The evolutionary enhancement of genotype-phenotype linkages in the presence of multiple copies of genetic material

Abstract

Genetic evolutionary mechanisms employed by protolife developed without accompanying regulatory mechanisms for the amounts of genetic material in protocells. When many copies of genetic material are present, inactive copies generated by mutations are not effectively excluded through phenotypic selection. We demonstrate a model of gene evolution initiated with different amounts of DNA inside artificial protocells. We adopted transcription- and translation-coupled RNA replication and liposome-based in vitro compartmentalization. Despite the fact that the average number of DNA copies in each liposome was 6.4, DNA encoding active genes was maintained until the 16th selection round. Our experimental and theoretical results indicated that gene evolution can occur in the presence of multiple DNA copies. Most genetic material became junk code through gene mutations, and consequently the linkage between genotype and phenotype was enhanced through the associated decreases in active genetic material.

Keywords: RNA replication; artificial protocells; cell-free protein synthesis; directed evolution; liposomes.