast. Wide wetland environmentscharacterize the region with extremevariations in extension, temporalevolution, and spatial complexity. Thiswork was based on different digitalprocessing techniques separately applied toLandsat TM and RADARSAT-1 images. Inaddition, both data were merged on apixel-to-pixel basis using algorithms,which rendered an enhancement of thecoastal landforms and a betterdiscrimination of wetlands and landformtypes. The interpretation of the integratedproduct, aided by field validation, made itpossible to significantly extend existingmapping. Nineteen geobotanical units wereidentified: estuarine channels, submergedsand banks, sandflats, old estuarinesandbanks, mudflats, ebb-tidal deltas,barrier-beach ridges, coastal dunes,chenier sand ridges, young intertidalmangroves, intertidal and supratidalmangroves, outer and inner marshes, fluvialflood plains, coastal plateau, degraded andregenerated mangroves, and an artificiallagoon. The digital integration of Fine RADARSAT-1 and Landsat TM data sensitivelyhighlighted geobotanical coastal features,providing a useful tool for a synopticanalysis of their natural and man-drivenchanges.     

A revision of the Neotropical genus Paraberismyia Woodley (Diptera,Stratiomyidae, Beridinae) with three new species

The Neotropical genus Paraberismyia Woodley, 1995, is revised. Three new species, P. chiapas sp. n., P. mathisi sp. n., and P. triunfo sp. n. are described, all having type localities in Chiapas, Mexico. A key to the four known species is provided.     

Was it an explosion? Using population genetics to explore the dynamics of a recent radiation within Protea (Proteaceae L.)

Adaptive radiations likely underlie much of the world’s diversity, especially that of hyper‐diverse regions. They are usually characterized by a burst of speciation early in their evolutionary history, a pattern which can be detected using population genetic tools. The Cape Floristic Region (CFR) of southwestern South Africa is home to many spectacular plant radiations. Here, we investigate the white proteas (Protea section Exsertae), a typical CFR radiation, to determine if it demonstrates the burst of speciation associated with adaptive radiations in recent models. Inferences from individual assignment, tree‐based population relationships, and pairwise F‐statistics based on 10 microsatellite loci reveal that while the white proteas radiated recently they did not radiate explosively. In addition, we found evidence that there is little gene flow between sampled populations of most species. Taken together, these results demonstrate that within a small clade, the processes underlying the radiation are different from those envisioned by current models of adaptive radiation and suggest that geographical isolation could have played a role in the diversification of the group. Our study implicates both adaptive and non‐adaptive processes in the evolution of botanical diversity of the CFR.     

Land use and climate influences on waterbirds in the Prairie Potholes

Aim We examined the influences of regional climate and land‐use variables on mallard (Anas platyrhynchos), blue‐winged teal (Anas discors), ruddy duck (Oxyura jamaicensis) and pied‐billed grebe (Podilymbus podiceps) abundances to inform conservation planning in the Prairie Pothole Region of the United States. Location The US portion of Bird Conservation Region 11 (US‐BCR11, the Prairie Potholes), which encompasses six states within the United States: Montana, North Dakota, South Dakota, Nebraska, Minnesota and Iowa. Methods We used data from the North American Breeding Bird Survey (NABBS), the National Land Cover Data Set, and the National Climatic Data Center to model the effects of environmental variables on waterbird abundance. We evaluated land‐use covariates at three logarithmically related spatial scales (1000, 10,000 and 100,000 ha), and constructed hierarchical spatial count models a priori using information from published habitat associations. Model fitting was performed using a hierarchical modelling approach within a Bayesian framework. Results Models with the same variables expressed at different scales were often in the best model subset, indicating that the influence of spatial scale was small. Both land‐use and climate variables contributed strongly to predicting waterbird abundance in US‐BCR11. The strongest positive influences on waterbird abundance were the percentage of wetland area across all three spatial scales, herbaceous vegetation and precipitation variables. Other variables that we included in our models did not appear to influence waterbirds in this study. Main conclusions Understanding the relationships of waterbird abundance to climate and land use may allow us to make predictions of future distribution and abundance as environmental factors change. Additionally, results from this study can suggest locations where conservation and management efforts should be focused.     

Freshwater marsh vegetation response to flooding patterns in the lower delta of the Parana river

Freshwater marshes are the only significant natural ecosystems remaining in the Buenos Aires province section of the Lower Delta of the Parana River (Argentina), occupying 80% of the total island area. The Lower Delta hydrology is dominated mainly by the Parana river and the De La Plata estuary; different temporal superpositions of floods and landscape configurations of the islands result in four distinct flooding patterns. We studied the response of freshwater marsh vegetation to the flooding patterns using principal component analysis and cluster analysis. The study area was gridded and 13 cells were selected representing the different flooding patterns. We found significant environmental heterogeneity in the region and a consequent response in the vegetation, expressed through successive species replacements, and variation in species richness and the number and type of dominant species. The environmental heterogeneity of the region is caused by hydrological variations, geomorphological changes in the islands from upstream to downstream areas of the delta, and patterns of human activity.     

Potential role of vaccines in elimination of Plasmodium vivax

The unique biology of Plasmodium vivax, with its ability to form latent hypnozoites in the liver stage and the early appearance of gametocytes during blood stage infection, makes it difficult to target for elimination with standard malaria control tools. Here, we use modelling studies to demonstrate that vaccines that target different stages of P. vivax could greatly assist efforts to eliminate P. vivax. Combination of vaccines that target different P. vivax life cycle stages may be required to achieve high efficacy. Our simulations demonstrate that repeated rounds of mass vaccination with multi-stage vaccines can help achieve pre-elimination levels of P. vivax in both low and high transmission settings. We review the status of global efforts to develop vaccines for P. vivax malaria. We describe the status of the leading P. vivax vaccine candidates and share some thoughts on the prospects for availability of an effective vaccine for P. vivax malaria.