The focus of this research is to probe the role of secondary metabolites in the evolutionary success of the organisms that produce or acquire them. Metabolites from opisthobranch molluscs will be studied to define their function as defense compounds. Further, the possibility of the production of metabolites by symbionts of selected marine invertabrates will be studied. The focus here will be placed on the production of polychlorinated metabolites and alkaloids. %%% With this renewal award, the Synthetic Organic Program is supporting the research of Dr. John D. Faulkner of the University of California, San Diego, Scripps Institute. Professor Faulkner will focus his work on chemical studies of marine invertebrates in an effort to discover new natural products and to investigate their ecological and evolutionary roles.