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Abgrall, C., Chauvat, M., Langlois, E., Hedde, M., Mouillot, D., Salmon, S., et al. (2017). Shifts and linkages of functional diversity between above- and below-ground compartments along a flooding gradient. Funct. Ecol., 31(2), 350–360.
Résumé: 1. Trait-based approaches have the potential to reveal general and predictive relationships between organisms and ecosystem functioning. However, the mechanisms underlying the functional structure of communities are still unclear. Within terrestrial ecosystems, several studies have shown that many ecological processes are controlled by the interacting above-and belowground compartments. However, few studies have used traits to reveal the functional relationships between plants and soil fauna. Mostly, research combining plants and soil fauna solely used the traits of one assemblage in predictive studies. 2. Above-ground (plants) and below-ground (Collembola) compartments were sampled over a flooding gradient in northern France along the Seine River. First, we measured the effect of flooding on functional and taxonomic assembly within both communities. We then considered the linkages between plant and Collembolan species richness, community traits and assessed whether traits of both compartments converged at high flooding intensity (abiotic filtering) and diverged when this constraint is released (biotic filtering). 3. Species richness of both taxa followed the same bell-shaped pattern along the gradient, while a similar significant pattern of functional richness was only observed for plants. Further analyses revealed a progressive shift from trait convergence to divergence for plants, but not for Collembola, as constraints intensity decreased. Instead, our results highlighted that Collembola traits were mainly linked to the variations in plant traits. This leads, within Collembola assemblages, to convergence of a subset of perception and habitat-related traits for which the relationship with plant traits was assessed. 4. Synthesis. Using a trait-based approach, our study highlighted that functional relationships occur between above-and below-ground compartments. We underlined that functional composition of plant communities plays a key role in structuring Collembola assemblages in addition to the role of abiotic variables. Our study clearly shows that functional diversity provides a new approach to link the above-and below-ground compartments and might, therefore, be further considered when studying ecological processes at the interface between both compartments.
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Hattab, T., Albouy, C., Lasram, F. B., Le Loc'h, F., Guilhaumon, F., & Leprieur, F. (2015). A biogeographical regionalization of coastal Mediterranean fishes. Journal of Biogeography, 42(7), 1336–1348.
Résumé: AimTo delineate the biogeographical regions of the continental shelf of the Mediterranean Sea based on the spatial distributions of coastal marine fishes and their evolutionary relationships, with a view to furthering our capacity to answer basic and applied biogeographical, ecological and evolutionary questions. LocationMediterranean Sea. MethodsWe used a dataset summarizing the occurrences of 203 coastal Mediterranean fishes (0.1 degrees resolution grid system) and a molecular phylogenetic tree to quantify both compositional and phylogenetic dissimilarity (or beta diversity) between cells. We then applied multivariate analyses to delineate biogeographical regions and to evaluate how they related to broad-scale environmental gradients. We also assessed the differences between the biogeographical regions identified using phylogenetic beta diversity versus those obtained using compositional beta diversity. ResultsThe bioregionalization schemes based on phylogenetic and compositional beta diversity identified broadly similar regions, each consisting of six distinct pools of coastal fishes. Clear separations between northern and southern regions were observed, as well as a disjunct between inshore and offshore areas. These beta diversity patterns were mainly related to a north-south gradient in sea-surface temperature and bathymetric constraints. Main conclusionsIncorporating phylogenetic information into the measurement of beta diversity did not offer further insights to the bioregionalization scheme based solely on compositional beta diversity. This suggests that evolutionary and historical processes played only a minor role in shaping the contemporary patterns of beta diversity in the Mediterranean coastal fish fauna. However, our results support the view that contemporary environmental conditions play a major role in determining the distribution of these species.
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Husson, B., Certain, G., Filin, A., & Planque, B. (2020). Suitable habitats of fish species in the Barents Sea. Fish Oceanogr., 29(6), 526–540.
Résumé: Many marine species exhibit poleward migrations following climate change. The Barents Sea, a doorstep to the fast-warming Arctic, is experiencing large scale changes in its environment and its communities. Tracking and anticipating changes for management and conservation purposes at the scale of the ecosystem necessitate quantitative knowledge on individual species distribution drivers. This paper aims at identifying the factors controlling demersal habitats in the Barents Sea, investigating for which species we can predict current and future habitats and inferring those most likely to respond to climate change. We used non-linear quantile regressions (QGAM) to model the upper quantile of the biomass response of 33 fish species to 10 environmental gradients and revealed three environmental niche typologies. Four main predictors seem to be limiting species habitat: bottom and surface temperature, salinity, and depth. We highlighted three cases of present and future habitat predictability: (a) Habitats of widespread species are not likely to be limited by the existing conditions within the Barents Sea. (b) Habitats limited by a single factor are predictable and could shift if impacted by climate change. If the factor is depth, the habitat may stagnate or shrink if the environment becomes unsuitable. (c) Habitats limited by several factors are also predictable but need to be predicted from QGAM applied on projected environmental maps. These modeled suitable habitats can serve as input to species distribution forecasts and end-to-end models, and inform fisheries and conservation management.
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Keller, S., Hidalgo, M., Alvarez-Berastegui, D., Bitetto, I., Casciaro, L., Cuccu, D., et al. (2017). Demersal cephalopod communities in the Mediterranean: a large-scale analysis. Mar. Ecol.-Prog. Ser., 584, 105–118.
Résumé: Cephalopod assemblages at the scale of the entire Mediterranean Sea were analysed using information from 2 decades of standardized scientific bottom trawl surveys. Western and eastern assemblages (6 yr of data) were compared using a combined approach of multivariate ordination techniques and non-linear regressions. These methods enabled us to distinguish assemblages and simultaneously analyse the influence of geographic, bathymetric and environmental (sea surface temperature and chlorophyll a concentration) gradients on observed community patterns. Despite few differences in species composition between sub-basins, the relative contribution of species differed. Bathymetry was the primary structural driver for the cephalopod communities of both basins, and contributed to 3 assemblages (shallow water, upper slope and middle slope). Winter temperature influenced community assemblages more strongly in the western than in the eastern basin, in contrast to a small but consistent winter productivity influence on community assemblages in both basins. Thus, the environmental parameters analysed did not cause an immediate change in cephalopod assemblages, but rather an effect lagged by several months. Differences in the relative importance of environmental drivers show that different processes operate in the 2 basins. These results demonstrate similarities and differences between Mediterranean basins regarding important cephalopod functional groups. This information should help integrative ecosystem management approaches currently used in fisheries and conservation management.
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Qian, H., Jin, Y., Leprieur, F., Wang, X., & Deng, T. (2020). Geographic patterns and environmental correlates of taxonomic and phylogenetic beta diversity for large-scale angiosperm assemblages in China. Ecography, .
Résumé: A full understanding of the origin and maintenance of beta-diversity patterns in a region requires exploring the relationships of both taxonomic and phylogenetic beta-diversity (TBD and PBD, respectively), and their respective turnover and nestedness components, with geographic and environmental distances. Here, we simultaneously investigated all these aspects of beta-diversity for angiosperms in China. Specifically, we evaluated the relative importance of environmental filtering vs dispersal limitation processes in shaping beta-diversity patterns. We found that TBD and PBD as quantified using a moving window approach decreased towards higher latitudes across the whole of China, and their turnover components were correlated with latitude more strongly than their nestedness components. When quantifying beta-diversity as pairwise distances, geographic and climatic distances across China together explained 60 and 53% of the variation in TBD and PBD, respectively. After the variation in beta-diversity explained by climatic distance was accounted for, geographic distance independently explained about 23 and 12% of the variation in TBD and PBD, respectively, across China. Overall, our results suggest that environmental filtering based on climatic tolerance conserved across lineages is the main force shaping beta-diversity patterns for angiosperms in China.
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