Dynamique du peuplement et activités agro-pastorales durant l’âge du Bronze dans les massifs du haut Champsaur et de l’Argentiérois

Des programmes de recherche pluridisciplinaires sur l’occupation du sol et le pastoralisme de la Préhistoire au Moyen Âge dans le sud du massif alpin sont menés, depuis 1998, sur les massifs du Haut Champsaur, de Freissinières et de l’Argentièrois (Hautes-Alpes). Des dix phases d’occupation et d'activité agropastorale mises en évidence (prospections pédestres et fouilles), entre 1600 et 2700 m d’altitude, trois se distinguent: la fin du Néolithique, l’âge du Bronze et la période médiévale. Au travers des premières données archéologiques et environnementales, cet article présente, depuis le milieu du IIIe millénaire au début du Ier millénaire, les grandes caractéristiques de l’occupation du sol mais aussi l’originalité et l’importance de l’activité humaine dans cette zone alpine. La fin du Néolithique et l’âge du Bronze correspondent à une multiplication des gisements archéologiques marquant de façon évidente une rupture dans la gestion de l'espace montagnard. Les paysages sont largement façonnés par les activités humaines et l’entretien des terres cultivées, des prairies et des alpages, paraît continu. À la lumière des données de terrain, l’une des évolutions qui apparaît sur les sites d’altitude durant cette période concerne l’apparition de structures pastorales bâties entre 2 067 et 2 303 m d’altitude (datation 14C).

Molecular dating of caprines using ancient DNA sequences of Myotragus balearicus, an extinct endemic Balearic mammal

Background: Myotragus balearicus was an endemic bovid from the Balearic Islands (Western Mediterranean) that became extinct around 6,000-4,000 years ago. The Myotragus evolutionary lineage became isolated in the islands most probably at the end of the Messinian crisis, when the desiccation of the Mediterranean ended, in a geological date established at 5.35 Mya. Thus, the sequences of Myotragus could be very valuable for calibrating the mammalian mitochondrial DNA clock and, in particular, the tree of the Caprinae subfamily, to which Myotragus belongs. Results: We have retrieved the complete mitochondrial cytochrome b gene (1,143 base pairs), plus fragments of the mitochondrial 12S gene and the nuclear 28S rDNA multi-copy gene from a well preserved Myotragus subfossil bone. The best resolved phylogenetic trees, obtained with the cytochrome b gene, placed Myotragus in a position basal to the Ovis group. Using the calibration provided by the isolation of Balearic Islands, we calculated that the initial radiation of caprines can be dated at 6.2 ± 0.4 Mya. In addition, alpine and southern chamois, considered until recently the same species, split around 1.6 ± 0.3 Mya, indicating that the two chamois species have been separated much longer than previously thought. Conclusion: Since there are almost no extant endemic mammals in Mediterranean islands, the sequence of the extinct Balearic endemic Myotragus has been crucial for allowing us to use the Messinian crisis calibration point for dating the caprines phylogenetic tree.

MEDEX: a general overview

The general objective of the international MEDiterranean EXperiment (MEDEX) was the better understanding and forecasting of cyclones that produce high impact weather in the Mediterranean. This paper reviews the motivation and foundation of MEDEX, the gestation, history and organisation of the project, as well as the main products and scientific achievements obtained from it. MEDEX obtained the approval of World Meteorological Organisation (WMO) and can be considered as framed within other WMO actions, such as the ALPine EXperiment (ALPEX), the Mediterranean Cyclones Study Project (MCP) and, to a certain extent, THe Observing System Research and Predictability EXperiment (THORPEX) and the HYdrological cycle in Mediterranean EXperiment (HyMeX). Through two phases (2000 2005 and 2006 2010), MEDEX has produced a specific database, with information about cyclones and severe or high impact weather events, several main reports and a specific data targeting system field campaign (DTS-MEDEX-2009). The scientific achievements are significant in fields like climatology, dynamical understanding of the physical processes and social impact of cyclones, as well as in aspects related to the location of sensitive zones for individual cases, the climatology of sensitivity zones and the improvement of the forecasts through innovative methods like mesoscale ensemble prediction systems.