Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 6: Statistical Physics of Biological Systems II (joint DY, BP)

BP 6.3: Talk

Monday, March 14, 2011, 14:45–15:00, HÜL 186

Strong Noise Effects in one-dimensional Neutral Populations — •Luca Dall'Asta¹, Fabio Caccioli², and Deborah Beghè³ — ¹ICTP, Trieste, Italy — ²Santa Fe Institute, Santa Fe, NM — ³Università di Parma, Parma, Italy

The dynamics of well-mixed biological populations is studied using mean-field methods and weak- noise expansions. Similar methods have been applied also in spatially extended problems, relying on the fact that these populations are organized in colonies with a large local density of individuals. We provide a counterexample discussing a one-dimensional neutral population with negative frequency- dependent selection. The system exhibits a continuous phase transition between genetic fixation and coexistence that is unexpected from weak-noise arguments. We show that the behavior is a non-perturbative effect of the internal noise that is amplified by presence of spatial correlations (strong- noise regime).