WormNet: Reconstructing the early evolution of segmented annelid worms

K. M. Halanych, M. Martindale, E. Seaver, D. McHugh, and the Joint Genome Institute (J. Boore, D. Rokhsar)

Understanding metazoan phylogeny has been confounded by interpretations of the degree and nature of segmentation in body plans. In particular, the Annelida, commonly called segmented worms, has been central to debates on the role of segmentation in animal evolution. Recent evidence suggests that several non-segmented or partially segmented worm taxa, that were previously regarded as separate phyla, are within the annelid radiation. These recent results conflict with the only comprehensive phylogenetic analyses to date on the annelids, the morphological analyses of Rouse and Fauchald (1997). Furthermore, because annelids are one of the most evolutionarily successful "phyla" and because they diversified in the late PreCambrian to early Cambrian, understanding their early evolutionary history is paramount to understanding the evolution of animal life.

The proposed work has two goals: 1) Genomic approaches will be used to reconstruct the early phylogenetic events of the "Annelida", which includes several previously recognized phyla, and 2) Functional genomic techniques will be used to characterize the developmental mechanisms employed in segmentation in several key lineages. Interpreting the segmentation, a hallmark of annelids, in the context of the phylogeny will allow novel insights on the role and plasticity of segmentation during animal evolution. This project has been called "WormNet" because it represents an interdisciplinary network of researchers, at four institutions, focusing on these goals in a manner that enhances education and outreach activities.

Additionally, this program is designed to jumpstart other areas of research in the major metazoan clade Lophotrochozoa (annelids, mollusks, lophophorates, and their allies). Publicly available cDNA and genomic BAC libraries will be produced, and data from approximately 130 completely sequenced mitochondrial genomes will provide needed markers for population genetic and systematic studies. Given that annelids are the most abundant and ubiquitous animal "phlyum" in the deep sea (which covers 70% of the planet), serve as bioindicators, have a role in bioremediation, and include up-and-coming model organisms, the importance of understanding their evolution cannot be understated.