title: Disentangling the effect of body size and phylogenetic distances on zooplankton top-down control of algae.
abstract: A negative consequence of biodiversity loss is reduced rates of ecosystem functions. Phylogenetic-based biodiversity indices have been claimed to provide more accurate predictions of ecosystem functioning than species diversity alone. This approach assumes that the most relevant traits for ecosystem functioning present a phylogenetic signal. Yet, traits-mediating niche partitioning and resource uptake efficiency in animals can be labile. To assess the relative power of a key trait (body size) and phylogeny to predict zooplankton top-down control on phytoplankton, we manipulated trait and phylogenetic distances independently in microcosms while holding species richness constant. We found that body size provided strong predictions of top-down control. In contrast, phylogeny was a poor predictor of grazing rates. Size-related grazing efficiency asymmetry was mechanistically more important than niche differences in mediating ecosystem function in our experimental settings. Our study demonstrates a strong link between a single functional trait (i.e. body size) in zooplankton and trophic interactions, and urges for a cautionary use of phylogenetic information and taxonomic diversity as substitutes for trait information to predict and understand ecosystem functions.
authors.affiliation: Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven, Charles Deberiotstraat 32, 3000 Leuven, Belgium andros.taroucogianuca@bio.kuleuven.be.
authors.forename: Andros T
authors.identifier: http://orcid.org/0000-0001-9639-3846
authors.initials: AT
authors.lastname: Gianuca
authors.affiliation: Centre d'Ecologie fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-EPHE, Campus CNRS, 1919 route de Mende 34293, Montpellier, Cedex 05, France.
authors.forename: Jelena H
authors.initials: JH
authors.lastname: Pantel
authors.affiliation: Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven, Charles Deberiotstraat 32, 3000 Leuven, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: De Meester
mesh_terms: D000818:Animals; D044822:Biodiversity; D049628:Body Size; D033361:Cladocera / Q000502:physiology; D020387:Food Chain; D058086:Microalgae / Q000502:physiology; D010802:Phylogeny; D010839:Phytoplankton / Q000502:physiology*; D011157:Population Dynamics; D015048:Zooplankton / Q000502:physiology*
keywords: competitive asymmetry; functional ecology; niche partitioning; selection effect; trait divergence; trait diversity