Conférence Nicolas Mouquet

Jeudi 6 février. Nicolas Moquet (Institut des Sciences de l'Evolution, Univ Montpellier)

"Phylogenetic constraints on ecosystem functioning"

It has been hypothesized that evolutionary history should influence the Biodiversity Ecosystem Functioning (BEF) relationship. This important new direction in the BEF literature is however based on few empirical investigations. Here we combine re-analysis of one of the plant dataset from one of the European BIODEPTH experiments and ecological experiments with bacteria to illustrate how evolutionary constraints impact the BEF Relationship. Using the dataset collected at the German site of the pan-European BIODEPTH project we have examined the unique and additional effect of phylogenetic and functional diversity on the prediction of ecosystem processes. Mainly we found that functional diversity was a better predictor of ecosystem function, particularly as the number of traits used to compute functional diversity was increasing. This a posteriori analysis is very useful but is limited by the strong co-variation between species richness and phylogenetic diversity. In an experiment with bacteria we manipulated phylogenetic diversity and species richness independently. Combining experimental ecological and evolutionary mechanisms, we found that productivity is significantly related to species richness and phylogenetic diversity for this system, and that the latter is a much stronger predictor of ecosystem functioning. However, by evolving lineages under different environments, we were able to randomize the distribution of traits across the phylogeny, breaking the relationship between phylogenetic diversity and ecosystem functioning. These different results show how the BEF relationship depends critically on the legacy of past evolutionary events and the limitation of using phylogenetic structure to predict ecosystem function without good knowledge on the evolutionary forces and phylogenetic constraints that shaped species diversity within ecological communities