[Genetic Differentiation among Natural Populations of the Lizard Complex Darevskia raddei as Inferred from Genome Microsatellite Marking].

The article presents the genetic parameters of the populations of lizards of the Darevskia raddei complex (D. raddei nairensis and D. raddei raddei) and the populations of D. valentini calculated on the basis of the analysis of variability of 50 allelic variants of the three nuclear genome microsatellite-containing loci of 83 individuals. It was demonstrated that the F(st) genetic distances between the populations of D. raddei nairensis and D. raddei raddei were not statistically significantly different from the F(st) genetic distances between the populations of different species, D. raddei and D. valentini. At the same time, these distances were statistically significantly higher than the F(st) distances between the populations belonging to one species within the genus Darevskia. These data suggest deep divergence between the populations of D. raddei raddei and D. raddei nairensis of the D. raddei complex and there arises the question on considering them as separate species.

The parthenogenetic rock lizard lacerta unisexualis: An example of limited genetic polymorphism

Protein electrophoresis of Lacerta unisexualis from three populations found that 21 of 36 allozyme loci were homozygous, while 14 expressed fixed heterozygotes and one locus was variable. Three clones were detected at the locus Cat-A. Two individuals represent two rare clones while all others form a common clone. Our favored explanation is the mutation of a preexisting common clone rather than multiple origins.

Disjunct habitats as islands: genetic variability in the Caucasian rock lizard Lacerta portschinskii.

Genetic diversity at 37 allozyme loci was surveyed in Lacerta portschinskii from contiguous populations and from a disjunct population. Indices of genetic diversity (heterozygosity, number of alleles per locus, and percentage of loci polymorphic) were greater in contiguous populations than in the smaller disjunct population. In this regard, disjunct populations appear to be similar to island populations. Indices of genetic diversity in Caucasian Lacerta are less than those reported from vagile lizard taxa and more similar to those of sit-and-wait predators.

Clonal variation in the parthenogenetic rock lizard Lacerta armeniaca.

Genetic diversity at 35 allozyme loci was surveyed in seven populations of Lacerta armeniaca. Fixed heterozygotes were present at 16 loci, with homozygotes at 17 loci. Variation occurred at two loci, one in each of two populations, indicating one widespread clone, one restricted clone, and one apparently restricted clone. The low level of variation in this species suggests a recent restricted origin, involving few parental individuals.

Old age, multiple formations or genetic plasticity? Clonal diversity in the uniparental Caucasian rock lizard, Lacerta dahli.

Allozyme variation at 35 gene loci is investigated in 161 specimens of the uniparental Caucasian lizard Lacerta dahli from several locations in Armenia and Georgia. All individuals are heterozygotic at 12 loci, and homozygotic at 21 loci. Variation at two loci results in five uniparental clones. One clone is widespread whereas four are geographically restricted and are represented by only one or two individuals. Because successful formation of uniparental clones is rare, and because the biparental species forming them are now allopatric, the most probable explanation for the origin of the observed clonal diversity is either mutation or recombination within the common clone. The rare clones have lower levels of enzyme activity at four loci, suggesting that these organisms may be genetically deficient. Although the evidence points to change in a pre-existing clone, the possibility of multiple origins cannot be ruled out.

Instability of (GATA)n microsatellite loci in the parthenogenetic Caucasian rock lizard Darevskia unisexualis (Lacertidae).

Mini- and microsatellites, comprising tandemly repeated short nucleotide sequences, are abundant dispersed repetitive elements that are ubiquitous in eukaryotic genomes. In humans and other bisexual species hypervariable mini- and microsatellite loci provide highly informative systems for monitoring of germline and somatic instability. However, little is known about the mechanisms by which these loci mutate in species that lack effective genetic recombination. Here, multilocus DNA fingerprinting was used to study M13 minisatellite and (GATA)n microsatellite instability in the parthenogenetic Caucasian rock lizard Darevskia unisexualis (Lacertidae). DNA fingerprinting of 25 parthenogenetic families, from six isolated populations in Armenia (comprising a total of 84 siblings), using the oligonucleotide (GATA)4 as a hybridization probe, revealed mutant fingerprinting phenotypes in 13 siblings that differed from their mothers in several restriction DNA fragments. In three families (8 siblings), the mutations were present in the germline. Moreover, the mutant fingerprint phenotypes detected in siblings were also present in population DNA samples. No intrafamily variations in DNA fingerprint patterns were observed with the M13 minisatellite probe. Estimates of the mutation rate for (GATA)n microsatellite loci in D. unisexualis showed that it was as high as that seen in some bisexual species, reaching 15% per sibling or 0.95% per microsatellite band. Furthermore, in one case, a somatic (GATA)n microsatellite mutation was observed in an adult lizard. These findings directly demonstrate that mutations in (GATA)n microsatellite loci comprise an important source of genetic variation in parthenogenetic populations of D. unisexualis.

Genetic variation in parthenogenetic Caucasian rock lizards of the genus Lacerta (L. dahli, L. armeniaca, L. unisexualis) analyzed by DNA fingerprinting.

Multilocus DNA fingerprinting has been used to study the variability of some mini- and microsatellite sequences in parthenogenetic species of Caucasian rock lizards of the genus Lacerta (L. dahli, L. armeniaca and L. unisexualis). We demonstrate that these clonally reproducing lizards possess species-specific DNA fingerprints with a low degree of intra- and interpopulation variation. Mean indices of similarity obtained using M13 DNA, (GACA)4 and (TCC)50 as probes were 0.962 and 0.966 in L. dahli and L. armeniaca, respectively. The mean index of similarity obtained using M 13 and GATA probes in L. unisexualis was estimated to be 0.95. However, despite the high degree of band-sharing, variable DNA fragments were revealed in all populations with the microsatellite probes. An particularly high level of variability was observed for (TCC)n microsatellites in populations of L. unisexualis. In fact TCC-derived DNA fingerprints were close to being individual-specific, with a mean index of similarity of 0.824. Fingerprint analysis of parthenogenetic families of L. armeniaca showed that all maternal fragments were inherited together by the progeny, and no differences in fingerprint patterns were observed. On the other hand, while identical DNA fingerprints were obtained from L. unisexualis families with M13 and (GATA)4 probes, use of the (TCC)50 probe revealed remarkable intrafamily variation in this species. It is assumed that the genetic heterogeneity observed in parthenogenetic populations may be explained, at least in part, by the existence of genetically unstable microsatellite loci. Our data serve to illustrate processes of spontaneous mutagenesis and the initial stages of clonal differentiation in natural populations of the lizard species studied.