Aim To assess the exposure of 10 spider species to two drivers of global change (climate and land use), the suitability of the current network of protected areas with respect to this exposure, and the implications for a national conservation programme.Location The western Palearctic and France.Methods We predicted the current and future potential distributions of 10 spider species using species distribution models (SDMs). We explicitly quantified uncertainties in the models and estimated the future environmental suitability with discounted uncertainty. We analysed the predicted future suitability for protected versus unprotected occurrence cells. ResultsIn this first forecast of the future of multiple spider species in the face of environmental changes, we showed that environmental changes could be confidently predicted to have serious impacts on all the studied species, with significant range contractions and expansions within a relatively short timescale (up to 2050). We predicted that for seven of the 10 species, the current network of protected areas will conserve at least one occurrence cell in suitable conditions in the future. However, we showed that there is considerable room for improvement.Main conclusions This study illustrated how SDMs could be applied to a conservation programme for an understudied taxon such as spiders, in spite of significant uncertainties in their predictions. In addition, the uncertainties raised here compel us to emphasize the pressing need to improve our knowledge on understudied taxa such as spiders. We advocate the necessity of increasing monitoring schemes, experiments and forecasts of environmental change effects on a larger and more diversified range of species than is currently the case in the literature.

Spiders are known to commonly use aerial dispersal, so-called ballooning, especially at juvenile stages. They produce a silk thread that allows them to rise up in the air to disperse, which serves as inbreeding avoidance or to find an optimal over-winter habitat. Studies of phenology, species and meteorological factors associated with aerial dispersal have been limited to laboratory settings, with few data obtained under natural settings and no studies to date executed in France. To understand aerial dispersal, we conducted daily sampling between 2000 and 2002 at a height of 12m. For adults, high proportions of "ballooners" were observed during four seasonal peaks, with dispersal most prevalent during summer, while for juveniles dispersal was protracted across summer and fall. Linyphiidae is the most abundant family among the 10,879 individuals caught. We show a significant and negative influence of high wind speeds on ballooning, an effect that increased even under low temperatures (<19°C). At wind speeds greater than 4m·s(-1) dispersal becomes difficult, and is almost impossible beyond 5.5m·s(-1). Ballooning ability is reported for the first time for several species. This study increases our knowledge on aerial dispersal in spiders in an agricultural context. Such behaviour can be seen as a survival strategy to escape from a disturbed and unstable landscape.

Secondary (or recent) woodlands, whose development is favoured by massive farmland abandonment, are increasingly seen as promising habitats that limit losses of biodiversity and ecosystem processes. The importance of temporal forest continuity (i.e. the duration of an uninterrupted forest state) for conservation of the forest fauna has been demonstrated for several taxa, but its influence on functional diversity and conservation importance of communities remains unclear. We studied how temporal continuity can shape taxonomic and functional composition and structure of forest-ground spider communities at a regional scale. According to broad-scale ecological site characteristics, species composition and-to a lesser extent-trait distribution substantially diverged between ancient and recent forest sites. Yet, we found hardly any significant differences in functional β-diversity, community structure, or conservation importance between the two forest categories. The only difference was for functional originality, which quantifies the average functional uniqueness of species within an assemblage: spiders' communities of the ancient forests was more functionally original than those of the recent woodlands. Thus, in a conservation perspective, our study provides evidence that each forest harbours original species combinations, suggesting that each of them is irreplaceable, especially for ancient forests, which are functionally more original; however, recent woodlands have a high potential to spontaneously recover typical forest fauna communities with very similar structural and functional profiles to those of ancient forests.

In this paper, we validate the doubtful species status of E. guianae, with redescriptions of (supposedly lost) type and holotype males, and a first description of the female. Both sexes are measured and illustrated by pictures of habitus and copulatory organs. Seventeen new salticid species for French Guiana are also reported and a detailed catalogue of all salticid species from the Trinité National Nature Reserve is provided.