SJ (2007) Empirical fitness landscapes reveal accessible evolutionary paths. Nature 445: 383-386. 34. Woods It.J. Banick JE. Cooper Tr. Shrestha U, Kauth MR. et al. (2011) Second.order selection Ihr evolvahility in a large escherichia coli population. Science 331: 1433-1436. 35. JimenexJl• NUM./Iron