Saliy T. Cryptic invasion of clonal spined loaches (Cyprinformes, Cobitidae) of the group of species S. elongatoides – taenia – tanaitica in the Dnieper basin

To confirm the fact of numerical predominance of polyploids throughout Ukraine. To prove that the process of numerical predominance of polyploids over diploids, which began in the 1950s due to the mass migration of hybrids from the Danube basin, continues up to now. Morphological analysis using modern multidimensional approaches proved the absence of morphological hiatus and diagnostic features among individuals of the parent species and hybrid forms, which confirms the cryptic nature of the invasion. The comparison of a number of biological indicators: reproductive potential, resistance to blood parasites, the stability of the genetic apparatus gives a reason to believe that certain differences between diploids and polyploids are real. Nevertheless, the clear mechanisms of the extraordinary adaptive success of clonal individuals remain unclear. The most probable purely genetic circumstances are: heterosis and rejection of meiotic reproduction of hybrids.