IR9-50 (IMAGE) University of Wisconsin-Madison Caption This graph depicts when different mutations (colored lines) entered and left one of the four E. coli populations in the study, all the way up to cycle 50. Lines that make it all the way to the top are then present in 100% of the population. Some mutations don't quite make it there and are then outcompeted by different mutations that do a better job at conferring resistance. Credit Michael Cox Lab Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.