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TERRA TYPICA. Vicinity of the settlement Ijevan, Armenia. DISTRIBUTION. It has a comparatively limited distribution range in the northern Armenia and adjacent regions of Azerbaijan. The recent distribution range is divided into several more or less isolated populations. One of them, now extinct, existed on the north-eastern shore of the Lake Sevan in Armenia. CONSERVATION STATUS. The number is stable.

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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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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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Background. From the genus Darevskia in the territory of Azerbaijan Republic noted 11 species (D. armeniaca, D. caucasica, D. chlorogaster, D. daghestanica, D. derjugini, D. portschinskii, D. praticola, D. raddei, D. rostombekovi, D. rudis, D. valentini). Information on the condition of rock lizards in the republic has not been updated for a long time. The aim of the work was to clarify the data on the distribution and abundance of these species in Azerbaijan.
Materials and methods. The research was carried in the Talysh Mountains (Lenkoran, Lerik and Yardimli districts of Azerbaijan in 2008–2011), in the Great Caucasus (Guba, Gusar, Gabala and Zagatala districts in 2013–2016), in the Minor Caucasus (Dashkesen, Gadabay and Tovuz districts in 2017–2018).
Results. On the basis of own data and analysis of literature sources the data on the distribution and number of rock lizards from the genus Darevskia in Azerbaijan are given. The authors note that the areas of forest lizards of the Talysh (D. chlorogaster and D. praticola hyrcanica) are being reduced and these species need legisla- tive protection. The extinct species for the territory of the Republic should be considered D. derjugini.

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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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The study of the sympatric population, located in the Ijevan region of Armenia, where the bisexual species D. raddei coexists with three partenogenetic species - D. rostombekovi, D. dahli and D. armeniaca has shown that in this population a hybridization process is taking place between the D. raddei and D. rostombekowi species. Of the captured 104 D. rostombekowi in the study area, 18 triploid hybrid males have been found. A comparative study of the smears and histological slides prepared from the testicles of 9 hybrid males has detected their possible fertility. The recorded triploid hybrid males could potentially play important role in hybrid speciation.

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Four parthenogenetic subspecies of Lacerta . saxicola Eversmann (Transcaucasia) have closely overlapping sympatric ranges. The lizards show no intermediate forms in zones of their mutual habitat. On the border - line of their ranges parthenogenetic lizards can mate with males of neighbouring bisexual forms of Lacerta saxicola, producing hybrids that always are sterile triploid (3n=57) females. Therefore, application of geographical and physiological species criteria to parthenogenetic forms allows to regard them as independent species. However, geographical .and physiofogiical criteria are based on the effect of reproductive isolation mechanisms whose realization is possible upon the occurrence of both sexes in the population. Thus, both criteria should not be unconditionally applied to parthenogenetic and agamic species consisting of females alone. However, the absence of males also plays the role of a peculiar isolation mechanism which maintains the integrity of parthenogenetic species. Due to this, parthenogenetic forms of Lacerta saxicola Eversmann which can be easily distinguished in the morphological respect should be considered as independent agamic species: Lacertra armeniaca Meh., L. dahli Dar., L. rostombekovi Dar. and L. unisexualis Dar.

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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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Hybridization is a common evolutionary process with multiple possible outcomes. In vertebrates, interspecific hybridization has repeatedly generated parthenogenetic hybrid species. However, it is unknown whether the generation of parthenogenetic hybrids is a rare outcome of frequent hybridization between sexual species within a genus or the typical outcome of rare hybridization events. Darevskia is a genus of rock lizards with both hybrid parthenogenetic and sexual species. Using capture sequencing, we estimate phylogenetic relationships and gene flow among the sexual species, to determine how introgressive hybridization relates to the origins of parthenogenetic hybrids. We find evidence for widespread hybridization with gene flow, both between recently diverged species and deep branches. Surprisingly, we find no signal of gene flow between parental species of the parthenogenetic hybrids, suggesting that the parental pairs were either reproductively or geographically isolated early in their divergence. The generation of parthenogenetic hybrids in Darevskia is, then, a rare outcome of the total occurrence of hybridization within the genus, but the typical outcome when specific species pairs hybridize. Our results question the conventional view that parthenogenetic lineages are generated by hybridization in a window of divergence. Instead,

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Considering all costs associated to sex, sexual reproduction could be expected to be rare. However, we find sexual reproduction to be pervasive in nature, and only a reduced number of taxa are completely asexual. In fact, the variety of sex reproductive systems, mating techniques and traits, reveals that the organisms’ reproduction has been an expressive target of selection and adaptation throughout evolution. Sex is selected because it facilitates adaptation in complex and changing environments (Weismann, 1889), and this has been already shown empirically in several models. However, studies and theories developed concerning the paradox of sex will not be able to clarify the current distribution and abundance of asexual lineages in nature. The understanding of rates of origin and extinction of asexual lineages, together with the putative differential evolution rates in organisms with sexual or asexual reproduction, should be considered in the main “origin of sex” question. The model used here, the genus Darevskia, is the first true parthenogenetic vertebrate described. It is a highly speciose genus, currently including 27 species, of which seven are parthenogenetic and of hybrid origin. Only a few of the sexual species contributed for the hybridization events which originated the parthenogens clonal lineages, and these were directional: the maternal species were always Darevskia raddei or D. mixta, and the paternal always D. valentini or D. portshinskii. Using a set of microsatellite and mtDNA markers, we first start to study the role of hybridization in the origin of vertebrate parthenogens, the extent of gene flow with sexual relatives and the relation between hybridization, asexuality and polyploidy, in the context of the main theories of asexual evolution proposed to date. We focus on the D. unisexualis, D. uzzelli and D. armeniaca parthenogens and polyploid backcrosses found in sympatric locations between the parthenogens and its sexual parentals. We find that only specific parental pairs are responsible for the origin of vertebrate parthenogenesis, regardless of their phylogenetic distance. Despite the recurrent hybridization presently reported in Darevskia, asexuality originated multiple times but only in a single temporal event the past. Parthenogenetic females are capable of backcrossing with sexual males, but can only produce polyploid individuals with reduced fertility that do not contribute for gene flow between parthenogens and sexuals. The sexual reproduction machinery can be lost with time in the parthenogenetic hybrids, which are most likely the result of a post-zygotic reproductive barrier to gene flow in the speciation continuum of Darevskia sexual species. In order to reconstruct the phylogenetic inference of this group, a set of capture sequence probes were designed from a transcriptome de novo assembly. Phylogenetic inference reconstruction has been extensively used to ask several evolutionary biology questions. However, despite the exponential use of high-throughput sequencing technologies and its promising applications in phylogenetics, next generation sequencing (NGS) techniques are still far from being as widely used in this field as in other areas of evolutionary genetics. The workflow developed in this thesis has proved to be not only cost-effective, but also to produce a very high number of cross genome phylogenetically informative markers in this non-model species. Finally, taking advantage of the hundreds of cross genome markers developed, a species tree was constructed and within genus relationships evaluated. Introgression tests showed a widespread pattern of gene flow across the genus, not only recent between recently diverged clades, but also both recent and ancient gene flow between early diverging Darevskia clades. Several evidences of hybridization with gene flow between diverging clades have been found in other systems. However, such widespread patterns where introgression has happened between all major clades, and in a very high number of species pairs, are not frequently found. It is also found that gene flow is completely absent between parthenogens sexual parental pairs. In groups with sexual-parthenogenetic reproducing species, pre- or post-zygotic reproductive barriers could be more difficult to attain and hybrid asexuality can, thus, effectively create reproductive barriers between diverging sexual taxa, that were likely faced with recurrent secondary contact. The work presented in this thesis shows that only a few sexual species pairs were responsible for the origin of the parthenogens, that some species acted always as the maternal species and others always as the paternal, that the phylogenetic distances between each pair are included in a wide range interval, and that introgression is found widespread across the genus but absent between the parental pairs. Regardless of the reproduction type, this study also shows the relevance and depth of hybridization during divergence. As has been shown intensively, gene flow is common during speciation and clades divergence. However, it would be interesting to analyse other groups together and test if deep branch gene flow is found only in some exclusive groups (such as sexual-asexual genera) or if it is something more widespread. This work presented here moves Darevskia towards providing a model that can be used to understand the origin of asexuality in vertebrates. Here the basis for future studies about sex and asexuality is provided, so that a focus on the differential evolution rates genomes of both reproduction mode can be analysed.

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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 life and work of the Alsatian Louis Amédée Lantz (1886-1953), a pioneer of European herpetology. A trained and professional research-chemist, the Alsatian Louis Amédée Lantz was an active and particularly dynamic herpetologist. His residence of nearly twelve years in Russia enabled him to make several field trips to regions such as the Caucasus and Iran. He always carried with him a home made telescopic net that he used to catch lizards. That net became symbolic of Lantz for most people around him. He realized significant herpetological collections mainly deposited in the Museum of the Zoology Institute of the Russian Academy of Sciences in St. Petersburg. Soon after the Russian Revolution in 1917, he had to leave the country and stayed for a few years in France before joining England. During this period, Lantz visited the French Pyrenees and the Mediterranean border (Hyeres Islands, Bandol), enabling him to discover for the first time oviparous populations of common lizard and also to describe a new species of lizard from the French Pyrenees. Lantz is also at the origin of the discovery of unisexual reproduction by parthenogenesis in reptiles. His collaboration with the Swedish amateur herpetologist Otto Cyrén, whom he met through the German herpetologist Willy Wolterstorff, was particularly successful throughout his career. Lantz died at the age of 66 years, in Switzerland, as he was about to join the team of herpetologists at the Natural History Museum in Paris.

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The molecular structure of the allelic variants of (AAT) n of the Du47D microsatellite locus was determined in parthenogenetic lizards Darevskia dahli, D. armeniaca, and D. rostombekovi. Comparative analysis of these alleles showed that they were characterized by perfect structure of microsatellite cluster, and were different in the number of (AAT) monomeric units, as well as in the combinations of species-specific substitutions and deletions in the microsatellite flanking regions. Molecular structure of microsatellite cluster, species-specific single nucleotide polymorphism (SNP), and different representation of alleles Du47 in the samples of parthenogenetic species examined point to the origin of the alleles from different bisexual species, which is consistent with the hybrid nature of unisexual species of the genus Darevskia. In addition, these data reflect different combination patterns of interspecific hybridization events with the participation of the same bisexual species upon the formation of hybrid genomes of parthenogenetic species. Possible application of the allelic variants of microsatellite loci of parthenogenetic lizards as the genetic markers for the analysis of the genomes of parthenogenetic species in the light of evolution, ecology, and parthenogenetic type of reproduction in vertebrates is discussed.

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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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Among vertebrates, true parthenogenesis (self-perpetuating all-female species) occurs only in reptiles; these species are of hybrid origin. To date, all diploid parthenogenetic reptiles examined exhibit some genetic diversity, resulting in the existence of more than one clone. The sole exception to this is the Caucasian rock lizard Lacerta rostombekovi, which appears to consist of only a single clone.

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Rostombekov’s lizard (Darevskia rostombekovi) is one of the seven parthenogenetic, all - female, Caucasus rock lizard species of hybrid origin (parental species D. portschinskii and D. raddei). The species consists of several isolated populations of different size from northern foothills of the Caucasus Minor, Northern Armenia, adjacent regions of north - western Azerbaijan, and a remote small highly mountainous (2000 m a.s.l.) relict ( _ 12000 years) population of the southeastern coast of the Sevan Lake. As the other parthenogenetic species from the genus Darevskia, D. rostombekovi has diploid chromosome set, high fi xed heterozygosity of allozyme loci and low variation of mtDNA. The allozyme data for 35 loci of D. rostombekovi did not show variation in population of the species. Thus in contrast to D. dahli, D. armeniaca, D. unisexualis, D. rostombekovi is considered a monoclonal species. Multilocus DNA fi ngerprinting was used to analyze genetic variation in samples of 21 animals from three isolated populations of North Armenia and in a sample of 5 animals from relict population of the Sevan Lake. The mean intrapopulation similarity index (S) was 0.995; 0.946; 0.951 and 0.946 for each of the four populations examined respectively (p _ 0.05). However intraspecifi c similarity index, calculated using a sample of 26 animals (3 populations of the North Armenia and population of southern coast of the Sevan Lake) was equal to 0.815. Comparative interpopulation analysis of S values indicated that relict population of the coast of the Sevan Lake is different from other populations of North Armenia (S = 0.536; p _ 0.001). Taking into account that D. rostombekovi is considered monoclonal on the basis of allozyme data, the problem of clonal variation is discussed with regard to the evidence on nuclear DNA markers. It is suggested that hybrid unstable karyotype of D. rostombekovi generates a series of chromosomal mutations which may lead to the appearance of a geographically isolated chromosome race (clone) in the population inhabiting the southern coast of the Sevan Lake.

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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.

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Variation and clonal diversity in populations of the parthenogenetic rock lizard Darevskia rostombekovi was examined by means of multilocus DNA fingerprinting using mini- and microsatellite DNA markers M13, (GATA)4, and (TCC)50). The animals examined were shown to exhibit a clonally inherited, species-specific pattern of DNA markers (fingerprint profile) that is different from the species-specific patterns of parthenogenetic species D. dahli, D. armenica, and D. unisexualis. The mean intraspecific similarity indexS was 0.950 (0.003) for a sample of 19 animals from three isolated populations of North Armenia. This significantly differed from the estimate of this parameter for a sample of 21 animals including two individuals from mountainous, relict population from the vicinity of the Sevan Lake, which was equal to 0.875 (0.001). A comparison of DNA fingerprints showed differences between 21 individuals attaining 79 DNA fragments of 1801 mini- and microsatellite markers included in the analysis. The results obtained show that intraspecific variation in D. rostombekovi is higher than that in the previously studied parthenogenetic species D. dahli (S = 0.962) andD. unisexualis (S= 0.950) (P< 0.001). Taking into account that D. rostombekovi is considered monoclonal on the basis of allozyme data, the problem of clonal variability is discussed with regard to the evidence on nuclear DNA markers. It is suggested that the hybrid karyotype of D. rostombekovi, which is more unstable than that of D. dahli and D. unisexualis, generates a series of chromosomal rearrangements (mutations). This may lead to the appearance of a geographically isolated chromosomal race (clone) in the population inhabiting the southeastern coast of the Sevan Lake.

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Aim Body size is instrumental in influencing animal physiology, morphology, ecology and evolution, as well as extinction risk. I examine several hypotheses regarding the influence of body size on lizard evolution and extinction risk, assessing whether body size influences, or is influenced by, species richness, herbivory, island dwelling and extinction risk. Location World-wide. Methods I used literature data and measurements of museum and live specimens to estimate lizard body size distributions. Results I obtained body size data for 99% of the world`s lizard species. The body size–frequency distribution is highly modal and right skewed and similar distributions characterize most lizard families and lizard assemblages across biogeographical realms. There is a strong negative correlation between mean body size within families and species richness. Herbivorous lizards are larger than omnivorous and carnivorous ones, and aquatic lizards are larger than non-aquatic species. Diurnal activity is associated with small body size. Insular lizards tend towards both extremes of the size spectrum. Extinction risk increases with body size of species for which risk has been assessed. Main conclusions Small size seems to promote fast diversification of disparate body plans. The absence of mammalian predators allows insular lizards to attain larger body sizes by means of release from predation and allows them to evolve into the top predator niche. Island living also promotes a high frequency of herbivory, which is also associated with large size. Aquatic and nocturnal lizards probably evolve large size because of thermal constraints. The association between large size and high extinction risk, however, probably reflects a bias in the species in which risk has been studied.

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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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Assessment of genetic diversity of unisexual (parthenogenetic) species of vertebrates is among the major objectives of research in these species. Various nuclear or mitochondrial genome markers can be used for such an assessment. Microsatellite DNAs are among the most efficient genetic markers, since the mutation rate in these fragments is high. Identification and characterization of such markers are the basic stages of genetic research in parthenogenetic species. Allelic polymorphism of three microsatellite loci in populations of the parthenogenetic species Darevskia rostombekovi (n = 42) and bisexual parent species D. raddei (n = 6) and D. portschinskii (n = 6) has been assessed by locus-specific PCR for the first time. All representatives of the parthenogenetic species D. rostombekovi used in the present study turned out to be heterozygous. The number of alleles of the different loci ranged from two to five in the populations investigated. The nucleotide sequence of the allelic variants of the loci investigated has been determined. The differences between the alleles were apparently related to variation in the structure of microsatellite clusters and single-nucleotide substitutions in DNA fragments located in the vicinity of the clusters at fixed distances from the latter. Structural variants of the alleles formed allele-specific haplotype markers that were inherited from the bisexual parent species. The origin (inheritance from the maternal or paternal species) has been determined for each allele of the parthenogenetic species. The distribution, frequency of occurrence, and pattern of combination of the alleles of microsatellite loci in D. rostombekovi populations have been characterized; these features determined the identity of each population. The data obtained can be used for assessment of the clonal diversity of the parthenogenetic species D. rostombekovi and the identification of a possible scenario of the emergence of the diversity in the populations.

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The all-female Caucasian rock lizard Darevskia rostombekowi and other parthenogenetic species of this genus reproduce normally via true parthenogenesis. Typically, diploid parthenogenetic reptiles exhibit some amount of clonal diversity. However, allozyme data from D. rostombekowi have suggested that this species consists of a single clone. In the present study, we evaluate variation at three microsatellite loci in 42 specimens of D. rostombekowi from four populations from Armenia. The analyses reveal multiclonal genetic structure in this species. All individuals are heterozygous at the loci and they yield five genotypes. The major clone occurs in 24 individuals and involves three populations. Four rare clones involve one or several individuals from one or two populations.

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In this work, we tested the conditions for fulfilling the concept of geographic parthe- nogenesis by a comparative analysis of the breadth of the ecological niches of parental and par- thenogenetic lizards of the genus Darevskia with a various number of established hybridization events. Estimates of the breadth of ecological niches of the parthenogenetic species D. ros- tombekowi Nb = 0.6(±0.08) and parental bisexual species D. raddei raddei – Nb = 0.86(±0.9), D. portschinskii – Nb = 1.21(±0.17) showed that for this parthenogenetic species one of the most important conditions of geographic parthenogenesis is fulfilled, i.e. the niche breadth of the parthenogenetic species is smaller than its parental bisexual species. The niche breadth of another parthenogenetic species D. dahli Nb = 0.86(±0.12) is smaller than that of the «paternal» species D. portschinskii – Nb = 1.21(±0.17), but larger than that of the «maternal» species D. mixta Nb = 0.48 (±0.08), which only partially agrees with the condition of geographic par- thenogenesis. This mismatch is due to the fact that D. dahli was formed as a result of several independent hybridization events, which resulted in the formation of multiple clonal lines de- rived from different parental pairs of D. portschinskii and D. mixta.

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The results of the analysis of the genetic variability of parthenogenetic Darevskia rostombekowi (Darevsky, 1957) species using four microsatellite-containing loci are presented. Based on 118 records with geographical coordinates of the presence of this species in Transcaucasia, the maps of potential range were created. The analysis of the genetic structure of populations demonstrated that despite the established multiclonality (seven clonal lines in four populations), D. rostombekowi was formed as a result of a single act of hybridization between closely related bisexual species. The predicted distribution of D. rostombekowi using the modelling of potential range revealed new suitable habitats, where the presence of the species has not been reported previously. The results of this study and the absence of multiple acts of hybridization during the formation of these clones may indicate a regression of population size of the species. Consequently, the estimation of the conservation status of this parthenogenetic species seems to be justified.

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We presented data on reproductive traits of the rare parthenogenetic species Darevskia rostombekowi from the surroundings of the city in Dilijan and on the southern shore of the lake Sevan. Comparison of two populations showed that the length of the body of adult lizards from the Sevan population was significantly higher (p <0.01) than from the Dilijan population (51.75 ± 0.75). Lizards of the two populations do not differ in the number of eggs, they laid eggs in the laboratory in the 20-26 June, 2017, and hatching takes place in the period 08 -10 August 2017, the development of eggs was 45-47 days. Newbornlizardshadabodylengthof 26-27 mm.

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The parthenogenetic species Darevskia rostombekowi is listed in the Red Book of Armenia and the IUCN Red List as ‘Endangered’. Among the noted threats to this species is competition with syntopic species. Therefore, our main goal was to compare the coexistence patterns among syntopic species. Census was conducted along five different transects (about 1 km long each) during May – September 2015, in two isolated populations. The numbers of counted parthenogenetic lizards of D. rostombekowi (40-46%, 23 individuals/ha) and D. unisexualis (60-54%, 35 individuals/ha) were not different between among (P= 0.87) in Sevan Lake population, but differed (P< 0.001) among the three parthenogenetic species [D. rostombekowi (30-34%, 6 individuals/ha), D. dahli (60-54%, 11 individuals/ha), and D. armeniaca (10-12%, 2 individuals/ha)] in the area of coexistence, in the vicinity of Dilijan city. Population density of D. rostombekowi from Sevan Lake was significantly higher (t-value = 6.50, P< 0.0001) than that in the Dilijan population. Herein, we analyze the temporal and spatial niches of lizards living synoptically to assess the degree of niche differentiation among them. No differences in vegetation density in the microhabitats used by syntopic species have been revealed for both populations. The comparison of daily activities have shown similar bimodal patterns for D. rostombekowi and D. dahli in Dilijan populations while in Sevan D. unisexualis shows a bimodal pattern of daily activity while D. rostombekowi a unimodal one. Moreover, it was noted that D. unisexualis appeared on the surface before D. rostombekowi in the morning and remained active longer. However, the number of D. rostombekowi individuals in May, just after hibernation, and in September, before hibernation, was higher than D. unisexualis. The lower density of D. rostombekowi in Dilijan population may have allowed synchronous activity cycles due to the lack of competition between species, in contrast to Sevan Lake populations.

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The daily activities of two isolated populations of endangered species of rock lizards Darevkia rostombekowi were studied. The main aim of our study was the show the competition among syntopic species of rock lizards. Our results have shown the similarity of patterns of daily activities for lizards belonging to different species and sharing the same territories and differences in peak of their activities, which allow them to avoid the competition.

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An integrated approach for constructing maps of suitable habitats and ecological niches of parthenogenetic and their parental species of the genus Darevskiain the Caucasus is presented. It is shown that this approach is a powerful tool for analyzing species-specific requirements of lizards for the habitat and differentiating their niches in the multidimensional space of predictor variables.

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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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The all-female Caucasian rock lizard Darevskia rostombekowi and other unisexual species of this genus reproduce normally via true parthenogenesis. Typically, diploid parthenogenetic reptiles exhibit some amount of clonal diversity. However, allozyme data from D. rostombekowi have suggested that this species consists of a single clone. Herein, we test this hypothesis by evaluating variation at three variable microsatellite loci for 42 specimens of D. rostombekowi from four populations in Armenia. Analyses based on single nucleotide polymorphisms of each locus reveal five genotypes or presumptive clones in this species. All individuals are heterozygous at the loci. The major clone occurs in 24 individuals and involves three populations. Four rare clones involve one or several individuals from one or two populations. Most variation owes to parent-specific single nucleotide polymorphisms, which occur as heterozygotes. This result fails to reject the hypothesis of a single hybridization founder event that resulted in the initial formation of one major clone. The other clones appear to have originated via post-formation microsatellite mutations of the major clone.

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Darevskia rostombekowi, the most outstanding of the seven known parthenogenetic species in the genus Darevskia, is the result of an ancestral cross between two bisexual species Darevskia raddei and Darevskia portschinskii. The chromosomal set of this species includes a unique submetacentric autosomal chromosome; the origin of this chromosome was unresolved as only acrocentric chromosomes are described in the karyotypes of Darevskia genus normally. Here, we applied a suite of molecular cytogenetic techniques, including the mapping of telomeric (TTAGGG) n repeats using fluorescence in situ hybridization (FISH), comparative genomic hybridization (CGH), and whole-chromosome painting (WCP) in both D. rostombekowi and parental (D. portschinskii and D. raddei) species. The obtained results in total suggest that a de novo chromosomal rearrangement via Robertsonian translocation (centric fusion) between two maternal (D. raddei) acrocentric chromosomes of different size was involved in the formation of this unique submetacentric chromosome present in the parthenogenetic species D. rostombekowi. Our findings provide new data in specific and rapid evolutional processes of a unisexual reptile species karyotype.

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Elements of the herpetofauna are in the author`s opinion of great importance for the zoogeographical division of the Palaearctic region. It is suggested that this region be divided into the following four subregions: 1/ arctic, 2/ boreal Euro-Siberian, 3/ bo- real Himalayan-Manchurian and 4/ Mediterranean-Central-Asiatic.

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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.