DIVERSITY AND PRODUCTIVITY PEAK AT INTERMEDIATE DISPERSAL RATE IN EVOLVING METACOMMUNITIES

Venail P.A.*, MacLean R.C.*, Bouvier T., Brockhurst M.A., Hochberg M.E. and Mouquet N.* (2008). (* These authors contributed equally to this study)

Nature, 452, 210-215, doi:10.1038/nature06554

Key message : Positive relationships between species diversity and productivity have been reported for a number of ecosystems. Theoretical and experimental studies have attempted to determine the mechanisms that generate this pattern over short timescales, but little attention has been given to the problem of understanding how diversity and productivity are linked over evolutionary timescales. Here, 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 rate. Moreover, we demonstrate that these two pat- terns are linked: selection at intermediate rates of dispersal leads to high niche differentiation between genotypes, allowing greater coverage of the heterogeneous environment and a higher regional productivity. We argue that processes that operate over both eco- logical and evolutionary timescales should be jointly considered when attempting to understand the emergence of ecosystem-level properties such as diversity–function relationships.

Metacommunity productivity as a function of dispersal rate. b, Mean metacommunity productivity as a function of dispersal rate at the end of the selection period (transfer 40). Productivity peaks at intermediate dispersal rates, as judged by quadratic regression and multiple means comparison. The solid line represents the mean productivity of the replicate measures of the ancestral clone. This pattern is consistent over the plateau period (summed metacommunity productivity values over the last twenty transfers. c–f, Frequency distributions of mean productivity on individual substrates of the three replicates of each dispersal treatment at the beginning (T1), middle (T20) and at the end of the selection period (T40) for no dispersal (c), 1% dispersal (d), 10% dispersal (e) and 100% dispersal (f) treatments.

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OTHER TOPICS: Aesthetics of Biodiversity, Biogeography, Macroecology & Ecophylogenetics, Experimental Evolution, Functional Biogeography, Functional Rarity, Nature for Future, Metacommunities, Metaecosystems, Reviews and Synthesis, Trophic Biogeography & Metaweb