THE MARINER TRANSPOSABLE ELEMENT IN THE DROSOPHILIDAE FAMILY

The distribution of the mariner transposable element among Drosophilid ae species was investigated using three different techniques, i.e. squ ash blots, Southern blots and PCR amplification, using two sets of pri mers (one corresponding to the Inverted Terminal Repeats and the other to two conserved regions of the putative transposase). Our results an d those of others show that the distribution of mariner is not uniform and does not follow the phylogeny of the host species. An analysis of geographical distribution, based on endemic species, shows that marin er is mainly present in Asia and Africa. At least two hypotheses may b e proposed to explain the specific and geographical distributions of t his element. Firstly, they may be the results of several horizontal tr ansmissions between Drosophila species and/or between Drosophila speci es and one or several donor species outside the Drosophilidae family. Secondly, these particular distributions may correspond to the evoluti on of the mariner element from an ancestral copy which was present in the ancestor of the Drosophilidae family.