Limited overlap of the community of bees and wasps (Hymenoptera: Aculeata) nesting in reed galls with those nesting in other cavities

Hymenopterans occurring in wetlands represent specific community with bioindicative characters but poorly understood nesting biology. We have studied the nesting preferences of these insects in ten reed beds—five represented by natural wetlands, and the other five localized to anthropogenic sites. We reared the hymenopterans from trap-nests consisting of reed stalks and goldenrod stems, which were installed at the localities through the nesting season, and compared them with quantitative data of hymenopterans reared from reed galls collected at the same localities. Most of the species that nested in reed galls accepted the reed stalk traps but not vice versa. Some of the species that accepted both these nesting resources strongly differed in their frequency of use of these two nesting resources. Moreover, the species composition differed substantially between goldenrod stems and either reed stalks or reed galls. The digger wasp Pemphredon fabricii was eudominant in reed galls with higher abundance at anthropogenic sites, while it was also observed in reed stalks but in much lower numbers. Hylaeus pectoralis was frequent in reed galls at both habitat types and only one individual was reared from reed stalks. Trypoxylon deceptorium was quite numerous in reed galls but much more frequent in reed stalks. Species unknown from reed galls (Psenulus pallipes, Hylaeus confusus, Gymnomerus laevipes) were numerous in reed stalks. We experimentally confirmed that P. fabricii and H. pectoralis show high preference of reed galls and are dependent on these nesting resources. The available evidence suggests that the management of both natural and anthropogenic sites needs to implement tools preserving reed beds, especially the terrestrial ones with reed galls.     

Phylogenetic relationships of typical antbirds (Thamnophilidae) and test of incongruence based on Bayes factors

Background  

The typical antbirds (Thamnophilidae) form a monophyletic and diverse family of suboscine passerines that inhabit neotropical forests. However, the phylogenetic relationships within this assemblage are poorly understood. Herein, we present a hypothesis of the generic relationships of this group based on Bayesian inference analyses of two nuclear introns and the mitochondrial cytochrome b gene. The level of phylogenetic congruence between the individual genes has been investigated utilizing Bayes factors. We also explore how changes in the substitution models affected the observed incongruence between partitions of our data set.     

Skewed adult sex ratios in Columbina ground doves from Venezuela

Although sex ratios at conception are close to 1:1 in most species of birds, skewed adult sex ratios (ASRs) are not uncommon in populations of birds, and occur frequently at local and temporal scales. ASRs are a key variable influencing population demography, breeding systems, and many aspects of the behavior of birds. However, factors contributing to variation in ASRs, particularly for tropical species of birds, remain poorly understood. By compiling information from field sites and records from bird collections, we found that the ASRs of four species of Columbina ground doves from Venezuela deviated significantly from parity. Males of all species outnumbered females at all field sites and in all museum samples. ASR, expressed as the proportion of males, ranged from 0.59 for Common Ground Doves (Columbina passerina) to 0.65 for Plain‐breasted Ground Doves (Columbina minuta) in the overall samples. Males outnumbered females by ~ 44% in Common Ground Doves and by 85% in Plain‐breasted Ground Doves. Our samples included birds collected as specimens over many decades and across broad geographic areas, suggesting that skewed ASRs are characteristic of Venezuelan ground doves. Because these ground doves do not exhibit pronounced sexual size dimorphism and have socially monogamous breeding systems, selection would be expected to favor equal investment in males and females at hatching. As such, we argue that greater post‐hatching mortality of females, rather than deviations in the sex ratio of embryos, is the main cause of the biased ASRs of Venezuelan ground doves.     

Metagenomic Analysis of the Microbiota from the Crop of an Invasive Snail Reveals a Rich Reservoir of Novel Genes

The shortage of petroleum reserves and the increase in CO₂ emissions have raised global concerns and highlighted the importance of adopting sustainable energy sources. Second-generation ethanol made from lignocellulosic materials is considered to be one of the most promising fuels for vehicles. The giant snail Achatina fulica is an agricultural pest whose biotechnological potential has been largely untested. Here, the composition of the microbial population within the crop of this invasive land snail, as well as key genes involved in various biochemical pathways, have been explored for the first time. In a high-throughput approach, 318 Mbp of 454-Titanium shotgun metagenomic sequencing data were obtained. The predominant bacterial phylum found was Proteobacteria, followed by Bacteroidetes and Firmicutes. Viruses, Fungi, and Archaea were present to lesser extents. The functional analysis reveals a variety of microbial genes that could assist the host in the degradation of recalcitrant lignocellulose, detoxification of xenobiotics, and synthesis of essential amino acids and vitamins, contributing to the adaptability and wide-ranging diet of this snail. More than 2,700 genes encoding glycoside hydrolase (GH) domains and carbohydrate-binding modules were detected. When we compared GH profiles, we found an abundance of sequences coding for oligosaccharide-degrading enzymes (36%), very similar to those from wallabies and giant pandas, as well as many novel cellulase and hemicellulase coding sequences, which points to this model as a remarkable potential source of enzymes for the biofuel industry. Furthermore, this work is a major step toward the understanding of the unique genetic profile of the land snail holobiont.     

Antimicrobial resistance and species identification of staphylococci isolated from the meat of wild rabbits (<Emphasis Type="Italic">Oryctolagus cuniculus</Emphasis>) in Slovakia

In 2009, a total of 113 strains of staphylococci were isolated from the thigh muscles of ten hunted and 20 farmed wild rabbits (Oryctolagus cuniculus) in the Slovak Republic. Only two isolates (1.8%) possessed coagulase activity, the rest of 111 staphylococcal isolates were coagulase-negative. Among them, six isolates (5.4%) showed the production of DNase. In each isolate, resistance to eight antibiotics by means of agar dilution test was tested. Based on these results, 110 isolates were found to be resistant to at least one antibiotic. Only one isolate was susceptible to all eight antibiotics tested. Another two isolates were susceptible, however, they showed intermediate susceptibility to cefoxitin. Resistance to ampicillin (78.8%), erythromycin (58.4%), penicillin (51.3%) and oxacillin (46.0%) was found most frequently. Twenty-six isolates (23.0%) were resistant to novobiocin. On the other hand, resistance to cefoxitin (8.0%) and gentamicin (1.8%) were quite rare. Fifteen percent of isolates were resistant to one antibiotic, simultaneous resistance to two, three, four and five antibiotics was confirmed in 22.1%, 23.9%, 21.2% and 13.3% of isolates, respectively. Except for two coagulase-positive Staphylococcus aureus isolates (1.8%), seven species of coagulase-negative staphylococci were identified using the MALDI BioTyper (TM) sytem as follows: Staphylococcus warneri (45.1%), Staphylococcus epidermidis (21.2%), Staphylococcus pasteuri (13.3%), Staphylococcus xylosus (8.0%), Staphylococcus capitis (7.1%), Staphylococcus haemolyticus (1.8%) and Staphylococcus cohnii ssp cohnii (1.8%).     

Chromate reductase activity of the Paracoccus denitrificans ferric reductase B (FerB) protein and its physiological relevance

The homodimeric flavoprotein FerB of Paracoccus denitrificans catalyzed the reduction of chromate with NADH as electron donor. When present, oxygen was reduced concomitantly with chromate. The recombinant enzyme had a maximum activity at pH 5.0. The stoichiometric ratio of NADH oxidized to chromate reduced was found to be 1.53 ± 0.09 (O₂ absent) or > 2 (O₂ present), the apparent K _M value for chromate amounted to 70 ± 10 μM with the maximum rate of 2.9 ± 0.3 μmol NADH s⁻¹ (mg protein)⁻¹. Diode-array spectrophotometry and experiments with one-electron acceptors provided evidence for oxygen consumption being due to a flavin semiquinone, formed transiently during the interaction of FerB with chromate. At the whole-cell level, a ferB mutant strain displayed only slightly diminished rate of chromate reduction when compared to the wild-type parental strain. Anaerobically grown cells were more active than cells grown aerobically. The activity could be partly inhibited by antimycin, suggesting an involvement of the respiratory chain. Chromate concentrations above ten micromolars transiently slowed or halted culture growth, with the effect being more pronounced for the mutant strain. It appears, therefore, that, rather than directly reducing chromate, FerB confers a protection of cells against the oxidative stress accompanying chromate reduction. With a strain carrying the chromosomally integrated ferB promoter-lacZ fusion, it was shown that the ferB gene is not inducible by chromate.     

Young-of-the-year fish assemblages as an alternative to adult fish monitoring for ecological quality evaluation of running waters

Studies on the Upper Mississippi River, particularly over the last 15 years, have contributed to our understanding of trophic processes in large rivers. The framework established by earlier population-specific studies, however, cannot be overlooked. Examination of the feeding habits of fish ranging from planktivores to piscivores gave the first indication that trophic processes were influenced by the spatial complexity and annual hydrological patterns of river-floodplain ecosystems. Experimental studies, which have often been considered impossible or impractical in large rivers, demonstrated the potential for biotic controls of system dynamics through predator–prey and competitive interactions. Such studies have been particularly helpful in understanding the potential impact of non-native species, including zebra mussels and Asian carp, to biodiversity and secondary production. Our understanding of riverine ecosystem function expanded greatly as food web studies began the application of a new tool—natural stable isotopes. Studies employing stable isotopes illustrated how food webs in a number of large rivers throughout the world are supported by the autochthonous production of microalgae. This study, coupled with other studies testing the prevailing models of riverine ecosystem function, has brought us to a point of better understanding the nature of river ecosystem functions. It is through looking back at the earlier studies of fish diet that we should realize that the temporal and spatial complexities of river ecosystem function must still be addressed more fully. This and a better grasp of the significance of the arrangement of patches within the riverine landscape will prove beneficial, as we assess the appropriate scale of river rehabilitation with an eye on how rehabilitation promotes productivity within complex ecosystems, including the Upper Mississippi River.     

Lack of reproductive isolation between the Western and Eastern phylogroups of the tench

The Eurasian range of the tench distribution is subdivided into deeply divergent Western and Eastern phylogroups evidenced by nuclear and mitochondrial DNA sequence markers. A broad zone of overlap exists in central and western Europe, suggesting post-glacial contact with limited hybridisation. We conducted a population genetic test of this indication that the two phylogroups may represent distinct species. We analysed variation at introns of nuclear genes, microsatellites, allozymes and mitochondrial DNA in populations from two postglacial lakes within the contact zone in Germany. The test is based on the expectation that in the presence of strong barriers to reproduction, a hybrid population will show genome-wide associations among alleles and genotypes from each phylogroup even after hundreds of generations of interbreeding. In contrast to this expectation, no consistent significant deviations from linkage and Hardy–Weinberg equilibria were found. Samples from both lakes did show significant disequilibria but they were limited to individual loci and were not concordant between populations, and were not robust to the method used. The single consistent association can be attributed to physical linkage between two microsatellite loci. Thus, results of our study support the hypothesis of free interbreeding between the two phylogroups of tench. Therefore, although the phylogroups may be considered as separate phylogenetic species, the present data suggest that they are a single species under the biological species concept.     

New oligo-β-(1,3)-glucan derivatives as immunostimulating agents

Oligo-β-(1,3)-glucans were chemically modified in order to introduce a structural variation specifically on the reducing end of the oligomers. The impact of well defined structural modulations was further studied on cancer cells and murin models to evaluate their cytotoxicity and immunostimulating potential.     

Bridging global and microregional scales: ploidy distribution in Pilosella echioides (Asteraceae) in central Europe

Background and Aims

A detailed knowledge of cytotype distribution can provide important insights into the evolutionary history of polyploid systems. This study aims to explore the spatial distribution of different cytotypes in Pilosella echioides at various spatial scales (from the whole distributional range to the population level) and to outline possible evolutionary scenarios for the observed geographic pattern.

Methods

DNA-ploidy levels were estimated using DAPI flow cytometry in 4410 individuals of P. echioides from 46 populations spread over the entire distribution range in central Europe. Special attention was paid to the cytotype structure in the most ploidy-diverse population in south-west Moravia.

Key Results

Five different cytotypes (2x, 3x, 4x, 5x and 6x) were found, the last being recorded for the first time. Although ploidy-uniform (di- or tetraploid) sites clearly prevailed, nearly one-quarter of the populations investigated harboured more (up to all five) cytotypes. Whereas penta- and hexaploids constituted only a minority of the samples, a striking predominance of the triploid cytotype was observed in several populations.

Conclusions

The representative sampling confirmed previous data on cytotype distribution, i.e. the spatial aggregation of mixed-ploidy populations in south-west Moravia and Lower Austria and the predominance of ploidy-uniform populations in other parts of the area investigated. Recurrent origin of polyploids from diploid progenitors via unreduced gametes and their successful establishment are considered the key factors promoting intrapopulational ploidy mixture (‘primary hybrid zones’). As an alternative to the generally accepted theory of cytotype co-existence based on the development of different means of inter-ploidy reproductive isolation, it is suggested that a long-term ploidy mixture can also be maintained in free-mating populations provided that the polyploids originate with a sufficient frequency. In addition, the prevalence (or subdominance) of the triploid cytotype in several mixed-ploidy populations represents the first evidence of such a phenomenon in plant systems with exclusively sexual reproduction.