Natural range expansion and human-assisted introduction leave different genetic signatures in a hermaphroditic freshwater snail

Colonization events like range expansion or biological invasions can be associated with population bottlenecks. Small population size may lead to loss of genetic diversity due to random genetic drift, to loss of heterozygosity due to increased inbreeding and should leave a signature on the genetic polymorphism and genetic structure of populations. The mating system might additionally influence the outcome of such a process. Here, we compare invasive and native populations of the hermaphroditic freshwater snail Lymnaea stagnalis. In the native range we included populations that were ice-free during the last glaciation period and populations that were glaciated and are located at the edge of the species' native distribution range. The microsatellite data show substantial loss of genetic variation in the introduced range and no signs of high propagule pressure or admixture. The expressed polymorphism was so low that mating system analysis was not possible. In the native region, all populations display strong levels of differentiation (global F ST: 0.341) independent of colonization history and exhibit no significant pattern of inbreeding. However, the populations in more recently colonized habitats show diminished genetic diversity. Overall, these results illustrate how dramatic the reduction in genetic diversity can be for hermaphroditic animals and that gene flow in the native range can be surprisingly low despite short distance

Traumatization and mental distress in long-term prisoners in Europe

This article investigates the prevalence of traumatization and mental distress in a sample of 1055 male European long-term prisoners as part of a wider study of the living conditions of prisoners serving sentences of at least five years in Belgium, Croatia, Denmark, England, Finland, France, Germany, Lithuania, Poland, Spain and Sweden. Data were collected in a written survey using the Posttraumatic Diagnostic Scale (PDS), the Brief Symptom Inventory (BSI) as well as questions on attempted suicide and auto-aggressive behaviour. Participants experienced a mean of three traumatic events, with 14 per cent developing a Posttraumatic Stress Disorder (PTSD) subsequently. In each national sample, more than 50 per cent of the participants were in need of treatment because of psychological symptoms and nearly one-third had attempted suicide

Potential climatic transitions with profound impact on Europe

We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field. For each subsystem we summarize the mechanism of a potential transition in a warmer climate along with its impact on Europe and assess the likelihood for such a transition based on published scientific literature. As a summary, the ‘tipping’ potential for each system is provided as a function of global mean temperature increase which required some subjective interpretation of scientific facts by the authors and should be considered as a snapshot of our current understanding. <br/

Natural range expansion and human-assisted introduction leave different genetic signatures in a hermaphroditic freshwater snail

ISSN:0269-7653ISSN:1573-847

Overland transport of recreational boats as a spreading vector of zebra mussel Dreissena polymorpha

In aquatic ecosystems invasive species are among the most important threats to biodiversity worldwide. Understanding the dispersal mechanisms of aquatic invaders is very important for protection and management of vulnerable water bodies. Here we ask how recreational boats that are transported overland could contribute to the dispersal of invasive zebra mussels among lakes in Switzerland. Using a questionnaire sent to registered boat owners, we surveyed properties of transported boats and collected information on self-reported mussel fouling and transport activities of boat owners. We also sampled boat hulls at launching ramps and harbors for biofouling invertebrates. Boats that were kept seasonally or year-round in water were found to have high vector potential with mussel fouling rates of more than 40 %. However, only about 6 % of boats belonging to these groups were transported overland to other water bodies. Considering that approximately 100,000 recreational boats are registered in Switzerland, we estimated that every year around 1400 boats fouled with mussels are transported overland. Such boats pose a high risk of distributing zebra mussels between water bodies. Our results suggest that there is a considerable risk that recreational boats may spread new fouling species to all navigable water bodies within the study area. We speculate that one such species could be the quagga mussel, which has not yet invaded lakes in Switzerland. On a more positive note, our study has identified the group of high-risk boats so that possible control measures would only affect a relatively small number of boat owners

infection_experiments_2009_2011

Infection status of individual Potamopyrgus antipodarum snails in the laboratory infection experiments of 2009 and 2011. Descriptions of column headings and abbreviations used: A: SNAIL - individual snail number. B: DATASET - "I2009"- infection experiment of 2009, "I2011"- infection experiment of 2011. C: YEAR - 2009, 2011. D: TREATMENT: "alex" - parasite source from Lake Alexandrina, "control" - control for parasite exposure. E: HABITAT: Lake Alexandrina habitat zone from which the snails were sampled. F: REP: Replicate number. In 2009 the experimental snails were exposed in 2 trays, and control snails in 2 trays. In 2011 the experimental snails were exposed in 6 trays and control snails in 2 trays; the control snails were combined into one tray before terminating the experiment. G: LENGTH: Snail length [mm]. H: SEX: Snail sex: "F"- female, "M"- male. I: MIC: Microphallus sp. infection: "1"- present, "0"- absent. J: PLOIDY - 2- diploid, 3- triploid. K: GENOTYPE_ID - The numbers above zero are unique clone numbers. Zeroes indicate genotypes for which unique clone number could not be assigned. Sexual snails are marked as "S"

Data from: Parasite resistance predicts fitness better than fecundity in a natural population of the freshwater snail Potamopyrgus antipodarum

The cost of males should give asexual females an advantage when in competition with sexual females. In addition, high-fecundity asexual genotypes should have an advantage over low-fecundity clones, leading to reduction in clonal diversity over time. To evaluate fitness components in a natural population, we measured the annual reproductive rate of individual sexual and asexual female Potamopyrgus antipodarum, a New Zealand freshwater snail, in field enclosures that excluded competitors and predators. We used allozyme genotyping to assign the asexual females to particular clonal genotypes. We found that the most fecund asexual clones had similar or higher fecundity as the top 10 % of sexual families, suggesting that fecundity selection, even without the cost of males, would lead to replacement of the sexual population by clones. Consequently, we expected that the clones with the highest fecundity would dominate the natural population. Counter to this prediction, we found that high annual reproductive rates did not correlate with the frequency of clones in the natural population. When we exposed the same clones to parasites in the laboratory, we found that resistance to infection was positively correlated with the frequency of clones in the population. The correlation between fecundity and parasite resistance was negative, suggesting a trade-off between these two traits. Our results thus suggest that parasite resistance is an important short-term predictor of the success of asexual P. antipodarum in this population

field_experiment

Fecundity and offspring size of Potamopyrgus antipodarum snails in the field experiment. Descriptions of column headings and abbreviations used: A: FAMILY_NUMBER - number of experimental enclosure (cage). B: GENOTYPE_ID - Asexual families were assigned unique clone numbers, "S" - sexual families, "NA" - unresolved genotypes. Allozyme genotypes were obtained from one or two (if available) snails per family. C: PLOIDY - 2- diploid, 3- triploid. D: LINEAGE_TYPE - 1- unresolved, 2- common clone, 3- rare clone, 4 -sexual. We assigned clone as common if the clone was replicated by at least three independent families. E: LENGTH_mm - snail length [mm]

Data from: Parasite resistance predicts fitness better than fecundity in a natural population of the freshwater snail Potamopyrgus antipodarum

The cost of males should give asexual females an advantage when in competition with sexual females. In addition, high-fecundity asexual genotypes should have an advantage over low-fecundity clones, leading to reduction in clonal diversity over time. To evaluate fitness components in a natural population, we measured the annual reproductive rate of individual sexual and asexual female Potamopyrgus antipodarum, a New Zealand freshwater snail, in field enclosures that excluded competitors and predators. We used allozyme genotyping to assign the asexual females to particular clonal genotypes. We found that the most fecund asexual clones had similar or higher fecundity as the top 10 % of sexual families, suggesting that fecundity selection, even without the cost of males, would lead to replacement of the sexual population by clones. Consequently, we expected that the clones with the highest fecundity would dominate the natural population. Counter to this prediction, we found that high annual reproductive rates did not correlate with the frequency of clones in the natural population. When we exposed the same clones to parasites in the laboratory, we found that resistance to infection was positively correlated with the frequency of clones in the population. The correlation between fecundity and parasite resistance was negative, suggesting a trade-off between these two traits. Our results thus suggest that parasite resistance is an important short-term predictor of the success of asexual P. antipodarum in this population

Evidence-based (S3) guidelines for the treatment of psoriasis vulgaris

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1 to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, patient surveys have revealed lack of satisfaction with the efficacy of available treatments and a high rate of non-compliance. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologische Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) initiated a project to develop evidence-based guidelines for the management of psoriasis. These resulting Guidelines focus on induction therapy in cases of mild, moderate, and severe plaquetype psoriasis in adults. The Guidelines include evidence-based evaluation of the efficacy of all currently available therapeutic options in Germany. In addition, they offer detailed information on how best to administer the various treatments and give information on contraindications, adverse drug reactions, and drug interactions as well as estimates of practicability and cost. The Guidelines were developed following the recommendations of the Arbeitsgemeinschaft wissenschaftlicher medizinischer Fachgesellschaften (AWMF). The therapeutic recommendations were developed by an expert group and finalized during interdisciplinary consensus conferences