Berlin 2015 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 2: Statistical Physics in Biological Systems (joint session DY/ BP/CPP)

DY 2.1: Invited Talk

Monday, March 16, 2015, 09:30–10:00, BH-N 243

Chemical warfare and survival strategies in bacterial range expansions — Markus F Weber, Gabriele Poxleitner, Elke Hebisch, Erwin Frey, and •Madeleine Opitz — Center for NanoScience, Faculty of Physics, Ludwig-Maximilians-Universität München, Munich, Germany

Spreading of species into uncolonized territory is a fundamental ecological process in the evolution and maintenance of biological diversity. Although interactions between species have experimentally been identified as major determinants of species coexistence in spatially extended populations, their role in spatially expanding populations is largely unknown. Here, we address the roles of resource and interference competition by genetically tuning a bacterial model system of three Escherichia coli strains: a toxin (colicin) producing strain, a sensitive strain, and a resistant strain. We show that maintenance of biodiversity is determined by three strongly interdependent ecological factors: the relative ratio of the competing strains, their growth rates and the strength of toxicity. Our mathematical analysis suggests, that despite general expectations, a non-hierarchical interaction network is not a necessary prerequisite for biological diversity. Moreover, we find that robust three-strain coexistence requires a balance between growth rates and a small enough toxicity range or, alternatively, a reduced initial ratio of the colicin-producing strain. We expect that the approach presented in this study will be useful to identify further mechanisms for the maintenance of biodiversity in microbial communities.