Meeting Abstract

P2.55  Wednesday, Jan. 5  Re-emergence of coloniality in Tubulariidae (Cnidaria: Hydrozoa: Aplanulata): Insights from morphology, life history and developmental gene expression NAWROCKI, Annalise M.*; JOHNSON, Adam B.; CARTWRIGHT, Paulyn; The University of Kansas nawrocki@ku.edu

Molecular phylogenetic studies reveal complex patterns of life history evolution in hydrozoans, including transitions between colonial and solitary forms. Aplanulata is a clade of diverse hydrozoans comprising both colonial and solitary hydroid forms, including the solitary, freshwater model organism Hydra. Phylogenetic reconstruction and character mapping suggest that coloniality evolved independently in Aplanulata from a solitary ancestor. Observations of colony formation in the aplanulate species Ectopleura larynx support this pattern in that its organization is distinct amongst colonial hydrozoans. While other hydrozoan colonies form through asexual budding, E. larynx colonies represent a fusion of offspring polyps to the parent colony as well as budding. The proximity of offspring polyps to the parent can be explained by the unique life cycle of the species, in that they brood their larvae. We are developing molecular markers to study the developmental genetics of coloniality in E. larynx and compare this species to its close relatives, including the solitary hydroids Hydra and Candelabrum and other more distantly related colonial hydrozoans. Using next generation DNA sequencing approaches (454 pyrosequencing) we characterized expressed sequence tags (ESTs) for Ectopleura larynx and Candelabrum sp. From these ESTs we isolated genes that may be involved in regulating coloniality. Preliminary gene expression results in Ectopleura larynx will be discussed.