6.1.04
Emmanuel Tannenbaum
Title: Semiconservative Replication in the Quasispecies Model: Modelling Evolution at Arbitrary Mutation Rates.
In 1971, Manfred Eigen introduced the quasispecies equations as a way to model the evolutionary dynamics of single-stranded RNA molecules replicating in in vitro evolution experiments. Eigen showed that at low mutation rates, the distribution of genomes is localized about the genome corresponding to the fastest replicator. Above a critical mutation rate, replicative selection can no longer counter the loss of informat ion due to mutations, and the genomes delocalize over the entire sequence space, a phenomenon which Eigen termed the error catastrophe. The error catastrophe has been the primary focus of the past thirty years or so of quasispecies research, and has also been observed experimentally.
In this talk, we present an extension of the quasispecies equations to account for the semiconservative nature of DNA replication. This is a necessary first step if we wish to use the quasispecies equations to model the evolution of DNA-based life. We go on to solve the model for the simplest case of a landscape consisting of a single, "fast" repl icator. We also show that the semiconservative quasispecies equations pr ovide a mathematical basis for the efficacy of mutagens as chemotherapeutic agents, something which Eigen's original equations fail to do.