Biologically relevant landscape models are based on the assumption that genotypes give rise to phenotypes that are evaluated by their environment and hence determine the genotype's fitness. A large degree of neutrality, giving rise to neutral networks and shape space covering, is a generic feature of RNA and polypeptide sequence-structure maps.
Neutrality qualitatively changes the dynamics of evolution.
While rugged landscapes without neutral neighbors lead to localized populations, trapping in local optima, and the existence of a critical replication rate beyond which sequence information is lost, we find diffusion in sequence space and ever-lasting innovation of novel mutants on landscapes arising from RNA or protein folding. Fitness landscapes, molecular evolution, RNA secondary structures, biopolymer folding, graph laplacian Submitted to J. Mol. All rights reserved.