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Skeletochronological study of rock lizards hybrids Darevskia valentini × D. unisexualis, D. valentini × D. armeniaca, D. nairensis × D. unisexualis, and their parental species, collected from three mixed populations (near village of Kuchak, Lchashen, Lchap — mountainous regions of central Armenia) proved their similar pattern of growth. However, the hybrids are characterized by faster rate of growth and predominantly bigger size of body in each age group contrary to their parental species. The longevity of studied hybrids is same as in parental species and reaches 6 – 7 years.

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Age determination based on counting the annual layers in the femur was performed for three parthenogenetic species of Armenian rock lizards, Lacerta armeniaca (n = 147), L. unisexualis (n = 68), and L. dahli (n = 18), and for two bisexual species, L. nairensis (n = 29) and L. raddei (n = 32). Comparison of parthenogenetic and bisexual species shows that the growth rate, sexual maturity age, and life longevity in rock lizards are independent of the type of reproduction. The examined Lacerta species reach maturity by the second or third year of life. The maximum age of individuals in the samples studied is 7 and 5 years for L. armeniaca and L. nairensis, respectively, and 6 years for L. unisexualis, L. dahli, and L. raddei.

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The age of the parthenogenetic species, Lacerta armeniaca (N = 147), L. unisexualis (N = 68), and L. dahli (N = 18), and that in the bisexual species, L. nairensis (N = 29) and L. raddei (N = 32), were determined from femur bone layers. Parthenogenesis does not influence the growth rate, age of sexual maturation and longevity of rock lizards. The species of lizards under study reach sexual maturity during the second or third year of life. The maximum age of individuals in the samples studied was 7 years for L. armeniaca, 6 years for L. unisexualis, L. dahli, L. raddei, and 5 years for L. nairensis.

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Ilya S. Darevsky co-described 70 taxa (three genera, 46 species, 21 subspecies) in 44 publications belonging to five orders, eight families of amphibians and reptiles during his career in herpetology. Of this number, three taxa are fossil and 57 taxa are currently considered as valid. By the regions where new taxa were discovered Southeast Asia and Western Asia (includes Caucasus and Asia Minor) dominates. The largest number of descriptions was published in the Russian Journal of Herpetology.

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The final part of a series of papers on the lizards of the Caucasus, that have been published in previous years. The paper reports on the life habits, capture and keeping in terraria of several lizards of Soviet Transcaucasia. In these respects the agamid Phrynocephalus helioscopus persi- cus and three species of the lacertid genus Eremias occuring in that area (i. e. strauchi, velox, pleskei) are discussed. Finally a !ist of all lizard species and subspecies actually known to occur in this region is given.

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In Georgia, 16 species of rock lizards of the Genus Darevskia are occuring (D. alpina, D. „armeniaca`, D. brauneri, D. caucasica, D. clarkorum, D. daghestanica, D. „dahli`, D. derjugini, D. mixta, D. nairensis, D. parvula, D. portschinskii, D. praticola, D. rudis, D. „unisexualis` and D. Valentini). Besides short presentations of the single species and hints on their distribution and habitats, also some systematic remarks are given.

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Georgia, its history and the nature are briefly described. This is supplied by a short overview of the country`s herpetological fauna, with particular attention to the especially diverse family of true lizards. At the end, brief description of our common trip to Georgia (May - Juny 2002) is given.

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Lacertca raddei and Lacerta nairensis have been recognized as two separate species based on morphology and behavior, and each has been implicated as a sexual parent of different parthenogenetic forms. However, recent mitochondrial DNA work failed to distinguish these two as separate species. We examined genetic diversity at 36 allozyme loci from six populations of L. nairensis and four populations of L. raddei. There were no fixed allelic differences between the two. Mean heterozygosity was slightly higher among populations of L. raddei than among populations of L. nairensis. A Distance Wagner phenogram showed that the northernmost population of L. raddei clustered with the L. nairensis populations; the other L. raddei populations clustered together. We suggest that L. raddei and L. nairensis may not be separate species, a finding which has important implications for determining the origins of some parthenogenetic Lacerta.

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The phenomenon of twins is very rare in lacertids. This conclusion was reached by looking at a recent instance of twins hatching from a single egg in Lacerta nairensis, an older but comparable occurrence in Algyroides fitzingeri, as well as my personal experience over many years of incubating lizard eggs. It is estimated that twins occur in 1:5000 to 1:500 eggs.

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Many regions of the former USSR still re- ceive little attention from Western visitors, herpetologists not excluded. For the Cau- casus Mountains this is all the more sur- prising since the area forms a zone where northern and Middle Eastern flora and fauna meet, and which is thus of considera- bly zoogeographical interest. Presently we find three larger states in the Caucasus: Georgia, Azerbaijan and Arme- nia. Turkey borders to the southwest, Iran to the southeast, and in the north it is the Russian federation. Various smaller parts claim independence. The Black Sea forms the natural western boundary, the Caspian Sea the eastern one. Herpetologically the Caucasus is historically well-known because of the work of Darev- sky and collaborators on the rock lizards (at the time still in the large genus Lacerta, now in Darevskia) and the discovery of the first case of parthenogenesis in vertebrates (DAREVSKY, 1967; DAREVSKII, 1978; DAREVSKY & KULIKOVA, 1961). Below we will concentrate on the results of our field trip to Georgia during the last two weeks of June 2003. Predictably, because of our common interest in the group, the lacertids will receive the most attention.

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The structure and evolution of a satellite DNA family was examined in lizards from the genus Darevskia(family Lacertidae). Comparison of tandem units of repeated DNA (satDNA), CLsat, in all species from the genus Darevskiahas shown that their variability is largely explained by single-nucleotide substitutions, which form about 50 diagnostic positions underlying classification of the family into three subfamilies. Maximum differences between the subfamilies reached 25%. At this level of tandem unit divergence in the subfamilies, no cross-hybridization between them was observed (at 65°C). The individual variability within one subfamily within the species was on average 5% while the variability between species consensuses within a subfamily was 10%. The presence of highly conserved regions in all monomers and some features of their organization show that satellites of all Darevskia species belong to one satDNA family. The organization of unit sequences of satellites CLsat and Agi160 also detected by us in another lizard genus, Lacerta s. str. was compared. Similarity that was found between these satellites suggests their relatedness and common origin. A possible pathway of evolution of these two satDNA families is proposed. The distribution and content of CLsat repeat subfamilies in all species of the genus was examined by Southern hybridization. Seven species had mainly CLsatI (83 to 96%); three species, approximately equal amounts of CLsatI and CLsatIII (the admixture of CLsatII was 2–5%); and five species, a combination of all three subfamilies in highly varying proportions. Based on these results as well as on zoogeographic views on the taxonomy and phylogeny of the Darevskia species, hypotheses on the evolution of molecular-genetic relationships within this genus are advanced.

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The genetic relatedness of several bisexual and of four unisexual Lacerta saxicola complexlizards was studied, using monomer sequences of the complex-specific CLsat tandem repeats and anonymous RAPD markers. Genomes of parthenospecies were shown to include different satellite monomers. The structure of each such monomer is specific for a certain pair of bisexual species. This fact might be interpreted in favor of co-dominant inheritance of these markers in bisexual species hybridogenesis. This idea is supported by the results obtained with RAPD markers; i.e., unisexual species genomes include only the loci characteristic of certain bisexual species. At the same time, in neither case parthenospecies possess specific, autoapomorphic loci that were not present in this or that bisexual species.

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1. Sexual dimorphism and geographical variability in signs of external morphology are revealed in the species of the studied complexes of rock lizards. The most important for their diagnosis are the features of folidosis of the head. Interspecific and intraspecific differences in morphometric features, color and pattern of the body were detected. 2. In the phylogenetic analysis, the Darevskia (caucasica) samples were divided into the group of the northern slope of the Central Caucasus (D. caucasica), the East Caucasus (D. daghestanica), the Western Caucasus (D. alpina), the northern slope of the Central and Western Caucasus (D. alpina ). Reliable identification and significant genetic differences of D. caucasica and D. daghestanica samples favor their attribution to different species. Within D. alpina two groups with high genetic differences (distances) were identified. Inside Darevskia (saxicola) two lines are described, one of which is connected with the Crimea and the Western Caucasus (D. lindholmi-D. Brauneri), and the second - with the North and West Caucasus (D. saxicola-D. Szczerbaki). 3. As a result of the nomenclatural revision, the lectotype Lacerta praticola pontica, L. saxicola brauneri, L. saxicola daghestanica, L. saxicola lindholmi, and the neotype L. saxicola; Specific locations, years and authors of the description of a number of taxa have been refined. 4. It has been established that the studied supernumerary complexes include the following valid taxa: Darevskia (praticola) - D. pontica pontica, D. pontica hungarica, D. praticola praticola, D. praticola hyrcanica, D. praticola loriensis; Darevskia (caucasica) - D. alpina, D. caucasica caucasica, D. caucasica vedenica, D. daghestanica; Darevskia (saxicola) - D. brauneri brauneri, D. brauneri myusserica, D. saxicola, D. szczerbaki, D. lindholmi. Lacerta saxicola darevskii is regarded as a minor synonym for Lacerta saxicola brauneri. 5. For the first time accurate inventories of findings (1,443 locations) and GIS maps of species arealways were compiled, reliably characterizing the features of their distribution; The structure of areals, the current trends of their changes and the factors influencing the distribution of rock lizards are revealed. It is recommended to carry out conservation measures of international and national level in order to preserve the populations of D. alpina, D. brauneri myusserica and D. szczerbaki, especially in typical territories. 6. The first and only reliable paleontological find of Darevskia sp. - Darevskia sf. brauneri from the Pleistocene site, the caves of Mezmaiskaya. A hypothesis is proposed for the formation of species of complexes, according to which the isolation of their common ancestor from a hypothetical form it is logical to associate with the Miocene and Pliocene boundaries, or with the Cimmerian century of the Pliocene, 153 and the radiation of modern species - with the Akchagylian age, corresponding to the Piacenza and Gelazian tiers. The parallel formation of several Darevskia (praticola) and Darevskia (caucasica) lines around the Greater Caucasus is assumed in the early Pliocene. At the end of the Pontian age, the primary area of ​​the ancestor of the modern forms of Darevskia (saxicola) and the subsequent formation in the Mediterranean landscapes of the Black Sea coast, along the surviving cliff, D. szczerbaki, and the cuestas of the North Caucasus - D. saxicola, could have occurred at the periphery of the Caucasian peninsula.

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Due to its geographic location, the Caucasus region connects species from three diferent continents in a heterogeneous landscape, creating an environment prune to the development of speciation events and multiple endemisms. Among them, the lacertid genus Darevskia is a group of rock lizards radiating and diversifying in the region. Among their highly polymorphic members a number of parthenogenetic forms are present result from the hybridisation between bisexual Darevskia species. However, the origin of these forms lacks an explicit spatiotemporal context. One of the most interesting bisexual species in the group is Darevskia raddei which is responsible for the motherhood of some unisexual forms, namely D. unisexualis, D. uzzeli and D. bendimahiensis and D. sapphirina). Fruthermore, this species is considered conspeciic to D. nairensis and D. (raddei) vanensis, two forms of unclear status which link to the parthenogenetic forms need to be clariied. This, this study aims to reach a global comprehension of the three putative bisexual taxa within of the D. raddei complex (D. raddei, D. nairensis and D. (raddei) vanensis), and their phylogenetic relationships with the parthenogenetic forms they theoretically parented. A phylogenetic analysis was conducted on samples of the D. raddei complex, ranging from Turkey, Armenia, Georgia and Iran. Maximum Likelihood and Bayesian methods were applied on a combination of mitochondrial and nuclearmarkers. Namely, three mtDNA (cytochrome b, ND4 and 12s) and two nDNA (MC1R and c-mos) markers were used. Our results conirm that Darevskia raddei (sensu lato) is the proposed maternal species for at least D. unisexualis, D. uzzeli, D. bendimahiensis, D. sapphirina and D. rostombekowi, as already supported by previous studies. However, it does not support a genetic diferentiation between the three forms described within the complex, which are to be considered conspeciic. Moreover, there is reinforced evidence that the three parthenogenetic forms considered arose more than once in the history of the genus, from diferent lineages of the bisexual parents.

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Darevskia rock lizards include both sexual and parthenogenetic species, mostly distributed in the heterogeneous and ecologically diverse Caucasus. The parthenogenetic species originated via directional hybridogenesis, with only some of the sexual species known to serve as parentals. However, it remains unclear when and where these events happened and how many parental lineages were involved. A multilocus phylogeographic analysis was performed on the parthenogens D. unisexualis, D. bendimahiensis and D. uzzeli, and their putative maternal species D. raddei. Results show the parthenogenetic species all have relatively recent origins, approximately 200–70 kyr ago, and at least three hybridization events were involved in their formation. Ecological niche models identify the region where hybridization events leading to the formation of D. unisexualis took place, namely in the northeast of the current distribution. Models also suggest that the sexual D. raddei might have undergone a habitat shift between the Last Interglacial and the Last Glacial Maximum.

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The genetic diversity of 34 loci was surveyed from among five populations of the supposed conspecific taxa Lacerta c. caucasica, L. c. alpina, and L. c. daghestanica. Twelve loci exhibited variation. Fixed or nearly fixed allelic differences between L. c. caucasica and L. c. daghestanica were found at two loci, mannose-6-phosphate isomerase-A and creatine kinase-C. These two taxa differed from L. c. alpina at eight loci. Nei`s (1978) genetic distance values among populations of L. c. daghestanica ranged from 0.000 - 0.029, between L. c. caucasica and L. c. daghestanica from 0.076 - 0.087 and between L. c. alpina and the other taxa from 0.472 - 0.501. Fixed allelic differences and consistent morphological character states support the recognition of these three taxa as separate species. Therefore, we recommend use of the names L. alpina, L. caucasica, and L. daghestanica for these taxa.

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A maximum parsimony phylogeny of 14 Caucasian species of rock lizards, genus Ijicerta, subgenus Archaeolacerta, was constructed from mitochondrial cytochrome b and ATPase 6 partial gene sequences. Congruence analyses were carried out between the two genes. A synthesis of the data sets reveals three well supported monophyletic groups: (1) the caucasica group including (Lacerta derjugini ((Lalpina, L. clarkorum) (L. caucasica, L. daghestanica))); (2) the rudis group including (L. parvula (L. portschinskii (L. vakntini, L. rudis))); and (3) the saxicola group including (L. mixta (L. nairensis (L. saxicola, L. raddeijj). Despite the diagnosis of three groups, the placement of L. praticola as a basal taxon is uncertain, as are the relationships among the three groups. The mitochondrial DNA sequence data suggested prior hybridization between L. mixta and L. alpina and possibly between L. saxicola and L. nairensis. Lacerta raddei was resolved as a paraphyletic species on the mtDNA tree; this may result from either hybridization or random gene sorting.

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Cloning and sequencing of the partial reverse transcriptase gene (750 bp) of the Bov-B LINE retrotransposon have been held in parthenogenetic lizards Darevskia unisexualis and its assumed parental bisexual species D. nairensis and D. valentini. It was shown that the percentage of transcriptionally active copies of this gene, which does not contain a stop codon, is almost the same in the three species and is about 75%. The intragenomic divergence level of these sequences is low and was found to be 2.6% in D. unisexualis, 1.9% in D. nairensis, and 1.6% in D. valentini. The phylogenetic analysis shows the distribution of copies of D. unisexualis in each of the two clusters of RT sequences characteristic of D. nairensis and D. valentini. This result supports the view of the hybrid origin of D. unisexualis and does not exclude intraspecific hybridization between D. nairensis and D. valentini.

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To characterize the molecular genetic diversity of the genus Darevskia, several populations were examined by the inter-SINE-PCR method, reporting the number and sizes of the spacers between individual copies of SINE-like interspersed repeats. Examination of 17 D. raddei geographical populations and several reference species revealed unequal genetic differences, measured as Nei and Li’s genetic distances (DNL), for different groups of samples. The highest homogeneity was observed for the apparently panmictic D. raddei nairensis population from the basin of the Hrazdan River: genetic differences within each of the five samples and between them were similarly low (less than 0.1). The difference between ten samples of D. raddei raddei from Armenia and Karabakh (0.2–0.3) was somewhat higher than the interindividual difference within each sample (0.1–0.2), indicating that the samples belonged to different populations. The assumption was supported by the phylogenetic tree topology and multidimensional scaling. The differences between samples from the morphological subspecies D. raddei raddei and D. raddei nairensis ranged 0.3–0.4. The difference of two D. raddei raddei samples of Talysh (Azerbaijan) from other samples of the same subspecies corresponded to the subspecific level. The genetic distances between the good species D. raddei and D. rudis was 0.6–0.7. In terms of DNL, a questionable population from northwestern Turkey (“D. tristis”) was closer to D. rudis (DNL = 0.45), probably representing its subspecies. The phylogeography of D. raddei is discussed.

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The Caucasian parthenogenetic rock lizards of the L. saxicola complex probably originated by hybridisation of some bisexual species. We verified this hypothesis using a new approach based on comparison of repetitive DNA characters, which produce species-specific patterns (named `taxonprint`). The method relies on restriction endonuclease hydrolysis of genomic DNA, with the following 32P-end labeling and polyacrylamide gel electrophoretic separation of the fragments. The parthenogenetic species L. armeniaca and L. dahli possess specific features both of putative maternal L. mixta (in some taxonprints), and of paternal L. valentini (in other ones), whereas L. portschinskii and L. rudis also could be the paternal species. Parthenoclones L. unisexualis and L. uzzelli have the specific DNA features in several taxonprints of L. raddei or L. nairensis (which cannot be discriminated by taxonprints) which are supposed to be maternal species for L. unisexualis and paternal ones for L. uzzelli. The specific features of L. valentini (or L. portschinskii) are observed in L. unisexualis; L. uzzelli has not been investigated in this respect. Parthenogenetic L. rostombekovi also possesses properties of L. raddei or L. nairensis, but we have not be able to find any features of supposed paternal L. portschinskii in this parthenogenetic species.

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Multiple band patterns of DNA repeats in the 20–500-nucleotide range can be detected by digesting genomic DNA with short—cutting restriction endonucleases, followed by end labeling of the restriction fragments and fractionation in nondenaturing polyacrylamide gels. We call such band patterns obtained from genomic DNA ‘‘taxonprints’’ (Fedorov et al. 1992). Here we show that taxonprints for the taxonomic groups studied (mammals, reptiles, fish, insects—altogether more than 50 species) have the following properties: (1) All individuals from the same species have identical taxonprints. (2) Taxonprint bands can be subdivided into those specific for a single species and those specific for groups of closely related species, genera, and even families. (3) Each restriction endonuclease produces unique band patterns; thus, five to ten restriction enzymes (about 100 bands) may be sufficient for a statistical treatment of phylogenetic relationships based on polymorphisms of restriction endinuclease sites. We demonstrate that taxonprint analysis allows one to distinguish closely related species and to establish the degree of similarity among species and among genera. These characteristics make to use this phenomenon for phylogenetic aims (Cooke 1975; Christie and Skinner 1979; Brown and Dover 1979, 1980; Elizur et al. 1982; Hembelen et al. 1982; Buckland 1983; Dandieu et al. 1984; Lima de Faria et al. 1984; Shubina and Mednikov 1986; Turner et al. 1991), but this approach has not been extensively applied. In this paper we have reexamined the problem on the basis of our own preliminary results, partly published in Russian journals, confirming the ideas about possible correlations between evolution of DNA repeats and speciation (Fedorov et al. 1992; Grechko et al. 1993; Potapov and Ryskov 1993). We have demonstrated that the modified method designated ‘‘DNA taxonprint’’ (Fedorov et al. 1992) can be effectively used for revealing species—specific genomic markers in different taxonomic groups. These taxonprint markers are found to be helpful for evaluation of the degree of species similarity between species, genera, and families. More than 50 species from different taxa were studied.

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The study of genome size variation in cells of vertebrates using the DNA flow cytometry makes it possible to precisely determine polyploid individuals, which is extremely important when studying the processes of reticulate speciation. In addition, in many groups of vertebrates, closely related species often differ in the nuclear DNA content. Therefore, the purpose of our study was to explore the variability of genome size and ploidy in populations of 29 species and subspecies of mountain lizards of the genus Darevskia, as well as their hybrids. As a result of the study, the range of variability in individuals of different ploidy (91% of diploid and 9% of triploid individuals) was established not to overlap. Among diploid species, no correlation was found between the nuclear DNA content and phylogenetic relationships, geographic coordinates, altitude, average annual temperatures and precipitation. Representatives of all studied species complexes (with the exception of D. adjarica) had approximately the same limits of variability. Two species (D. derjugini and D. saxicola) show significant intraspecific variability. Comparisons of the genome size of parthenogenetic and bisexual species generally revealed no noticeable differences between them. Studies of triploid hybrids have shown that their genome size as a whole roughly corresponds to the sum of the average size of the diploid genome of the maternal parthenogenetic species and the haploid genome of the paternal species. The variability of genome sizes within samples of triploid hybrids was on average slightly higher than in most parthenogenetic species, but some lower than in bisexual species. The paper discusses peculiarities of reticulate speciation in this group of animals.

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The Bov-B LINE retrotransposon was first discovered in Ruminantia and was long considered to be specific for this order. Later, this mobile element was described in snakes and some lizard species. Analysis of phylogenetic relationships of Bov-B LINE elements from different ruminants, snakes, and lizard species led to the suggestion on horizontal transfer of this retrotransposon from Squamata to Ruminantia. In the Squamata group, Bov-B LINE element was found in all snakes and some lizard species examined. The element was not detected in the genomes of some species of the genera Lacerta and Podarcis. In the present study, using PCR amplification and sequencing of PCR products, Bov-B LINE element was identified in the genomes of parthenogenetic and bisexual species of the genus Darevskia (Lacertidae), as well as in such species as Lacerta agilis and Zootoca vivipara, where this retrotransposon had not been not detected before.

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Restriction enzymes were used to assay variation among mitochondrial DNAs from parthenogenetic and sexual species of Lacerta. This permitted identification of the sexual species that acted as the maternal parent of the various hybrid-parthenogenetic lineages. Lacerta mixta was the maternal parent for both L. dahli and L. armeniaca, L. valentini was the maternal parent for L. uzzelli, and L. raddei was the maternal parent of L. rostombekovi. The maternal ancestry of L. unisexualis is not as clear. The sample of L. nairensis was very similar to one from a population of L. raddei and either species could be the maternal parent of L. unisexualis. The parthenogenetic species all had very low nucleotide diversity in absolute terms and in comparison to their sexual relatives. The close similarity between mtDNAs from the parthenogenetic species and their respective sexual maternal ancestor species provides strong evidence for the recent origin of the parthenogens. The low diversity of the parthenogens indicates that few females were involved in their origins; the maternal parents of L. dahli and L. armeniaca could have come from a single population. The patterns of mtDNA variation in Lacerta are very similar to those in Cnemidophorus and Heteronotia, establishing recent and geographically restricted origins as a general feature of parthenogenetic lizards.

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The phylogeny of 12 species of Caucasian rock lizards and ground lizards, genus Lacerta, subgenus Archacolacerta, was determined from allozyme data. Three additional species of Lacerta Sorlned the outgroup. Of the 35 loci resolved, 20 were phylogenetically informative. Permutation tail probabilities calculated using Hennig86 and RandomCladistics and g, statistics obtained in PAUP revealed significant pattern in the data. Our analysis resolved 12 most parsimonious trees; among which were three well-supported monophyletic groups: I) (Lacerta alpina, L. caucasica, L. daglzestanica) [the L. caucasica group]; 2) (L. mixta. L. saxicola. L. raddei-nairensis) [the L. saxicola group]; and 3) (L. parvlila, L. portschinskii (L. valentini, L. rudis)) [the L. ruciis group]. The second and third groups formed a clade. The ground lizards L. praticola and L. derj~cginwi ere resolved as ingroup members. but their placement in the globally most parsimonious trees was ambiguous. A preferred tree was chosen by alternately pruning L. praticola and L. devugini from the tree. In doing so, L. praticola was resolved as the sister taxon of the L. calccasica group; and L, derjligini was resolved as the sister taxon of the clade containing the L. snxicola and L. rrldis groups. Our results are somewhat congruent with the morphology-based phylogeny of Darevsky (1967).

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In order to decide a disputed taxonomic rank of two close forms of rock lizards of genus Darevskia we compared form “nairensis” from the city of Yerevan in the gorge of Razdan river (1006 m above sea level) and “raddei” from a vicinity of the Geghard monastery in the gorge of Azat river (1940 m) approximately at distance of 24-25 km from each other. Morphological researches have shown their similarity: “nairensis” and “raddei” significantly differ only by number of dorsal scales (P<0.01 for both sexes) and scales between the masseteric shield and the supratemporal (P<0.01 for males and P<0.001 for females), where the number of scales of “raddei” exceed that of “nairensis”. Despite the close morphological similarity, earlier was suggested that two close forms of lizards may be reproductive isolated. Our researches have shown that terms of breeding of males and females of “nairensis” were on 7-10 days earlier than “raddei”, however this may result of different climate conditions in concerning with elevation. Our parasitological observation of blood smears have shown that two forms of lizards contain different forms of blood parasites, where “nairensis” were infected mostly by parasites identified according to their morphology as specimens of genus Karyolysus, while “raddei” were mostly infected by parasites of genus Hepatazoon, which also may result of different habitats rather than species rank differences.

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Caucasian rock lizards of the genus Darevskia are unique taxa, including both bisexual and parthenogenetic species. The parthenogenetic species have originated as a result of natural hybridisation between females and males of different bisexual species. The species involved in interspecific hybridisation are called parental. However, sympatric zones (SZ) of unisexual and bisexual rock lizards of the Caucasus are still poorly studied, although they are very important for understanding the role of hybrid individuals of different origin in reticulate evolution. This paper presents the location of the SZs of parthenogenetic and their parental bisexual rock lizards of the genus Darevskia in Armenia and adjacent territories of Georgia and Nagorno-Karabakh. We summarised the locations of the SZs identified from 1957 to the present, based on our field survey data gathered in 2018-2019 and records from publications and museum collections. This dataset includes 39 SZs of three types: SZ of parental bisexual species, SZ of parental species with unisexual species and SZ of the parthenogenetic species. For each zone, species composition, geographical and altitudinal distribution are presented. New records expand our knowledge of the geographical and altitudinal distribution of SZs in these species and provide additional data for understanding the mechanisms of reticulate evolution and hybridogeneous speciation in the past, present and future.

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The hypothesis of hybridogenous origin of lacertid parthenogenetic species was verified by RAPD method with several arbitrary primers. The hypothesis appeared to be correct as both parthenogenetic lizard DNAs contain only the RAPD loci of putative parental bisexual species and practically no ones specific for parthenospecies. The most probable parentals are L. mixta and L. portschinskii for L. dahli, and some of the populations of L. raddei/nairensis complex and L. portschinskii, too, for L. rostombekovi.

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Darevskia rock lizards include 29 sexual and seven parthenogenetic species of hybrid origin distributed in the Caucasus. All seven parthenogenetic species of the genus Darevskia were formed as a result of interspecific hybridization of only four sexual species. It remains unknown what are the main advantages of interspecific hybridization along with switching on parthenogenetic reproduction in evolution of reptiles. Data on whole transcriptome sequencing of parthenogens and their parental ancestors can provide value impact in solving this problem. Here we have sequenced ovary tissue transcriptomes from unisexual parthenogenetic lizard D. unisexualis and its parental bisexual ancestors to facilitate the subsequent annotation and to obtain the collinear characteristics for comparison with other lizard species. Here we report generated RNAseq data from total mRNA of ovary tissues of D. unisexualis, D. valentini and D. raddei with 58932755, 51634041 and 62788216 reads. Obtained RNA reads were assembled by Trinity assembler and 95141, 62123, 61836 contigs were identified with N50 values of 2409, 2801 and 2827 respectively. For further analysis top Gene Ontology terms were annotated for all species and transcript number was calculated. The raw data were deposited in the NCBI SRA database (BioProject PRJNA773939). The assemblies are available in Mendeley Data and can be accessed via doi:10.17632/rtd8cx7zc3.1.

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Parasitological studies of 6 species of parthenogenetic and bisexual rock lizards of Armenia were carried out. The Helminthic and blood-parasite infections of these lizards were compared.

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Endoparasites of 10 reptiles species were studied. Two classes of helminths (Nematoda and Cestoda) were found. Extensity and intensity of infection were investigated.

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Darevskia rock lizards is a unique complex taxa, including more than thirty species, seven of which are parthenogenetic. in mixed populations of Darevskia lizards, tri- and tetraploid forms can be found. the most important issues in the theory of reticulate evolution of Darevskia lizards are the origin of parthenogenetic species and their taxonomic position. However, there is little data on how meiosis proceeds in these species. The present work reports the complex results of cytogenetics in a diploid parthenogenetic species – D. unisexualis. Here we detail the meiotic prophase I progression and the specific features оf mitotic chromosomes organization. The stages of meiosis prophase I were investigated by immunocytochemical analysis of preparations obtained from isolated primary oocytes of D. unisexualis in comparison with maternal species D. raddei nairensis. It has been shown that in D. unisexualis at the leptotene-zygotene stages the axial elements and the synaptonemal complex (SC) form typical “bouquets”. At the pachytene-diplotene stage, 18 autosomal SC-bivalents and thickened asynapted sex Z and w univalents were observed. The presence of SYCP1 protein between the lateral elements of autosomal chromosomes proved the formation of assembled Scs. comparative genomic hybridization (cGH) on the mitotic metaphase chromosomes of D. unisexualis was carried out using the genomic DnA isolated from the parental species D. raddei nairensis and D. valentini. in the pericentromeric regions of half of the mitotic chromosomes of D. unisexualis, specific regions inherited from maternal species have been found. Following our results, we suggest a model for diploid germ cells formation from diploid oocytes without premeiotic duplication of chromosomes in the oogenesis of diploid parthenogenetic lizards D. unisexualis. Taken as a whole, our findings confirm the hybrid nature of D. unisexualis and shed light on heterozygosity and automixis in diploid parthenogenetic forms.

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Background: The majority of parthenogenetic vertebrates derive from hybridization between sexually reproducing species, but the exact number of hybridization events ancestral to currently extant clonal lineages is difficult to determine. Usually, we do not know whether the parental species are able to contribute their genes to the parthenogenetic vertebrate lineages after the initial hybridization. In this paper, we address the hypothesis, whether some genotypes of seven phenotypically distinct parthenogenetic rock lizards (genus Darevskia) could have resulted from back-crosses of parthenogens with their presumed parental species. We also tried to identify, as precise as possible, the ancestral populations of all seven parthenogens. Results: We analysed partial mtDNA sequences and microsatellite genotypes of all seven parthenogens and their presumed ansectral species, sampled across the entire geographic range of parthenogenesis in this group. Our results confirm the previous designation of the parental species, but further specify the maternal populations that are likely ancestral to different parthenogenetic lineages. Contrary to the expectation of independent hybrid origins of the unisexual taxa, we found that genotypes at multiple loci were shared frequently between different parthenogenetic species. The highest proportions of shared genotypes were detected between (i) D. sapphirina and D. bendimahiensis and (ii) D. dahli and D. armeniaca, and less often between other parthenogens. In case (ii), genotypes at the remaining loci were notably distinct. Conclusions: We suggest that both observations (i-ii) can be explained by two parthenogenetic forms tracing their origin to a single initial hybridization event. In case (ii), however, occasional gene exchange between the unisexual and the parental bisexual species could have taken place after the onset of parthenogenetic reproduction. Indeed, backcrossed polyploid hybrids are relatively frequent in Darevskia, although no direct evidence of recent gene flow has been previously documented. Our results further suggest that parthenogens are losing heterozygosity as a result of allelic conversion, hence their fitness is expected to decline over time as genetic diversity declines. Backcrosses with the parental species could be a rescue mechanism which might prevent this decline, and therefore increase the persistance of unisexual forms.

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Five proteins (mannosephosphate isomerase, glucosephosphate isomerase, lactate dehydrogenase, creatine kinase, hemoglobin) were examined for six bisexual Transcaucasian taxa related to Lacerta saxicola (Lacerta valentini, L. portschinskii, L. raddei raddei, L. r. nairensis, L. mixta, L. parvula) and four unisexual taxa (Lacerta armeniaca, L. dahli, L. rostombekovi, L. unisexualis). Heterozygosity in the bisexual taxa was very limited for this sample of proteins. All individuals examined of each unisexual were heterozygous at loci specifying at least two of these proteins (L. armeniaca: mannosephosphate isomerase and creatine kinase; L. dahli, mannosephosphate isomerase and hemoglobin; L. rostombekovi, glucosephosphate isomerase, mannosephosphate isomerase and hemoglobin; L. unisexualis, glucosephosphate isomerase, mannosephosphate isomerase and creatine kinase). High levels of heterozygosity in unisexuals appears to result from the hybrid origin of the unisexuals. The exact combinations of alleles present in unisexuals would readily result from certain crosses among the bisexuals, and from no others. The first point supports the hypothesis that hybridization accounts for the observed heterozygosity, the second identifies, biochemically at least, the probable parents. On these biochemical grounds, L. armeniaca arose by hybridization of L. valentini and L. mixta; L. unisexualis from L. valentini and L. r. nairensis; L. rostombekovi from L. r. raddei and L. portschinskii; and L. dahli from L. portschinskii and L. mixta. With regard to altitudinal distribution, vegetational associations and geographic distribution, each unisexual species appears to be intermediate between its putative parental species. L. armeniaca, L. unisexualis and L. rostombekovi all live in drier situations than either parental species. L. dahli is an exception since it occupies slightly more moist habitats than L. portschinskii. Biogeographical considerations appear to place the age of L. unisexualis and L. rostombekovi at greater than 5000 years. It is possible that their occupancy of more extreme habitats than their parental species represents a relic ecology, reflecting the adaptations of the parental bisexual species when the unisexual species arose, rather than a weed habitat into which they moved to escape from competition with their parental species. The fixed heterozygosity of the unisexual species of Lacerta indicates that the restitution of somatic diploidy results either from a premeiotic endoduplication without cytokinesis, or from fusion of the female pronucleus with one of the second division meiotic products of the first polar nucleus. The first mechanism is inconsistent with the number of bivalents reported, the second is otherwise unknown in organisms in which the first polar nucleus becomes a polar body. The bisexual taxa are treated as several distinct species, four pairs of which are partly sympatric with little or no hybridization. Morphological and ecological differences between the other taxa are so great that there seems little question about specific distinctness. The degree of biochemical and morphological difference between these non-sympatric taxa is as great as that between those that do occur sympatrically without fusing. The formation of parthenogenetic species as a result of past hybridization between some pairs indicates a great selective disadvantage to these pairs of hybridizing, and is thus compelling evidence that the two members of each pair are not conspecific.

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We genotyped multiple populations of all seven parthenogenetic species of rock lizards, genus Darevskia, as well as their putative sexual parental populations, using double digest RAD sequencing genomic markers. Taking advantage of the conserved homology of the ZW/ZZ sex chromosomes among lacertid lizards, we aligned our short sequence reads to a reference Z chromosome assembly of the common wall lizard Podarcis muralis. This provided unique insight into the origin of all-female hybrid populations, which inherited their single Z chromosome exclusively from a paternal ancestor. The mapped Z-linked loci were used to construct a robust time-calibrated phylogeny. In each parent–offspring species pair, the geographically nearest population of the paternal species was identified as the most likely ancestor of the respective parthenogen, mirroring the trend observed previously on the maternal side in mitochondrial DNA. The estimated splits between the sampled paternal sexual ancestors and their daughter species occurred much earlier than suggested previously and during two narrow time periods: (1) the parthenogenetic Darevskia armeniaca, D. dahli, D. uzzelli and D. rostombekowi dated back to ~0.5 or ~0.9 Mya, depending on the calibration point used, while (2) D. bendimahiensis, D. sapphirina and D. unisexualis appear to have diverged ~1 or ~2 Mya.