9528964 MARSHALL In the past ten to fifteen years molecular sequence data have provided powerful tools for investigating the phylogenetic relationships or associations of lineages in many diverse groups of organisms. Such data have often helped to resolve relationships where classical morphological data were insufficient or suggested alternative and conflicting results. Yet, just as morphological data includes convergent/parallel derived features, the same molecular sequence can arise independently. Such convergent or parallel features, known as homoplasies, can be very problematic if they are unrecognized and thus unwittingly used to associate taxa. This project seeks to develop a methodology for eliminating homoplasies from molecular data by drawing only from "middle-repetitive sequences", thereby selectively utilizing rare genomic events. Recognizable assemblages of these ("families") will be unique to a lineage and therefore "homoplasy-free" data will be available for phylogenetic reconstruction. This methodology will be developed and tested with DNA sequence data from nine species of sea urchins. If the investigator's suppositions are bore out with this test case, the results of this research may have very broad applicability and utility for numerous molecular systematists. This award is made under NSF's Small Grants for Exploratory Research (SGER) Program, which is designed to fund innovative, high-risk research with the potential, if successful, for major discovery or contribution to future research directions. If successful with this particular project for developing a refined methodology for obtaining informative molecular sequence data, Dr. Marshall will have made a contribution of potential utility to systematists working with a broad diversity of organisms with radiations in the Cenozoic. A more efficient and reliable means of deriving reliable molecular phylogenies can offer great savings in both time and research funds.
