Anyone who has ever been to an aquarium knows the great diversity of feeding structures that characterize fishes. Research using a popular model organism, the zebrafish, has focused on understanding how cells undergo changes to give rise to the final structures of the head. However much of this work has investigated differentiation and not subsequent growth of these structures. The Hedgehog genes have been shown to be involved in a number of important proliferative functions, including proliferation of tissues involved in head development. These genes play a key role in both early development and later growth of the head skeleton. Dr. Hernandez proposes that this pathway is important in effecting evolutionarily changes in ultimate head size and shape within fishes and proposes a detailed functional analysis of Hedgehog signaling in the growth and development of the zebrafish skull, along with preliminary comparative examination of the role of these genes in growth of the head of closely related species. Dr. Hernandez is a minority PI who strives to maintain an ethnically diverse lab in which integrative investigation is the rule. The PI is also actively involved in a number of activities to broaden participation within the sciences.