Selective advantage of topological disorder in biological evolution

Abstract

We examine a model of biological evolution of Eigen's quasispecies in a holey fitness landscape, where the fitness of a site is either 0 (lethal site) or a uniform positive constant (viable site). So, the evolution dynamics is determined by the topology of the genome space. It is modeled by the random Bethe lattice. We use the effective medium and single-defect approximations to find the criteria, under which the localized quasispecies cloud is created. We find that shorter genomes, which are more robust to random mutations than average, represent a selective advantage which we call ``topological''. A way of assessing empirically the relative importance of reproductive success and topological advantage is suggested.