455 research outputs found
fastsimcoal: a continuous-time coalescent simulator of genomic diversity under arbitrarily complex evolutionary scenarios
No full textAbstract
Motivation: Genetic studies focus on increasingly larger genomic regions of both extant and ancient DNA, and there is a need for simulation software to match these technological advances. We present here a new coalescent-based simulation program fastsimcoal, which is able to quickly simulate a variety of genetic markers scattered over very long genomic regions with arbitrary recombination patterns under complex evolutionary scenarios.
Availability and Implementation: fastsimcoal is a C++ program compiled for Windows, MacOsX and Linux platforms. It is freely available at cmpg.unibe.ch/software/fastsimcoal/, together with its detailed user manual and example input files.
Contact: [email protected]
Supplementary Information: Supplementary data are available at Bioinformatics online.</jats:p
Cultural transfers in Yiddish and Belarusian children’s literature and illustrations in the BSSR (1921-1939)
No full textThe article offers an overview of the production of books for children in Yiddish and Belarusian in the BSSR between 1921 and 1939. While situating the study in the wider context of the development of Jewish and Russian/Soviet children’s literature in the early 20th century, it analyses the creation of two corpuses of texts and images in parallel, taking into consideration the specificity of the Belarusian policy towards national minorities. The article evaluates the level of transfers between Belarusian, Jewish, Russian and other children’s literature, through the number and choice of translations, the mobility of the artists that illustrated these books and the circulation of themes and styles. Although the number of translations between the Belarusian and Yiddish corpora was limited, the author argues that the cultural transfers were visible in the themes of the books and the style of the illustrations
Correcting for ascertainment bias in the inference of population structure
No full textBackground: The ascertainment process of molecular markers amounts to disregard loci carrying alleles with low frequencies. This can result in strong biases in inferences under population genetics models if not properly taken into account by the inference algorithm. Attempting to model this censoring process in view of making inference of population structure (i.e. identifying clusters of individuals) brings up challenging numerical difficulties. Method: These difficulties are related to the presence of intractable normalizing constants in Metropolis-Hastings acceptance ratios. This can be solved via an Markov chain Monte Carlo (MCMC) algorithm known as single variable exchange algorithm (SVEA). Result: We show how this general solution can be implemented for a class of clustering models of broad interest in population genetics that includes the models underlying the computer programs STRUCTURE, GENELAND and GESTE. We also implement the method proposed for a simple example and show that it allows us to reduce the bias substantially
L’école artistique de Vitebsk (1897-1923). Eveil et rayonnement autour de Pen, Chagall et Malevitch
No full textThis work represents the first attempt to give a synthetical picture of the history of the Vitebsk Art School as the whole. It is based on archival and artistic material and presents all the aspects of this unique art school on the Byelorussian territory.The book begins with a detailed description of the historical background and artistic context of creation of an Art studio by Iouri Pen. This chapter includes information about the situation of Jews in the Russian empire and the city of Vitebsk. The second part of the book is dedicated to the “revolutionary period” of the Vitebsk Art School. From 1918 to 1923, Marc Chagall, Vera Ermolaeva and Kazimir Malevitch transformed the modest art studio of Pen in a Free Artistic Workshop, where professors and pupils had the possibility to discover and practice the most recent and innovative tendencies of Art: cubism, futurism, expressionism, suprematism. The author inquires all the spheres of activities of the art school: teaching, exhibitions, conferences, “prop arts”, or propaganda, publications, decorations for official holidays, theater and ballet, etc. Finally, the third chapter deals with the question of Jewish Art. It inscribes the Vitebsk Art School in the larger context of the Jewish Art Renaissance in Russia at the turn of the Century. The Vitebsk Art School represents indeed a fascinating case study for this complex problem. The experience of Vitebsk Art School is helpful to apprehend Jewish Art, when trying to define the place it occupied in the general debates about Jewish Art and in the emergence of a Modern Jewish Art in Russia.<br/
Белорусский паспорт Бялика: Белорусская народная республика и евреи в 1921 году
No full textStarting from a seemingly anecdotal detail – Bialik’s Belarusian passport -, this article explores a little known page of the Belarusian People’s Republic history and of Jewish/non-Jewish relations in Eastern Europe, i.e. the rapprochement between Jewish and Belarusian political activist in Berlin in 1921, before and after the peace treaty of Riga. Using published and unpublished archival sources, the author reconstitutes the efforts of three Jewish officials of the BNR government – David Anekshtein, Isaac Lur’e and Samuil Zhitlovsky – to raise awareness of the Belarusian cause among Jewish, and particularly, Zionist circles in Berlin and in the West. The article explores the BNR government in exile’s last attempt to secure statehood at a turning point in the history of the region through active cooperation with the Jewish community. It confirms the central role attributed to the Jewish nation in the Belarusian national project but also reveals the tensions and frustrations on both sides. While this cooperation failed to produce the expected outcome – BNR independence – it was crucial in shaping the BNR’s response to the violent anti-Jewish pogroms during the summer 1921 and broadening the public knowledge about the Belarusian cause to various émigré circles in Berlin, as well as laid the basis for mutual political and cultural recognition in the BSSR
Quantifying population structure using the F-model
No full textWe review a model-based approach to estimate local population F(ST)'s that is based on the multinomial-Dirichlet distribution, the so-called F-model. As opposed to the standard method of estimating a single F(ST) value, this approach takes into account the fact that in most if not all realistic situations, local populations differ in their effective sizes and migration rates. Therefore, the use of this approach can help better describe the genetic structure of populations. Despite this obvious advantage, this method has remained largely underutilized by molecular ecologists. Thus, the objective of this review is to foster its use for studying the genetic structure of metapopulations. We present the derivation of the Bayesian formulation for the estimation of population-specific F(ST)'s based on the multinomial-Dirichlet distribution. We describe several recent applications of the F-model and present the results of a small simulation study that explains how the F-model can help better describe the genetic structure of populations.</p
Evolutionary forces shaping genomic islands of population differentiation in humans
No full textAbstract Background Levels of differentiation among populations depend both on demographic and selective factors: genetic drift and local adaptation increase population differentiation, which is eroded by gene flow and balancing selection. We describe here the genomic distribution and the properties of genomic regions with unusually high and low levels of population differentiation in humans to assess the influence of selective and neutral processes on human genetic structure. Methods Individual SNPs of the Human Genome Diversity Panel (HGDP) showing significantly high or low levels of population differentiation were detected under a hierarchical-island model (HIM). A Hidden Markov Model allowed us to detect genomic regions or islands of high or low population differentiation. Results Under the HIM, only 1.5% of all SNPs are significant at the 1% level, but their genomic spatial distribution is significantly non-random. We find evidence that local adaptation shaped high-differentiation islands, as they are enriched for non-synonymous SNPs and overlap with previously identified candidate regions for positive selection. Moreover there is a negative relationship between the size of islands and recombination rate, which is stronger for islands overlapping with genes. Gene ontology analysis supports the role of diet as a major selective pressure in those highly differentiated islands. Low-differentiation islands are also enriched for non-synonymous SNPs, and contain an overly high proportion of genes belonging to the 'Oncogenesis' biological process. Conclusions Even though selection seems to be acting in shaping islands of high population differentiation, neutral demographic processes might have promoted the appearance of some genomic islands since i) as much as 20% of islands are in non-genic regions ii) these non-genic islands are on average two times shorter than genic islands, suggesting a more rapid erosion by recombination, and iii) most loci are strongly differentiated between Africans and non-Africans, a result consistent with known human demographic history.</p
Enhanced AFLP genome scans detect local adaptation in high-altitude populations of a small rodent (Microtus arvalis)
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