Dynamics of Molecular Evolution
Schuster, P.
Institut für Theoretische Chemie, Universität Wien, Währingerstr.17,
A-1090 Wien, Austria
Evolution of ribonucleic acids (RNA) molecules in the test-tube provides an excellent possibility to study evolutionary optimization and adaptation to the environment on time scales that are accessible to a human observer. RNA molecules which are resistent to cleavage by specific RNases, ribozymes with new functions as well as molecules which bind preferentially to predefined targets were derived by evolutionary methods. Despite impressive sucesses of certain experiments there is still no comprehensive theory of molecular evolution available. A major problem one has to deal with is the diversity of genotypes which is prohibitive for complete experimental recordings. In particular, the numbers of RNA sequences and structures involved in the optimization process are by far too large to be determined by means of current techniques. Computer simulation, in contrary, is able to handle large numbers of individual sequences, and has no problem with data retrieval, but it can deal only with simplified relations between genotypes and phenotypes, being RNA sequences and structures, respectively. A comprehensive model of evolution has been developed which allows to follow optimization at full molecular resolution for RNA secondary structures. This model describes the course of in vitro evolution and provides straightforward explanation for characteristic features observed experimentally. One example is the occurence of steps consisting of fast adaptive phases interrupted by long periods of approximately constant fitness. Punctuation, thus, does not require external triggers and appears to be a consequence of neutrality against selection. Evolution is viewed as a complex process taking place simultaneously in genotype and phenotype space where the attainability of new phenotypes is determined by the mutation rate as well as the local and global properties of the genotype-phenotype map.
Schuster, P. (1997) Genotypes with phenotypes. Adventures in an RNA toy world. Biophys.Chem. 66, 75-110
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Wednesday, April 8 |
11:30 am |