Manfred Eigen Lecture: Bridging from Chemistry to Life Sciences -- Evolution seen with the Glasses of a Physicist

Manfred Eigen Lecture

  • Datum: 09.05.2018
  • Uhrzeit: 15:00 - 17:00
  • Vortragende(r): Prof. Dr. Peter Schuster
  • Institut für Theoretische Chemie, Universität Wien / Santa Fe Institute, Santa Fe
  • Ort: Max-Planck-Institut für biophysikalische Chemie (MPIBPC)
  • Raum: Manfred Eigen Hall
  • Gastgeber: Dirk Görlich
  • Kontakt: helena.miletic@mpibpc.mpg.de
The growth of evolutionary thinking since the publication of Darwin’s “Origin of Species” can be split into four rather distinct periods: (i) The neo-Darwinian period that combines natural selection of Darwin and Wallace with Weismann’s concept of germline and soma, (ii) the unification of genetics, which was received hostilely by evolutionists at the beginnings around 1900, and neo-Darwinian theory in the “modern synthesis”, (iii) molecular evolution initiated by Watson and Crick’s centennial paper on the structure of the DNA double helix, and spanning the bridge from chemistry to evolutionary biology, and (iv) current molecular genetics, which is characterized by complex interactions in gene regulatory networks (GNR) and a variety of epigenetic effects on top of conventional genetic phenomena.
In this lecture we shall be concerned with the last two periods: Manfred Eigen’s kinetic theory of molecular evolution is revisited and converted into a dynamical model, which describes evolution as the interplay of competition, cooperation and variation. Most theoretical work was done in the large population size limit but here we shall also discuss the stochastic consequences of finite sizes and show that both, sufficiently large population size and large enough fitness differences are required for the success of selection. The discrete quasispecies – a quasispecies with integer valued particle numbers – behaves quite differently from the conventional continuous distribution of mutants: It is concentrated in sequence space and begins to drift randomly when the mutation rate exceeds the error threshold.
In order to yield a self-contained and consistent description of evolution the dynamical model is complemented by a genotype-phenotype mapping. In the simplest case of in vitro evolution this mapping represents the relation between sequences and molecular structures of RNA molecules. For higher multi-cellular organisms the genotype-phenotype map, in principle, contains also the evolutionarily relevant contributions of development. Then, the complexity of evolution is more or less encapsulated in the genotype-phenotype relation. In principle, all complications of modern molecular genetics can be incorporated into the kinetic theory of evolution. Thereby, complexity does not disappear, it is transferred into the genotype-phenotype map or into the environment. The difficulties, of course, are not resolved but it becomes easier to classify problems and to separate influences.
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