Fig. 1From: Concordant morphological and molecular clines in a contact zone of the Common and Spined toad (Bufo bufo and B. spinosus) in the northwest of FranceLocation of 17 Bufo spinosus and B. bufo populations over a transect in northwestern France. The pie diagrams at the bottom show the observed mtDNA haplotype frequencies, with haplotypes typical for the species in red (B. spinosus) and blue (B. bufo). The B. bufo–B. spinosus hybrid population reported by [18] is shown by an XBack to article page