The effect of immigration on the adaptation of microbial communities to warming

Theory predicts that immigration can either enhance or impair the rate at which species and whole communities adapt to environmental change, depending on the traits of genotypes and species in the source pool relative to local conditions. These responses in turn will determine how well whole communities function in changing environments. We tested the effects of immigration and experimental warming on microbial communities during an 81 day field experiment. The effects of immigration depended on the warming treatment. In warmed communities immigration was detrimental to community growth whereas in ambient communities it was beneficial. This result is explained if colonists came from a local species pool pre-adapted to ambient conditions. Loss of metabolic diversity, however, was buffered by immigration in both environments. Communities showed increasing local adaptation to temperature conditions during the experiment and this was independent of whether or not they received immigration. Genotypes that comprised the communities were not locally adapted, however, indicating that community local adaptation can be independent of adaptation of component genotypes. Our results are consistent with a greater role for species interactions rather than adaptation of constituent species in determining local adaptation of whole communities, and confirm that immigration can either enhance or impair community responses to environmental change depending on the environmental context

A rapid and scalable method for multilocus species delimitation using Bayesian model comparison and rooted triplets

Multilocus sequence data provide far greater power to resolve species limits than the single locus data typically used for broad surveys of clades. However, current statistical methods based on a multispecies coalescent framework are computationally demanding, because of the number of possible delimitations that must be compared and time-consuming likelihood calculations. New methods are therefore needed to open up the power of multilocus approaches to larger systematic surveys. Here, we present a rapid and scalable method that introduces two new innovations. First, the method reduces the complexity of likelihood calculations by decomposing the tree into rooted triplets. The distribution of topologies for a triplet across multiple loci has a uniform trinomial distribution when the 3 individuals belong to the same species, but a skewed distribution if they belong to separate species with a form that is specified by the multispecies coalescent. A Bayesian model comparison framework was developed and the best delimitation found by comparing the product of posterior probabilities of all triplets. The second innovation is a new dynamic programming algorithm for finding the optimum delimitation from all those compatible with a guide tree by successively analyzing subtrees defined by each node. This algorithm removes the need for heuristic searches used by current methods, and guarantees that the best solution is found and potentially could be used in other systematic applications. We assessed the performance of the method with simulated, published and newly generated data. Analyses of simulated data demonstrate that the combined method has favourable statistical properties and scalability with increasing sample sizes. Analyses of empirical data from both eukaryotes and prokaryotes demonstrate its potential for delimiting species in real cases

Effects of phylogenetic reconstruction method on the robustness of species delimitation using single-locus data

1. Coalescent-based species delimitation methods combine population genetic and phylogenetic theory to provide an objective means for delineating evolutionarily significant units of diversity. The Generalized Mixed Yule Coalescent (GMYC) and the Poisson Tree Process (PTP) are methods that use ultrametric (GMYC or PTP) or non-ultrametric (PTP) gene trees as input, intended for use mostly with single-locus data such as DNA barcodes. 2. Here we assess how robust the GMYC and PTP are to different phylogenetic reconstruction and branch smoothing methods. We reconstruct over 400 ultrametric trees using up to 30 different combinations of phylogenetic and smoothing methods and perform over 2,000 separate species delimitation analyses across 16 empirical datasets. We then assess how variable diversity estimates are, in terms of richness and identity, with respect to species delimitation, phylogenetic and smoothing methods. 3. The PTP method generally generates diversity estimates that are more robust to different phylogenetic methods. The GMYC is more sensitive, but provides consistent estimates for BEAST trees. The lower consistency of GMYC estimates is likely a result of differences among gene trees introduced by the smoothing step. Unresolved nodes (real anomalies or methodological artefacts) affect both GMYC and PTP estimates, but have a greater effect on GMYC estimates. Branch smoothing is a difficult step and perhaps an underappreciated source of bias that may be widespread among studies of diversity and diversification. 4. Nevertheless, careful choice of phylogenetic method does produce equivalent PTP and GMYC diversity estimates. We recommend simultaneous use of the PTP model with any model-based gene tree (e.g. RAxML) and GMYC approaches with BEAST trees for obtaining species hypotheses

La "Lingua Franca" de la ciència

El predomini de l'anglès en les publicacions científique

Calcium-binding protein S100A4 in health and disease

AbstractThe S100 proteins contain two EF-hand motifs and are of generally unknown function. One of these proteins, S100A4, is an intracellular calcium-binding protein that is present in normal rodent and human cells. In cultured rodent mammary cells, S100A4 is expressed at a higher level in some metastatic epithelial cells than in non-metastatic counterparts. Similarly, in human breast cell lines, S100A4 is present at a higher level in cultured cells from the more malignant, than in those from the more benign tumours. Gene transfer experiments have shown that rodent or human S100A4 is able to induce metastatic capability in otherwise non-metastatic breast tumour cells. Furthermore, expression of rodent S100A4 transgenes can induce metastasis of benign tumours arising in transgenic model systems. Possible mechanisms for the metastasis-inducing effect of S100A4 and the relevance of these observations to human cancer are discussed

‘Transforming the Trolls: The Metamorphosis of the Troll-Woman in Bárðar saga Snæfellsáss’

Bárðar saga is an intriguing yet puzzling text, which chronicles the life of the blendingr (half-troll, half-giant) Bárðr Dumbsson and his family, from an exposition of his ancestry to the death of his son Gestr on the night of his conversion to Christianity. Beginning with the reign of Dumbr (Bárðr’s troll-king father) in Norway, the saga tracks Bárðr’s settlement at Snæfellsness in Iceland and his self-imposed exile following the disappearance of his daughter Helga. As he retreats into the mountains, Bárðr is cast in a new supernatural mould, embracing his giant heritage in order to become the guardian spirit of the district. Finally, the story turns to his son Gestr and his adventures at the court of King Óláfr Tryggvason. He converts to Christianity at the request of the king, but on the night of his baptism Bárðr appears, accusing Gestr of betraying his pagan ancestors before killing him. Bárðar saga follows many features of structure and plot typical to the Íslendingasögur (family sagas), the genre to which it is assigned, including the protagonists’ settlement of Iceland, district feuds and conversions to Christianity. However, the conventions of this socially realistic genre are fundamentally subverted when a pagan clan of monstrous descent takes centre stage as a set of unlikely protagonists. Consequently, Bárðar saga presents us with numerous difficulties in terms of its generic classification, thematic preoccupations and unusual characterisations. However, its rich manuscript transmission suggests continuing popularity almost to the present day, both in literary circles and in popular culture. Nevertheless, the saga’s unconventional design has baffled modern scholars, who have found it particularly difficult to reconstruct a ‘horizon of expectations’ upon which to base an understanding of the piece This paper is concerned primarily with the characterisation of Helga Bárðardóttir, the enigmatic daughter of Bárðr Dumbsson. It will concentrate on the metamorphosis of the conventional figure of the troll woman, particularly focussing on the saga motif of the love affair between a mortal hero and a giantess. In sagas that feature characters such as trolls in a more conventional form, the figures tend to be presented somewhat two-dimensionally, fulfilling the function of a ‘narrative-vehicle’ for the heroic protagonist in his early rites of passage. Thus, a troll-woman such as Helga would usually be a peripheral and underdeveloped figure in the saga, appearing briefly in the course of the hero’s adventures before disappearing when he continues on to further expeditions or returns to human society. Yet in Bárðar saga, Helga is the focal point of this particular narrative set piece. This seems to be an intentional part of the saga’s wider literary design, in which the shadowy figures who typically act along the dim edges of the saga stage are pushed into the spotlight, forcing more-orthodox protagonists out into the wings of the narrative. In her analysis of the relationships between heroes and giants, Riti Kroesen states, ‘Whether [the hero] goes out to meet the giants in order to serve the community or to serve his own ends […] the sympathies of the original audience must always have been on [his side]’. Yet Bárðar saga entirely overturns the accepted convention that such stories are written to enhance the glory of the heroic protagonist

Stigma Perceptions of Adolescents with Emotional and/or Behavioral Difficulties

The current study sought to better understand how adolescents with serious mental health problems participating in inpatient psychiatric treatment experience self- and perceived public stigma, using demographic and clinical factors to help further explain adolescents\u27 experience of self- and perceived public stigma. Participants reported moderate levels of both self- and perceived public stigma, though these adolescents did not report significantly higher levels of self- or perceived public stigma than community/outpatient based samples. Although neither the three demographic nor three clinical factors were able to account for a significant amount of reported self- or perceived public stigma, the current research examined an understudied, acute population not previously found in the literature. This study begins to fill the gap in research about stigma experiences from the most acute populations