Adaptation at different points along antibiotic concentration gradients

Antibiotic concentrations vary dramatically in the body and environment. Hence, understanding dynamics of resistance evolution along antibiotic concentration gradients is critical for predicting slowing emergence spread resistance. While it has been shown that increasing an slows evolution, how adaptation to one correlates with fitness at other points gradient not received much attention. Here, we selected populations Escherichia coli several a three different antibiotics, asking rapidly evolved whether became specialized they were on. Populations higher more slowly but exhibited equal or across whole gradient. lower rapidly, overall presence antibiotics was lower. However, these readily adapted upon subsequent selection. Our results indicate management strategies must account only rates also strains.