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Auteur Villeger, S.; Maire, Eva; Leprieur, F.
Titre On the risks of using dendrograms to measure functional diversity and multidimensional spaces to measure phylogenetic diversity: a comment on Sobral et al. (2016) Type Article scientifique
Année 2017 Publication Revue Abrégée (up) Ecol. Lett.
Volume 20 Numéro 4 Pages 554-557
Mots-Clés assemblages; cophenetic distance; dendrogram; Euclidean space; functional diversity; functional space; phylogenetic diversity; reveals
Résumé Sobral et al. (Ecology Letters, 19, 2016, 1091) reported that the loss of bird functional and phylogenetic diversity due to species extinctions was not compensated by exotic species introductions. Here, we demonstrate that the reported changes in biodiversity were underestimated because of methodological pitfalls.
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Auteur Chao, A.; Chiu, C.-H.; Villeger, S.; Sun, I.-F.; Thorn, S.; Lin, Y.-C.; Chiang, J.-M.; Sherwin, W.B.
Titre An attribute-diversity approach to functional diversity, functional beta diversity, and related (dis)similarity measures Type Article scientifique
Année 2019 Publication Revue Abrégée (up) Ecol. Monogr.
Volume 89 Numéro 2 Pages Unsp-e01343
Mots-Clés attribute diversity; biodiversity; biological diversity; consensus; conservation; differentiation measures; diversity decomposition; evenness; framework; functional (dis)similarity; functional beta diversity; functional diversity; Hill numbers; phylogenetic diversity; quadratic entropy; similarity; species diversity; species richness; species traits; trait diversity
Résumé Based on the framework of attribute diversity (a generalization of Hill numbers of order q), we develop a class of functional diversity measures sensitive not only to species abundances but also to trait-based species-pairwise functional distances. The new method refines and improves on the conventional species-equivalent approach in three areas: (1) the conventional method often gives similar values (close to unity) to assemblages with contrasting levels of functional diversity; (2) when a distance metric is unbounded, the conventional functional diversity depends on the presence/absence of other assemblages in the study; (3) in partitioning functional gamma diversity into alpha and beta components, the conventional gamma is sometimes less than alpha. To resolve these issues, we add to the attribute-diversity framework a novel concept: tau, the threshold of functional distinctiveness between any two species; here, tau can be chosen to be any positive value. Any two species with functional distance >= tau are treated as functionally equally distinct. Our functional diversity quantifies the effective number of functionally equally distinct species (or “virtual functional groups”) with all pairwise distances at least tau for different species pairs. We advocate the use of two complementary diversity profiles (tau profile and q profile), which depict functional diversity with varying levels of tau and q, respectively. Both the conventional species-equivalent method (i.e., tau is the maximum of species-pairwise distances) and classic taxonomic diversity (i.e., tau is the minimum of non-zero species-pairwise distances) are incorporated into our proposed tau profile for an assemblage. For any type of species-pairwise distance matrices, our attribute-diversity approach allows proper diversity partitioning, with the desired property gamma >= alpha and thus avoids all the restrictions that apply to the conventional diversity decomposition. Our functional alpha and gamma are interpreted as the effective numbers of functionally equally distinct species, respectively, in an assemblage and in the pooled assemblage, while beta is the effective number of equally large assemblages with no shared species and all species in the assemblages being equally distinct. The resulting beta diversity can be transformed to obtain abundance-sensitive Sorensen- and Jaccard-type functional (dis)similarity profiles. Hypothetical and real examples are used to illustrate the framework. Online software and R codes are available to facilitate computations.
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ISSN 0012-9615 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2620
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Auteur Loiseau, N.; Gaertner, J.-C.; Kulbicki, M.; Mérigot, B.; Legras, G.; Taquet, M.; Gaertner-Mazouni, N.
Titre Assessing the multicomponent aspect of coral fish diversity: The impact of sampling unit dimensions Type Article scientifique
Année 2016 Publication Revue Abrégée (up) Ecological Indicators
Volume 60 Numéro Pages 815-823
Mots-Clés Evenness; Functional diversity; Index sensitivity; Sampling unit dimensions; species richness; Visual censuses
Résumé The influence of variations in sampling unit dimensions on the assessment of fish species structuring has been widely documented. However, this issue has been restricted to a very limited range of community and population indices (mainly species richness and density). Here, we have investigated this issue through the analysis of 13 diversity indices related to 3 diversity components (number of species, evenness and functional diversity). We analyzed a large set of 257 standardized underwater visual census (UVC) transects dealing with 254 coral fish species. The sensitivity of the indices to the variation in sampling unit dimensions was studied by comparing a range of 55 couples of transect length and width representing 34 sampling surfaces. We found that the extent and profile of the sensitivity to changes in transect dimensions strongly varied both from one index to another and from one dimension to another (length and width). The most sensitive indices were more strongly impacted by variation in length than width. We also showed that for a fixed transect surface, the couple of chosen length and width may alter the assessment of indices related to each of the three main diversity components studied. Some widely used diversity indices, such as species richness and Shannon index, appeared to be very sensitive to changes in transect length and width. In contrast, while still very little used in coral fish studies, two functional diversity indices (FDiv, FEve), and to a lesser extent an evenness index (Berger–Parker), remained robust in the face of change in sampling dimensions. By showing that the variation in sampling dimensions (length, width and surface) may impact diversity indices in a contrasting manner, we stress the need to take into account the sensitivity of the indices to this criterion in the process of selection of the indices to be analyzed in diversity studies. Finally, we found that 30 m long*5 m wide transects might be a suitable compromise size for assessing the patterns of each of the three major complementary components of coral fish diversity.
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ISSN 1470-160x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1320
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Auteur Albouy, C.; Lasram, F.B.R.; Velez, L.; Guilhaumon, F.; Meynard, C.N.; Boyer, S.; Benestan, L.; Mouquet, N.; Douzery, E.; Aznar, R.; Troussellier, M.; Somot, S.; Leprieur, F.; Le Loc'h, F.; Mouillot, D.
Titre FishMed: traits, phylogeny, current and projected species distribution of Mediterranean fishes, and environmental data Type Article scientifique
Année 2015 Publication Revue Abrégée (up) Ecology
Volume 96 Numéro 8 Pages 2312-2313
Mots-Clés climate change; coastal fishes; functional diversity; Mediterranean fish species; Mediterranean Sea; Nemomed8; phylogenetic diversity; species distribution models; taxonomic diversity
Résumé The FishMed database provides traits, phylogeny, current and projected species distribution of Mediterranean fishes, and associated sea surface temperature (SST) from the regional oceanic model NEMOMED8. Data for the current geographical distributions of 635 Mediterranean fish species were compiled from a published expert knowledge atlas of fishes of the northern Atlantic and the Mediterranean (FNAM) edited between 1984 and 1986 and from an updated exotic fish species list. Two future sets of projected species distributions were obtained for the middle and end of the 21st century by using an ensemble forecasting approach for 288 coastal Mediterranean fish species based on SST according to the IPPC/SRES A2 scenario implemented with the Mediterranean climatic model NEMOMED8. The functional part of the database encompasses 12 biological and ecological traits (maximal and common lengths, vertical distribution, habitat, migration type, mode of reproduction, sex shift, semelparity, diet type (larvae and adults), social behavior, species origin, and depth) for the 635 fish species. To build the phylogeny we inferred the timing and geographic origins of Mediterranean teleost species diversity using nucleotide sequences collected from GenBank including 62% of Mediterranean teleost species plus nine outgroups. Maximum likelihood Bayesian phylogenetic and dating analyses were calibrated using 20 fossil species. An additional 124 fish species were grafted onto the chronogram according to their taxonomic affinity to obtain a phylogenetic tree including 498 species. Finally we also present the associated SST data for the observed period (1961–1980) and for the middle (2040–2059) and the end of the 21st century (2080–2099) obtained from NEMOMED8 according to the IPCC A2 scenario. The FishMed database might be of interest in the context of global anthropogenic changes as coastal Mediterranean ecosystems are currently recognized as one of the most impacted ecosystems on earth.
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Numéro d'Appel MARBEC @ alain.herve @ collection 1471
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Auteur Parravicini, V.; Villeger, S.; McClanahan, T.R.; Arias-Gonzalez, J.E.; Bellwood, D.R.; Belmaker, J.; Chabanet, P.; Floeter, S.R.; Friedlander, A.M.; Guilhaumon, F.; Vigliola, L.; Kulbicki, M.; Mouillot, D.
Titre Global mismatch between species richness and vulnerability of reef fish assemblages Type Article scientifique
Année 2014 Publication Revue Abrégée (up) Ecology Letters
Volume 17 Numéro 9 Pages 1101-1110
Mots-Clés Vulnerability; biodiversity; biodiversity loss; conservation; coral-reefs; extinction; fisheries; functional diversity; hotspots; macroecology; marine; patterns; protected areas; risk assessment; sensitivity
Résumé The impact of anthropogenic activity on ecosystems has highlighted the need to move beyond the biogeographical delineation of species richness patterns to understanding the vulnerability of species assemblages, including the functional components that are linked to the processes they support. We developed a decision theory framework to quantitatively assess the global taxonomic and functional vulnerability of fish assemblages on tropical reefs using a combination of sensitivity to species loss, exposure to threats and extent of protection. Fish assemblages with high taxonomic and functional sensitivity are often exposed to threats but are largely missed by the global network of marine protected areas. We found that areas of high species richness spatially mismatch areas of high taxonomic and functional vulnerability. Nevertheless, there is strong spatial match between taxonomic and functional vulnerabilities suggesting a potential win-win conservation-ecosystem service strategy if more protection is set in these locations.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 630
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