Berlin 2018 – scientific programme
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BP: Fachverband Biologische Physik
BP 18: Focus Session: Physics of Microbial Systems - organized by Tobias Bollenbach and Benedikt Sabass
BP 18.3: Talk
Wednesday, March 14, 2018, 10:15–10:30, H 2013
Sex or Simplicity: Phenotypic interference and the cost of complexity in asexual evolution — Torsten Held1,2, •Daniel Klemmer1,2, and Michael Lässig1 — 1Institut für Theoretische Physik, Universität zu Köln, Köln, Deutschland — 2Equal contribution
The asexual evolution of microbes and viruses often generates clonal interference, a mode of competition between genetic clades within a population. We show that interference strongly constrains genetic and phenotypic complexity. Our analysis is based on a minimal biophysical model that represents each gene by a quantitative molecular phenotype, its fold stability. The model displays a generic mode of asexual evolution called phenotypic interference, which occurs over a wide range of evolutionary parameters appropriate for microbial populations. It generates a strong burden of complexity: The fitness cost of mutations increases faster than linearly with the number of genes. We show that recombination eliminates the superlinear cost through a first-order phase transition to a mode of sexual evolution. This implies a large fitness advantage of even facultative recombination and provides a biophysically grounded scenario for the evolution of sex. In a broader context, our analysis suggests that the systems biology of microbial organisms is strongly intertwined with their mode of evolution.