Josh Trapani has been selected to serve as AGU's 2005--2006 Congressional Science Fellow. Trapani is a paleontologist who most recently studied the genetic basis of tooth development in fish as a postdoctoral fellow in the Ecology and Evolutionary Biology Department at the University of Colorado, in Boulder. By studying the complexity of genetic differences between species of fish with different dentition patterns, we are able to begin to determine the evolutionary processes-chiefly selection and constraint-responsible for the evolution and maintenance of these differences over geologic time, He noted.