ИСТИНА

The discovery of clonal vertebrates stimulated principally new complex of evolution and ecological investigations. The trends of these studies may be combined in five main blocs: 1) the origin of clonal vertebrate forms; 2) cytogenetic mechanisms of clonal heritability; 3) clonal diversity and its sources; 4) new genetic systems different from both clonal and bisexual reproduction; 5) ecological problems of co-existance of clonal and bisexual forms. Ecological aspects of the co-existance of gynogenetic and bisexual forms are the least studied and the most discussed. Genetic and ecological closeness of clonal and bisexual forms in relation with their simultaneous genetic and evolution independence propose several questions on their co-existance. The most obvious questions are the next ones. 1. What advantages or faults in nature resource utilization are characterized for clonal forms contrast to bisexual species? 2. Do ecological factors regulate relative numbers of clonal and bisexual forms and to what extent? And are they decisive components in maintenance of the balance within clonal-bisexual complexes for a long time? 3. If clonal-bisexual complexes exist for a long time, is it possible that their equilibrium state depends from any internal characteristics, but not from ecological factors? Obviously, the analysis of mentioned problems will be more complicated in the case of multi-clonal structure of unisexuals. Ecological relations between clonal and bisexual form of spined loaches from genus Cobitis in different river systems, namely Volga, Don, Dnieper, Dniestr, Zapadnaya Dvina, Southern Bug, etc., are analyzed in recent study. This analysis is based on both original and literature data on the structure of clonal-bisexual complexes, relative numbers of different forms in different years, their biotopic distribution during spawning period, fecundity, age and size structure, etc.