Rhizobium leguminosarum evolved in varied water and soil nitrogen content
We evolved a heterogenous population of rhizobia under variable watering conditions, with and without soil nitrogen and with and without the presence of plant hosts to investigate the role of combined selection from the host and abiotic environment on microbial evolution. Through sequencing the descendant strains after the experimental evolution, we can evaluate how the genomes of the rhizobia evolve and how that explains the rapid adaptation to drought conditions. Specifically, we ask if selection acts upon de novo mutations or standing variation in the ancestral population.