Fig. 1From: All-male hybrids of a tetrapod Pelophylax esculentus share its origin and genetics of maintenanceMap showing the investigated water frog populations in the upper Oder River. Numbers next to the dots correspond with numbers of localities given in Table 1. Dark gray dots refer to the R-E male system, light gray dots to the L-E system. The inset indicates the geographic location of the study area in EuropeBack to article page