GENETIC COMPATIBILITY BETWEEN SEXUAL AND CLONAL GENOMES IN LOCAL-POPULATIONS OF THE HYBRIDOGENETIC RANA-ESCULENTA COMPLEX

Hybridogenetic species possess a hybrid genome: half is clonally inher ited (hemiclonal reproduction) while the other half is obtained each g eneration by sexual reproduction with a parental species. We addressed the question of whether different hemiclones of the hybridogenetic wa ter frog Rana esculenta are locally adapted for genetic compatibility with their sexual parental host Rana lessonae. We artificially crossed R. esculenta females of three hemiclones (GUT1, GUT2 and GUT3) from a pond near Gutighausen, Switzerland and one hemiclone (HEL1) from near Hellberg, Switzerland each to R. lessonae males from both populations . We also created primary hybrids by crossing the same R. lessonae mal es from both populations to R. ridibunda females from Poznan, Poland ( POZ). Tadpoles were then reared in the laboratory at two food levels t o assess their performance related to early larval growth rate, body s ize at metamorphosis and length of the larval period. Tadpoles from he miclons GUT1, GUT3 and POZ had higher growth rates than those from hem iclones GUT2 and HEL1 at the low food level, but at the high food leve l all growth rates were higher and diverged significantly between hemi clones GUT2 and HEL1. Tadpoles from the intrapopulational crosses GUT2 x GUT and HEL1 x HEL were larger at metamorphosis than those from the interpopulational crosses GUT2 x HEL and HEL1 x GUT. A high food leve l increased the size at metamorphosis in all tadpoles. A high food lev el also decreased the days to metamorphosis and tadpoles from GUT1, GU T3 and POZ had the shortest larval period whereas those from GUT2 and HEL1 had the longest. These results indicate that the differential com patibility of clonal genomes may play an important role in hybridogene tic species successfully using locally adapted sexual genomes of paren tal species and that interclonal selection is likely important in dete rmining the distribution of hemiclones among local populations.