FIG. 2.

Hypothetical evolutionary scheme for the various Tn1546 derivatives characterized in this study from the archetypal transposon Tn1546 (type A1) as described by Arthur et al. in 1993 (1). The types A2, B1, E1, and E3 were described previously by Willems et al. (27) and not in this study. They were included for better understanding of the different Tn1546 type evolutionary relationships. Boxes represent the different Tn1546 types. Solid arrows indicate the transition of Tn1546 type A1 to the other Tn1546 types. The two different lineages, I and II, are indicated. The names of the countries where the different transposon types were found are indicated in parentheses. This scheme was partly based on the evolutionary scheme described by Willems et al. (27).