It has been brought to our attention that there is an error in the estimated time of occurrence of horizontal transfers in the Drosophila genome in our article 1 . The twelfth paragraph of the Results and discussion section should read:

The distributions of Ks values among the little-diverged TEs display a peak within the range 0.03-0.05 (Figure 3). If we assume a mutational clock of 0.011 substitutions per nucleotide per million years [46], this suggests that most HT has occurred over a broad period of time centered between 1.4 and 2.3 MYA, well after the split of the D. melanogaster and D. simulans lineages 5.4 +/- 1.1 MYA or the time of their most recent common ancestor with D. yakuba, 12.8 +/- 2.7 MYA [46].