PASSAMANECK, Y.J.*; HALANYCH, K.M.: Lophotrochozoan relationships inferred from 28S rDNA sequences

28S rDNA has been sequenced from a variety of taxa to investigate evolutionary relationships within the Lophotrochozoa. The clade Lophotrochozoa, which includes annelids, mollusks, and the three lophophorate taxa (bryozoans, brachiopods, and phoronids), was first identified based based upon analysis of 18S rDNA. Analyses of 18S rDNA has also suggested a polyphyletic origin for the lophophorates, with bryozoans branching seperately from brachiopods and phoronids. Despite identifying these novel groupings, the ability of 18S rDNA sequences to resolve relationships between the major taxa within the Lophotrochozoa appears to be limited. Preliminary results suggest that full-length 28S rDNA sequence provides more characters for phylogenetic reconstruction than does 18S rDNA. Increased resolution of relationships between lophotrochozoan taxa provides an important framework for understanding character evolution within the Lophotrochozoa.