Krill: a possible model for investigating the effects of ocean currents on the genetic structure of a pelagic invertebrate

Abstract

This paper reviews the information available on the population genetics and systematics of krill (Euphausiidae, Crustacea), integrating the published data with new data collected in our laboratory. Phylogenetic analysis of several Antarctic and sub-Antarctic Euphausia species indicates the importance of dispersal in determining the present-day geographic distribution. Dating speciation events suggest that the formation of the Antarctic Convergence, the oceanographic barrier isolating the Southern Ocean, may have played a role in separating the ancestral Antarctic and sub-Antarctic lineages. Intraspecific data show that the Antarctic krill (Euphausia superba) is characterized by weak genetic differentiation, whereas the northern krill (Meganyctiphanes norvegica) is more structured showing discrete genetic pools. This difference can be explained, at least partly, by the oceanographic conditions in the areas inhabited by the two species.