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Auteur Villeger, S.; Grenouillet, G.; Brosse, S.
Titre Decomposing functional β-diversity reveals that low functional β-diversity is driven by low functional turnover in European fish assemblages Type Article scientifique
Année 2013 Publication Revue Abrégée Global Ecology and Biogeography
Volume 22 Numéro 6 Pages 671-681
Mots-Clés Europe; Functional richness; beta-diversity; convex hull volume; freshwater fish; functional diversity; functional traits; overlap
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ISSN 1466-8238 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 507
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Auteur Granger, V.; Bez, N.; Fromentin, J.-M.; Meynard, C.; Jadaud, A.; Mérigot, B.
Titre Mapping diversity indices: not a trivial issue Type Article scientifique
Année 2015 Publication Revue Abrégée Methods Ecol Evol
Volume 6 Numéro 6 Pages 688-696
Mots-Clés interpolation methods; map; quadratic entropy; spatial statistics; species diversity; species richness; β-diversity
Résumé (up) * Mapping diversity indices, that is estimating values in all locations of a given area from some sampled locations, is central to numerous research and applied fields in ecology. * Two approaches are used to map diversity indices without including abiotic or biotic variables: (i) the indirect approach, which consists in estimating each individual species distribution over the area, then stacking the distributions of all species to estimate and map a posteriori the diversity index, (ii) the direct approach, which relies on computing a diversity index in each sampled locations and then to interpolate these values to all locations of the studied area for mapping. * For both approaches, we document drawbacks from theoretical and practical viewpoints and argue about the need for adequate interpolation methods. First, we point out that the indirect approach is problematic because of the high proportion of rare species in natural communities. This leads to zero-inflated distributions, which cannot be interpolated using standard statistical approaches. Secondly, the direct approach is inaccurate because diversity indices are not spatially additive, that is the diversity of a studied area (e.g. region) is not the sum of the local diversities. Therefore, the arithmetic variance and some of its derivatives, such as the variogram, are not appropriate to ecologically measure variation in diversity indices. For the direct approach, we propose to consider the β-diversity, which quantifies diversity variations between locations, by the mean of a β-gram within the interpolation procedure. We applied this method, as well as the traditional interpolation methods for comparison purposes on different faunistic and floristic data sets collected from scientific surveys. We considered two common diversity indices, the species richness and the Rao's quadratic entropy, knowing that the above issues are true for complementary species diversity indices as well as those dealing with other biodiversity levels such as genetic diversity. * We conclude that none of the approaches provided an accurate mapping of diversity indices and that further methodological developments are still needed. We finally discuss lines of research that may resolve this key issue, dealing with conditional simulations and models taking into account biotic and abiotic explanatory variables.
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ISSN 2041-210x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1212
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Auteur Si, X.; Baselga, A.; Leprieur, F.; Song, X.; Ding, P.
Titre Selective extinction drives taxonomic and functional alpha and beta diversities in island bird assemblages Type Article scientifique
Année 2016 Publication Revue Abrégée J Anim Ecol
Volume 85 Numéro 2 Pages 409-418
Mots-Clés Beta diversity; community assembly; dispersal; diversity–area relationship; environmental filtering; functional trait; island biogeography; nestedness; null model; turnover
Résumé (up) * Taxonomic diversity considers all species being equally different from each other and thus disregards species’ different ecological functions. Exploring taxonomic and functional aspects of biodiversity simultaneously can better understand the processes of community assembly. * We analysed taxonomic and functional alpha and beta diversities of breeding bird assemblages on land-bridge islands in the Thousand Island Lake, China. Given the high dispersal ability of most birds at this spatial scale (several kilometres), we predicted (i) selective extinction driving alpha and beta diversities after the creation of land-bridge islands of varying area and (ii) low taxonomic and functional beta diversities that were not correlated to spatial distance. * Breeding birds were surveyed on 37 islands annually from 2007 to 2014. We decomposed beta diversity of breeding birds into spatial turnover and nestedness-resultant components, and related taxonomic and functional diversities to island area and isolation using power regression models (for alpha diversity) and multiple regression models on distance matrices (for beta diversity). We then ran simulations to assess the strength of the correlations between taxonomic and functional diversities. * Results revealed that both taxonomic and functional alpha diversities increased with island area. The taxonomic nestedness-resultant and turnover components increased and decreased with difference in area, respectively, but functional counterparts did not. Isolation played a minor role in explaining alpha- and beta-diversity patterns. By partitioning beta diversity, we found low levels of overall taxonomic and functional beta diversities. The functional nestedness-resultant component dominated overall functional beta diversity, whereas taxonomic turnover was the dominant component for taxonomic beta diversity. The simulation showed that functional alpha and beta diversities were significantly correlated with taxonomic diversities, and the observed values of correlations were significantly different from null expectations of random extinction. * Our assessment of island bird assemblages validated the predictions of no distance effects and low beta diversity due to pervasive dispersal events among islands and also suggested that selective extinction drives taxonomic and functional alpha and beta diversities. The contrasting turnover and nestedness-resultant components of taxonomic and functional beta diversities demonstrate the importance of considering the multifaceted nature of biodiversity when examining community assembly.
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ISSN 1365-2656 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1543
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Auteur Baselga, A.; Leprieur, F.
Titre Comparing methods to separate components of beta diversity Type Article scientifique
Année 2015 Publication Revue Abrégée Methods Ecol Evol
Volume 6 Numéro 9 Pages 1069-1079
Mots-Clés beta diversity; community composition; dissimilarity coefficients; nestedness; replacement; richness difference; turnover
Résumé (up) * Two alternative frameworks have been proposed to partition compositional dissimilarity into replacement and nestedness-resultant component or into replacement and richness-difference components. These are, respectively, the BAS (Baselga 2010, Global Ecology and Biogeography, 19, 134–143) and POD (Podani & Schmera . Oikos, 120, 1625–1638) frameworks. * We conduct a systematic comparison of parallel components in alternative approaches. We test whether the replacement components derived from the BAS and POD frameworks are independent of richness difference. We also evaluate whether previously reported tests of monotonicity between indices and ecological processes are informative to assess the performance of indices. Finally, we illustrate the consequences of differences between the BAS and POD frameworks using the North American freshwater fish fauna as an empirical example. * In the BAS framework, the nestedness-resultant component (βjne or βsne) accounts only for richness differences derived from nested patterns while, in the POD framework, richness-difference dissimilarity (βrich or βrich.s) accounts for all kind of richness differences. Likewise, the replacement components of both alternative methods account for different concepts. Only the replacement component of the BAS framework (βjtu or βsim) is independent of richness difference, while the parallel component in the POD framework (β−3 or β−3.s) is not (i.e. it is mathematically constrained by richness difference). * Therefore, only the BAS framework allows separating (i) the variation in species composition derived from species replacement which is independent of richness difference (i.e. not mathematically constrained by it) and (ii) the variation in species composition derived from nested patterns.
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Volume de collection Numéro de collection Edition
ISSN 2041-210x ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1473
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Auteur Gravel, D.; Poisot, T.; Albouy, C.; Velez, L.; Mouillot, D.
Titre Inferring food web structure from predator-prey body size relationships Type Article scientifique
Année 2013 Publication Revue Abrégée Methods in Ecology and Evolution
Volume 4 Numéro 11 Pages 1083-1090
Mots-Clés Body size; Niche model; biodiversity; climate-change; community; constraints; ecological networks; ecology; ecosystems; food web; impacts; interaction strengths; metaweb; models; species richness
Résumé (up) 1. Current global changes make it important to be able to predict which interactions will occur in the emerging ecosystems. Most of the current methods to infer the existence of interactions between two species require a good knowledge of their behaviour or a direct observation of interactions. In this paper, we overcome these limitations by developing a method, inspired from the niche model of food web structure, using the statistical relationship between predator and prey body size to infer the matrix of potential interactions among a pool of species. 2. The novelty of our approach is to infer, for any species of a given species pool, the three species-specific parameters of the niche model. The method applies to both local and metaweb scales. It allows one to evaluate the feeding interactions of a new species entering the community. 3. We find that this method gives robust predictions of the structure of food webs and that its efficiency is increased when the strength of the body-size relationship between predators and preys increases. 4. We finally illustrate the potential of the method to infer the metaweb structure of pelagic fishes of the Mediterranean sea under different global change scenarios.
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Langue English Langue du Résumé Titre Original
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ISSN 2041-210x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 674
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