World-wide genetic differentiation of Eubalaena: questioning the number ofright whale species

Few studies have examined systematic relationships of right whales (Eubalae na spp.) since the original species descriptions, even though they are one of the most endangered large whales. Little morphological evidence exists t o support the current species designations for Eubalaena glacialis in the n orthern hemisphere and E. australis in the southern hemisphere. Differences in migratory behaviour or antitropical distribution between right whales i n each hemisphere are considered a barrier to gene flow and maintain the cu rrent species distinctions and geographical populations. However, these dis tinctions between populations have remained controversial and no study has included an analysis of all right whales from the three major ocean basins. To address issues of genetic differentiation and relationships among right whales, we have compiled a database of mitochondrial DNA control region se quences from right whales representing populations in all three ocean basin s that consist of: western North Atlantic E. glacialis, multiple geographic ally distributed populations of E. australis and the first molecular analys is of historical and recent samples of E. glacialis from the western and ea stern North Pacific Ocean. Diagnostic characters, as well as phylogenetic a nd phylogeographic analyses, support the possibility that three distinct ma ternal lineages exist in right whales, with North Pacific E. glacialis bein g more closely related to E. australis than to North Atlantic E. glacialis. Our genetic results provide unequivocal character support for the two usua lly recognized species and a third distinct genetic lineage in the North Pa cific under the Phylogenetic Species Concept, as well as levels of genetic diversity among right whales world-wide.