Between-population variation of average size (snout–vent length – SVL) for each Pelobates species, measured separately for females (pink) and males (blue). This compiles average size-data from 82 populations, representing at least 6,004 individuals (Suppl. material 1, Table S1). For P. balcanicus, it only includes populations from the nominal P. b. balcanicus. For P. syriacus, it only includes populations from P. s. boettgeri.