A case of pulmonary cryptococcosis in a free-living toad (Bufo bufo)

Pulmonary cryptococcosis was observed in a free-living adult female common toad (Bufo bufo) that was killed by a vehicle. Both lungs had various eosinophilic, monomorphic, and spherical to elliptical organisms identified as Cryptoccocus spp. The yeasts were demonstrated by Grocott's silver method and the periodic acid-Schiff reaction and the capsule was positive for mucin with a mucicarmine stain. The agent was confirmed by immunohistochemistry, using the monoclonal antibody anti-Cryptococcus neoformans, and by a polymerase chain reaction-based method using a C. neoformans-specific primer. This report, to the best of our knowledge, represents the first case of cryptococcosis in a common toad.     

Genetic diversity and population structure of Eugenia dysenterica DC. (``cagaiteira' – Myrtaceae) in Central Brazil: Spatial analysis and implications for conservation and management

Studies about the organization of the genetic variability and population structure in natural plant populations are used to support conservation and management programs. Among the Cerrado fruit tree species that possess potential economic importance in agriculture, the “Cagaiteira” (Eugenia dysenterica DC. – Myrtaceae), deserves an special position. We obtained information about allele and genotypic frequencies in 10 local populations, situated up to 250 km apart, from six isozymes that furnished a total of 8 loci. The average within-population fixation index (f) was 0.337, and the out crossing rate was 0.835, suggesting a mixed mating system for this species, which seems to be preferably alogamous. Based on genetic diversity and analysis of variance techniques, a high degree of population differentiation (θ_P = 0.154) was found, in comparison with other tropical tree species. Genetic divergence, analyzed by Nei's genetic distances, clustered with UPGMA and ordinated by non-metric multidimensional scaling, showed spatial patterns of clusters of local populations. Explicit spatial analyses, using Mantel tests and boundary tests, basically confirmed these patterns and revealed a complex pattern of genetic variation in geographic space. The intercept of the multivariate spatial correlograms was around 120 km, an indication of the minimum distance between samples needed to conserve genetic diversity among samples. This spatial scale can be used to define population genetics units for conservation programs or to establish sampling strategies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparing grazing by Dreissena polymorpha on phytoplankton in the presence of toxic and non-toxic cyanobacteria

SUMMARY 1. The feeding behaviour of the zebra mussel ( Dreissena polymorpha ) was studied in the laboratory on different combinations of food, including a green alga ( Chlamydomonas reinhardtii ) and toxic and non-toxic strains of the cyanobacterium Microcystis aeruginosa .
2. The highest clearance rate of phytoplankton by zebra mussels was found when the mussels were feeding on a mixture of Chlamydomonas and non-toxic Microcystis , the lowest on a mixture of Chlamydomonas and toxic Microcystis .
3. The differences found in the clearance rates between food combinations can be partly explained by the production of pseudofaeces containing live phytoplankton cells. Zebra mussels expelled significantly more live phytoplankton cells in the presence of toxic Microcystis than in the presence of non-toxic Microcystis . The pseudofaeces contained predominantly live Chlamydomonas cells. Proportionately much less live Microcystis cells were encountered in the pseudofaeces.
4. Consequently, grazing of zebra mussels on a combination of Chlamydomonas and Microcystis may finally result in a dominance of Chlamydomonas over Microcystis . The presence of toxic Microcystis may even strengthen this shift.     

Edaphically distinct habitats shape the crown architecture of <Emphasis Type="Italic">Lychnophora ericoides</Emphasis> Mart. (Asteraceae) on tropical mountaintops

Different architectural arrangements may represent contrasting morphological solutions to different environmental pressures. This work aims to elucidate whether the crown architecture of Lychnophora ericoides (Asteraceae) modifies in response to harsh soil conditions (nutrient poor and heavy metal rich) and how its crown architecture affects its reproduction. One hundred and sixty L. ericoides individuals were randomly sampled from eight populations, four on quartzite and four on iron canga rocky complexes in the Iron Quadrangle, southeastern Brazil. We performed soil analyses to characterize edaphic differences and used eight morphometric parameters to describe the crown architecture of the plants. We calculated the population density and reproductive potential to verify the relationship between habitat, architecture, and fitness. Canga soils were more nutrient rich than quartzite soils and plants were architecturally distinct in each habitat. Plants established on canga soils were shorter, had a thinner main branch, and a smaller leaf than those established on quartzite soils. Moreover, plants on canga soils had a larger crown diameter and a greater number of branches and inflorescences. There was no difference in population density but the reproductive potential varied among populations and habitats. The crown architecture of L. ericoides closely relates to reproductive potential and may favor the reproduction of more architectonically complex plants, regardless of habitat.     

Partitioning beta‐diversity through different pond hydroperiod lengths reveals predominance of nestedness in assemblages of immature odonates

Patterns of freshwater invertebrate assemblage structure in the transition from permanent to non‐permanent lentic habitats are well described in the literature. However, the effects of small changes in the hydroperiod of non‐permanent ponds on invertebrate assemblage structure remain less studied, especially on β‐diversity. Thus, we tested the effects of different pond hydroperiod lengths on the assemblage structure of immature odonates, in terms of both α‐ and β‐diversity. Small high‐altitude ponds with different hydroperiod lengths (assigned to ‘short’, ‘medium’ and ‘long’ hydroperiods) were sampled in southern Brazil between 2013 and 2014. Based on the hypothesis that shorter hydroperiods filter constituents of lentic fauna, i.e. that long‐living species cannot inhabit shorter‐hydroperiod ponds, we expected to find higher α‐ and β‐diversity in longer hydroperiods, as well as predominance of the nestedness component in β‐diversity. Restricted occurrence of some genera and higher α‐diversity of immature odonate assemblages was detected in long‐hydroperiod ponds. Within‐hydroperiod β‐diversity values did not vary among hydroperiods, because the occasional occurrence of some genera with high dispersal ability of adults in short‐hydroperiod ponds yielded similar values of the β‐diversity among hydroperiods. Partitioning of β‐diversity among hydroperiods revealed a significant higher contribution of the nestedness component rather than turnover. This pattern is explained by the occurrence of some generalist genera across the whole gradient of hydroperiod, as a subset of fauna in longer‐hydroperiod ponds. Thus, our results suggest that reduction in hydroperiod length, if occurring in the future climate change, would favor habitat‐generalist taxa in lentic ecosystems.     

Credit of ecological interactions: A new conceptual framework to support conservation in a defaunated world

As defaunation spreads through the world, there is an urgent need for restoring ecological interactions, thus assuring ecosystem processes. Here, we define the new concept of credit of ecological interactions, as the number of interactions that can be restored in a focal area by species colonization or reintroduction. We also define rewiring time, as the time span until all the links that build the credit of ecological interactions of a focal area have become functional again. We expect that the credit will be gradually cashed following refaunation in rates that are proportional to (1) the abundance of the reintroduced species (that is expected to increase in time since release), (2) the abundance of the local species that interact with them, and (3) the traits of reintroduced species. We illustrated this approach using a theoretical model and an empirical case study where the credit of ecological interactions was estimated. This new conceptual framework is useful for setting reintroduction priorities and for evaluating the success of conservation initiatives that aim to restore ecosystem services.     

Grazing on colonial and filamentous, toxic and non-toxic cyanobacteria by the zebra mussel Dreissena polymorpha

Colony forming and toxic cyanobacteria form a problem in surfacewaters of shallow lakes, both for recreation and wildlife. Zebramussels, Dreissena polymorpha, have been employed to help torestore shallow lakes in the Netherlands, dominated by cyanobacteria,to their former clear state. Zebra mussels have been presentin these lakes since they were created in the 19th century bythe excavation of peat and are usually not considered to bean invasive species. Most grazing experiments using Dreissenahave been performed with uni-cellular phytoplankton laboratorystrains and information on grazing of larger phytoplankton taxahardly exists. To gain more insight in to whether D. polymorphais indeed able to decrease cyanobacteria in the phytoplankton,we therefore performed grazing experiments with zebra musselsand two species of cyanobacteria, that greatly differ in shape:colony forming strains of Microcystis aeruginosa and the filamentousspecies Planktothrix agardhii. For both species a toxic anda non-toxic strain was selected. We found that zebra musselscleared toxic Planktothrix at a higher rate than non-toxic Planktothrix,toxic or non-toxic Microcystis. Clearance rates between theother strains were not significantly different. Both phytoplanktonspecies, regardless of toxicity, size and shape, were foundin equal amounts (based on chlorophyll concentrations) in theexcreted products of the mussels (pseudofaeces). The resultsshow that zebra mussels are capable of removing colonial andfilamentous cyanobacteria from the water, regardless of whetherthe cyanobacteria are toxic or not. This implies that the musselsmay be used as a biofilter for the removal of harmful cyanobacterialblooms in shallow (Dutch) lakes where the mussels are alreadypresent and not a nuisance. Providing more suitable substratefor zebra mussel attachment may lead to appropriate mussel densitiescapable of filtering large quantities of cyanobacteria.