- Dr. Stock's research seeks to identify the changes in genes and developmental mechanisms underlying the diversification of animal form using teeth and scales of fishes as the primary model system. Gene expression during tooth and scale development is compared in several species of fishes differing in the location, shape and number of these structures. Gene expression differences that correlate with differences in teeth and scales are used as entry points into the genetic and developmental pathways that have been modified during their evolution. Transgenic methods are used to identify the DNA changes responsible for expression differences among species and the functional consequences of these changes. Similar experimental approaches are being used to investigate the evolution of additional morphological features of fishes such as barbels ('whiskers'), fins, and breeding tubercles.