Increase of karyotypic variability in sturgeon hybrids

Arefjev, V.A.

Various forms of bester (i.e. hybrid between great sturgeon, Huso huso, and sterlet, Acipenser ruthenus; in F1 , F2. F3 and FB), hybrid between A. ruthenus and ship, A. nudiventris, as well of hybrid between Russian sturgeon, A. gueldenstaedtii, and Siberian sturgeon, A. baeri, are characterized by authentical increase of karyotypic variability estimate from coefficients of variation of quantitative parameters of karyotype such as diploid chromosome number, number of microchromosome and number of chromosome arms. However. some hybrid forms (F3 and FB in second generation of bester) show the karyotype variability practically identical of that characteristic for parental species. Koryotypic variability in sturgeon hybrids as well as apparently in “clean” species is basically realized at the expense of aneuploidy on microchromosomes. The problems of the reality or individual karyotypic variations and of presumptive nature of sturgeons microchromosomes as supernumeraries are briefly discussed.