Genomic Approaches to Metazoan Evolution: Lophotrochozoans and Hox Genes

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This project will examine the Hox genes, which specify the fundamental organization of body plans, to reconstruct the evolutionary relationships of lophotrochozoans. As one of the three major lineages of bilateral animals, this group contains the greatest diversity of body plan organization and are purported to encompas at least 10 recognized phyla (including annelids, mollusks, ectoprocts, brachipods, and platyhelminthes). Before the factors that shaped metazoan macroevolution and diversification are understood, the evolutionary relationships of the lophotrochozoans are critically needed. In addition to constructing gene geneologies, this work will employ information on organization and gene composition of the Hox cluster. To this end, four bacterial artifical chromosome libraries will be produced, thus allowing the entire Hox cluster to be sequenced. To augment this library, evolutionary history will be reconstructed from 28S rDNA and COI genes for 49 lophotrochozoan taxa. This study will provide data that can be used to address several long-standing issues, including understanding the evolutionary and developmental plasticity of segmentation and embryogenesis.