Clinal variation in populations of the common blue butterfly Polyommatus icarus Rott. (Lepidoptera, Lycaenidae)

Geographical trends in variation of wing pattern characters of the common blue butterfly Polyommatus icarus Rott. have been established. Peripheral populations were shown to be more rich and diverse phenotypically than those of the central parts of the species range. Phenotypic diversity of the populations increased from the center to the periphery of the range. The range boundaries were characterized by strong fluctuations of frequencies of wing pattern phenotypes. Hybrid areas were found on the part of the range examined.