Topic Overview:

One of the major quests in biology is to understand how the spectacular diversity of animal forms on our planet evolved. Merging the study of embryonic development with evolutionary biology, the field of “evo-devo” seeks to uncover genes and mutations that contribute to differences in anatomy. Early work in this field revealed how the vastly different creatures of the animal kingdom are built using a similar set of body-patterning genes, suggesting that form largely evolves by changes in how genes are patterned during development. Gene expression is controlled in time and space by transcriptional switches, stretches of DNA that bind combinations of transcription factors to activate genes. A multitude of empirical examples have illustrated how the evolutionary modification of these switches contributes to phenotypic differences among species.

Rebeiz’s research focuses on how regulatory switch evolution is involved in the generation of novel phenotypes; for example, how do completely new structures—such as a turtle’s shell or a bird’s feather—evolve? At the root of this problem lies the question of how new transcriptional switches come into being. Using closely related Drosophila speciesas a model, Rebeiz investigates switches that were very recently born. By tracing the origins of recently evolved gene expression patterns, he has found that new switches may tend to evolve on top of preexisting switches, creating a developmental network of multiple switches. Rebeiz will discuss this expanding view of transcriptional switches and his group’s ongoing research into the development of recently derived anatomical structures in Drosophila.