Nicolas Mouquet is a community ecologist with some experience in theoretical and experimental ecology, microbiology and evolution. He has developed some of the early metacommunity models and is now working of spatial food web ecology and metaecosystems. He is also interested in incorporating elements of evolutionary biology and biogeography into the understanding of the relationship between diversity and ecosystem functioning. http://nicolasmouquet.free.fr/

ABSTRACT:

It has been recently 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 experimental evolution and ecological experiments with bacteria to show how evolutionary constraints impact the BEF relationship. In a first experiment, we investigate the role of dispersal in determining both diversity and productivity over evolutionary timescales, using experimental metacommunities of the bacterium Pseudomonas fluorescens assembled by divergent natural selection. We show that both regional diversity and productivity peak at an intermediate dispersal. Selection at intermediate dispersal leads to high evolutionary niche differentiation between genotypes, allowing greater coverage of the heterogeneous environment and a higher regional productivity. This result in an emerging positive BEF relationships.  In a second experiment we isolated bacterial strains from a marine environment and evolved them to be generalists or specialists. We then constructed assemblages of increasing diversity of each lineages and found that assemblages of generalists were more productive on average because of their superior ability to exploit the environmental heterogeneity. The slope of the BEF relationship was however stronger for the specialist assemblages because of enhanced niche complementarity. In a third experiment we used the same lineages and varied phylogenetic and species richness independently to determine their relative contribution to the BEF. We found a positive relationship between phylogenetic diversity and productivity for ancestor but that this relationship was broken for the evolved lineages (in the presence of directional selection). Our results show how the BEF relationship depends critically on the legacy of past evolutionary events. We argue that processes that operate over both ecological and evolutionary timescales should be jointly considered when attempting to understand the emergence of ecosystem-level properties such as the BEF relationships.