Deep Metazoan Phylogeny: Diploblastic Animals

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Knowledge of the phylogeny and evolution of the diploblast phyla is critical for reconstructing the origin and diversification of animal life. At the base of metazoan evolution four phyla are generally accepted, Placozoa, Cnidaria, Porifera, and Ctenophora. Phylogenetic relationships between these diploblast phyla, class-level relationships within phyla, the protozoan ancestor and the split off of higher (triploblastic) animals have been subject of controversial discussion for more than a century. We seek to generate and analyze a variety of molecular markers to resolve deep phylogenetic relationships in basal metazoans (Porifera will be excluded, since these data are generated by two collaborating groups). Representatives from all classes and orders of Placozoa, Cnidaria, and Ctenophora and a broad spectrum of molecular markers will be analyzed. It has become clear that the base of the metazoan Tree of Life cannot be resolved by molecular sequence markers only and we will also include characters from morphology, rRNA molecule morphology, mitochondrial genomes, and the genomic organization of Antp-class genes. In the third and final period we seek to complete data sets, perform concatenated analyses and address the critical issue of character weighting in a concatenated data set. Eventually this study is meant to provide the root for the metazoan tree of life generated by the DFG priority program “Deep Metazoan Phylogeny”.