Population genetic structure of the Humboldt squid (Dosidicus gigas d'Orbigny, 1835) inferred by mitochondrial DNA analysis

The Humboldt squid is the source of supply for the largest cephalopod fishery of the world. Essential knowledge for the management of this mollusc must include information about the genetic structure and evolutionary history of populations because it presents a complex population structure and atypical features compared with other ommastrephins. Sequences were analyzed of a 367 bp fragment from the mitochondrial Cytochrome b region identified by the technique of Single Strand Conformation Polymorphism (SSCP). Molecular diversity statistics were moderate while the genetic structure detected was low but significant; this was found to support weakly the Northern–Southern division of the populations. This pattern as well as the very recent divergence (< 10,000 years) among South–North populations could be explained by oceanographic and biological factors, in particular those attaining ocean productivity. Also, the genetic variation was consistent with an incomplete lineage sorting and a spatial expansion probably originated more than 200,000 years ago.