Population history associated with hydrothermal vent activity inferred from genetic structure of neoverrucid barnacles around 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. © Inter-Research 2005.