Studies on the population genetics of Euphausiids: a comparison of patterns in plagic taxa displaying different distributions and life-histories

Abstract

The systematic and population genetic relationships were characterised for three ecologically related euphausiid species: Euphausia lucens, E. recurva and E. vallentini. These species have different geographical distributions and life histories. All three species have a circumpolar distribution in the Southern Hemisphere while E. recurva is also distributed in the North Pacific. DNA sequence variation was determined for three regions of mitochondrial DNA and a single nuclear gene. It was conclusively demonstrated that both E. lucens and E. vallentini represent valid taxonomic species with fixed differences observed in both the nuclear and mitochondrial genes and that the low divergences previously reported for these species with 16SrRNA and CO1 resulted from a species misidentification. It was also shown that previous attempts to date the divergence between Antarctic and Sub-Antarctic euphausiid species based on 16SrRNA distances suffer from a large overestimation due to a calculation error.