Phylogenetic relationships among the MediterraneanAlexandrium(Dinophyceae) species based on sequences of 5.8S gene and Internal Transcript Spacers of the rRNA operon

Abstract

A phylogenetic analysis of the genus Alexandrium, including both the most common and rare species from coastal areas of the Mediterranean Sea was carried out. Nucleotide sequences of 5.8 S gene and Internal Transcribed Spacer regions of the rRNA operon were examined and analysed together with isolates of Alexandrium spp. from elsewhere in the world. These rDNA ribosomal markers were useful in delineating the phylogenetic position of species in the genus, as well as in determining relationships among isolates within each species collected from different localities. Results of phylogeographical analyses within the 'Alexandrium tamarense' species complex identified three lineages in the Mediterranean Sea: the Mediterranean (ME), Western European (WE) and Temperate Asian (TA) clades. The phylogenetic grouping of the isolates is consistent with the ribotype clades, but not with the morpho-species that constitute the complex. Additional non-toxic isolates were included in the ME clade. The NA (North Atlantic) clade is the fourth group within the 'Alexandrium tamarense' species complex identified by phylogenetic analyses. Based on its higher genetic diversity and phylogeographical relationships, it can be hypothesized that the NA clade represents the ancestral group of the 'Alexandrium tamarense' species complex. Alexandrium minutum isolates of the NW Mediterranean clustered with strains from Brittany and Australia. Alexandrium minutum constituted a sister clade of A. tamutum, which is another species strongly associated with the Mediterranean area. Another typical Mediterranean species, A. taylori, was placed as a sister clade of A. pseudogoniaulax by the phylogenetic analysis. Finally, the phylogenetic relationships of some Alexandrium morpho-species that were infrequently observed in the Mediterranean Sea have been resolved.

Unexpected Genetic Diversity among and within Populations of the Toxic Dinoflagellate Alexandrium catenella as Revealed by Nuclear Microsatellite Markers

“…Furthermore, the A. catenella cluster contains some A. tamarense morphotypes from China. The phylogenic grouping of isolates in this complex is consistent with the ribotype clades but not with the morphospecies that form the complex (37). They are in accordance with the recently developed trends (27, 37, 52) which question the phylogenetic, proteomic, biological, and morphological species definition for the A. tamarense complex.…”

“…Until now, differentiation among Alexandrium lineages has been investigated mainly by using ribosomal sequences (18,37,38,(43)(44)(45)(46). These analyses showed that the Alexandrium lineages are notably related to their geographic origins, and the lineages are defined as the North American, Western European, Mediterranean, Temperate Asian, Tropical Asian, and Tasmanian ribotypes.…”

Mitochondrial, but not rDNA, genes fail to discriminate dinoflagellate species in the genus Ostreopsis

“…PCR conditions were as follows: an initial denaturation at 95 8C for 10 min, 35 cycles of 30 s at 95 8C, 30 s at 52-56 8C, and 90 s at 72 8C and a final extension step of 7 min at 72 8C. PCR amplifications of 5.8S-ITS and LSU (D1/D2 domains) ribosomal genes has been reported in Penna et al (2008) and Fraga et al (2008), respectively. All PCR amplified products were purified using DNeasy gel extraction Kit (Qiagen, Valencia, CA, USA), and the products were directly sequenced (Eurofins MWG Operon, Ebersberg, Germany).…”

First Report of a Marine Dinoflagellate, Alexandrium Andersonii (Dinophyaceae) in Malaysian Waters

“…The posterior sulcal plate (s.p) is wider than long ( Figure 1D) 27,28]. Other than Malaysia, Alexandrium andersonii was also been found in the Irish coastal waters [27], Gulf of Naples, Italy [29], Aegean Sea, Greece [26,30] and along the coast of China [31]. …”