MEPS 288:233-240 (2005)  -  doi:10.3354/meps288233

Population history associated with hydrothermal vent activity inferred from genetic structure of neoverrucid barnacles around Japan

Hiromi Watanabe1,*, Shinji Tsuchida2, Katsunori Fujikura2, Hiroyuki Yamamoto2, Fumio Inagaki2, Masanori Kyo2, Shigeaki Kojima1

1Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo 164-8639, Japan
2Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan

ABSTRACT: The population histories of neoverrucid barnacles occurring at 2 different hydrothermal vent systems around Japan, namely the Izu-Ogasawara Arc and the Okinawa Trough, were investigated based on the sequence variation in a 661 bp fragment of the mitochondrial COI gene. Compared with other barnacles, the investigated neoverrucids showed low levels of genetic diversity. The mismatch analysis suggested that these neoverrucids have experienced extinction–recolonization events associated with vent activity, and this may have led to the low levels of genetic diversity in neoverrucids around Japan. No haplotypes were shared between the Izu-Ogasawara Arc and the Okinawa Trough and no significant genetic differences were detected among the populations within each of these 2 regions. These results suggest that neoverrucid larvae only disperse within each area and are unable to migrate between the 2 areas. The haplotypes of the Okinawa Trough formed a paraphyletic cluster, with the exclusion of a monophyletic cluster from the Izu-Ogasawara Arc. Furthermore, the population expansion date of the Okinawa Trough, as estimated from the mismatch analysis, was earlier than that of the Izu-Ogasawara Arc. These results suggested that the neoverrucid population in the Okinawa Trough was a source of neoverrucids inhabiting the Izu-Ogasawara Arc.

KEY WORDS: Neoverrucidae · Barnacle · Population structure · Dispersal · Hydrothermal activity

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