Abstracts (first author)
The rapid life cycle of Drosophila orphans
Author(s): Schlötterer C, Palmieri N, Nolte V, Kosiol C
Orphans are genes restricted to a single phylogenetic lineage. They emerge at high rates and frequently provide a selective advantage or even essential functions to their host. While these features predict an accumulation of genes, the gene number has remained remarably constant through evolution. This paradox of a stable gene number in the presence of a high rate of gene birth has not been resolved. Because orphan genes were mainly analyzed over large evolutionary time scales, orphan loss, a key factor of orphan evolution, remained unexplored. Here, we study the patterns of orphan turnover among close relatives in the Drosophila obscura group. We show that orphans are not only emerging at a high rate, but they are also rapidly lost. The pattern of orphan loss is clearly non-random: young orphans are more likely to be lost than orphans, which originated earlier. Furthermore, highly expressed orphan genes with a strong male-bias are more likely to be retained. Since lost and retained orphans show similar evolutionary signatures of functional conservation, we propose that intron loss is not driven by different evolutionary rates, but lineage specific functional requirements.