Galileo
is a transposon notoriously involved with inversions in
Drosophila buzzatii
by ectopic recombination. Although
widespread in
Drosophila
, little is known about this transposon
in other lineages of Drosophilidae. Here, the abundance of the canonical
Galileo
and its evolutionary history in Drosophilidae
genomes was estimated and reconstructed across genera within its two
subfamilies. Sequences of this transposon were masked in these genomes and their
transposase sequences were recovered using BLASTn. Phylogenetic analyses were
employed to reconstruct their evolutionary history and compare it to that of
host genomes.
Galileo
was found in nearly all 163 species,
however, only 37 harbored nearly complete transposase sequences. In the
remaining,
Galileo
was found highly fragmented. Copies from
related species were clustered, however horizontal transfer events were detected
between the
melanogaster
and
montium
groups of
Drosophila
, and between the latter and the
Lordiphosa
genus. The similarity of sequences found in the
virilis
and
willistoni
groups of
Drosophila
was found to be a consequence of lineage
sorting. Therefore, the evolution of
Galileo
is primarily
marked by vertical transmission and long-term inactivation, mainly through the
deletion of open reading frames. The latter has the potential to lead copies of
this transposon to become miniature inverted-repeat transposable elements.