PDFDOI: https://doi.org/10.1515/vzoo-2017-0006
Comparison of reproductive parameters in several Cobitis forms with diff erent ploidy shows that the maximum fertility is found in diploid Cobitis, the triploids are less fertile and the tetraploids even less fecund. The latter reach maximum values of size and weight indicators but minimum number of eggs, the smallest size of the ovaries but the biggest eggs. Nevertheless, the combined reproductive potential of polyploid females is higher than of diploid spiny loaches with equal ratios of males to females in populations. The obvious reasons for the successful expansion of polyploid individuals of the spiny loaches are both their higher fertility at the population level and the changes in environmental conditions associated with the regulation of all major rivers in Ukraine in the 1960–1970s.