Phylogeny of Lower Worms of the Meiofauna

NSF project 0118804 for research in the laboratories of

Seth Tyler, Professor of Zoology, UMaine
Matt Hooge, Postdoctoral Fellow, UMaine
Wolfgang Sterrer, Bermuda Aquarium
Christiane Todt, Postdoctoral Fellow, U. Vienna, UMaine

Through support of the National Science Foundation in its PEET initiative (Partnerships for Enhancing Expertise in Taxonomy), we are engaged in research on the taxonomy of tiny, cryptic worms that many consider to be the most primitive of all bilaterally symmetrical animals (that is, all animals excluding the cnidarians and sponges). These worms comprise two small groups called acoel and catenulid turbellarians which are now classified in the phylum Platyhelminthes (flatworms) but that, according to some systematists, may not even be related to the more familiar flatworms such as planarians and polyclads. Another of these primitive worm groups is the Gnathostomulida, whose relationships to other phyla of invertebrates have been similarly controversial; by some theories, gnathostomulids are like the ancestors of the flatworms.

With our research, we hope to arrive at a better understanding of how each of these lower worm groups is related to other groups of invertebrates and to each other. We are conducting a comprehensive survey of the groups to gauge their biodiversity, decribing new species, mapping out their distribution to see where they might have arisen, and studying them with fluorescence and electron microscopy as well as molecular techniques for new characters that could hold clues to their origins.

S. Tyler and W. Sterrer, the two Principal Investigators on this project, have long studied these worms, and are using the NSF support to train new students in how to find and handle them and in how to decipher systematic relationships. Knowing more about these animals will undoubtedly help us to answer many fundamental questions about the relationships of all animals, their origins and genetic connections.

Students working in S. Tyler's laboratory at the University of Maine are concentrating on microscopical techniques and taxonomy of flatworm groups. New characters discerned through applying fluorescence and electron microscopy on these animals show that the relationships among them are not well represented by the current classification system. Students working with Sterrer in his laboratory in Bermuda and accompanying him on sampling trips will gauge patterns of distribution of flatworms and gnathostomulids and gather specimens for the microscopical and molecular studies to be done in the laboratories. He also trains students in curatorial techniques. The results of these students' research will be displayed on a Web site so that anyone with a Web browser will be able to use that data to identify similar worms they might find or to gauge the historical relationships of geographic sites. The major focus of this project is the training of students to give them the tools to discover and describe the many species of these difficult-to-find, yet remarkably abundant, enigmatic animals and to make sense of their diversity. The knowledge these students unearth will very likely provide critical clues to resolve the far-reaching question of how the major groups of animals originated.