EN
In the present paper the results are given of the studies, i.e. intra- and inter-strain crosses carried out between the Polish and the Czech strains (from the Sudeten Mts) and the standard one. Also inter-strain crosses were made between strains from remote regions of Europe, i.e. from Poland and Romania, and from Poland and Spain. The results showed that strains coming from different habitats of the Sudeten Mts as well as from the remote regions of Europe, i.e. Poland, Spain, and Romania, or even originating from Europe and the USA, were not genetically differentiated within P. triaurelia. The studied strains can interbreed in spite of their geographical isolation. The results indicate that in the studied species of the P. aurelia complex there exists a type of breeding system which can be called moderate inbreeding.