Characterization of Herves-like transposable elements (hATs) in Drosophila species and their evolutionary scenario

A monophyletic group of Drosophila hAT transposable elements, referred to as Herves-like, was characterized and found to be present in 46% of 57 screened Drosophila species. A remarkable characteristic of these elements is the presence of a long array of minisatellite repeats (MnRs) in both subterminal extremities of the elements. The copy number of these minisatellites was highly variable between and within populations. Twenty-three strains of Drosophila willistoni, covering its geographic distribution, were screened for polymorphism in the copy number of 5' MnRs, showing a variation from 7 to 20 repeat copies. These MnRs are well conserved among Drosophila species and probably function as transposase binding sequences, as provided by short subterminal repeats in other hAT elements. Miniature inverted repeat transposable elements were found in 27% of species carrying Herves-like elements. Phylogenetic analysis showed incongruences between transposable elements and species phylogenies, suggesting that at least four horizontal transfer events have occurred.