Experimental evolution reveals contrasting adaptive landscapes in lab and field environments.

Laboratory evolution of Curtobacterium shows higher mutation rates and coding locus parallelism than field evolution, which favors intergenic mutations and diverse targets.

• Why it matters: Understanding microbial adaptation in natural environments is limited by laboratory studies that use constant, well-mixed conditions, potentially misrepresenting real-world evolutionary processes.
• What they did: The study compared genomic changes in Curtobacterium strains from laboratory and field experiments under control and warming treatments, analyzing mutation accumulation, targets, and repeatability across 20 isolates.
• The result: Laboratory conditions favored mutations in a few coding loci with strong parallelism, while field isolates exhibited fewer mutations, more intergenic mutations, and diffuse functional targets, indicating environment-specific adaptive landscapes.