Rapid evolutionary diversification of the flamenco locus in the D. simulans clade

Maintaining genomic integrity through suppression of transposable elements (TEs) is paramount to organismal fitness. In D. melanogaster flamenco is the master regulator of TE suppression, preventing TEs from moving from the somatic support cells of the ovary to the germline. It is thought to operate as a trap, suppressing TEs upon their transposition into the locus, with a high representation of recent horizontally transferred TEs. We find that in the simulans clade flamenco has undergone physical and functional diversification. In D. simulans flamenco has duplicated and diverged from its original, maintaining no synteny within the locus but conserving its promotor. In D. simulans and D. mauritiana, flamenco acts as a dual stranded cluster with ping pong signals in some tissues. This expansion in function has been accompanied by an increase in the number of multicopy elements, as expected for regions operating as dual stranded clusters. In addition, we find that in D. simulans presence of a TE in either flamenco or a germline cluster, may be necessary for suppression of a TE but it may not be entirely sufficient. This physical and functional diversity of flamenco in the simulans clade redefines our understanding of this locus.