Phylogenetic relationships of Amur sturgeon Acipenser schrenckii Brandt, 1869 based on 18S rDNA sequencing

The phylogenetic relationships of Amur sturgeon A. schrenckii Brandt, 1869 with related species have been analyzed based on sequencing of the 18S rDNA small subunit. The complete sequence (1746 bp) of 18S rDNA has been estimated in seven individual A. schrenckii clones. The results show that the rDNA mutation profile of A. schrenckii 18S is very similar to that of A. fulvescens (Genbank data). Structural-functional and phylogenetic analyses allowed us to identify a presumably expressed variant, as well as taxon-specific mutation (adenine insertion after position 658 bp), for A. schrenckii 18S rDNA. Phylogenetic reconstructions performed with various approaches (NJ, MP, ML and Bayesian) support the monophyly of the genus Acipenser and point (1), based on which, in accordance with the classification based on ecological and morphological data (Artyukhin, 2006), the Amur sturgeon is closer to the sterlet than the Baltic sturgeon and (2) to substantial differentiation between North American (A. fulvescens) and Eurasian (A. schrenckii, A. ruthenus, and A. sturio) species of Acipenseridae.