Fig. 7.

Outcomes of crosses for the putative hybridogenetic systems proposed to inhabit Ticino. Northern populations correspond to the classic L-E system (a). In southern Ticino, the hypothetical maintenance of LR hybrid frogs without triploids and without P. lessonae requires that frogs from both sexes alternatively eliminate the L and the R genomes (b). RR and LL genotypes are supposedly unfit (hybridogenetic load) but can arise in populations, as we found in STA