title: Unexpected genetic diversity among and within populations of the toxic dinoflagellate Alexandrium catenella as revealed by nuclear microsatellite markers.
abstract: Since 1998, blooms of Alexandrium catenella associated with paralytic shellfish poisoning have been repeatedly reported for Thau Lagoon (French Mediterranean coast). Based on data obtained for rRNA gene markers, it has been suggested that the strains involved could be closely related to the Japanese temperate Asian ribotype of the temperate Asian clade. In order to gain more insight into the origin of these organisms, we carried out a genetic analysis of 61 Mediterranean and 23 Japanese strains using both ribosomal and microsatellite markers. Whereas the phylogeny based on ribosomal markers tended to confirm the previous findings, the analysis of microsatellite sequences revealed an unexpected distinction between the French and Japanese populations. This analysis also highlighted great intraspecific diversity that was not detected with the classical rRNA gene markers. The Japanese strains are divided into two differentiated A. catenella lineages: the Sea of Japan lineage and the east coast lineage, which includes populations from the Inland Sea and the Pacific Ocean. A. catenella strains isolated from Thau Lagoon belong to another lineage. These findings indicate that microsatellite markers are probably better suited to investigations of the population genetics of this species that is distributed worldwide. Finally, application of the population genetics concepts available for macroorganisms could support new paradigms for speciation and migration in phytoplankton assemblages.
authors.affiliation: Université Montpellier II, CNRS, Ifremer, UMR 5119 Ecosystèmes Lagunaires 5119, cc093, Place E. Bataillon, 34095 Montpellier, France. estelle.masseret@univ-montp2.fr
authors.forename: Estelle
authors.initials: E
authors.lastname: Masseret
authors.forename: Daniel
authors.initials: D
authors.lastname: Grzebyk
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nagai
authors.forename: Benjamin
authors.initials: B
authors.lastname: Genovesi
authors.forename: Bernard
authors.initials: B
authors.lastname: Lasserre
authors.forename: Mohamed
authors.initials: M
authors.lastname: Laabir
authors.forename: Yves
authors.initials: Y
authors.lastname: Collos
authors.forename: André
authors.initials: A
authors.lastname: Vaquer
authors.forename: Patrick
authors.initials: P
authors.lastname: Berrebi
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004141:Dinoflagellida / Q000145:classification* / Q000235:genetics*; D014644:Genetic Variation; D008522:Mediterranean Sea; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010140:Pacific Ocean; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal