Biogeography of Lacerta (Zootoca) vivipara: reproductive mode and enzyme phenotypes in Bulgaria

Lacerta (Zootoca) vivipara, has allopatric oviparous and viviparous populations: viviparity is observed from central France and the British Isles to Scandinavia and Russia, while oviparity is restricted to northern Spain and southwestern France, i.e. the extreme southwestern part of the range. Recent observations in the Rila, Balkan, Vitocha, Pirin and Rhodopes mountains indicate that Bulgarian populations of Lacerta (Zootoca) vivipara are indeed viviparous. The electrophoretic study of allozymes and the estimation of genetic distances indicate that viviparous lizards from northwest and central France are more closely related to those of Bulgaria, than to the oviparous lizards of southwest France and northwest Spain. Variations in reproductive mode and allozymes are not directly related to geographic distances between populations, nor to their latitude: populations located at the southwest limit of distribution are oviparous and exhibit alleles${\rm ATA}^{-150}$or${\rm ATA}^{-200}$, whereas, at a comparable latitude, the Bulgarian populations are viviparous and exhibit allele${\rm ATA}^{-100}$characteristic of other distant viviparous populations. These findings underline the originality of the oviparous southwestern populations. They do not contradict our previous biogeographic scenario.