In addition , no back mutation to obtain a maximal complexity ( i . e . - resistant and sensitive species coexistence ) or original ecology ( i . e . original - lysogen ) for the evolution occurs 而且,逆反應變異回原有菌相而成對噬菌體敏感及阻抗菌相共存之最大分歧度或回歸至起始單一對噬茵體敏感菌相并未曾演化發生。