Repression precedes independent evolutionary gains of a highly specific gene expression pattern

This study addresses how activator and repressor sequences evolve and interact during enhancer evolutiom in the context of a fatty acyl-CoA elongase gene that contributes to pheromone production in Drosophila. The highly specific tissue expression of the gene in the ejaculatory bulb resulted from the initial evolution of a repressor sequence prior to the independent evolution of an activator sequence. Transcriptomic profiles were obtained from 8-day old D. melanogaster male ejaculatory bulbs.