Karyotype dispersal of the common lizard Zootoca vivipara (Lichtenstein, 1823) in eastern and northeastern Fennoscandia

Abstract

The wide-ranging Eurasian common lizard Zootoca vivipara (Lichtenstein, 1823) is remarkably uniform morphologically but highly varied in its karyotype. Previous studies have revealed two distinctly different chromosomal forms of Z. v. vivipara in the Baltic basin. Moreover, a zone of secondary contact between these forms has been localized on the southern Baltic Sea seashore. Intraspecific karyotype diversity for Z. vivipara and new zones of secondary contact have recently been suggested for other parts of the Baltic Sea seashore. We studied the karyotype of Z. vivipara in central, western and northern parts of Finland. All the individuals karyotyped represented the Russian form of Z. v. vivipara that differs from the western form of the subspecies located at the southern and western Baltic Sea seashore. Together with previous data sets, our results suggest intraspecific karyotype diversity in the northern and northwestern parts of Fennoscandia. The results give support to the hypothesis of Z. vivipara’s re-colonization of the Baltic Sea basin. Moreover, the results support the previous observations of Voipio (1961, 1968 and 1969) who has reported variability in the shield pattern of Z. vivipara in the same region.