Karyotypes of the Siberian Sturgeon, Acipenser baeri, of the Lena River and Some Aspects of Karyotype Evolution in Acipenseriformes

V.P. VasiI ‘yev, L.I. Sokolov and Ye. V. Serebryakova A,N, Severtsov Institute of Evolutionary Morphology and Animal Ecology, USSR Academy of Sciences, Moscow; Department of Ichthyology, Moscow University; All- Union Research Institute for Sea Fisheries and Oceanography

The diploid set of chromosomes of the Siberian sturgeon Acipenser baeri of the Lena River is 249±5, the number of chromosome arms is (308±4)±18, where ±4 is the accuracy of identification of chromosomes with two arms, ±8 is the accuracy of the recording of microchromosomes. Polyploidy apparently occurred twice in the evolution of the Acipenseriformes. The first polyploidization (inception of a 120 chromosomes karyotype) may be assumed, whereas the second (inception of a 240 chromosome karyotype) may be regarded as proven, karyological data rule out the view of the hybrid origin of the Siberian sturgeon of the Lena River.