Life in sediments fosters 'sexual' speciation in the Shewanella baltica complex.

Sediment-associated Shewanella baltica strains exhibit extensive genomic diversification, forming three distinct evolutionary groups with 'sexual' recombination-driven divergence.

• Why it matters: Understanding microbial speciation in natural environments is crucial for revealing bacterial evolution mechanisms, especially in complex habitats like sediments where diversity is often underestimated.
• What they did: Researchers analyzed 112 genomes from sediment and water samples across spatial scales, using population genomics to identify genetic and metabolic differences among strains.
• The result: Findings show sediment habitats promote rapid divergence and speciation without spatial separation, highlighting ecological interactions as key drivers of bacterial evolution at microgeographic scales.