University of Hawaii
Kewalo Marine Laboratory
41 Ahui Street
Honolulu, HI 96813

Telephone: (808) 539-7324
Fax: (808) 599-4817
E-mail Address: seaver@hawaii.edu

Research Interests:

The Seaver Lab is interested in the origins of body plan novelty during evolution. We approach questions of body plan evolution from a developmental perspective, utilizing a number of cellular and molecular techniques. Because the adult body plan forms as the result of the developmental process, it is likely that examination of mechanisms of development will provide important information about how novelty arises. The group of animals upon which we focus most of our studies are annelids, specifically polychaetes, and even sipunculids and echiurans.

Current Research:

One of the main research areas in the lab is the study of the evolution of the segmented body plan in the Metazoa. The number of times segmentation has arisen in the Metazoa is a long-staining controversy and although a large number of species in both the marine and terrestrial environments are segmented, they are all contained within 3 major clades: the chordates, arthropods, and annelids. It is likely that if 2 species share a common segmented ancestor the mechanisms by which their segmented body plan is generated during development will be shared. Of the three major segmented taxa, the annelids are the least understood in the molecular mechanisms of how they generate segments during development. One approach we have taken is to determine whether the genes involved in arthropod or vertebrate segmentation or are involved in the segmentation process in polychaetes. A comparative approach allows one to more readily determine generalizable traits for a phylogenetic group and we study multiple polychaete species with different life history characteristics and distinct body plan morphologies including species such as Capitella sp. I, Hydroides elegans, and Chaetopterus sp.

One focus of the lab has been to develop Capitella sp. I, a polychaete annelid, as a developmental model for studies of body plan evolution within the lophotrochozoans. Capitella has a number of advantages for developmental studies including the ability to culture it in the laboratory and obtain embryos and larvae yar round. The Capitella genome has recently been sequenced to 8x coverage by the Joint Genome Institute (Department of Energy, http://genome.jgi-psf.org/Capca1/Capca1.home.html) providing another importance resource.

The large variation of body plan within the polychaetes make them an ideal group of animals to study the origin of differences along the anterior-posterior axis such as segment identity and levels of tagmatization. The Hox gene complex has been has been implicated in patterning along the anterior-posterior axis across the Metazoa and we have characterized expression patterns of the eleven Hox genes that comprise the Hox gene complex in Capitella sp. I. In addition, because polychaetes continue to add segments into adulthood and have robust regenerative capacities, they offer a unique system in which to study the dynamic maintenance of axial position in the adult body.

Additional ongoing projects of the lab include studies of the evolution of the nervous system in annelids, development of the through gut in annelids, evolution of mesoderm, charaterization of the cell lineage and establisment of a fate map for the Capitella body plan.

Selected References:

• Dill, K.K. and Seaver, E.C. Vasa and nanos are co-expressed in somatic and germ line tissue from early embryonic cleavage stages through adulthood in the polychaete Capitella sp. I. (in press).
• Boyle, M.J. and Seaver, E.C. Evidence of a dorsal pharynx in the marine polychaete, Capitella sp. I (Polychaeta: Capitellidae). Zootaxa (in press).
• Thamm, K. and Seaver, E. C. 2008. Notch, Delta and hes gene expression during larval and juvenile segmentation in the polychaete annelid Capitella sp. I. Developmental Biology doi:10.1016/j.ydbio.2008.04.015.
• Boyle, M. J. and Seaver, E. C. (2008) Developmental expression of foxA and gata genes during gut formation in the polychaete annelid, Capitella sp. I. Evolution and Development 10(1):89-105.
• Dill, K. K., Thamm, K. and Seaver, E. C. (2007) Characterization of twist and snail gene expression during mesoderm and nervous system development in the polychaete annelid Capitella sp. I. Development, Genes and Evolution 217(6):435-47.
• Fröbius, A. C. and Seaver, E. C. (2006) Capitella sp. I EBX, the first lophotrochozoan member of a novel paired-like homeobox gene family. Mechanisms of Development 6(8):985-91.
• Irvine, S. Q. and Seaver, E. C. (2006). Early Annelid Development, A Molecular Perspective. in Greg Rouse and Fredrick Pleijel, eds. Reproductive Biology and Phylogeny of Annelida. Pp. 93-140. Reproductive Biology and Phylogeny, v. 4. Barrie G.M. Jamieson, series ed. Science Publishers: Enfield, NH.
• Fröbius, A. C. and Seaver, E. C. 2006. ParaHox gene expression in the polychaete annelid Capitella sp. I. Development, Genes and Evolution 216(2): 81-88.
• Seaver, E. C. and Kaneshige, L. M. 2006. Expression of 'segmentation' genes during larval and juvenile development in the polychaetes Capitella sp. I and H. elegans. Developmental Biology 289: 179-194.
• Seaver, E. C. , Thamm, K., and Hill, S. 2005. Growth patterns during segment formation in the two annelids Capitella sp. I and Hydroides elegans: comparisons at distinct life history stages. Evolution and Development 7(4): 312-326.
• Seaver, E. C. 2003. Segmentation: mono or polyphyletic? Int. J. Dev Biol. 47: 583-595.
• Seaver, E. C., Paulson, D., Irvine, S. Q. and Martindale, M. Q. 2001. The spatial and temporal expression the Ch-en, the engrailed gene in the polychaete Chaetopterus does not support a role in body axis segmentation. Developmental Biology 236: 195-209.
• Shankland, M., and Seaver, E. C. 2000. Evolution of the bilaterean body plan: what have we learned from annelids? PNAS 97: 4434-4437.
  

seaver@hawaii.edu