Molecular systematics and biogeography of Oithona spp. of the Atlantic Ocean

CEPEDA, G. C.; BLANCO-BERCIAL, L.; BUCKLIN, A.; BERÓN, C.; VIÑAS, M. D.

Simposio; 5th International Zooplankton Production Symposium; 2011

The family Oithonidae Dana, 1853 (Copepoda, Cyclopoida) is one of the most abundant groups in the pelagic realm throughout the worlds oceans. Although knowledge has increased about the life history and ecology of Oithona spp. in recent years, few studies to date have used molecular genetic approaches. This study analysed rDNA sequence variation of a portion of the large subunit (28S) ribosomal rRNA gene for individuals of three Oithona species: O. nana, O. helgolandica (sensu Ramirez, 1969) and O. atlantica in samples collected from selected regions of the North and South Atlantic Ocean. The 28S rRNA gene tree and pairwise distance matrix clearly resolved Oithona species and confirmed the presence of three distinct species in the sampled regions.Analysis of geographic variation of 28S rRNA haplotype frequencies of O. helgolandica (sensu Ramirez, 1969) revealed evidence of genetic differentiation among populations in three regions: western and eastern North Atlantic and western South Atlantic. Population genetic analysis using additional  and more highly variable molecular markers is needed to reveal pathways of dispersal in ocean currents and any barriers to genetic cohesion among Atlantic Ocean populations of this species.