Mechanisms underlying biological diversities at different scales have received significant attention over the last decades. The hypothesis of whether local abiotic factors, driving functional and phylogenetic diversities, can differ among taxa of arthropods remains under-investigated. In this study, we compared correlations and drivers of functional diversity (FD) and phylogenetic diversity (PD) between spiders and carabids, two dominant taxa of ground-dwelling arthropods in salt marshes. Both taxa exhibited high correlation between FD and PD; the correlation was even higher in carabids, probably owing to their lower species richness. Analyses using structural equation modelling highlighted that FD and PD were positively linked to taxonomic diversity (TD) in both taxa; however, abiotic factors driving the FD and PD differed between spiders and carabids. Salinity particularly drove the TD of carabids, but not that of spiders, suggesting that spiders are phenotypically more plastic and less selected by this factor. Conversely, PD was influenced by salinity in spiders, but not in carabids. This result can be attributed to the different evolutionary history and colonization process of salt marshes between the two model taxa. Finally, our study highlights that, in taxa occupying the same niche in a constrained habitat, FD and PD can have different drivers, and thereby different filtering mechanisms.

The Biological Field Station of Paimpont (Station Biologique de Paimpont, SBP), owned by the University of Rennes and located in the Brocéliande Forest of Brittany (France), has been hosting student scientific research and field trips during the last 60 years. The study area of the SBP is a landscape mosaic of 17 ha composed of gorse moors, forests, prairies, ponds and creeks. Land use has evolved over time. Historical surveys by students and researchers focused on insects and birds. With this study, we aimed to increase the range of taxa observations, document changes in species composition and landscape and provide a basis for interdisciplinary research perspectives. We gathered historical data, implemented an all-taxon biodiversity inventory (ATBI) in different habitats of the SBP study area, measured abiotic factors in the air, water and soil and performed a photographical landscape observation during the BioBlitz held in July 2017. During the 24 h BioBlitz, organised by the SBP and the EcoBio lab from the University of Rennes and the French National Center of Scientific Research (CNRS), different habitats were individually sampled. Seventy-seven experts, accompanied by 120 citizens and 12 young people participating in the European Volunteer Service, observed, identified and databased 660 species covering 5 kingdoms, 8 phyla, 21 classes, 90 orders and 247 families. In total, there were 1819 occurrences including records identified to higher taxon ranks, thereby adding one more kingdom and four more phyla. Historical data collection resulted in 1176 species and 4270 occurrences databased. We also recorded 13 climatic parameters, 10 soil parameters and 18 water parameters during the BioBlitz. Current habitats were mapped and socio-ecological landscape changes were assessed with a diachronic approach using 32 historical photographs and historical maps. The coupling of historical biodiversity data with new biotic and abiotic data and a photographic comparison of landscape changes allows an integrative understanding of how the SBP changed from agriculturally-used land to a managed natural area within the last 60 years. Hence, this BioBlitz represents an important holistic sampling of biodiversity for studies on trophic webs or on trophic interactions or on very diverse, but connected, habitats. The integration of social, biotic and abiotic data opens innovative research opportunities on the evolution of socio-ecosystems and landscapes.

20While mechanisms underlying biological diversities at different scales received huge attention over 21 the last decades, whether local abiotic factors driving functional and phylogenetic diversities can 22 differ among ecologically and phylogenetically closely related taxa remains under-investigated. In 23 this study, we compared correlations and drivers of functional (FD) and phylogenetic (PD) diversities 24 between two dominant taxa of ground-dwelling arthropods in salt marshes, spiders and carabids. 25Pitfall trapping in two sampling sites of N-W France resulted in the collection and identification of 26 more than 7000 individuals belonging to 67 species. Morphological and behavioral traits, as well as 27 molecular sequences of COI gene, were attributed to all species for calculating functional and 28 phylogenetic diversities respectively. Both taxa exhibited high correlation between FD and PD, which 29 was even higher in carabids probably due to their lower species richness. Analyses using Bayesian 30 framework and structural equation modeling revealed that FD and PD were positively influenced by 31 taxonomic diversity in spiders and carabids, but abiotic factors driving FD and PD differed between 32 taxa. Salinity especially drove the taxonomic diversity of carabids, but not that of spiders, suggesting 33 that spiders are more plastic and less selected by this factor. Phylogenetic diversity was conversely 34 influenced by salinity in spiders but not in carabids. This interesting result can be interpreted by 35 different evolutionary history and colonization process of salt marshes between the two model taxa. 36Our study finally highlights that, even in taxa of the same phylum and occupying the same niche in a 37 highly constrained habitat, functional and phylogenetic diversities can have different drivers, showing 38 different filtering mechanisms and evolutionary history at small spatial and temporal scales. 39 40

Une méthode standardisée et flexible permettant de hiérarchiser et de synthétiser la valeur de préservation des espèces est développée et appliquée pour les oiseaux nicheurs (131 espèces) à l’échelle du département d’Ille-et-Vilaine (35). La méthodologie se base sur trois critères couramment utilisés pour l’évaluation de la valeur de préservation : la vulnérabilité des espèces, la rareté et l’originalité biologique (distinctivité phylogénétique et fonctionnelle). Ces critères sont décrits par neuf indicateurs complémentaires (renseignés en variables continues ou discrètes). Le principe calculatoire de l’indice est basé sur la méthode de score qui réparti les valeurs des indicateurs de chaque critère en cinq catégories croissantes de scores. La moyenne pondérée des valeurs de chaque indicateur permet d’attribuer un score global pour chaque espèce, évaluant la valeur de préservation de manière continue. Des spécificités départementales sont mises en évidence par rapport aux espèces à enjeux évaluées au niveau régional. L’Indice de Valeur de Préservation (IVP) constitue un indice d’intégration multicritère borné et flexible, qui peut être applicable pour d’autres taxons quelle que soit la méthode d’évaluation développée pour les indicateurs et quels que soient les indicateurs choisis. Il peut être utilisé en routine pour des mises à jour rapides et pour standardiser des comparaisons sur différents territoires administratifs à plusieurs échelles dont des niveaux infranationaux et infrarégionaux.