Marine Biotech Fellowship: Population Genetics and Gene Flow in Hydrothemal Vent Communities

点击翻译按钮获取中文摘要

Deep-sea hydrothermal vents comprise systems of patchy habitats with obligate, diverse, highly specialized communities of sessile organisms. These sites provide a promising opportunity to study dispersal and gene flow in the deep sea. Previous allozyme studies of several of these animals have revealed generally low levels of genetic variability and only limited indications of genetic separation between populations. What is most surprising is that genetic studies of Riftia pachyptila (a vestimentiferan tube worm), indicated little or no inter-population variation, but it has been suggested to have limited larval dispersal ability, whereas studies of Bathymodiolus thermophilus (a vent mussel) demonstrated significant genetic separation between vent populations in spite of what appears to be a small, broadly dispersing larva. Given the large taxonomic difference between these two species and a low level of observed genetic variation in R. pachyptila, the above discrepancy provides little insight into population-genetic processes in these unique communities. What is most needed is sufficient genetic variation in taxonomically closely related species in order to detect population genetic sub-structuring while at the same time considering phylogenetic constraints. Studies currently underway at Rutgers (NSF OCE-8917211) are aimed at assessing rates of gene flow and systematic relationships of molluscan populations associated with deep-sea hydrothermal vents. Allozyme studies of mytilid and vesicomyid bivalves from a variety of vent sites are nearly completed, and mitochondrial DNA (mtDNA) studies have just begun. Parallel studies of tube worms, Riftia pachyptila, are also underway. This project will expands upon these ongoing studies in two main ways. First, since previous studies found only a low level of allozyme polymorphism in B. thermophilus and R. pachyptila, a more sensitive technique of assaying anonymous nuclear DNA restriction- site polymorphism will be developed to survey genetic variation. These data, along with the mtDNA restriction-site data, will provide a comprehensive, multi-locus analysis of genetic variation, within and between sites (both maternally and biparentally derived) in these organisms. Second, this project will survey genetic variation in the giant vent clam, Calyptogena magnifica. C. magnifica has large eggs and a larval stage that is believed to be non-planktotrophic. By including C. magnifica, this research will be able to make direct genetic comparisons to the results obtained with another vent bivalve, B. thermophilus, which appears to have planktotrophic larvae and presumably greater dispersal abilities.