Research topics: Invertebrate biology; electron and fluorescence microscopy; phylogeny of lower invertebrates; meiofauna
Research program: Invertebrate biology is the broad area of my research interests, and I concentrate on invertebrates of the meiofauna---that is, small animals living in the interstices of marine sediments, especially the more primitive worms such as turbellarians and gnathostomulids. I apply electron microscopy and fluorescence microscopy to these animals, comparing their anatomies in search of clues to phylogenetic relationships among major taxa and clues to the functional morphology of microorgans. A major project now underway centers on phylogenetic relationships of three groups of lower worms: the Acoela, Catenulida, and Gnathostomulida. The acoels and gnathostomulids have both served in some theories of animal evolution as the most primitive of the bilaterally symmetrical metazoans. Microscopy as well as bioinformatics and molecular sequencing are the tools of this project, and they are used to determine how these animals are related to each other and to other major groups of invertebrates. Together with Dr. Wolfgang Sterrer of the Bermuda Aquarium and Zoo, with whom we are collaborating on this project, we are sampling these taxa worldwide and correlating hypotheses of phylogenetic relationships with geographic distribution.
Selected Publications
Hooge, M.D., and S. Tyler (2005) Concordance of molecular and morphological data: Example of the Acoela. Integrative and Comparative Biology (in review)
Hooge, M.D., and S. Tyler (2005) New tools for resolving phylogenesis: A systematic revision of the Convolutidae (Acoelomorpha, Acoela). J. Zoological Systematics and Evolution Research (in press)
Tyler, S., and M.D. Hooge (2004) Comparative morphology of the body wall of flatworms (Platyhelminthes). Can. J. Zool. 82:193-210.
Petrov, A., M.D. Hooge, and S. Tyler (2004). Ultrastructure of sperm in acoels (Acoela, Platyhelminthes) and its concordance with molecular systematics. Invertebrate Biology 123:183-197
Hooge, M.D., and S. Tyler (2003) Acoels (Platyhelminthes, Acoela) from the Atlantic coast of North America. Meiofauna Marina 12:1-30
Tyler, S. (2003) Epithelium---the primary building block for metazoan complexity. Integrative and Comparative Biology 43:55--63.
Sørensen, M.V., S. Tyler, M. Hooge, and P. Funch (2003) Organization of the pharyngeal hard parts and musculature in Gnathostomula armata (Gnathostomulida: Gnathostomulidae). Can. J. Zool. 81:1463-1470
Hooge M.D., P.A. Haye, S. Tyler, M.K. Litvaitis, and I. Kornfield. 2002. Molecular systematics of the Acoela (Acoelomorpha, Platyhelminthes) and its concordance with morphology. Molec. Phylog. Evol. 24: 333-342
Tyler, S. (2001) The early worm---origins and relationships of the lower flatworms. In: Littlewood DTJ, Bray R (eds) Interrelationships of the Platyhelminthes, London: Taylor & Francis, pp 3-12
Tyler, S. and R. M. Rieger (1999) Functional morphology of musculature in the acoelomate worm Convoluta pulchra (Platyhelminthes). Zoomorphology 119: 127-141
Other publications from this laboratory