DAO 68:251-259 (2006)  -  doi:10.3354/dao068251

Sequence variation in four mitochondrial genes of the salmon louse Lepeophtheirus salmonis

Kjersti Tjensvoll1,*, Kevin A. Glover2, Are Nylund1

1Department of Biology, University of Bergen, 5020 Bergen, Norway
2Population Genetics Research Group, Institute of Marine Research, PO Box 1870 Nordnes, 5817 Bergen, Norway

Abstract: A total of 210 Lepeophtheirus salmonis collected from 7 locations (Scotland, Russia, Canada, Japan and 3 locations in Norway), were screened for sequence variation in 4 mitochondrial genes; ATPase subunit 6 (A6), Cytochrome b oxidase subunit I (COI), Cytochrome b (Cyt b) and 16S rRNA. A high level of intraspecific variation was observed within all genes. The majority of polymorphisms were present in single individuals only, which resulted in a high number of private haplotypes within each gene. Little evidence of genetic differentiation was observed among the 3 Norwegian locations or between L. salmonis samples from Norway, Scotland and Russia. Pairwise FST values indicated that a weak degree of sub-division between L. salmonis sampled in Canada and the Northeast Atlantic might, however, exist. All samples collected in the Atlantic were highly different from the Japanese sample. It is suggested that the lack of genetic differentiation among lice samples from the North Atlantic is a result of extensive gene flow mediated by passive transport of L. salmonis larvae, and the migratory pattern of its salmonid hosts.

KEY WORDS:Lepeophtheirus salmonis · A6 · COI · 16S rRNA · Cyt b · Sequence variation · Population genetics · Sea lice

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