EN
Inter- and intra-strain crosses were made in Paramecium biaurelia of the P. aurelia species complex for studying the relation of strains within the species. Altogether ten strains originating from Scotland, Spain, Romania, Czech Republic, Ukraine, Italy, Germany, Russia, and Poland (two strains) were studied. A high percentage of surviving clones in both generations, F1 (obtained by conjugation) and F2 (obtained by autogamy), was observed in strain crosses, indicating a strong relation between the strains, and absence of genetic barriers between them in P. biaurelia.