Biomedical subjects

A P Ryskov

Publications and source records attributed to A P Ryskov.

At least 19 recordsLinked to original sources

PubMed2006

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

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

Animals↗

PubMed2006

[Finding of Bov-B LINE retroelement in parthenogenetic and bisexual lizard species of the genus Darevskia (Lacertidae)].

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.

Animals↗

PubMed2006

[Genetic diversity and differentiation of Russian common carp (Cyprinus carpio L.) breeds inferred from RAPD markers].

Polymorphic components of the common carp Cyprinus carpio L. genome were examined by means of polymerase chain reaction with random primers (RAPD-PCR). Using four primers, genetic diversity estimates were obtained for 12 populations and seven strains of Russian common carp breeds, as well as for European Hungarian common carp and Amur wild common carp (N = 87). The highest number of polymorphic loci was revealed in Angelinskii common carp, as well as in the samples of Altai common carp and Amur wild common carp (P = 23.8-18.7%), while the lowest number of polymorphic loci was in the BB strain of Ropsha common carp. The index of genetic diversity, H, was high (11%) in Amur wild common carp, as well as in Altai and Angelinskii common carps. In the remaining breeds, the value of this index varied from 4 to 8%. Based on summarized RAPD profile (132 bands), a dendrogram of genetic differences was constructed. In this dendrogram, all breeds examined grouped into two clusters. One of the clusters was formed by Hungarian and Angelinskii common carps, and the three samples of Altai common carp. The second cluster was formed by the group consisting of the representatives of Cherepetskskii, Stavropol, and Ropsha common carps, along with the differing from them Amur wild common carp. The observed differentiation was confirmed by the analysis of the polymorphic markers variance by the method of principle components. Evolutionary history and the reasons for genetic differentiation of Russian common carp breeds are discussed.

Animals↗

PubMed2005

[Individual and population variation in cercariae of bird schistosomes of the Trichobilharzia ocellata species group as revealed with the polymerase chain reaction].

The polymerase chain reaction with arbitrary (RAPD-PCR) or specific primers was used to study the population variation and to identify the species in cercariae of schistosomes of the Trichobilharzia ocellata species group (Trematoda, Schistosomatidae). In total, 28 cercariae were obtained from two spontaneously invaded mollusks Lymnaea stagnalis (LS) and L. ovata (LO), which were collected in different water bodies of Moscow. RAPD-PCR was carried out with two arbitrary primers, OPA9 and OPB11, which each detected different levels of individual and among-group variation and revealed considerable genetic differentiation of cercariae from different host mollusks. To check whether the cercariae of the two samples belong to one species, sequencing was performed with a region corresponding to intergenic transcribed spacer 2 (ITS2), which was earlier proposed for cercaria identification in three European species of bird schistosomes of the genus Trichobilharzia (T. franki, T. regenti, and T. szidati). The ITS2 sequences of two LO cercariae were identical, each consisted of 319 bp, and showed 100% homology to the T. franki ITS2 sequence. The ITS2 sequences of two LS cercariae were identical, each consisted of 323 bp, and showed 99.4% homology to the T. szidati counterpart. The causes of genetic variation in cercariae and prospects of using RAPD markers to study different stages of the life cycle in trematodes are discussed.

Animals↗

PubMed2004

PCR-generated artificial ribosomal DNAs from premature termination at Alu sequences.

PCR-amplified product may sometimes not correlate with a DNA state in vivo due to formation of recombinant molecules. Here we show that recombinant product can form in vitro on amplifying the region upstream of the rRNA transcription start point in human ribosomal intergenic spacer. These results provide the first information concerning definite Alu sites where premature polymerase termination occurs.

Alu Elements↗

PubMed2004

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

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

Alleles↗

PubMed2004

[RAPD variation in Mediterranean turtle Testudo graeca L. (Testudinidae)].

The polymerase chain reaction with arbitrary primers (RAPD-PCR) was used to study intraspecific variation in Mediterranean turtle Testudo graeca, which is represented by the Dagestan (T. g. pallasi) and Nikolskii (T. g. nikolskii) subspecies in Russia. To study the phylogenetic relationships, the RAPD variation was also compared in two other T. graeca subspecies (T. g. ibera and T. g. terrestris), two closely related Testudo species (T. kleinmanni and T. marginata), and Central Asian turtle Agrionemys horsfieldii. Parameters of RAPD variation showed that the sample from different geographical regions of Dagestan was more polymorphic and heterogeneous than that from Central Asia. The two samples differed in the mean number of RAPD fragments N (48.761 vs. 40.400), number of polymorphic fragments P (78.7 vs. 32.3), and within-group similarity index APS (0.607 vs. 0.784). In T. g. pallasi, no significant difference in N, P, or APS was observed between samples from different localities of Dagestan or between groups of turtles with four- or five-clawed forelegs. A dendrogram of genetic similarity between the species and subspecies under study contained two clusters, one comprising all A. horsfieldii individuals and the other, all turtles of the genus Testudo. In the latter, T. marginata and T. kleinmanni showed higher similarity to each other than to T. graeca. The four T. graeca subspecies clustered separately from each other with a high reliability, T. g. nikolskii and T. g. ibera (Turkey) being more similar to each other than to T. g. terrestris or T. g. pallasi. The possible causes of the presence of four claws on a foreleg and the relationships among members of the genus Testudo were discussed.

Animals↗

PubMed2003

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

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

Animals↗

PubMed2003

[Was August Weismann right?].

A new hypothesis of the genetic regulation of cell differentiation is put forward. The hypothesis is based on the assumption that the diminution and hyper-replication patterns of repetitive nucleotide sequences depend on the differentiation pathways of cells and tissues.

Animals↗

PubMed2003

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

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

Animals↗

PubMed2003

[Assessment of population differentiation using DNA fingerprinting and modified Wright's Fst-statistics].

Using our results and literature data on multilocus DNA fingerprinting, we propose a method of obtaining unbiased estimates of the between--population genetic similarity index and a measure of population subdivision based on modified Wright's FST-statistics. On the basis of multiple comparison T2 Hotelling's test and Holmes' procedure, the FST-statistics was applied to assess differentiation of four (Pacific and Atlantic) subpopulations of humpback whale Megaptera novaeangliae, six populations of California island gray fox Urocyon littoralis, and geographically isolated Ob' and Yakutia populations of Siberian white crane Crus leucogeranus. It was shown that the regional humpback whale subpopulations do not constitute a single panmictic unit (P < 10(-4)). The subdivision index of the Pacific and Atlantic populations expressed in terms of FST-statistics varied from 0.101 to 0.157. The differentiation estimates for the island fox populations, which ranged from 0.2109 to 0.4027, indicate that subdivision of these populations is a function of the distance between the islands, island size, and population size. In particular, the smallest and the greatest differences were found respectively between the populations of the geographically closest northern islands (FST = 0.2157, FST = 0.2109) and between those of the most distant northern and southern islands (FST = 0.4027, FST = 0.3869). Subdivision of the island populations with minimum areas and low population number was intermediate (FST = 0.3789). Mean values of heterozygosity, within-population genetic similarity index, and the number of coinciding fragments for two random individuals of Siberian white crane from the Ob' and Yakutia population were not statistically significantly different (P > or = 0.852, (P > or = 0.491, (P > or = 0.325). However, pairwise comparisons of mean FST values indicated that the differentiation estimates for samples from these populations fall within the limits of population subdivision (P = 0.01). The subdivision estimate (0.108-0.133) of various groups of Siberian white cranes is comparable to interregional subdivision of humpback whale. Based on the results of this study, we recommend the approach based on modified Wright's FST-statistics for studying genetic population structure aimed at detecting population subdivision.

Animals↗

PubMed2003

[Superinstability (TCT/TCC)n of microsatellite DNA in parthenogenetic lizards Darevskia unisexualis (family Lacertidae)].

Using multilocus DNA fingerprinting, we have examined variability of (TCT)n microsatellite and M13 minisatellite DNA repeats in populations, families, and tissues of Caucasian parthenogenetic rock lizards Darevskia unisexualis (Lacertidae). It has been shown for the first time that population and family DNA samples of D. unisexualis (75 samples in total) have individually specific DNA fingerprinting patterns of (TCT)n fragments. Analysis of inheritance of (TCT)n microsatellites in 46 first-generation progeny in 17 parthenogenetic D. unisexualis families revealed their extremely high instability. Mutant TCT fingerprint phenotypes were found in virtually each animal of the progeny. Moreover, varying fragments in the progeny and their original variants in the mothers were shown to simultaneously contain (TCT)n and (TCC)n polypyrimidine clusters. At the same time, no variability of (TCT)n fragments has been detected in the tissues and organs of mature parthenogenetic lizards and in the analogous tissues of the two-week-old progeny of this year. This suggests the absence of somatic mosaicism and methylation of the corresponding loci in the samples. Along with the hyperinstability of (TCT/TCC)n polypyrimidine clusters, we have shown that the population and family DNA fingerprinting patterns of M13 minisatellites were invariable and monomorphic in the same DNA samples of D. unisexualis. Our results indicate that mutations at loci containing polypyrimidine microsatellites significantly contribute to the total genomic variability of parthenogenetic lizards D. unisexualis.

Animals↗

PubMed2003

[Quantitative evaluation of gene variation and interpopulation differentiation of parthenogenetic species of Darevskia lizards based on mini- and microsatellite DNA markers].

Methods of estimating within- and between-population gene diversity in parthenogenetic species using mini- and microsatellite DNA markers and modified Wright's FST statistic are presented with special reference to model populations of lizards of the genus Darevskia (D. dahli, D. armeniaca, D. unisexualis). We used DNA fingerprinting data for several populations of these species examined earlier. The effects of variation in M13, minisatellite, (GACA)n and (TCC)n microsatellite loci on the formation of within-population gene diversity in parthenogenetic species D. dahli and D. armeniaca were shown to be different. The equality of the realized gene diversity H and its maximum possible value Hmax in two populations of D. dahli (Hmax = 0.032, H = 0.031, P < < 0.0431; Hmax = 0.024, H = 0.027, P = 0.09) and D. armeniaca (Hmax = 0.05, H = 0.053, P = 0.03; Hmax = 0.054, H = 0.055, P = 0.02) suggests that variation in (GACA)n loci substantially contributes to the maintenance of within-population genetic diversity. Analysis of between-population genetic diversity using loci M13, (GACA)n, and (TCC)n showed differentiation of D. dahli populations from northeastern and northwestern Armenia (FST = 0.0272, P = 3 x 10(-13)) and genetic homogeneity of the Armenian and Introduced to the Ukraine populations of D. armeniaca characteristic of one clone (FST = 0, P = 1).

Animals↗

PubMed2002

[Quantitative analysis of genetic parameters in populations of European (Capreolus capreolus L.) and Siberian (Capreolus pygargus Pall.) roe deer with RAPD markers].

A technique for obtaining unbiased estimates of genetic parameters (allelic frequencies of RAPD loci, heterozygosity (H), Wright's F statistic, and Nei's genetic distances) in populations of the European (Capreolus capreolus L.) and Siberian (Capreolus pygargus Pall.) roe deer is presented. The technique employs jackknifing and multiple comparative analysis based on a modified Holmes's procedure for Bonferroni's test. It was demonstrated that samples from local groups of roe deer in the Trans-Ural region did not differ significantly in allelic frequencies (0.8, 0.81, and 0.78; P > 0.447) or Nei's genetic distances (0.0056, 0.0273, and 0.0218; P = 0.26), but they could be differentiated based on Wright's F statistic (0.0346, 0.0519, and 0.0450; P = 10(-9)). The parameters of intrapopulation heterozygosity (from 0.18 to 0.042) formed a gradient from the east to the west. Calibration estimates of molecular evolution rate in the family Cervidae obtained based on published data and Jukes-Cantor genetic distances estimated in this study demonstrated that the Siberian roe deer has split into two subspecies, C. pygargus pygargus Pall. and C. pygargus tianschanicus Satunin in the interval between 229 and 462.3 thousand years ago. The species formation of the Siberian and European roe deer was dated between 1.375 and 2.75 Myr ago. Based on the results obtained we recommend the approaches used in the study for analysis of population genetic structure and phylogenetic relationships between populations, subspecies, species, and higher taxa.

Animals↗

PubMed2002

[Variation of mini- and microsatellite DNA markers in populations of parthenogenetic rock lizard Darevskia rostombekovi].

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. armeniaca, and D. unisexualis. The mean intraspecific similarity index S 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) and D. 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.

Animals↗

PubMed2002

[Genetic analysis and estimation of genetic diversity in east-European breeds of swift hounds (Canis familiaris L.) based on the data of genomic studies using RAPD markers].

The method of polymerase chain reaction with a set of arbitrary primers (RAPD-PCR) was used to describe genetic variation and to estimate genetic diversity in East-European swift hounds, Russian Psovyi and Hortyi Borzois. For comparison, swift hounds of two West-European breeds (Whippet and Greyhound) and single dogs of other breed groups (shepherd, terriers, mastiffs, and bird dogs) were examined. For all dog groups, their closest related species, the wolf Canis lupus, was used as an outgroup. Variation of RAPD markers was studied at several hierarchic levels: intra- and interfamily (for individual families of Russian Psovyi and Hortyi Borzois), intra- and interbreed (for ten dog breeds), and interspecific (C. familiaris-C. lupus). In total, 57 dogs and 4 wolfs were studied. Using RAPD-PCR with three primers, 93 DNA fragments with a length of 150-1500 bp were detected in several Borzoi families with known filiation. These fragments were found to be inherited as dominant markers and to be applicable for estimation of genetic differences between parents and their offspring and for comparison of individuals and families with different level of inbreeding. A high level of intra- and interbreed variation was found in Russian Psovyi and Hortyi Borzois. In these dog groups, genetic similarity indices varied in a range of 72.2 to 93.4% (parents-offspring) and 68.0 to 94.5 (sibs). Based on the patterns of RAPD markers obtained using six primers, a dendrogram of genetic similarity between the wolf and different dog breeds was constructed, and indices of intragroup diversity were calculated. All studied breeds were found to fall into two clusters, swift hounds (Borzoi-like dogs) and other dogs. Russian Borzois represent a very heterogeneous group, in which the Russian Psovyi Borzoi is closer to Greyhound than the Russian Hortyi Borzoi. All studied wolfs constituted a separate cluster. Significant differences were found between the wolf and dogs by the number of RAPD markers (92.8 and 86.1, respectively) and by the indices of genetic diversity (54.3 and 64.8%, respectively). The reasons for the high intraspecific variation of dogs (including Russian Borzois) and the prospects of using the studied group of markers for genetic analysis and differentiation in C. familiaris are discussed.

Animals↗

PubMed2002

[Cloning and comparative characterization of the rIGS regulatory regions in humans and the pygmy chimpanzee Pan paniscus].

Investigation of randomly cloned genomic and chromosome-specific sequences of ribosomal DNA (rDNA) from different organisms show that different regions of this long repeat unit evolve at different rates. This proves to be true not only with regard to evolutionary variability of transcribed and nontranscribed intergenic (spacer) regions of rDNA. The intergenic spacer (rIGS) of human ribosomal DNA contains both highly variable and more conservative regions with putative regulatory functions. In the present study a comparative analysis of some segments of the rIGS pre-promoter (regulatory) region in human and pygmy chimpanzee (Pan paniscus) was carried out. For these purposes, the corresponding DNA fragments were amplified in PCR with oligonucleotide primers specific to human rIGS and sequenced. Our results show that at the background of substantial structural similarity of these regions in man and chimpanzee, i.e., the presence of highly homologous sequences and similar repetitive units, there are substantial differences between them. These differences are associated with point mutations, insertions, deletions, and complex structural rearrangements.

Animals↗

PubMed2002

[RAPD variation in two trematode species (Fasciola hepatica and Dicrocoelium dendriticum) from a single cattle population].

The method of random DNA amplification by PCR with arbitrary primers (RAPD-PCR) was used for the description and estimation of genetic variation in two trematode species, Fasciola hepatica (n = 21) and Dicrocoelium dendriticum (n = 8). The studied trematodes were liver parasites of five cattle individuals belonging to the same herd. To study the F. hepatica population, five primers were selected, which revealed 320 RAPD markers in five samples of parasites isolated from five different host individuals. Using 87 RAPD markers, a comparison of variation was conducted between F. hepatica and D. dendriticum samples from the same host individual. Based on the estimates of RAPD variation for the individual samples of parasites collected from each of five host individuals and for the total F. hepatica population, standard indices of genetic similarity (S), diversity (H), polymorphism (P), and population subdivision (FST) were calculated. From the indices of similarity in pairs (S), dendrograms were constructed, which reflect genetic relationship between the representatives of two species and between F. hepatica individuals isolated from the same or different host individuals. It was revealed that polymorphism level (P) varied within a range of 35.5 to 83.2% in the studied F. hepatica population and reached 95.1% in the studied D. dendriticum population. Two different trematode species that simultaneously parasitize the same host animal were characterized by similar estimates of polymorphism and genetic diversity and by similar topology of genetic similarity dendrograms. The degree of genetic similarity between F. hepatica and D. dendriticum was significantly lower (20%) than between five F. hepatica samples (41.4%) that formed two unequal clusters. Each of these clusters represents a heterogeneous group consisting of parasites collected from three or four host individuals. In the individual samples of parasites related to each of the studied host individuals, the indices of genetic similarity (S) and diversity (H) varied within a range of 43.3 to 64.8% and 25.1 to 56.6%, respectively. In the total F. hepatica sample, the estimates of intraspecific variation, the topology of dendrograms, and the FST index (7.4%) indicate the absence of clear genetic differentiation between the samples of parasites isolated from different host individuals. Possible reasons for the high level of genetic variation in the studied trematode populations and the genetic consequences of host--parasite interaction are discussed.

Animals↗