Phylogenic and systematic study on sturgeons

Sturgeons are anadromous and potamodromous species inhabiting the northern hemisphere, which have been existing for almost 100 million years. These species have been caught and processed by human for the past 2500 years. The native habitats of the genus Acipenser include Eastern America, Adriatic - Ponto - Caspian region, Amur River, the Pacific Ocean and Siberia. Some members of this genus, which belong to 120 and 240 Chromosome Group and lack the monophyletic structure inhabit the brackish waters of Adriatic - Ponto - Caspian region. However this region is considered to be the richest and most ancient habitat of the Acipenser genus. The seven sub-genera with common characteristics living in this region can be identified as follows: Subgenus 1- A. Sturio 2- A. Gladostomus 3- A. Sterleta 4- A. Antaceus 5- A. Sinosturio 6- A. Parasinosturio 7- A. Dinectus Beside morphological, biological and ecological knowledge, conducting physiological studies as well as field studies would provide considerable assistance to study the systematic of sturgeons. Observations such as the difference in the structure of their bentophage stomach and existence of oocytes with average weight of 9-18 mg in species with 120 chromosomes and oocytes with average weight of 17-22 mg in species with 240 chromosomes living in the same region are among the valuable indicators. Based on the conducted research, the sturgeons can be classified as follows: 1) Family Acipenseridae including 5 genera (one fossil genus) and 26 species 2) Family Polyodontidae including 4 genera (two fossil genus) and 2 species 3) Family Chondrosteidae including 2 fossil genera In the present paper beside the phylogenetic path and systematic classification, exact scientific name, distribution and intraspecific forms (races) of the sturgeons have also been discussed.

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