Beyond trait distances: Functional distinctiveness captures the outcome of plant competition

Mahaut Lucie, Violle Cyrille, Shihan Ammar, Pélissier Rémi, Morel Jean-Benoit, de Tombeur Felix, Rahajaharilaza Koloina, Fabre Denis, Luquet Delphine, Hartley Sue E., Thorne Sarah J., Ballini Elsa, Fort Florian. 2023. Beyond trait distances: Functional distinctiveness captures the outcome of plant competition. Functional Ecology, 37 (9) : 2399-2412.

https://doi.org/10.1111/1365-2435.14397

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Url - jeu de données - Entrepôt autre : https://doi.org/10.5061/dryad.95x69p8qc

Résumé : Functional trait distances between coexisting organisms reflect not only complementarity in the way they use resources, but also differences in their competitive abilities. Accordingly, absolute and relative trait distances have been widely used to capture the effects of niche dissimilarity and competitive hierarchies, respectively, on the performance of plants in competition. However, multiple dimensions of the plant phenotype are involved in these plant–plant interactions (PPI), challenging the use of relative trait distances to predict their outcomes. Furthermore, estimating the effects of competitive hierarchy on the performance of a group of coexisting plants remains particularly difficult since relative trait distances relate to the effects of a focal plant on another. We argue that trait distinctiveness, an emerging facet of functional diversity that characterizes the eccentric position of a species (or genotype) in a phenotypic space, can reveal the unique role played by a given individual plant in a group of competing plants. We used the model crop species Oryza sativa spp. japonica to evaluate the ability of trait distances and trait distinctiveness to predict the outcome of intraspecific PPI on the performance of single genotype and genotype mixtures. We performed a screening experiment to characterize the phenotypic space of 49 rice genotypes based on 11 above-ground and root traits. We selected nine genotypes with contrasting positions in the phenotypic space and grew them in pots following a complete pairwise interaction design. Relative distances and distinctiveness based on traits associated with light competition were by far the best predictors of the performance of single genotypes—taller genotypes that acquired resource faster being the best competitors—while absolute trait distances had no effect. These results indicate that competitive hierarchy for light dominates PPI in this experiment. Consistently, trait distinctiveness in plant height and age at flowering had the strongest, positive effects on mixture performance, confirming that functional distinctiveness captures the effects of trait hierarchies and asymmetric PPI at this scale. Our findings shed new light on the role of trait diversity in regulating PPI and ecosystem processes and call for a greater consideration of functional distinctiveness in studies of coexistence mechanisms.

Mots-clés Agrovoc : Oryza sativa, génotype, performance de culture, phénotype, compétition végétale, amélioration des plantes, modélisation des cultures, variation génétique, photosynthèse, compétition intraspécifique

Mots-clés géographiques Agrovoc : France

Mots-clés libres : Biodiversity–ecosystem functioning, Competitive dominance, Crop genotype mixtures, Functional rarity, Symmetric and asymmetric plant–plant interactions

Classification Agris : F40 - Écologie végétale
F30 - Génétique et amélioration des plantes

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement européennes : European Commission

Agences de financement hors UE : Agence Nationale de la Recherche, Fondation pour la Recherche sur la Biodiversite, Office Français de la Biodiversité, Ministère de la Transition écologique et Solidaire, EDF Energy

Programme de financement européen : H2020

Projets sur financement : (FRA) MUSE, (EU) Silicon and the plant economics spectrum: a trait-based approach at the interface of physiological and ecosystem ecology

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