title: The ascent of the abundant: how mutational networks constrain evolution.
abstract: Evolution by natural selection is fundamentally shaped by the fitness landscapes in which it occurs. Yet fitness landscapes are vast and complex, and thus we know relatively little about the long-range constraints they impose on evolutionary dynamics. Here, we exhaustively survey the structural landscapes of RNA molecules of lengths 12 to 18 nucleotides, and develop a network model to describe the relationship between sequence and structure. We find that phenotype abundance--the number of genotypes producing a particular phenotype--varies in a predictable manner and critically influences evolutionary dynamics. A study of naturally occurring functional RNA molecules using a new structural statistic suggests that these molecules are biased toward abundant phenotypes. This supports an "ascent of the abundant" hypothesis, in which evolution yields abundant phenotypes even when they are not the most fit.
authors.affiliation: Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas, USA. mattccowp@mac.com
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Cowperthwaite
authors.forename: Evan P
authors.initials: EP
authors.lastname: Economo
authors.forename: William R
authors.initials: WR
authors.lastname: Harcombe
authors.forename: Eric L
authors.initials: EL
authors.lastname: Miller
authors.forename: Lauren Ancel
authors.initials: LA
authors.lastname: Meyers
mesh_terms: D003198:Computer Simulation; D004843:Epistasis, Genetic; D019143:Evolution, Molecular; D005838:Genotype; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation; D010641:Phenotype; D012313:RNA / Q000737:chemistry / Q000235:genetics; D012641:Selection, Genetic
chemical_list: D012313:RNA