Large group formation in European Roe deer : an adaptive feature ?

Le Chevreuil d'Europe (Capreolus capreolus) colonise les plaines cultivées depuis quelques décennies. Dans cet article, nous comparons la taille des groupes hivernaux de cette espèce dans six zones diversement ouvertes, ainsi que dans deux de ces zones pour différentes densités de population. Nos résultats montrent que la taille moyenne des groupes, atteignant huit animaux dans la plaine la plus ouverte, s'accroît avec l'ouverture de l'habitat et la densité de population. Le Chevreuil d'Europe ayant probablement évolué dans des habitats essentiellement forestiers jusqu'à une date récente, il est difficile d'interpréter le fait qu'il forme de grands groupes dans les plaines agricoles comme un trait mis en place par la sélection naturelle. Chez cette espèce, l'accroissement de la taille des groupes avec l'ouverture de l'habitat et la densité de population serait en fait la simple conséquence de l'instabilité des groupes. La formation de grands groupes pourrait bien sûr avoir un effet positif sur la valeur sélective des individus colonisant les plaines agricoles, mais ce trait devrait alors être considéré comme une « exaptation » (au sens de Gould et Vrba) et non comme une authentique adaptation

Fox faeces and vole distribution on a local range: ecological data in a parasitological perspective for Echinococcus multilocularis.

International audienceThe completion of the life cycle of Echinococcus multilocularis needs a spatial overlap between intermediate host species (voles) and definitive host (fox) faeces. Factors influencing the importance of this overlap were investigated in north eastern France. Kilometric transects were walked to collect fox faeces and to estimate vole relative densities through surface indices. Habitat and climatic conditions were the strongest predictors of the number of faeces collected, while vole densities had no predictive power. Densities of both Microtus sp. and fox faeces were higher in medium-height vegetation edge. The consequences of such results to understand local transmission processes and human exposure are discussed

Long-distance wolf recolonization of France and Switzerland inferred from non-invasive genetic sampling over a period of 10 years

In the early 1900s, the wolf (Canis lupus) was extirpated from France and Switzerland. There is growing evidence that the species is presently recolonizing these countries in the western Alps. By sequencing the mitochondrial DNA (mtDNA) control region of various samples mainly collected in the field (scats, hairs, regurgitates, blood or tissue; n = 292), we could (1) develop a non-invasive method enabling the unambiguous attribution of these samples to wolf, fox (Vulpes vulpes) or dog (Canis familiaris), among others; (2) demonstrate that Italian, French and Swiss wolves share the same mtDNA haplotype, a haplotype that has never been found in any other wolf population world-wide. Combined together, field and genetic data collected over 10 years corroborate the scenario of a natural expansion of wolves from the Italian source population. Furthermore, such a genetic approach is of conservation significance, since it has important consequences for management decisions. This first long-term report using non-invasive sampling demonstrates that long-distance dispersers are common, supporting the hypothesis that individuals may often attempt to colonize far from their native pack, even in the absence of suitable corridors across habitats characterized by intense human activities

Landscape genetics highlights the role of bank vole metapopulation dynamics in the epidemiology of Puumala hantavirus

Rodent host dynamics and dispersal are thought to be critical for hantavirus epidemiology as they determine pathogen persistence and transmission within and between host populations. We used landscape genetics to investigate how the population dynamics of the bank vole Myodes glareolus, the host of Puumala hantavirus (PUUV), vary with forest fragmentation and influence PUUV epidemiology. We sampled vole populations within the Ardennes, a French PUUV endemic area. We inferred demographic features such as population size, isolation and migration with regard to landscape configuration. We next analysed the influence of M. glareolus population dynamics on PUUV spatial distribution. Our results revealed that the global metapopulation dynamics of bank voles were strongly shaped by landscape features, including suitable patch size and connectivity. Large effective size in forest might therefore contribute to the higher observed levels of PUUV prevalence. By contrast, populations from hedge networks highly suffered from genetic drift and appeared strongly isolated from all other populations. This might result in high probabilities of local extinction for both M. glareolus and PUUV. Besides we detected signatures of asymmetric bank vole migration from forests to hedges. These movements were likely to sustain PUUV in fragmented landscapes. In conclusion, our study provided arguments in favour of source-sink dynamics shaping PUUV persistence and spread in heterogeneous, western European temperate landscapes. It illustrated the potential contribution of landscape genetics to the understanding of the epidemiological processes occurring at this local scale

Spatial distribution of soil contaminated with Toxoplasma gondii oocysts in relation to the distribution and use of domestic cat defecation sites on dairy farms

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