Cryptic genetic variation accelerates evolution by opening access to diverse adaptive peaks

Abstract

Cryptic alleles make a bridge for adaptation Protein function is generally constrained by selective parameters that can inhibit evolutionary potential. It has thus been difficult to determine how novelties arise. Zheng et al. allowed bacterial populations to accumulate mutations and then used directed evolution to evolve green fluorescent protein function from a gene that expressed yellow fluorescent protein (see the Perspective by Lee and Marx). Protein alternatives could evolve in cases where cryptic alleles—selectively neutral or mildly deleterious genetic variants with no apparent phenotypic differences—were present in the population. Thus, cryptic alleles provide an evolutionary bridge between diversity and selection and facilitate the generation of novel adaptations. Science , this issue p. 347 ; see also p. 318