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The present study of green frog hybrid populations of Ukraine, including analysis of allozyme variability and planimetric analysis oferythrocytes size has confirmed that the unique region in this area is the Severski Donets basin The allopolyploid individuals there are met very frequently (5.7% of all investigated frogs). In other areas of Ukraine only two polyploid hybrids have been recorded. Beside that, one frog was defined as triploid Rana ridibundus. According to our investigations, all triploid hybrids from the Severski Donets basin are identified as P. esculentu (=lessonae)--2 ridibundus males.

In this study, quantitative analysis of paternal genome inheritance by a hybrid form Rana "esculenta" (= Rana esculenta L., 1758 x Rana ridibunda Pall., 1881) (Amphibia, Ranidae) was examined. The hybrid form examined was characterized by a polymodal mode of inheritance (genome of any of the parental species can be inherited). The absence of correlation between the proportion of normal gametes and either sex or ploidity of the producer was demonstrated. The gametes produced could be both haploid and diploid (hybrid or homozygous). The mechanism of alloploid reproduction is discussed.

Transgenic fishes are the object for the specialists in different research fields. It seems very promising to cultivate the rapidly growing objects resistant to diseases and negative environmental factors as well as the indicators of pollutions, models for oncological investigations etc. Some methodical, piscicultural, medical, ecological and others aspects of investigations of transgenic fishes as well as the legislative basis of Ukraine on this problem are discussed in the article.

Research of the alleles of the species-specific genes in the gametal cells of Rana kl. esculenta hybrids proved the existence of three local populations within the territory of Ukraine. Their hybrids reject either the genome of lake frog (Danube lowland), either the previous one or another one genome (basin of Severskiy Donets river), either the genome of pond frog (the residuary territory of the areal). The research of skin transplants rejection of hybrids' parental species has shown that despite the orientation of genome elimination of this population the graft of lake frog always starts identifying and rejecting earlier. That is why the genetic skewness of hybrids becomes apparent at the skin level and corresponds to its manifestations at the organism level.

Spatial and temporal analysis of frequency distribution patterns of the Rana esculenta (=lessonae)-specific allele, Ldh-B71, in the populations and individuals of R. ridibunda from the Middle Dnieper region was performed. It was established that the allele was accumulated in the populations of Kiev, where on average 15 to 25% of individuals steadily preserved this allele through at least three to four generations. Furthermore, the allele frequency in juveniles and adults was similar. These findings suggest that the frogs carrying foreign genetic material were not eliminated from the populations, and hence, the observed introduction of foreign genes was adaptively neutral. The transfer of the genetic material from one species to another may be considered as a possible mechanism of the formation of an additional source for population genetic variation, which, however, do not seems to be evolutionary progressive.

The biochemical genetic marking and analysis of the ploidy and sexual structure of the green frog populations from the Transcarpathian lowlands have demonstrated that this region is inhabited by the unisexual populations composed of the allodiploid females only. Their genome includes a small portion of the marsh frog genic diversity. This phenomenon is discussed in relation to the unisexual population reproduction problem. The assumption is proposed that in the Transcarpathian hybrid populations the hybrids are spawned by the parthenogenesis.

The comparative analysis of hybrid populations of toads Bombina bombina and B. variegata from Ukraine and Croatia revealed the essential differences in their genetic structure. The population composition and the direction of genetic introgression are determined initially by the ecological factors (the locality type, the country relief). The clear predominance of the red-bellied toad Bombina bombina was found in two cases: in the lowland populations and in the big samples. The second parental species, B. variegata, predominates in the highlands and in the small samples, respectively.

Genetic distances between eight species of sousliks (Spermophilus) and five species of marmots (Marmota) were estimated on the basis of 39 biochemical loci. All taxa were shown to be genetically discrete. The genetic differentiation was minimal (Pfd = 11.3) between parapatric species of Palearctic sousliks of the suslicus pigmaeus group and Marmota species, intermediate (Pfd = 34.7) between allopatric sousliks species, and maximal (Pfd = 56.7) between representatives of different genera. The following trends were revealed in the geographic differentiation of the genus Spermophilus: (1) genetic similarity was associated with the geographic distance; (2) the eastern and western Palearctic phyla were markedly different genetically; (3) the eastern Palearctic forms exhibited higher differentiation than the western ones. The revealed speciation pattern is consistent with the general trend of temporal differentiation in Palearctic phyla and confirms the periodic speciation mode in the Palearctics.

Population-genetic analysis of hybrid populations of green frogs from the Dnepr basin demonstrated limited gene introgression in diploid hybrids in addition to semiclonal reproduction, which is typical for Rana esculenta hybrids. Introgression is largely confined to the Ldh-B locus: the gene of R. lessonae is introduced into the R. ridibunda genome. This phenomenon is unstable as it is geographically restricted and absent in populations of the E-L type.

Correlation analysis revealed close relationships between genetic differentiation (measured by percent of fixed gene differences of species and genera) and some biological indexes reflecting the peculiarities of ontogenesis, age, fecundity, body size, and taxonomic structure at the level of order. The most strong relationships were found between paleontological age of order, polytypic character of genera, linear body size, and duration of ontogenesis. The least significant were correlations of genetic differentiation with fecundity as well as with biological age of orders. The factors determining decrease in genetic differentiation among species and genera in large mammals, are 1) the young age of orders which determines the ranks of lower taxa; 2) the overestimation of taxonomic rank of orders of larger mammals in comparison with smaller ones.

Analysis of the genetic structure of two green frog Rana esculenta complex populations from Volyn' was performed for 7 diagnostical loci. Populations of R- and REL-type were detected in which the introgression of Ldh-B allelic gene locus from R. lessonae into genome of R. ridibunda, characteristic for hybrid populations of Dnieper basin, was absent. This may be associated with alterations in gene pools of parental species.

Genetic differentiation of 35 vole species, estimated at 18 to 31 biochemical loci, allowed us to identify the following phyla of the tribe level: Lemmini, Dicrostonychini, Ellobiini, Clethrionomyini, and Microtini. Average genetic differentiation between the tribes (D'Nei = 0.977) corresponds to separation of the phylogenetic branches in the middle Pleistocene. Tribe Lagurini was shown to be contained within Cletrionomyini. Ondatrini was the first branch that diverged from the common stem in the Miocene (D = 1.563), prior to the formation of the Arvicolidae family. Distribution of genetic distances indicates that family radiations comprised two stages, tribal (Pliocene) and specific (Pleistocene). Ages of the taxa, estimated by means of the molecular clock, agreed well with stratigraphic data. Marked periodicity of divergence in the family confirms the concept of punctuated evolution.

Analysis of genetic structure of geographically isolated population of hybrid complex Rana esculenta L. from Danube delta according to a complex of biochemical gene markers was conducted. A parental species of Rana ridibunda and hybrids ridibunda-lessonae of the first generation only were found in the population. The complete absence of genetic recombination and introgression of genes from the locus Ldh-B, which was found in Dnieper populations, is characteristic of the population. The differences observed may be explained by genetic nonuniformity of geographical forms of R. lessonae. This forms may have taxonomic differences.

A review of data on genetic differentiation of mammalian taxa has been made on the basis of estimating the percent of fixed gene differences (PFD). The results substantiate the existence of evident differences in the scale of genetic divergence between taxa in different mammalian orders. Among smaller mammals (marsupials, insectivores, chiropterans, myomorph and sciuromorph rodents, african mole rats, and elephant shrews) interspecific differences within a genus involve the average of 25-40% of investigated loci. At the genetic level the value is 50-60%, whereas at the familial level the differences are beyond the resolution capacity of the method (PFD = 60-80%). Orders of larger mammals can be divided into two subgroups. One of them that includes carnivores, artiodactylans, and hystricomorph rodents is characterised by PFD values of 10-14%, 30-50%, and 69-70% at respective levels. The other subgroup composed of proboscideans, primates, pinnipeds, and toothed whales, has a low level of genetic divergence expressed by PFD values of 0-3%, 7-36%, and 50-60% at species, generic and familial levels, respectively. Insufficiency of data on baleen whales and perissodactyls does not allow to cluster them ultimately with any of these groups. There are three possible, but not necessarily alternative, causes for the observed differences in genetic divergence: 1) over-ranking of genera in larger mammals; 2) different paleontological age of orders; 3) unequal rates of molecular evolution.

The directed ingression of Lhd-B gene from R. lessonae to R. ridibunda observed during hybridization between these species was confirmed in the present study. The ingression was accompanied by decreased of the initial allele activity, segregative disturbances in heterozygotes and changes in electrophoretic mobility. The population genetic analysis has shown stable preservation of abnormal alleles in hybrid populations. The results are discussed with reference to the concept of genetic instability, its application to speciation models, and the neutralist vs. adaptationist controversy. Our data supports the neutral concept of allozyme variation.

Population-genetic analysis conducted in hybrid populations of Rana esculenta complex from neighbourhood of Kiev has shown a high portion of recombinant frogs within Rana esculenta specimens and limitation of gene flows from one species to the other. The mechanisms of limitations are connected with assortative crossings within R. ridibunda and R. lessonae and low viability of frogs with a recombined genotype.