A preliminary study on phylogenetic relationship between five sturgeon species in the Iranian Coastline of the Caspian Sea

The phylogenetic relationship of five sturgeon species in the South Caspian Sea was investigated using mtDNA molecule. Sequence analysis of mtDNA D-loop region of five sturgeon species [Great sturgeon (Huso huso), Russian sturgeon (Acipenser gueldenstaedtii), Persian sturgeon (Acipenser persicus), Ship sturgeon (Acipenser nudiventris), Stellate sturgeon (Acipenser stellatus)] and DNA sequencing of two Escherichia coli cloned DNA fragments sized ۷۵۸ bp and ۹۲۲ bp was carried out. Sequence comparison of the mtDNA D-loop region between the five sturgeon species showed ۱۰۰ % sequence identity. However comparison between a short (۷۵۸ bp) and long (۹۲۲bp) mtDNA D-loop region within Russian sturgeon showed a ۵ bp differences. On the contrary a partial sequence of the mtDNA ND۵ gene region showed high sequence and organic base variability in the five species. These results indicate that direct sequencing of ND۵ gene provide more information for phylogenetic or population level studies in sturgeon species. The present study revealed a distinct classification among the five sturgeon species. On the basis of the phylogeny tree it is clear that a close evolutionary relationship exists between the great sturgeon and ship sturgeon that was verified in five phylogenetic trees. On the other hand a close resemblance was also seen between Persian and Russian sturgeon indicates that these two species have a closer evolutionary relationship. This study also showed a ۲.۲ % sequence divergence in sequence data for ND۵ gene between Persian sturgeon and Russian sturgeon which indicated that these two species diverged from each other approximately one million years ago. However the verification of this calls for DNA sequencing of different genes. 

Keywords:

Sturgeon , Caspian Sea , Phylogenetic , Iranian Coastline , PCR