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Auteur Calcagno, V.; Jarne, P.; Loreau, M.; Mouquet, N.; David, P.
Titre Diversity spurs diversification in ecological communities Type Article scientifique
Année 2017 Publication Revue Abrégée Nat. Commun.
Volume 8 Numéro Pages 15810
Mots-Clés adaptive radiations; biodiversity; colonization; competition; drive speciation; evolutionary emergence; limiting similarity; stability; sympatric speciation; trade-off
Résumé Diversity is a fundamental, yet threatened, property of ecological systems. The idea that diversity can itself favour diversification, in an autocatalytic process, is very appealing but remains controversial. Here, we study a generalized model of ecological communities and investigate how the level of initial diversity influences the possibility of evolutionary diversification. We show that even simple models of intra- and inter-specific ecological interactions can predict a positive effect of diversity on diversification: adaptive radiations may require a threshold number of species before kicking-off. We call this phenomenon DDAR (diversity-dependent adaptive radiations) and identify mathematically two distinct pathways connecting diversity to diversification, involving character displacement and the positive diversity-productivity relationship. Our results may explain observed delays in adaptive radiations at the macroscale and diversification patterns reported in experimental microbial communities, and shed new light on the dynamics of ecological diversity, the diversity-dependence of diversification rates, and the consequences of biodiversity loss.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 2041-1723 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2148
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Auteur Mason, N.W.H.; de Bello, F.; Mouillot, D.; Pavoine, S.; Dray, S.
Titre A guide for using functional diversity indices to reveal changes in assembly processes along ecological gradients Type Article scientifique
Année 2013 Publication Revue Abrégée J Veg Sci
Volume 24 Numéro 5 Pages 794-806
Mots-Clés Co-existence; Environmental filtering; Functional divergence; Functional evenness; Functional richness; Functional trait; Limiting similarity; Niche complementarity; Null models; species richness
Résumé Question Which functional diversity indices have the power to reveal changes in community assembly processes along abiotic stress gradients? Is their power affected by stochastic processes and variations in species richness along stress gradients?

Methods We used a simple community assembly model to explore the power of functional diversity indices across a wide range of ecological contexts. FD) and convex hull volume (FRic) – with a matrix-swap null model (yielding indices SESFD and SESFRic) to remove any trivial effects of species richness. We also compared two indices that measure both functional richness and functional divergence – Rao quadratic entropy (Rao) and functional dispersion (FDis) – with a null model that randomizes abundances across species but within communities. SESRao and SESFDis).

Results When mass effects operated, only SESRao and SESFDis gave reasonable power, irrespective of how species richness varied along the stress gradient. FD, FRic, Rao and FDis had low power when species richness was constant, and variation in species richness greatly influenced their power. SESFRic and SESFD were unaffected by variation in species richness. When priority effects operated, FRic, SESFRic, Rao and FDis had good power and were unaffected by variation in species richness. Variation in species richness greatly affected FD and SESFD. SESRao and SESFDis had low power in the priority effects model but were unaffected by variation in species richness.

Conclusions Our results demonstrate that a reliable test for changes in assembly processes along stress gradients requires functional diversity indices measuring either functional richness or functional divergence. We recommend using SESFRic as a measure of functional richness and either SESRao or SESFDis (which are very closely related mathematically) as a measure of functional divergence. Used together, these indices of functional richness and functional divergence provide good power to test for increasing niche complementarity with declining stress across a broad range of ecological contexts.
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Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1654-1103 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 406
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