Replicated anthropogenic hybridisations reveal parallel patterns of admixture in marine mussels.

Human-mediated transport creates secondary contacts between genetically differentiated lineages, bringing new opportunities for gene exchange. When similar introductions occur in different places, they provide informally replicated experiments for studying hybridisation. We here examined 4,279 Mytilus mussels, sampled in Europe and genotyped with 77 ancestry-informative markers. We identified a type of introduced mussels, called "dock mussels," associated with port habitats and displaying a particular genetic signal of admixture between M. edulis and the Mediterranean lineage of M. galloprovincialis. These mussels exhibit similarities in their ancestry compositions, regardless of the local native genetic backgrounds and the distance separating colonised ports. We observed fine-scale genetic shifts at the port entrance, at scales below natural dispersal distance. Such sharp clines do not fit with migration-selection tension zone models, and instead suggest habitat choice and early-stage adaptation to the port environment, possibly coupled with connectivity barriers. Variations in the spread and admixture patterns of dock mussels seem to be influenced by the local native genetic backgrounds encountered. We next examined departures from the average admixture rate at different loci, and compared human-mediated admixture events, to naturally admixed populations and experimental crosses. When the same M. galloprovincialis background was involved, positive correlations in the departures of loci across locations were found; but when different backgrounds were involved, no or negative correlations were observed. While some observed positive correlations might be best explained by a shared history and saltatory colonisation, others are likely produced by parallel selective events. Altogether, genome-wide effect of admixture seems repeatable and more dependent on genetic background than environmental context. Our results pave the way towards further genomic analyses of admixture, and monitoring of the spread of dock mussels both at large and at fine spacial scales.ANR Project HySea (ANR-12-BSV7-0011); Russian Science Foundation project N°19-74-2002

Eradication planétaire de la peste bovine: la dernière ligne droite

Planetary Eradication of Rinderpest: the Last Straight Line. Vingt-quatre moutons sahéliens âgés de deux ans et pesant en moyenne 30 kg ± 1,7 ont été répartis en deux groupes recevant l'un, une ration de production (B) et l'autre, une ration d'entretien (A). Dans chaque groupe existent un lot témoin et un lot infecté avec Trypanosoma congolense à raison de 104 trypanosomes par kilogramme de poids métabolique (kgP0,75 ). Les lots infectés ont développé une forte parasitémie avec un pic important après deux semaines d'infection. A partir du 17ème jour post infection les animaux infectés du lot A ont montré des températures rectales plus élevées, une chute de l'hématocrite plus importante que chez les animaux infectés du lot B. Cependant, la parasitémie s'est révélée plus importante chez les animaux recevant la ration de production B. En comparant les lots infectés avec leur témoins on a noté une différence hautement significative pour les GMQ. La réduction de l'ingestion volontaire de la matière sèche est plus marquée chez les animaux du lot B. Elle passe de 68,42 g MS/kgp0,75 à la première semaine post infection à 57,67 g MS/kp0,75 à la sixième poste infection pour les animaux du lot B et de 57,94 g MS/kgp0,75 à 53,09 g MS/kgp0,75 chez les animaux du lot A

New Insights on Modulation Instability in Optical Fibers

We provide the first longitudinal characterization in phase and amplitude of the nonlinear stage of Modulation instability in optical fibers by means of a heterodyne optical time domain reflectometer. This original setup allows to report the symmetry breaking of the process due to an initial condition change

Formation of murtoos by repeated flooding of ribbed bedforms along subglacial meltwater corridors

Fluctuations in meltwater discharge below modern glaciers and ice sheets due to diurnal, seasonal and long-term temperature variations are modulated by complex interactions between subglacial drainage, basal processes and bedform development. The bed of palaeo-ice sheets contains a variety of bedforms recording these modulations and provides an open window into the subglacial environment. Through the morphometric analysis of natural and experimental bedforms, respectively mapped along Scandinavian meltwater corridors and produced in a physical model simulating transitory subglacial water flow, we observe a morphological and genetic bedform continuum corresponding to the progressive transformation of ribbed bedforms into murtoos. Two alternating drainage configurations, related to repeated subglacial flooding events, are involved in this transformation: (i) significant meltwater discharge, high hydraulic connectivity and ice-bed decoupling during flooding events lead to hydraulic alteration of ribbed bedforms by erosion, sediment deposition and channel incision, while (ii) limited meltwater flow, low hydraulic connectivity and ice-bed recoupling that follow flooding events lead to their deformational reshaping into murtoos. The degree of transformation of ribbed bedforms into murtoos can be quantified by combining two dimensionless morphometric parameters (circularity and sinuosity) and provides a convenient proxy to constrain magnitudes, durations and/or frequencies of subglacial floods in palaeo-meltwater corridors

Konjunkturschwaeche durch Oelverteuerung? Thesen zum 42. Kieler Konjunkturgespraech

SIGLEAvailable from Institut fuer Weltwirtschaft an der Univ. Kiel (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman