The Tcl-mariner superfamily of transposons in animals

The encoded transposases of six mariner family and eight Tcl family transposons from nematodes, insects, fish, and a planarian are fully aligned. The alignment allows recognition of conserved amino acids that provide defining synapomorphies for the two families, and also that distinguish the superfamily from even more distantly related elements in ciliates and bacteria. Phylogenetic analysis of these transposases supports the distinction of the two families, however the relationships of the elements within families are largely unresolved. The possibility of horizontal transfer to new hosts therefore cannot be examined using these sequences, however examination of closely related mariners within subfamilies has revealed at least two instances of relatively recent horizontal transfer across orders of insects. Such transfers to new, and sometimes distantly related, host lineages probably underlie the widespread distribution and evolutionary persistence of these transposons.