We document the distribution of the common toad Bufo bufo and the spined toad B. spinosus at their contact zone across France with data from a mitochondrial DNA RFLP assay, complementing similar work including nuclear markers in the northwest and southeast of France and in Italy. We also reconstruct geographical clines across the species’ contact zone in central France. Bufo bufo is found in the north-eastern half of France. Bufo spinosus is found in the south-western complement. The contact zone they form runs from the Atlantic coast near Caen, France, to the Mediterranean coast near Savona, Italy, and has a length of over 900 km. In central France B. bufo and B. spinosus engage in a hybrid zone with a unimodal genetic signature. Leer más.