Uncovering Heterogeneity of Selection Pressures in Prokaryotic Genome Evolution
Hidden Battles in Genome Evolution
Prokaryotic genomes have long been thought to be shaped by either selection for streamlining or selection for functional diversification. However, determining which force dominates in a given environment has remained a challenging problem.
Innovative Phylogenomic Analysis and a New Perspective
The research team performed a large‑scale phylogenomic analysis encompassing over 10,000 prokaryotic species. By simultaneously tracking signals of horizontal gene transfer and genome streamlining, they demonstrated that selection pressure operates in a complex, environment‑dependent manner.
Finding: Heterogeneity of Selection Pressures
The results were striking. In some environments, streamlining was the primary driver, whereas in other microbial communities, the addition of functions via horizontal gene transfer had a greater impact. Thus, both mechanisms coexist and complement each other, creating a multifaceted selective landscape.
Implications and Future Outlook
These insights will form the foundation for new strategies to predict and manipulate microbial communities. In particular, they are expected to greatly aid the modeling of antibiotic‑resistant bacterial evolution and the design of tailored public‑health policies.
Proceedings of the National Academy of Sciences, Volume 123, Issue 19, May 2026. SignificanceGenome evolution in prokaryotes has been explained by either selection for streamlining or selection for functional diversification enabled by horizontal gene transfer. However, the extent to which these forces coexist or dominate in different ...
This study resolves the previously held notion that genome streamlining and functional diversification are mutually exclusive. As a result, even laypeople can predict the evolutionary trajectories of antibiotic‑resistant bacteria and design more effective public‑health strategies.