Dispersal and symbiosis of deep-sea hydrothermal vent mussels

Yong-Jin Won

Wednesday, March 5, 2003
3:00 p.m. Pacific Forum

Bathymodiolus mussels associated with deep-sea hydrothermal vents face two significant ecological and evolutionary problems. First, they must be capable of dispersing among habitat islands that are distributed widely along the global mid-ocean ridge system. Second, they must obtain endosymbiotic, chemoautotrophic microbes that provide the majority of nutrition. I used population genetic methods to address these problems in three ways. (1) Barriers to dispersal and rates of gene flow were examined among mussel populations occupying discrete vent fields spread across 5000 km in the eastern Pacific Ocean. Although gene flow was high among most habitats, the Easter microplate and associated cross-axis currents create a strong barrier to dispersal. (2) Genetic markers were used to show that Bathymodiolus mussels obtain their sulfur-oxidizing endosymbionts from the local environment. (3) As a conse-quence of environmental acquisition, a phylogenic tree of mussel species was independent of a corresponding evolutionary tree of endosymbiont lineages.

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