KNOWLES, J.; WENINK, E.; ORTOLANO, R.; REKHI, N.; HOCK, A.; SCHULT, N.; TUNNICLIFFE, V.; MCHUGH, D.; Colgate University; Colgate University; Colgate University; Colgate University; Colgate University; Colgate University; University of Victoria, Canada; Colgate University: Molecular analyses indicate gene flow among populations of Paralvinella pandorae, a polychaete annelid endemic to hydrothermal vents of the northeast Pacific.

The polychaete annelid Paralvinella pandorae is endemic to hydrothermal vents in the northeast Pacific, and is found at almost all vents sites along the 500-km long Juan de Fuca ridge system. The sperm morphology of P. pandorae indicates that fertilization occurs internally or in the worm�s tube, and the maximum observed oocyte size of 215 �m suggests that a dispersive larval phase is short or non-existent. Size frequency analyses of populations of P. pandorae suggest continuous or semi-continuous recruitment of juveniles. Given our limited knowledge of the species� life history, we predicted that populations of P. pandorae would exhibit a pattern of isolation-by-distance among populations along the Juan de Fuca ridge axis. Our analysis of cytochrome oxidase I (COI) gene sequences for 38 individuals from six sites along the Juan de Fuca ridge shows little sequence variation among individuals and no pattern of isolation-by-distance among populations. Our preliminary AFLP results also show no phylogeographic structure among five populations of P. pandorae that are separated by distances of up to 154 kilometers. These results indicate that gene flow occurs among all sites in the analyses. [Supported in part by NSF-DEB #9806848]