DSSS - Revisiting enhancer modularity and evolution in Drosophila

The diversification of morphological traits entails changes in size, changes in shape, as well as extensive quantitative variation of other phenotypic dimensions, such as color or texture. These changes often find their origin in gene regulation, particularly at the level of transcriptional enhancers. To understand how enhancers accommodate evolutionary changes underlying morphological diversity, we use various species of Drosophila with diverse patterns of pigmentation on their wings. We examine how transcriptional enhancers of a pigmentation gene involved in this variation emerge and diversify to tune pigmentation patterns. This leads us to integrate different levels of biological complexity, from atomic interactions between DNA and transcription factors, to the enhancer chromatin accessibility and its quantitative spatial output in developing tissue, and to the resulting pigmentation on fly wings. With a first project, I will show how our quantitative approach led us to reconsider the concept of enhancers as discrete and modular elements. With a second project, I will illustrate how the evolutionary tuning of the activity of a single enhancer has produced a continuum of the variation in wing pigmentation intensity between species.