Distribution de l’avifaune des milieux forestiers de substitution (plantation et jachères) au Sud du Bénin en relation avec les facteurs de l’habitat

Dans le Sud du Bénin, l’intensification de la récente déforestation par l’agriculture et l’urbanisation fait que les jachères et les plantations occupent plus de superficies que les forêts. Ainsi, ces agroécosystèmes sont à long terme susceptibles de remplacer les lambeaux forestiers. Pour tester la valeur conservatoire de ces milieux de substitution, les oiseaux ont été utilisés en tant qu’indicateur biologique en se basant sur une Analyse des Correspondances Multiples (ACM) et une Classification Hiérarchique Ascendante (CHA). 9 groupes écologiques d’oiseaux distribués dans les différents types de jachères et plantations ont été identifiés. Les jachères concentrent une forte proportion de l’avifaune de ces habitats de substitution forestiers. Ces résultats montrent que pour conserver la biodiversité des oiseaux dans ces habitats de substitution des forêts, les jachères sous plantations ou évoluées sont indispensables.© 2010 International Formulae Group. All rights reserved.Mots clés : Distribution, oiseaux, groupe écologique, plantation, jachère, Sud du Bénin

Biogeography and taxonomy of Apodemus sylvaticus (the woodmouse) in the Tyrrhenian region: Enzymatic variations and mitochondrial DNA restriction pattern analysis

In the western Mediterranean area, the taxonomic status of the various forms of Apodemus sylvaticus is quite unclear. Moreover, though anthropogenic, the origins of the island populations remain unknown in geographical terms. In order to examine the level of genetic relatedness of insular and continental woodmice, 258 animals were caught in 24 localities distributed in Belgium, France, mainland Italy, Sardinia, Corsica and Elba. Electrophoresis of 33 allozymes and mtDNA restriction fragments were performed and a UPGMA dendrogram built from the indices of genetic divergence. The dendrogram based on restriction patterns shows two main groups: 'Tyrrhenian', comprising all the Italian and Corsican animals and 'North-western', corresponding to all the other mice trapped from the Pyrenees to Belgium. Since all the Tyrrhenian mice are similar and well isolated from their relatives living on the western edge of the Alpine chain, they must share a common origin. The insular populations are consequently derived from peninsular Italian ones. From a taxonomic point of view and taking the priority rules into account, we have to invalidate A. s. clanceyi Harrison, 1948 and to consider the Tyrrhenian woodmice as belonging to A. s. milleri de Beaux, 1926, whereas the North-western ones must be referred to as the nominal subspecies. As far as the Elban woodmouse is concerned, at the moment we prefer to keep its present subspecific status because we only studied one animal

So close and so different: comparative phylogeography of two small mammal species, the yellow-necked fieldmouse (Apodemus flavicollis) and the woodmouse (Apodemus sylvaticus) in the Western Palearctic region.

In Europe, concordant geographical distribution among genetic lineages within different species is rare, which suggests distinct reactions to Quaternary ice ages. This study aims to determine whether such a discrepancy also affects a pair of sympatric species, which are morphologically and taxonomically closely related but which have slight differences in their ecological habits. The phylogeographic structures of two European rodents, the Yellow-necked fieldmouse (A. flavicollis) and the woodmouse (Apodemus sylvaticus) were, therefore, compared on the basis of mitochondrial DNA cytochrome b (mtDNA cyt b) sequences (965 base pairs) from 196 specimens collected from 59 European localities spread throughout the species distributions. The results indicate that the two species survived in different ways through the Quaternary glaciations. A. sylvaticus survived in the Iberian Peninsula from where it recolonized almost all Europe at the end of the last glaciation. Conversely, the refuge from which A. flavicollis recolonized Europe, including northern Spain, during the Holocene corresponds to the Italo-Balkan area, where A. sylvaticus suffered a serious genetic bottleneck. This study confirms that even closely related species may have highly different phylogeographic histories and shows the importance of ecological plasticity of the species for their survival through climate change. Finally, it suggests that phylogeographic distinctiveness may be a general feature of European species

Overview paper: New insights into aerosol and climate in the Arctic

Motivated by the need to predict how the Arctic atmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of Arctic aerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport, earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013. (1) Unexpectedly high summertime dimethyl sulfide (DMS) levels were identified in ocean water (up to 75 nM) and the overlying atmosphere (up to 1 ppbv) in the Canadian Arctic Archipelago (CAA). Furthermore, melt ponds, which are widely prevalent, were identified as an important DMS source (with DMS concentrations of up to 6 nM and a potential contribution to atmospheric DMS of 20 % in the study area). (2) Evidence of widespread particle nucleation and growth in the marine boundary layer was found in the CAA in the summertime, with these events observed on 41 % of days in a 2016 cruise. As well, at Alert, Nunavut, particles that are newly formed and grown under conditions of minimal anthropogenic influence during the months of July and August are estimated to contribute 20 % to 80 % of the 30-50 nm particle number density. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from seabird-colony emissions, and potentially also from coastal regions, tundra, and biomass burning. Via accumulation of secondary organic aerosol (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to Arctic marine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds (OVOCs) were inferred to arise via processes involving the sea surface microlayer. (3) The variability in the vertical distribution of black carbon (BC) under both springtime Arctic haze and more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol-climate interactions under Arctic conditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the Arctic via long-range transport mechanisms, with evidence for a dominant springtime contribution from eastern and southern Asia to the middle troposphere, and a major contribution from northern Asia to the surface. (4) Measurements of ice nucleating particles (INPs) in the Arctic indicate that a major source of these particles is mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the sea surface microlayer in the Arctic, and possibly play a role in ice nucleation in the atmosphere when mineral dust concentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high Arctic snow (0.03 cm s1)

Early phases of a successful invasion: mitochondrial phylogeography of the common genet (Genetta genetta) within the Mediterranean Basin

The Mediterranean Basin, connected by cultural exchanges since prehistoric times, provides an outstanding framework to study species translo- cations. We address here the early phases of the successful invasion of the common genet (Genetta genetta), a small carnivoran supposedly introduced from Africa to Europe during historical times, by assessing mitochondrial nucleotide variability in 134 individuals from its native and invasive ranges. We identify four lineages within the native species range [northern Algeria, Peninsular Arabia, southern Africa and western Africa + Maghreb (including northern Algeria)], in contradiction with morpho- logical taxonomy. We propose that the co- occurrence in Maghreb of two divergent lineages (autochthonous and western African) is due to secondary contact through intermittent permeability of the Saharan belt during the Plio-Pleistocene. Estimates of coalescence time and genetic diversity, in concert with other available evidences in the literature, indicate that the origin of European populations of common genets is in Maghreb, possibly restricted to northern Algeria. The autoch- thonous mitochondrial lineage of Maghreb was the only contributor to the European pool, suggesting that translocations were associated to a cultural constraint such as a local use of the species, which might have artificially excluded the western African lineage. Haplotype network and nested clade analysis (NCA) provide evidence for independent events of introductions throughout Spain (Andalucia, Catalun˜ a, and the Balearic Isl.)—and, to a lesser extent, Portugal—acting as a ‘translocation hotspot’. Due to the reduced number of northern Algerian individuals belonging to the autochthonous mitochondrial line- age of Maghreb, it remains impossible to test hypotheses of historical translocations, although a main contribution of the Moors is likely. Our demographic analyses support a scenario of very recent introduction of a reduced number of individ- uals in Europe followed by rapid population expansion. We suggest that an exceptional combi- nation of factors including multiple translocations, human-driven propagation across natural barriers, and natural processes of colonization allowed by a wide ecological tolerance, promoted the successful spread of the common genet into EuropePeer reviewe