9628094 MARTIN Lamniform sharks include infamous (Great White Shark) and spectacularly large (Basking Shark) forms among their sixteen living species. Despite work that has been done on the morphology and molecular biology of these fish, and fossils that appear beginning approximately 140 million years ago, the phylogenetic relationships of lamniform sharks, and therefore the origins of the extreme diversity among species in morphology, anatomy, physiology and habitat, are not well understood. In this study, Andrew Martin will evaluate the phylogenetic relationships among these sharks. He will obtain molecular sequence information from nuclear genes in the creatine kinase gene family, and use these sequences to construct phylogenetic trees. These trees will then be compared with trees constructed from other morphological and molecular information. Data from all these sources will attempt to answer questions about lamniform shark history; for example, whether the ability to eat plankton (as opposed to larger prey) arose once, or more than once, among these fish. The study should also help scientists understand how genes change during the history of a group of organisms, and how these changes may be related to changes in an organism's shape or behavior over long periods of time.