Intra-species differentiation and level of inbreeding of different siblingspecies of the Paramecium aurelia complex

A combination of classical inter- and intra-strain crosses by mating reacti ons and randomly amplified polymorphic DNA-polymerase chain reaction (RAPD- PCR) was used to detect different population specific genotypes within two species of the Paramecium aurelia complex. P. novaurelia strains originatin g from Spain, Germany, Scotland, Poland, Czech Republic, Ukraine, Turkey, a nd P. pentaurelia strains from Spain, Hungary, and the USA were studied. A high percentage of surviving clones in both generations, F1 (obtained by co njugation) and F2 (obtained by autogamy), was observed in strain crosses in these two species. The fingerprint method distinguished four genotypes wit hin the studied P. novaurelia strains. Genotype I was observed in Spanish s trains, genotype II in strains originating from Scotland and Turkey, genoty pe III was observed in the strain from Germany, and genotype IV described t he strains from Central and Eastern Europe (Poland, Czech Republic, Ukraine ). In contrast, the studied P. pentaurelia strains, originating from Europe (Spain, Hungary) and the USA showed the same genotype, in spite of the geo graphical isolation of strains. From these results, we conclude that both s pecies, P. novaurelia and P. pentaurelia may show different degrees of inbr eeding. While F1 novaurelia can be described as a moderate inbreeder consis ting of different genotypes which are able to mate under laboratory conditi ons, P. pentaurelia is described as a weak inbreeder which is open to gene flow, as the strains from distant places are characterized by only one sing le genotype. The species have different life history strategies as a conseq uence of different degrees of inbreeding. Remarkable ecogenetic differences are also true for strains within the same species.