and Acipenser oxyrinchus Mitchill, 1815: A review

Molecular phylogeny based on the analysis of partial sequences of mitochondrial (mt) cy-tochrome b (cyt b), 12S, and 16S genes supports a close relationship between the European Atlantic sturgeon Acipenser sturio L., 1758, and the American Atlantic sturgeon, Acipenser oxyrinchus Mitchill, 1815. These sister species form a separate clade within the genus Acipenser and appear to be the most basal clade with respect to all other species of the genus. Intraspecifically, at least two different genetic forms have been found within A. sturio (in the Northern and Baltic seas), but no defined subspecies exist. For A. oxyrinchus, fixed differences in the control region and cyt b gene distinguish the two subspecies, the Atlantic sturgeon A. oxyrinchus oxyrinchus Mitchill, 1815 and the Gulf of Mexico sturgeon A. oxyrinchus desotoi Vladykov, 1955. Within A. o. oxyrinchus, a pronounced latitudinal cline in haplotype diversity exists from north to south along the eastern coast of North America. This greater genetic diversity in southern populations is most likely a result of population continuity through the Pleistocene. Monomorphism within the two northernmost, post-Pleistocene A. o. oxyrinchus populations indicates a probable founder effect. A. o. desotoi also displays a significant geographic structuring of populations in different river sys