Springer Complexity Lecture
Peter SchusterUniversity of Vienna
Peter Schuster is a theoretical chemist, known for his work on evolution of molecules and structure based RNA bioinformatics. He has contributed to the understanding of origin of life models. He is professor emeritus at Vienna University, was founding director of the Institute of Molecular Biotechnology in Jena and served previously as the President of the Austrian Academy of Sciences. He is external faculty professor at the Santa Fe Institute.
September 12th 2011, 9:50-10:40
Lecture hall C1
Campus University of Vienna
Tracing the source of complexity in evolutionEvery biologist will - I think - agree with two statements: (i) Evolution is an enormously complex process and (ii) biological evolution on Earth proceeds from lower towards higher complexity. Each of the two assertions contains a paradox that needs to be resolved. Despite the apparent complexity of evolutionary processes, the dynamics of natural selection is exceedingly simple, and despite the undeniable increase in complexity from unicellular bacteria to man, prokaryotes were not replaced by more complex organisms as bacteria are still with us and even within us. The lecture will mainly address the first paradox and make a suggestion how to resolve it: Not the dynamics of evolutionary processes is complex, but complexity is an attribute of the relation between genotypes and phenotypes commonly addressed as fitness landscape, be it the mapping of polynucleotide sequences onto structures or the relation between the human genome and the entire spectrum properties and functions, which constitute the human phenotype. Fitness is an environment dependent, highly elaborate property projecting the phenotype onto the evolution relevant axis measuring reproductive success. In case of the exceedingly simple system of in vitro evolution of RNA molecules the genotype-phenotype map can be accessed through RNA folding of sequences into structures. The conventional simple case of one sequence forming one structure will be reviewed together with the more elaborate situation considering long-lived metastable conformations together with the minimum free energy structure. A suggestion is made for the introduction of complexity into simple model landscapes. Natural molecules, in particular single conformational RNA molecules like the tRNAs or RNA switches with two or more conformations, are designed by evolution for their specific function and their properties differ significantly from those of RNAs with random sequences.