Alexandrium: Evolutionary and ecological insights into the most prominent toxigenic dinoflagellate
Dinoflagellates are a major cause of harmful algal blooms, with consequences for coastal marine ecosystem functioning and services. Representatives of Alexandrium tamarense species complex are of the most abundant and widespread toxigenic species, and produces paralytic shellfish poisoning toxins as well as allelochemical substances. This species complex consists of four to five species. The debate of the separation of this complex into real species in long on going and here a concept for the divorce of this group will be proposed. Problems with identification of a toxic member of this species complex in November 2012, which led to the accidental export of toxic mussels to Japan, has now led to severe restrictions on Australian shellfish exports to Japan for a year, and resulting losses of many million $. Furthermore, population genetic insight and adaptive strategies in species interaction processes will be presented. Allelochemical mediated intra-population facilitation, may explain at least partly the high genotypic and phenotypic diversity of Alexandrium populations. Consequently, multiple traits within a population potentially allow mutual facilitation, and may promote the success of microbial planktonic populations.