Microsatellite diversity of the Nordic type of goats in relation to breed conservation: how relevant is pure ancestry?

In the last decades, several endangered breeds of livestock species have been re-established effectively. However, the successful revival of the Dutch and Danish Landrace goats involved crossing with exotic breeds and the ancestry of the current populations is therefore not clear. We have generated genotypes for 27 FAO-recommended microsatellites of these landraces and three phenotypically similar Nordic-type landraces and compared these breeds with central European, Mediterranean and south-west Asian goats. We found decreasing levels of genetic diversity with increasing distance from the south-west Asian domestication site with a south-east-to-north-west cline that is clearly steeper than the Mediterranean east-to-west cline. In terms of genetic diversity, the Dutch Landrace comes next to the isolated Icelandic breed, which has an extremely low diversity. The Norwegian coastal goat and the Finnish and Icelandic landraces are clearly related. It appears that by a combination of mixed origin and a population bottleneck, the Dutch and Danish Land-races are separated from the other breeds. However, the current Dutch and Danish populations with the multicoloured and long-horned appearance effectively substitute for the original breed, illustrating that for conservation of cultural heritage, the phenotype of a breed is more relevant than pure ancestry and the genetic diversity of the original breed. More in general, we propose that for conservation, the retention of genetic diversity of an original breed and of the visual phenotype by which the breed is recognized and defined needs to be considered separately

Investigations of the Dynamic Strength Variations in Metals

A line-imaging laser Doppler velocimeter has been employed to investigate the uniformity of strength properties of materials at load duration of ≈10-7 sec or less. The shock load puises were generated by a pulsed high-power proton beam facility. More or less noticeable spatial variations of the spall strength were found in such different materials as coarse-grain cast magnesium and molybdenum single crystals. In the case of magnesium, the variations of the tensile strength are governed by grain boundaries. In the single crystals, small reductions of the spall strength were accompanied by a decreasing acceleration of the fracture process.Un vélocimetre laser à résolution spatiale monodimensionelle a été utilisé pour l'étude des variations locales des propriétés mécaniques des matériaux auxquels sont appliquées des charges d'une durée de 10-7 s ou moins. Les charges impulsives sont générées par un faisceau de protons puisé à haute puissance. Des différences plus ou moins notables de la résistance mécanique ont été constatées sur des échantillons aussi différents que du magnésium moulé à gros grains et du molybdène monocristallin. Dans le cas du magnésium, les variations de la résistance sont gouvernées par les joints de grains. Dans les monocristaux, de petites réductions de la résistance furent accompagnées d'une évolution initiale des fractures plus lente