Deciphering metazoan phylogeny: The need for additional molecular data

Our interpretation of the evolution of development, morphology, and diversi ty of multicellular animals hinges on a clear understanding of the phylogen etic relationships of metazoans, Currently, the field of metazoan phylogeny is in a state of flux, with new hypotheses of metazoan relationships emerg ing from analyses of 18S rDNA sequence data. Some of these analyses have be en Limited in the numbers of taxa analyzed, others, with numerous taxa anal yzed, have not resolved deep level branching patterns, and all are hampered by properties of the 18S gene itself, Corroboration of the results from 18 S rDNA analyses can come from additional molecular data sets, such as highl y conserved nuclear coding genes, mitochondrial gene order, or gene duplica tion events. The enormous task of data accumulation for additional molecula r data from many representative taxa can most efficiently be undertaken in a coordinated, collaborative effort among different lab groups. Ultimately, a combined analysis of several independent data sets will be possible and may provide a more stable, robust phylogeny for the Metazoa.