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

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

Karyotype, chromosome structure, reproductive modalities of three Southern Eurasian populations of the common lacertid lizard, Zootoca vivipara (Jacquin, 1787)

According to a hypothesis of the evolution of viviparity the lacertid lizard Zootoca vivipara, rare relict oviparous populations of the species might occur in southern-eastern part of its distribution area. Such a hypothesis has been verified by comparing the karyotype, chromosome structure, and reproductive modality of three populations of south-eastern part of Russia, including Altai and neighbouring regions, where small territories remained isolated during the Pleistocene cooling and where Pleistocenic fossils of Z. vivipara have been found. The chromosomal study was carried out by conventional staining method and banding methods, namely C-banding and sequential staining of C-banding+ fluorochromes, CMA3 and DAPI. All studied females displayed viviparous reproductive modality and showed a karyotype of 2N = 35 acrocentric chromosomes, with a Z1Z2W sex chromosome system. Chromosome W was subtelocentric. No inter-population variability on karyotype and heterochromatin distribution and composition was observed. From the obtained data the three studied south-eastern Russian viviparous populations belong to the Russian viviparous form of Z. v. vivipara

Characterization of Two Transposable Elements and an Ultra-Conserved Element Isolated in the Genome of Zootoca vivipara (Squamata, Lacertidae)

: Transposable elements (TEs) constitute a considerable fraction of eukaryote genomes representing a major source of genetic variability. We describe two DNA sequences isolated in the lizard Zootoca vivipara, here named Zv516 and Zv817. Both sequences are single-copy nuclear sequences, including a truncation of two transposable elements (TEs), SINE Squam1 in Zv516 and a Tc1/Mariner-like DNA transposon in Zv817. FISH analyses with Zv516 showed the occurrence of interspersed signals of the SINE Squam1 sequence on all chromosomes of Z. vivipara and quantitative dot blot indicated that this TE is present with about 4700 copies in the Z. vivipara genome. FISH and dot blot with Zv817 did not produce clear hybridization signals. Bioinformatic analysis showed the presence of active SINE Squam 1 copies in the genome of different lacertids, in different mRNAs, and intronic and coding regions of various genes. The Tc1/Mariner-like DNA transposon occurs in all reptiles, excluding Sphenodon and Archosauria. Zv817 includes a trait of 284 bp, representing an amniote ultra-conserved element (UCE). Using amniote UCE homologous sequences from available whole genome sequences of major amniote taxonomic groups, we performed a phylogenetic analysis which retrieved Prototheria as the sister group of Metatheria and Eutheria. Within diapsids, Testudines are the sister group to Aves + Crocodylia (Archosauria), and Sphenodon is the sister group to Squamata. Furthermore, large trait regions flanking the UCE are conserved at family level

Karyotype, chromosome structure, reproductive modalities of three Southern Eurasian populations of the common lacertid lizard, <i>Zootoca vivipara</i> (Jacquin, 1787)

According to a hypothesis of the evolution of viviparity the lacertid lizard Zootoca vivipara, rare relict oviparous populations of the species might occur in southern-eastern part of its distribution area. Such a hypothesis has been verified by comparing the karyotype, chromosome structure, and reproductive modality of three populations of south-eastern part of Russia, including Altai and neighbouring regions, where small territories remained isolated during the Pleistocene cooling and where Pleistocenic fossils of Z. vivipara have been found. The chromosomal study was carried out by conventional staining method and banding methods, namely C-banding and sequential staining of C-banding+ fluorochromes, CMA3 and DAPI. All studied females displayed viviparous reproductive modality and showed a karyotype of 2N = 35 acrocentric chromosomes, with a Z1Z2W sex chromosome system. Chromosome W was subtelocentric. No inter-population variability on karyotype and heterochromatin distribution and composition was observed. From the obtained data the three studied south-eastern Russian viviparous populations belong to the Russian viviparous form of Z. v. vivipara

Isolation and Characterization of Interspersed Repeated Sequences in the Common Lizard, Zootoca vivipara, and Their Conservation in Squamata

The common lizard (Zootoca vivipara) displays characteristic cytogenetic, reproductive, molecular, and biogeographic variability. This species comprises oviparous and viviparous populations with disjunct distribution and sex chromosome polymorphisms, from simple ZZ/ZW to complex Z1Z1Z2Z2/Z1Z2W systems with different morphologies of the W chromosome. In this study, we used the primers SINE A and SINE B and a newly designed primer pair to (1) obtain information on the presence and distribution of transposable elements (TEs) in 8 squamate families and (2) assess the chromosomal location of SINE Squam elements in Z. vivipara. PCR amplification with SINE A and SINE B produced single or multiple products in different Z. vivipara populations, subsequently used to design the SINE-Zv primers. Using the newly designed SINE-Zv primers, we identified 2 sequences of about 700 and 300 bp (SINE-Zv 700 and SINE-Zv 300) in all the investigated populations of Z. vivipara. Fluorescence in situ hybridizations showed a preferential localization of SINE-Zv sequences in the peritelomeric regions of almost all chromosomes, with the exception of the W. Both sequences contained a distinct segment of SINE Squam2. SINE-Zv 700 appeared to be restricted to Z. vivipara, while SINE-Zv 300 contained a partial Gypsy sequence that is highly conserved among Squamata and showed high identity values (72-93%) with several transcripts from different species. Using the same primers, we also highlighted the presence of another highly conserved Gypsy-like fragment in snakes which displayed significant similarity with the stomatin-like protein 2 of colubrids. Our results suggest that SINEs and the Gypsy-like elements are widely distributed among squamates and may have played an active role in their genomic evolution and differentiation