Cis-regulatory evolution underlying the changes in wingless expression pattern associated with wing pigmentation of Drosophila

The co-option of regulatory genes has the potential to play an important role in the evolutionary gain of new traits. However, the changes at the sequence level that underlie such a co-option event are still elusive. We identified the changes in the cis-regulatory sequence of wingless that caused co-option of wingless and led to its expression in new places in Drosophila guttifera, which has unique pigmentation patterns on its wings. The newly gained function of gene expression activation was acquired evolutionarily via a combination of pre-existing sequences containing a putative binding site for SMAD transcription factors that exhibit an ancestral function in driving expression at crossveins, and a sequence that is specific to the lineage leading to D. guttifera.