Cytogenetical approaches to the problem of form-formation and subspeciation in the complex Lacerta (Zootoca) vivipara (Lacertidae, Sauria)

Results of the author's long-term study of the karyotype of Lacerta (Zootoca) vivipara (family Lacertidae, Sauria) have been generalized and supplemented with relevant literature data. Within the species an interpopular karyotype variability was established, and several chromosomal forms were described. Karyotypes of L. (Z.) vivipara from four new, previously not examined populations have been first presented in this paper, and cytogenetical features of their chromosomes are given. Finally, cytogenetical analysis of particular specimens from different localities enabled the author to reveal a new chromosomal form and to define the limits of distribution of other forms of the species. The complex L. (Z.) vivipara has appeared to be more complicated than earlier believed. This complex includes several chromosomal forms of unclear taxonomic status, and some subspecies characterized by various modes of reproduction and distinct distribution ranges. It has been confirmed that in the complex L. (Z.) vivipara intensive chromosomal changes accompany the processes of form-formation and subspeciation. Some cytogenetical regularities of these processes have been demonstrated and compared with hybridogeneous form-formation and speciation. Based on the critical analysis of the available karyological data, some mechanisms of chromosomal changes were described, and their tendencies were determined. In addition, intraspecific relationships were analysed. The proposed scheme was compared with the pattern of intraspecific phylogeny of L. (Z.) vivipara based on molecular data. It has been shown that a high cytogenetical differentiation of the found chromosomal forms and subspecies is correlated with their low morphological differentiation and with a rather low genetical differentiation. The results of the combined analysis suggest the leading role of cytogenetical data for understanding the processes of form-formation and subspeciation. The importance of chromosomal rearrangements in these processes is emphasized, with special reference to their role in the evolution and phylogeny of the complex L. (Z.) vivipara. Some modes of form-formation and subspeciation in this complex are discussed.