----------------------------------------------------------------------- BIOINFORMATICS COLLOQUIUM School of Computational Sciences George Mason University ----------------------------------------------------------------------- Living Fossils and Long Branches: Use of molecular data to infer the origins, phylogeny, ecology and biogeography of deep-sea snails Dr. Jerry Harasewych Research Zoologist and Curator of Marine Mollusca The National Museum of Natural History Smithsonian Institution Tuesday, September 6, 2005 4:30 pm Verizon Auditorium, Prince William Campus Pleurotomarioidean Gastropods are continuously present in the fossil record since the Upper Cambrian and survive into the modern fauna, thus providing rare insights into the evolutionary history of snails. The group reached its greatest diversity during the Paleozoic, and dominated global shallow water marine faunas during the Paleozoic and Mesozoic. Only a single family survived the end-Cretaceous extinction, but was restricted to deep water through most of the Cenozoic. The first living animal of the family Pleurotomariidae was discovered during the mid-19th century. Subsequently collected specimens of these “living fossils” revealed that these animals comprise a mosaic of primitive and highly derived characters that originally inspired a new model of gastropod evolution, but more recently defies the orderly inclusion of this group within a cladistic framework of gastropod evolution. Conflicts between morphological and molecular trees are discussed. Molecular data do produce a well-resolved phylogeny of living members of the group, and reveal that higher taxa segregate bathymetrically, while species within each genus segregate geographically, so that most species exist in allopatry. Analyses of amino acid racemization rates, calibrated using 14C decay, provide insights into longevity, and population structure for several taxa. Despite their thin and relatively fragile shells, Pleurotomariidae survive an extraordinary number of attacks by predators, primarily crustaceans and fish. Their hypobranchial glands are capable of secreting a viscous white fluid that likely serves as a chemical defense to repel predators. NMR analyses of purified secretion indicate a structural similarity to navanone, an alarm pheremone known from distantly related mollusks. Circumstantial evidence suggests that this defense mechanism may have originated during the Paleozoic. Despite the great antiquity of this lineage, pleurotomariids possess a substantial number of morphological, molecular, and ecological novelties. BIOGRAPHY Dr. Harasewych first started to work with mollusks at the age of ten, as a volunteer at the Academy of Natural Sciences in Philadephia. He earned his undergraduate degree in chemistry from Drexel University in Philadelphia (1972) specializing in analytical chemistry. Following his graduation he Worked for three years as a pharmaceutical chemist before beginning his graduate training at the University of Delaware where he earned both masters and doctoral degrees. (MS 1978; Ph. D. 1983). He has Worked at the Delaware Museum of Natural History outside of Wimington, before becoming a Research Fellow in Clinical Neurogenetics at the National Institute of Mental Health. He left this position two years later to become Curator of Mollusks at the National Museum of Natural History, Smithsonian Institution, were he has worked since 1985. During his career as a malacologist, he has conducted field work throughout the Caribbean (veteran of over 100 dives in research submersibles), both coasts of the United States, Polynesia, Russia, and Japan. Jerry has published about a hundred papers on a wide variety of mollusks, ranging from taxonomic works to studies of molecular evolution, population genetics, ecology, comparative anatomy, biogeography, morphometrics, and even popular articles and a coffee table book. For twelve years, Jerry was Editor-in-Chief of THE NAUTILUS, the second oldest journal specializing in Mollusca, and has served on the board of trustees of three museums, and is member of the adjuct or reseach faculty at several universities [GWU, William and Mary, American, Florida Atlantic University, ... not sure of status at GMU]. Research interests include: - Phylogeny and Molecular Evolution of Gastropoda, - Origin, Evolution, and Biogeography of Deep-Sea Molluscan Faunas. - Systematics, Evolution and Biogeography of th land snail genus Cerion. - Application of forensic techniques to resolve questions of evolutionary history within Mollusca.