Can we continue to neglect genomic variation in introgression rates when inferring the history of speciation? A case study in a Mytilus hybrid zone.

The use of molecular data to reconstruct the history of divergence and gene flow between populations of closely related taxa represents a challenging problem. It has been proposed that the long-standing debate about the geography of speciation can be resolved by comparing the likelihoods of a model of isolation with migration and a model of secondary contact. However, data are commonly only fit to a model of isolation with migration and rarely tested against the secondary contact alternative. Furthermore, most demographic inference methods have neglected variation in introgression rates and assume that the gene flow parameter (Nm) is similar among loci. Here, we show that neglecting this source of variation can give misleading results. We analysed DNA sequences sampled from populations of the marine mussels, Mytilus edulis and M. galloprovincialis, across a well-studied mosaic hybrid zone in Europe and evaluated various scenarios of speciation, with or without variation in introgression rates, using an Approximate Bayesian Computation (ABC) approach. Models with heterogeneous gene flow across loci always outperformed models assuming equal migration rates irrespective of the history of gene flow being considered. By incorporating this heterogeneity, the best-supported scenario was a long period of allopatric isolation during the first three-quarters of the time since divergence followed by secondary contact and introgression during the last quarter. By contrast, constraining migration to be homogeneous failed to discriminate among any of the different models of gene flow tested. Our simulations thus provide statistical support for the secondary contact scenario in the European Mytilus hybrid zone that the standard coalescent approach failed to confirm. Our results demonstrate that genomic variation in introgression rates can have profound impacts on the biological conclusions drawn from inference methods and needs to be incorporated in future studies.

The History of Rome in Painting

There are many paths to reach Rome, immense field open to the eye through the centuries and days, where the presence of the story is haunting. All the artists came to Rome: Italians of various Italian and also French, Dutch, Flemish, Spanish, English and Americans. These painters whose works tell its long history for having lived in the glare of light forever are the Roman pantheon of arts: what are all the anonymous authors of the frescoes of ancient Rome and medieval, but Fabriano, Cimabue , Giotto, Botticelli, Raphael, Giulio Romano, Michelangelo, Caravaggio, Guido Reni, Guercino, Titian, Vasari, Velasquez, Le Nain, Poussin, Zuccari, Van Wittel, Eckersberg, Giraudet, David, Panini, Hubert Robert, Reynolds, Fuseli, Ingres, Sargent, Caffi, Vernet, Turner, Corot, Caffi, De Chirico, etc..

Coulier, Paul-Jean (1824-1890) : a precursor in the history of fingermark detection and their potential use for identifying their source (1863)

An online copy of a 1863 French book, The Scientific and Industrial Year (English translation of the title), that predates other historically significant writings about fingerprints suggests the use of iodine stains to reproduce papillary lines of the skin and suggests the feasibility of identifying suspects by touch. It also suggests the use of a magnifying glass for comparing those impressions whose origins need to be determined.

Crises as a disease of the body politick: a metaphor in the history of nineteenth century economics

This paper examines the use of the medical metaphor in the early theories of crises. It first considers the borrowing of medical terminology and generic references to disease which, notwithstanding their relatively trivial character, illustrate how crises were originally conceived as disturbances (often of a political nature) to a naturally healthy system. Then it shows how a more specific metaphor, the fever of speculation, shifted the emphasis by treating prosperity as the diseased phase, to which crises are a remedy. The metaphor of the epidemic spreading of the disease introduced the theme of the cumulative character of both upswing and downswing, while the similitude with intermittent fevers accounted for the recurring nature of crises. Finally, the paper examines how the medical reflections on the causality of diseases contributed to the epistemology of crises theory, and reflects on the metaphisical shift accompanying the transition from the theories of crises to the theories of cycles.