Molecular structure of the allelic variants of (AAT)n microsatellite locus Du47D in the parthenogenetic species Darevskia unisexualis and bisexual parental species D. valentini and D. raddei

Microsatellite repeats are one of the most widespread elements of the eukaryotic genome, but are poorly studied in species with clonal reproduction. PCR analysis and DNA sequencing were used to study the molecular structure of the allelic variants of microsatellite locus Du47D in the parthenogenetic species Darevskia unisexualis and its evolutionary ancestors, bisexual species D. raddei and D. valentini, of the genus Darevskia (Lacerta saxicola complex). Sequencing showed that the allelic variants of the D. unisexualis Du47D locus and the alleles of its D. raddei and D. valentini orthologs have a perfect microsatellite cluster structure, differ in number of ATT monomeric units, and have certain species-specific combinations of nucleotide substitutions, deletions, and insertions in the microsatellite-flanking DNA sequences. The Du47D alleles that the parthenogenetic species inherited from D. valentini or from D. raddei were identified.     

Molecular characterization of allelic variants of (GATA)n microsatellite loci in parthenogenetic lizards Darevskia unisexualis (Lacertidae)

Populations of parthenogenetic lizards of the genus Darevskia consist of genetically identical animals, and represent a unique model for studying the molecular mechanisms underlying the variability and evolution of hypervariable DNA repeats. As unisexual lineages, parthenogenetic lizards are characterized by some level of genetic diversity at microsatellite loci. We cloned and sequenced a number of (GATA)n microsatellite loci of Darevskia unisexualis. PCR products from these loci were also sequenced and the degree of intraspecific polymorphism was assessed. Among the five (GATA)n loci analysed, two (Du215 and Du281) were polymorphic. Cross-species analysis of Du215 and Du281 indicate that the priming sites at the D. unisexualis loci are conserved in the bisexual parental species, D. raddei and D. valentini. Sequencing the PCR products amplified from Du215 and Du281 and from monomorphic Du323 showed that allelic differences at the polymorphic loci are caused by microsatellite mutations and by point mutations in the flanking regions. The haplotypes identified among the allelic variants of Du281 and among its orthologues in the parental species provide new evidence of the cross-species origin of D. unisexualis. To our knowledge, these data are the first to characterize the nucleotide sequences of allelic variants at microsatellite loci within parthenogenetic vertebrate animals.     

Study of allelic polymorphism of (GATA)n-containing loci in parthenogenetic lizards Darevskia unisexualis (Lacertidae)

The genesis of mini- and microsatellite loci, which is under extensive study in humans and some other bisexual species, have been virtually overlooked in species with clonal mode of reproduction. Earlier, using multilocus DNA fingerprinting, we have examined variability of some mini- and microsatellite DNA markers in parthenogenetic lizards from the genus Darevskia. In particular, mutant (GATA)n-restrictive DNA fragments were found in Darevskia unisexualis. In the present study, we examined intraspecific polymorphism of three cloned loci of D. unisexualis--Du323, Du215, and Du281--containing (GATA)7GAT(GATA)2, GAT(GATA)9, and (GATA)10TA(GATA) microsatellite clusters, respectively. Different levels of intrapopulation and interpopulation variability of these loci were found. Locus Du281 showed the highest polymorphism--six allelic variants (in the sample of 68 DNA specimens). Three alleles were found for locus Du215. The Du325 locus was electrophoretically invariant. The primers chosen for loci Du323, Du215, and Du281 were also used for PCR analysis of homologous loci in two presumptive parental bisexual species, D. valentini and D. nairensis. The PCR products of the corresponding loci of the parental species had approximately the same size (approximately 200 bp) as their counterparts in D. unisexualis, but the polymorphism levels of the paternal, maternal, and hybrid species were shown to be somewhat different. These data on the structure of the D. unisexualis loci provide a possibility to study genetic diversity in the parthenogenetic species D. unisexualis and other related unisexual and bisexual species of this genus, which can provide new information on the origin of parthenogenetic species and on the phylogenetic relationships in the genus Darevskia. These data can also be used for resolving problems of marking the lizard genome, which is still poorly studied.     

Molecular structure of allelic variants of microsatellite loci <Emphasis Type="Italic">Du281</Emphasis> and <Emphasis Type="Italic">Du47</Emphasis> in unisexual and bisexual lizard species of the genus <Emphasis Type="Italic">Darevskia</Emphasis>

Experimental data on the molecular structure and variability of microsatellite loci in unisexual and bisexual lizard species of the genus Darevskia were analyzed. The allelic variants of Du281 and Du47 were found to differ in the number of monomers, the structure of microsatellite clusters, and point mutations in these clusters and flanking DNA. Interspecific comparison of alleles of these loci revealed both variable regions in the microsatellite clusters and allele-specific evolutionarily conserved nucleotide groups. In general, the results of comparative structural analysis of allelic variants testify to a high genetic similarity of the unisexual and bisexual lizard species studied and reveals the characteristic features of their interspecies variability.     

Study of Allelic Polymorphism of (GATA) n -Containing Loci in Parthenogenetic Lizards Darevskia unisexualis (Lacertidae)

The genesis of mini- and microsatellite loci, which is under extensive study in humans and some other bisexual species, has been virtually overlooked in species with clonal mode of reproduction. Earlier, using multilocus DNA fingerprinting, we have examined variability of some mini- and microsatellite DNA markers in parthenogenetic lizards from the genus Darevskia. In particular, mutant (GATA)n-restriction DNA fragments were found in Darevskia unisexualis. In the present study, we examined intraspecific polymorphism of three cloned loci of D. unisexualis—Du323, Du215, and Du281—containing (GATA)₇GAT(GATA)₂, GAT(GATA)₉, and (GATA)₁₀TA(GATA) microsatellite clusters, respectively. Different levels of intrapopulation and interpopulation variability of these loci were found. Locus Du281 showed the highest polymorphism—(six allelic variants in the sample of 68 DNA specimens). Three alleles were found for locus Du215. The Du323 locus was electrophoretically invariant. The primers chosen for loci Du323, Du215, and Du281 were also used for PCR analysis of homologous loci in two presumptive parental bisexual species, D. valentini and D. nairensis. The PCR products of the corresponding loci of the parental species had approximately the same size (200 bp) as their counterparts in D. unisexualis, but the polymorphism levels of the paternal, maternal, and hybrid species were shown to be somewhat different. These data on the structure of the D. unisexualis loci provide a possibility to study genetic diversity in the parthenogenetic species D. unisexualis and other related unisexual and bisexual species of this genus, which can provide new information on the origin of parthenogenetic species and on the phylogenetic relationships in the genus Darevskia. These data can also be used for resolving problems of marking the lizard genome, which is still poorly studied.     

Molecular genetic characteristic of dinucleotide microsatellite loci in parthenogenetic lizards <Emphasis Type="Italic">Darevskia unisexualis</Emphasis>

In the present study, the first molecular genetic investigation of dinucleotide (GT) _n microsatellite loci in parthenogenetic lizards Darevskia unisexualis was performed. New polymorphic locus, Du214, (GenBank Ac. No. EU252542) was identified and characterized in detail. It was demonstrated that allele of this locus differed in the size and structure of microsatellite locus, as well as in point mutations, the combinations of which enabled the isolation of stabile fixed double nucleotide substitutions A-A (alleles 2 and 4) and G-T (alleles 1, 3, 5, and 6). Double nucleotide substitutions described were also identified in the orthlogous loci of the parental species genomes, D. raddei (G-T) and D. valentine (A-A). Based on the analysis of allele distribution pattern at this locus in all populations of parthenospecies D. unisexualis, mathematic model was elaborated and realized. Using this model, frequencies of allelic variants for all populations of the species of interest were calculated and population genetic structure of D. unisexualis was characterized. Genetic contribution of each population to the species gene pool was determined. The data obtained demonstrated that microsatellite variation was one of the factors of clonal and genetic diversity of a parthenospecies.     

Molecular and genetic characterization of the allelic variants of Du215, Du281, Du323, and Du47G microsatellite loci in parthenogenetic lizard <Emphasis Type="Italic">Darevskia armeniaca</Emphasis> (Lacertidae)

A key issue in the study of unisexual (parthenogenetic) vertebrate species is the determination of their genetic and clonal diversity. In pursuing this aim, various markers of nuclear and mitochondrial genomes can be used. The most effective genetic markers include microsatellite DNA, characterized by high variability. The development and characterization of such markers is a necessary step in the genetic studies of parthenogenetic species. In the present study, using locus-specific PCR, for the first time, an analysis of allelic polymorphism of four microsatellite loci is performed in the populations of parthenogenetic species Darevskia armeniaca. In the studied populations, allelic variants of each locus are identified, and the nucleotide sequences of each allele are determined. It is demonstrated that allele differences are associated with the variation in the structure of microsatellite clusters and single nucleotide substitutions at fixed distances in flanking DNA regions. Structural allele variations form haplotype markers that are specific to each allele and are inherited from their parental bisexual species. It is established which of the parental alleles of each locus were inherited by the parthenogenetic species. The characteristics of the distribution and frequency of the alleles of microsatellite loci in the populations of D. armeniaca determining specific features of each population are obtained. The observed heterozygosity of the populations at the studied loci and the mutation rates in genome regions, as well as Nei’s genetic distances between the studied populations, are determined, and the phylogenetic relationships between them are established.     

Molecular nature of allelic polymorphism of highly variable microsatellite locus <Emphasis Type="Italic">Du161(arm)</Emphasis> in unisexual lizard <Emphasis Type="Italic">Darevskia armeniaca</Emphasis> (lacertidae)

In the genome of unisexual (parthenogenetic) lizard Darevskia armeniaca, highly variable locus Du161 (arm) was discovered. Analysis of allelic polymorphism was carried out using locus-specific PCR of the lizard DNA specimens from 13 isolated Armenian populations (N = 138). In the sample examined, a total of 12 Du161(arm) alleles were identified, and their differences at the level of primary DNA structure were determined. Sequence analysis of the Du161(arm) alleles showed that their microsatellite clusters contained repeats of one type (GATA repeats). Allelic Du161(arm) variants differed in the number of GATA monomers in microsatellite, point mutations of transition and transversion types, located at fixed distances from micro-satellite cluster, and by single nucleotide insertions, as well as by longer insertions located within and outside of the microsatellite cluster. Moreover, point mutations formed different combinations (haplotypes), typical of certain alleles. These combinations can be used for the analysis of the origin and inheritance of these alleles in D. armeniaca, as well as for investigation of their interspecific variation in the representatives of the genus Darevskia.     

Revealing of allelic polymorphism in the populations of parthenogenetic lizards <Emphasis Type="Italic">Darevskia dahli</Emphasis> (Lacertidae) using locus-specific PCR

Locus-specific PCR was used to study the genetic polymorphism in three populations of parthenogenetic lizard species Darevskia dahli. The analysis was carried at the two (GATA) _n -containing loci (Du215 and Du281) using the sample of 26 individuals. A total of eight Du215 and three Du281 allelic variants were detected. It was demonstrated that all the lizards examined were heterozygous at these loci. In 12 animals, unusual Du215 allelic variant was revealed, the origin of which was thought to be associated with different types of genomic rearrangements, or segmental duplication. The populations studied were substantially different relative to the levels of allelic polymorphism, which could be explained by different habitation conditions, leading to accumulation of mutations in noncoding genome regions.     

Molecular nature of allelic polymorphism of highly variable microsatellite locus Du161(arm) in unisexual lizard Darevskia armeniaca (Lacertidae)

In the genome of unisexual (parthenogenetic) lizard Darevskia armeniaca, highly variable locus Du 161 (arm) was discovered. Analysis of allelic polymorphism was carried out using locus-specific PCR of the lizard DNA specimens from 13 isolated Armenian populations (N = 138). In the sample examined, a total of 12 Du 161(arm) alleles were identified, and their differences at the level of primary DNA structure were determined. Sequence analysis of the Du 161 (arm) alleles showed that their microsatellite clusters contained repeats of one type (GATA repeats). Allelic Du 161 (arm) variants differed in the number of GATA monomers in microsatellite, point mutations of transition and transversion types, located at fixed distances from microsatellite cluster, and by single nucleotide insertions, as well as by longer insertions located within and outside of the microsatellite cluster. Moreover, point mutations formed different combinations (haplotypes), typical of certain alleles. These combinations can be used for the analysis of the origin and inheritance of these alleles in D. armeniaca, as well as for investigation of their interspecific variation in the representatives of the genus Darevskia.     

Analysis of genetic variation in unisexual and bisexual lizard species of the genus Leiolepis from Southeast Asia

Using multilocus DNA fingerprinting with microsatellite probes (CAC)₅, (GACA)₄, (GGCA)₄, and (GATA)₄, intraspecific variation of the Southeast Asian lizards belonging to the genus Leiolepis (bisexual species Leiolepis reevesii and triploid parthenogenetic species Leiolepis guentherpetersi) was first examined. The L. guentherpetersi lizards were characterized by monophyletic DNA fingerprint profiles for the loci detected by the (GACA)₄, (GGCA)₄, and (CAC)₅ probes, in terms of intrapopulation similarity index constituting S = 0.96. This was different from the individual-specific profiles of the lizards from bisexual, presumably parental species, L. reevesii (S = 0.6; P < 0.001). Genetic homogeneity of triploid L. guentherpetersi lizards at the loci examined serves as one of the arguments for the parthenogenetic nature of this species. Genetic variability of triploid parthenogenetic species L. guentherpetersi appeared to be comparable with that reported earlier for the Caucasian rock lizards of the genus Darevskia, namely, D. dahli, D. armeniaca, and D. unisexualis (P > 0.05). The results of DNA fingerprinting analysis of the same L. guentherpetersi samples with the (GATA)₄ hybridization probe were unexpected. Variability of parthenogenetic species L. guentherpetersi at the (GATA)_n markers was remarkably higher than that at other DNA markers (S = 0.35; P = 3.08 × 10^?11), being comparable to the variation of the (GATA)_n DNA markers in bisexual species L. reevesii (P = 0.74). The reasons for high polymorphism of the (GATA)_n-containing loci in L. guentherpetersi still remain unclear. This polymorhism is probably associated with high instability of the loci, which can be revealed by means of family analysis of parthenogenetic offspring.     

Genetic variation and de novo mutations in the parthenogenetic Caucasian rock lizard Darevskia unisexualis

Unisexual all-female lizards of the genus Darevskia that are well adapted to various habitats are known to reproduce normally by true parthenogenesis. Although they consist of unisexual lineages and lack effective genetic recombination, they are characterized by some level of genetic polymorphism. To reveal the mutational contribution to overall genetic variability, the most straightforward and conclusive way is the direct detection of mutation events in pedigree genotyping. Earlier we selected from genomic library of D. unisexualis two polymorphic microsatellite containing loci Du281 and Du215. In this study, these two loci were analyzed to detect possible de novo mutations in 168 parthenogenetic offspring of 49 D. unisexualis mothers and in 147 offspring of 50 D. armeniaca mothers. No mutant alleles were detected in D. armeniaca offspring at both loci, and in D. unisexualis offspring at the Du215 locus. There were a total of seven mutational events in the germ lines of four of the 49 D. unisexualis mothers at the Du281 locus, yielding the mutation rate of 0.1428 events per germ line tissue. Sequencing of the mutant alleles has shown that most mutations occur via deletion or insertion of single microsatellite repeat being identical in all offspring of the family. This indicates that such mutations emerge at the early stages of embryogenesis. In this study we characterized single highly unstable (GATA)(n) containing locus in parthenogenetic lizard species D. unisexualis. Besides, we characterized various types of mutant alleles of this locus found in the D. unisexualis offspring of the first generation. Our data has shown that microsatellite mutations at highly unstable loci can make a significant contribution to population variability of parthenogenetic lizards.     

Analysis of genetic variation in unisexual and bisexual lizard species of the genus Leiolepis from Southeast Asia

Using multilocus DNA fingerprinting with microsatellite probes (CAC)5, (GACA)4, (GGCA)4 and (GATA)4, intraspecific variation of the Southeast Asian lizards belonging to the genus Leiolepis (bisexual species Leiolepis reevesii and triploid parthenogenetic species Leiolepis guentherpetersi) was first examined. The L. guentherpetersi lizards were characterized by monophyletic DNA fingerprint profiles for the loci detected by the (GACA)4, (GGCA)4, and (CAC)5 probes, in terms of intrapopulation similarity index constituting S = 0.96. This was different from the individual-specific profiles of the lizards from bisexual, presumably parental species, L. reevesii (S = 0.6; P < 0.001). Genetic homogeneity of triploid L. guentherpetersi lizards at the loci examined serves as one of the arguments for the parthenogenetic nature of this species. Genetic variability of triploid parthenogenetic species L. guentherpetersi appeared to be comparable with that reported earlier for the Caucasian rock lizards of the genus Darevskia, namely, D. dahlia, D. armeniaca, and D. unisexualis (P > 0.05). The results of DNA fingerprinting analysis of the same L. guentherpetersi samples with the (GATA)4 hybridization probe were unexpected. Variability of parthenogenetic species L. guentherpetersi at the (GATA)n markers was remarkably higher than that at other DNA markers (S = 0.35; P = 3.08 x 10(-11)), being comparable to the variation of the (GATA)n DNA markers in bisexual species L. reevesii (P = 0.74). The reasons for high polymorphism of the (GATA)n-containing loci in L. guentherpetersi still remain unclear. This polymorhism is probably associated with high instability of the loci, which can be revealed by means of family analysis of parthenogenetic offspring.     

Revealing of allelic polymorphism in the populations of parthenogenetic lizards Darevskia dahli (Lacertidae) using locus-specific PCR

Locus-specific PCR was used to study the genetic polymorphism in three populations of parthenogenetic lizard species Darevskia dahli. The analysis was carried at the two (GATA)n-containing loci (Du215 and Du281) using the sample of 26 individuals. A total of eight Du215 and three Du281 allelic variants were detected. It was demonstrated that all the lizards examined were heterozygous at these loci. In 12 animals, unusual Du215 allelic variant was revealed, the origin of which was thought to be associated with different types of genomic rearrangements, or segmental duplication. The populations studied were substantially different relative to the levels of allelic polymorphism, which could be explained by different habitation conditions, leading to accumulation of mutations in noncoding genome regions.     

Does reproductive mode affect sexually-selected coloration? Evaluating UV-blue spots in parthenogenetic and bisexual lizards of the genus Darevskia

Sexual selection often leads to evolution of conspicuous signals, raising the chances of attracting not only potential mates, but also predators. In lacertid lizards, ultraviolet (UV)–blue spots on flanks and shoulders represent such a trait. Some level of correlation between male and female ornamentation is also known to exist. Therefore, the phenotype of females may change in the absence of sexual selection. We tested this hypothesis on a complex of parthenogenetic and bisexual lizards of the genus Darevskia. We evaluated area, counts, and chromatic properties (UV opponency, saturation) of UV–blue spots and compared the values between the clones and their bisexual progenitor species. We found a fair heterogeneity between the parthenogenetic species, but no general tendency toward higher crypsis or conspicuousness. Values of the parthenogens were not significantly different from the values of sexual females. A possible explanation is that the changes in selective forces associated with parthenogenetic reproduction are too small to affect the resulting pattern of selective pressures on the studied traits, or that the phenotypes of the parthenogens result from the unique combination of parental genomes and are conserved by clonal reproduction.     

Variation of Mini- and Microsatellite DNA Repeats in Parthenogenetic Lizard Darevskia armeniaca as Revealed by DNA Fingerprinting Analysis

Population and family samples of two morphological forms (mutant and normal with respect to dorsal color) of parthenogenetic lizard species Darevskia armeniaca were examined by means of DNA fingerprinting using M13 mini- and (GACA) _n and (TCC) _n microsatellite DNA markers. The morphological forms examined were characterized by clonally inherited, species-specific patterns of the DNA markers, which were different from the species-specific DNA fingerprints of the other parthenogenetic species of the genus Darevskia (D. dahli, D. unisexualis, and D. rostombekovi). The mean index of similarity (S) obtained for a sample of 36 individuals from three isolated populations using three types of DNA markers was 0.966. This was similar to those observed in D. dahli (0.962) (P > 0.05), but higher than that in D. unisexualis (0.950) (P < 0.05) and D. rostombekovi(0.875) (P < 0.01). Inheritance of M13 minisatellite and (TCC) _n microsatellite DNA markers in the F1 offspring of parthenogenetic lizards was examined. It was shown that variability and clonal diversity of the fingerprint phenotypes observed in the populations and families of D. armeniaca could be at least partly explained by RFLP mutations in microsatellite repeats.     

Home ranges of parthenogenetic and bisexual species in a community of Darevskia lizards (Reptilia: Lacertidae)

We analysed the home ranges of a community of Darevskia rock lizards composed of a bisexual species (D. valentini), two parthenogens (D. armeniaca and D. unisexualis), and two backcross forms between bisexual and unisexual forms. We estimated home range areas of ink-marked, GPS-located lizards using Minimum Convex Polygon (MCP) and 95% of the locations for those individuals with five or more sightings. The bisexual D. valentini was the species with the largest home ranges, distances travelled, and the most intersections. No differences between unisexual species and backcrosses were recorded for any comparison. In males, home range size and perimeter were related to morphological characteristics. Contrary to what has been described in allopatry, unisexual species showed smaller home ranges and fewer overlaps than sympatric bisexual species. We tentatively suggest that the presence of potential bisexual partners might increase sexual competition among parthenogenetic females while differences in habitat use should also be considered.     

Nucleotide sequences of the microsatellite locus <Emphasis Type="Italic">Du215 (arm)</Emphasis> allelic variants in the parthenospecies <Emphasis Type="Italic">Darevskia armeniaca</Emphasis> (Lacertidae)

Using monolocus PCR analysis with the pairs of primers designed for the Du215 locus of Darevskia unisexualis, allelic polymorphism at the orthologous locus in the populations of the related parthenospecies D. armeniaca was investigated. It was demonstrated that Du215 (arm) locus was polymorphic and in the populations of parthenospecies D. armeniaca (n = 127) represented by at least three allelic variants, differing from each other by the size and composition of microsatellite cluster, and by single nucleotide substitutions in flanking DNA. Unlike the Du215 locus, Du215 (arm) was shown contain not only GATA, but also (GACA) repeats, which were absent in D. unisexualis. Thus, in this study, the data on the molecular nature of allelic polymorphism at one of the microsatellite loci of the parthenospecies D. armeniaca were reported.     

Variation of mini- and microsatellite DNA repeats in parthenogenetic lizard Darevskia armeniaca as revealed by DNA fingerprinting analysis

Population and family samples of two morphological forms (mutant and normal with respect to dorsal color) of pathogenetic lizard Darevskia armeniaca were examined by means of DNA fingerprinting using M13 mini- and (GATA)n and (TCC)n microsatellite DNA markers. The morphological forms examined were characterized by clonally inherited, species-specific patterns of the DNA markers, which were different from the species-specific DNA fingerprints of the other parthenogenetic species of the genus Darevskia (D. dahli. D. unisexualis, and D. rostombekovi). The mean index of similarity (S) obtained for a sample of 36 individuals from three isolated populations using three types of DNA markers was 0.966. This was similar to the variability level observed in D. dahli (0.962) (P > 0.05), but higher than that in D. unisexualis (0.950) (P < 0.05) and D. rostombekovi (0.875) (P < 0.01). Inheritance of M13 minisatellite and (TCC)n microsatellite DNA markers in the F1 offspring of parthenogenetic lizards was examined. It was shown that variability and clonal diversity of the fingerprint phenotypes observed in the populations and families of D. armeniaca could be at least partly explained by RFLP mutations in microsatellite repeats.     

Instability of (GATA)<Subscript> n</Subscript> microsatellite loci in the parthenogenetic Caucasian rock lizard<Emphasis Type="Italic"> Darevskia unisexualis</Emphasis> (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.Communicated by G. P. Georgiev