“Over the past decade, we have focused on uncovering the ecological and evolutionary consequences of the extensive genomic heterogeneity observed in natural prokaryotic populations. By leveraging the vast information generated through comparative genomics, transcriptomics, and metagenomics, we have made significant strides in characterizing the genomic diversity of key microbial groups inhabiting the ocean’s epipelagic zone. Recent advancements, such as long-read metagenomics and single-cell sequencing, allowed us to investigate this diversity at unprecedented resolution. For instance, we have published several studies on marine streamlined bacterial groups such as SAR11, HIMB59, SAR116, SAR86, and the two marine pelagic Actinobacteriota lineages: Candidatus Actinomarinales and the Acidimicrobiales. These studies, grounded in an ecogenomic perspective, have revealed critical insights into their genomic variability and ecological roles. Additionally, we have expanded our understanding of viral diversity associated with these microbes, which has improved our understanding of the interactions between microbial hosts and their associated viruses in marine ecosystems.

Our work highlights the evolutionary strategies of microbes with streamlined genomes to adapt and thrive under the oligotrophic conditions that dominate surface ocean waters. At the individual level, these microbes experience evolutionary pressures that optimize nutrient use through gene loss, as the «streamlining theory” proposes. At the population level, however, these species serve as reservoirs of extensive genetic diversity. Subpopulations coexist and share public goods, preserving this genetic richness within natural populations. This dynamic not only maximizes resource utilization but also fosters a form of evolutionary cooperation.”