Natural selection on crosstalk between gene regulatory networks facilitates bacterial adaptation to novel environments

At the level of the gene, mutation is the raw material for natural selection. However, at the level of the gene regulatory network (GRN), variation is revealed to selection via promiscuous regulator activity ('crosstalk'), which creates opportunities for genetic innovation that can facilitate adaptation. Many genetic and environmental features can contribute to increasing potential for crosstalk by facilitating non-cognate interactions between regulatory elements. If a novel interaction provides a fitness benefit, rewired GRNs with strengthened affinity for newly forged connections can be selected. Here, we identify factors that facilitate opportunities for crosstalk and rewiring between GRNs, consider whether features of some GRNs make them more 'rewireable' than others and if these features might constrain evolution towards convergent outcomes. We explore patterns from laboratory and natural microbial populations that show changes within GRNs during adaptation. Finally, we discuss the prospects and open questions in the field.

Automated summary

At the gene level, mutation is the raw material for natural selection, while at the gene regulatory network (GRN) level, crosstalk provides opportunities for genetic innovation and adaptation. Various genetic and environmental features can increase the potential for crosstalk and rewiring of GRNs, which can be selected if they provide fitness benefits. This article identifies factors that facilitate crosstalk and rewiring, and discusses the impact of GRN features on evolution.