Recent horizontal transfer of transposable elements in Drosophila

Transposable elements (TEs) are genetic elements also known as “jumping genes” that increase their copy numbers within a host through various mechanisms of transposition. TEs can also move between species through unknown intermediaries, infecting novel genomes and increasing in copy number. While many individual invasions have been documented, a large dataset of recent HT events that will allow us to understand larger more general patterns has not been assembled. In this manuscript we used almost 400 dipteran genomes to uncover 643 recent TE invasions, mostly in Drosophila . The majority of transfers occurred between closely related species, with the cosmopolitan melanogaster group showing the highest recent transfer activity. We even documented a single TE with 16 recent transfers, many between different Drosophila groups. Using species distance on a phylogenetic tree to measure the distance that TEs travel, we found that DNA transposons transfer between distantly related species much more frequently compared to retrotransposons. This potentially represents a different evolutionary strategy for exploiting naive genomes. Our phylogenetic framework advances the understanding of horizontal transfer dynamics at the species level within Drosophila .