The heart has dramatically increased in morphological complexity during vertebrate evolution but the molecular basis driving these major changes remains unknown. Using comparitive genomics approaches, this project will explore changes in the regulation of genes involved in heart formation that lead to changes in cardiac structure. It will elucidate for the first time the caridac regulatory repertoire in zebrafish and will compare it with that of fly and mouse using cutting edge bioinformatics pipelines. This work will unravel cardiac-specific regulatory modifications that give rise to evolutionary changes. On a broader scale, it will shed new light on the role of regulatory innovations over gene innovations in the emergence of new traits.