Open Journal of Marine Science, 2013, 3, 31-39 http://dx.doi.org/10.4236/ojms.2013.31003 Published Online January 2013 (http://www.scirp.org/journal/ojms) Dispersal Ability and Environmental Adaptability of Deep-Sea Mussels Bathymodiolus (Mytilidae: Bathymodiolinae) Jun-Ichi Miyazaki1*, Saori Beppu1, Satoshi Kajio1, Aya Dobashi1, Masaru Kawato2, Yoshihiro Fujiwara2, Hisako Hirayama2 1Faculty of Education and Human Sciences, University of Yamanashi, Kofu, Japan 2Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan Email: *
[email protected] Received October 12, 2012; revised November 17, 2012; accepted November 29, 2012 ABSTRACT Dispersal ability and environmental adaptability are profoundly associated with colonization and habitat segregation of deep-sea animals in chemosynthesis-based communities, because deep-sea seeps and vents are patchily distributed and ephemeral. Since these environments are seemingly highly different, it is likely that vent and seep populations must be genetically differentiated by adapting to their respective environments. In order to elucidate dispersal ability and envi- ronmental adaptability of deep-sea mussels, we determined mitochondrial ND4 sequences of Bathymodiolus platifrons and B. japonicus obtained from seeps in the Sagami Bay and vents in the Okinawa Trough. Among more than 20 spe- cies of deep-sea mussels, only three species in the Japanese waters including the above species can inhabit both vents and seeps. We examined phylogenetic relationships, genetic divergences (Fst), gene flow (Nm), and genetic population structures to compare the seep and vent populations. Our results showed no genetic differentiation and extensive gene flow between the seep and vent populations, indicating high dispersal ability of the two species, which favors coloniza- tion in patchy and ephemeral habitats.