mGem: Bacterial aversion to making new genes

ABSTRACT All genes must ultimately have arisen de novo from non-coding sequences, but to what extent is this process an ongoing contributor to the contents of contemporary genomes? Based on the expansive pangenome of Escherichia coli , genes created de novo are short-lived and have made virtually no contribution to the set of longer, conserved genes that form the bulk of the canonical gene repertoire. Due to the generality of bacterial genome dynamics, this trend likely applies across taxa, suggesting that the vast majority of truly novel genes were created in the deep evolutionary past, thereby consigning the role of the newly invented genes to transient adaptive challenges.