E. coli Microcosms Indicate a Tight Link between Predictability of Ecosystem Dynamics and Diversity

Marianne Imhof,Christian Schlötterer,Takashi Gojobori

doi:10.1371/journal.pgen.0020103

Abstract

The diversity-stability hypothesis proposes that ecosystem diversity is positively correlated with stability. The impact of ecosystem diversity is, however, still debated. In a microcosm experiment using diverged Escherichia coli cells, we show that the fitness of community members depends on the complexity (number of participants) of the system. Interestingly, the spread of a community member with a superior genotype is mostly stochastic in low-complexity systems, but highly deterministic in a more complex environment. We conclude that system complexity provides a buffer against stochastic effects.

Highlights

As early as 1872 Darwin [1] had envisioned the critical impact that species diversity has on ecosystem dynamics
The stability of the system was measured by the reproducibility of the dynamics of a beneficial mutation that occurred in the intact system
Beneficial mutations regularly arise in experimental E. coli populations [18,19]

Summary

Introduction

As early as 1872 Darwin [1] had envisioned the critical impact that species diversity has on ecosystem dynamics. Elton [2] explicitly formulated this thought with the diversitystability hypothesis, which proposes that ecosystem diversity is positively correlated with stability. The relationship between ecosystem functioning and species diversity is widely discussed [3,4,5,6]. While early empirical studies suggested that more diverse communities enhance ecosystem stability [2,7], subsequent ecological models indicated that diversity tends to destabilize community dynamics [8]. Food web structure has been discussed as centrally important in the relationship between ecosystem stability and diversity [11]. The intrinsic complication of measuring ecosystem stability has resulted in opposing outcomes, depending on how ecosystem stability is defined [13]

Methods

Results

Conclusion