Rana Lessonae Research Articles

Amphibians of Wałbrzych

In the city of Walbrzych 67 water bodies (about 95% of all Walbrzych ponds) were investi-gated. Among them, 58 water bodies (86.57%) are of anthropogenic origin. In the studied area 9 amphibian species were recorded: Rana temporaria (present in 44.78% of studied water bodies), Bufo bufo (44.78%), Triturus vulgaris (17.91%), Trirutus alpestris (16.62%), water frogs of the Rana esculenta complex (Rana lessonae and Rana kl. esculenta, 10.45% altogether), Bufo viridis (10.45%), Bufo calamita (4.48%) and Triturus cristatus (4.48%). Amphibians were present in 48 ponds (71.64% of studied water bodies). Maximum number of species (six) was recorded in only 1 water body; minimum number of species (1) was recorded in 19 ponds. Surprisingly, the maximum number of species occurred in the pond located within dense urban area. One bank of this pond was a vertical brick wall and there is not much vegetation in the pond. In industrial areas of Walbrzych presence of only 5 amphibian species was noted, however on 7 sites there were no amphibians atall. Similar low number of amphibian species (five) was also noted in mini-ponds in the allotments.

Amphibian communities in small water bodies in the city of Olsztyn

The aims of the study were determine the effects of anthropogenic pressure on the species composition and population size of amphibians of small water bodies in Olsztyn city (NE Poland). The presence of 11 amphibian species was noted in 83.5% of water bodies. The dominants were: the common frog Rana temporaria, the edible frog Rana esculenta, the pool frog Rana lessonae, the common toad Bufo bufo and the moor frog Rana arvalis. The fire-bellied toad Bombina bombina was an influent, while the common newt Triturns vulgaris, the common spadefoot Pelobates fnsciis, the tree frog Hyla arborea, the green toad Bufo viridis and the crested newt Tritimis cristatus were the recedents. The most frequent were “green frogs”, which occur in 71.9% of water bodies inhabited by amphibians (60.0% of all water bodies). The species characterized by the lowest occurrence frequency were the tree frog (6.0% and 5.0%, respectively), the green toad (5.4% and 4.5%) and the crested newt (3.6% and 3.0%). In the paper the urban pressure on amphibian communities is widely discussed.

Long term data on the amphibians of Wrocław

The paper presents information about the amphibian species in Wroclaw – frequency oftheir occurrence as well as number of individuals in water bodies. For the study 31 sites were selected. Only in two sites no amphibians were found. On the rest of the sites in total 11 amphibian taxons were present – Triturus cristatus, Triturus vulgaris, Bombina bombina, Bufo bufo, Bufo viridis, Hyla arborea, Pelobates fuscus, water frogs from the Rana esculenta complex (both a species Rana lessonae and a hybrid Rana kl. esculenta), Rana temporaria and Rana arvalis. The most numerous were water frogs (occurred on 90.3% of all sites), Bufo bufo (48.4% sites), Bombina bombina and Rana temporaria (both species on 45.2% si- tes). The rarest species were Triturus cristatus (16.1% sites) and Pelobates fuscus (9.7% sites). In Wroclaw amphibians are the most abundant in ponds located within river valleys. There are 10 species there (on the average 4.44 species per pond), with Bombina bombina and water frogs being the most numerous. Second amphibian-friendly environment are sites within the city forests, having 8 species (on the average 5.22 species). Water frogs, Rana temporaria and Rana arvalis were most common here, and Triturus cristatus and Triturus vulgaris occurred mostly in this category. The lowest frequency was observed in the city center (on the average 0.66 species), with one site without any amphibians, and with only water frogs in the remaining two sites. After a pond reconstruction populations of Triturus vulgaris and Bufo bufo disappeared, and the number of Bufo viridis increased. For three sites the changes in amphibian species assemblages in consecu- tive years of observations are provided. In two sites the trend of maintaining the same species composition was observed, and on third site the composition changed due to the pond reconstruction (T. vulgaris and B.bufo substituted by B. viridis).

Intraspecific variation of temperature-induced effects on metamorphosis in the pool frog (Rana lessonae)

Understanding the factors that affect the process of metamorphosis in species with complex life cycles, and in particular their variation within and among populations, has been rarely explored until recently. We examined the effects of temperature environment on several metamorphic characteristics in three populations of the pool frog ( Rana lessonae Camerano, 1882) by rearing individuals at two temperature environments (20 and 25 °C). Higher temperature shortened the metamorphic period and reduced the absolute mass loss, although there was no difference between the temperatures in the percentage of mass lost. No differences among the populations were detected, but there was significant intrapopulation variation both in the mean and in the plasticity for the duration of metamorphosis. These results indicate that several aspects of metamorphosis are plastic in amphibians, these traits may have considerable intrapopulation variation, and that temperature is a strong factor affecting the process of metamorphosis.

Bioacoustic assessment of the taxonomic status of pool frog populations (Rana lessonae) with reference to a topotypical population

Six structural and temporal features of the mating calls of pool frogs recorded at eight localities in Italy, Germany, Yugoslavia and Albania were compared with those of the calls of topotypical Rana lessonae in northern Italy. All populations shared three out of six characters studied: call duration, intercall interval and call period. The pool frogs of three localities in peninsular Italy significantly differed in three characters from those of the other six localities, including the northern Italian one: pulses per pulse group, pulse groups per call, and pulse groups per second. This study demonstrates the existence of Rana bergeri, a pool frog species different from R. lessonae in peninsular Italy, but does not support the species status of the chemotaxonomically established R. shqiperica, which is considered as a synonym of R. lessonae.

Genetic diversity in mitochondrial 12S rDNA of western Palearctic water frogs (Anura, Ranidae) and implications for their systematics

The nucleotide sequence of a part of the mitochondrial 12S rRNA gene of eight western Palearctic water frog species was analysed. The results are consistent with the species status of Rana bedriagae, Rana bergeri, Rana epeirotica, Rana lessonae, Rana perezi, Rana ridibunda, Rana saharica and Rana shqiperica. The obtained DNA data suggest that lake frogs from Greece and Yugoslavia on the one hand and lake frogs from Georgia, Uzbekistan and Turkmenistan on the other hand represent two distinct species. However, it is not yet clear whether lake frogs from Georgia, Uzbekistan and Turkmenistan belong to R. ridibunda or represent a new species. The very high similarity between the analysed 12S rDNA segments of German R. ridibunda and R. lessonae confirm the finding that mtDNA of R. lessonae was transmitted into the mitochondrial gene pool of R. ridibunda probably as a result of backcrosses with the hybridogenetic hybrid R. kl. esculenta. The results of parsimony analyses speak in favour of very close phylogenetic relations between R. perezi and R. saharica; with a high probability these species represent an adelphotaxon. Furthermore, the clades (R. lessonae + R. shqiperica + R. bergeri) and (R. ridibunda + R. bedriagae) are considered to be sister groups. According to the mt 12S rDNA data R. epeirotica seems to be more closely related to the supraspecific taxon (R. ridibunda + R. bedriagae) than to (R. lessonae + R. shqiperica + R. bergeri). Thus, it can be excluded that R. shqiperica and R. epeirotica represent sister species.

Microgeographic variation in the effects of larval temperature environment on juvenile morphology and locomotion in the pool frog

AbstractIn animals with complex life cycles, the environment experienced early during the development may have strong effects on later performance and fitness. We investigated the intraspecific variation in the effects of larval temperature environment on the morphology and locomotory performance of juvenile pool frogs Rana lessonae originating from three closely located populations of the northern fringe metapopulation in central Sweden. Tadpoles were raised individually at two temperatures (20 and 25 °C) until metamorphosis. We measured the morphology of the metamorphs and tested the jumping performance of the froglets after complete tail absorption. We found that early temperature environment affected juvenile morphology, metamorphs from high‐temperature environments having relatively longer hindlimbs (tibiofibulas) and longer tails when weight at metamorphosis was accounted for. In absolute terms, froglets from low temperature jumped significantly longer; however, after correcting for size differences the relationship was reversed, individuals raised at high temperature performing better. In both temperatures, relative jumping performance was positively associated with tibiofibula and body length. Populations differed both in metamorphic traits and in jumping capacity, especially at low temperature, suggesting microgeographical variation in temperature sensitivity within the metapopulation. Our results indicate that the temperature environment experienced during the early aquatic stages can influence the morphology and performance of juvenile frogs, and that these effects can be population specific.

Karyotype and serum protein pattern in a Swedish population of Rana lessonae (Amphibia, Anura)

The chromosomes were studied with the blood-culture technique in 3 males and 2 females of Rana lessonae from an isolated population in Central Sweden. All specimens were diploid with 2n = 26. The karyotype is similar, but not identical, to those reported for R. ridibunda and R. esculenta, and consists of 5 larger and 8 smaller chromosome pairs. No. 10 has a distinct secondary constriction in the long arm. No sex chromosomes could be distinguished. An idiogram was constructed from measurements of 10 well-spread metaphases. The relative length and centromeric index for each chromosome pair were calculated and compared with corresponding values for R. ridibunda and R. esculenta from Central Europe and R. nigromaculata and R. brevipoda from Japan. Serum protein patterns were studied in R. lessonae from C. Sweden (13 specimens), in R. esculenta from S. Sweden (5) and S. Germany (1), and in R. ridibunda from S. Germany (2) by means of polyacrylamide gel electrophoresis. The same differences in the mobility of the albumin fraction as reported by other investigators were established, viz. a single band exhibiting fast mobility in R. lessonae, a single band of slow mobility in R. ridibunda and a double band in R. esculenta. This, as well as other facts, is consistent with the theory that R. esculenta is a hybrid “species” between R. lessonae and R. ridibunda.

Potential impact of genome exclusion by alien species in the hybridogenetic water frogs (Pelophylax esculentus complex)

Globalization and increasing human impact on natural aquatic systems have facilitated the movement of species and the establishment of nonindigenous species enhancing hybridisation opportunities between naturally allopatric species. In this review, we focus on a special case of natural hybrid speciation and the consequences of recent anthropogenic hybridisation in the water frog complex (Pelophylax esculentus complex), which consists of two parental species, Pelophylax lessonae and Pelophylax ridibundus and a hybrid taxon. The hybrid water frogs reproduce hybridogenetically and eliminate the genome of the syntopic water frog species. Although the actual cause triggering chromosome exclusion remains elusive, it has been proposed that chromosome elimination takes place prior to meiosis and may involve enzymatic degradation of the discarded genome. Translocations of water frogs in Western Europe have become frequent the last decade leading to rapid expansion of the range of the marsh frog P. ridibundus. Subsequent hybridisation of the exotic P. ridibundus may dramatically affect the viability and maintenance of hybrid water frog populations throughout Europe. Interestingly, the impact of this introduced species may differ depending on their geographic origin, which defines the ability to induce genome elimination. This may result in fertile or sterile hybrids, making global conservation guidelines challenging. We predict a severe genetic and ecological impact of nonindigenous P. ridibundus prompting for strict conservation measures to reduce species translocations and for studies on the geographic origin of exotic frog species.

Influence of Landscape Elements in Riparian Buffers on the Conservation of Semiaquatic Amphibians

Studies on riparian buffers have usually focused on the amount of land needed as habitat for the terrestrial life stages of semiaquatic species. Nevertheless, the landscape surrounding wetlands is also important for other key processes, such as dispersal and the dynamics of metapopulations. Multiple elements that influence these processes should therefore be considered in the delineation of buffers. We analyzed landscape elements (forest cover, density of roads, and hydrographic network) in concentric buffers to evaluate the scale at which they influence stream amphibians in 77 distinct landscapes. To evaluate whether our results could be generalized to other contexts, we determined whether they were consistent across the study areas. Amphibians required buffers of 100-400 m of suitable terrestrial habitat, but interspecific differences in the amount of habitat were large. The presence of amphibians was related to roads and the hydrographic network at larger spatial scales (300-1500 m), which suggests that wider buffers are needed with these elements. This pattern probably arose because these elements influence dispersal and metapopulation persistence, processes that occur at large spatial scales. Furthermore, in some cases, analyses performed on different sets of landscapes provided different results, which suggests caution should be used when conservation recommendations are applied to disparate areas. Establishment of riparian buffers should not be focused only on riparian habitat, but should take a landscape perspective because semiaquatic species use multiple elements for different functions. This approach can be complex because different landscape elements require different spatial extents. Nevertheless, a shift of attention toward the management of different elements at multiple spatial scales is necessary for the long-term persistence of populations.

Expression of 5S rDNA in the oocytes of water frogs

BackgroundWe report the expression pattern of 5S rDNA in the eggs of water frogs Rana lessonae, Rana ridibunda and Rana esculenta using the quantitative real-time PCR. This kind of research had never been performed before.Results5S rDNA relative expression of the Rana ridibunda oocytes is approximately six times higher in comparison to the Rana lessonae oocytes. The oocytes of the investigated Rana esculenta frogs, in respect of 5S rDNA relative expression ratio, were very similar to the Rana ridibunda oocytes.ConclusionWe suggest the possibility of using 5S rDNA as the internal control gene, in the studies of relative mRNA quantitative assays in water frog oocytes, because of its characteristic specific expression pattern in the Rana lessonae, Rana ridibunda and Rana esculenta oocytes.

Microgeographic variation in temperature-induced plasticity in an isolated amphibian metapopulation

Variation in local environments may lead to variation in the selection pressures and differentiation among local populations even at microgeographic scale. We investigated variation in temperature-induced plasticity in larval life-history traits among populations of an isolated pool frog (Rana lessonae) metapopulation in Central Sweden. Successful breeding of this northern fringe metapopulation is highly dependent on early summer temperature, however, the metapopulation shows very little variation in molecular genetic markers suggesting limited potential for local differentiation. We exposed larvae from three closely-located populations to two temperatures (20 and 25°C) in laboratory to investigate their growth and development responses to temperature variation. In general, larvae exposed to warmer temperature experienced higher survival and metamorphosed faster, but at a smaller size than those at low temperature. We found differences among the populations in both trait mean values and in the plastic responses. Among-family variation within populations was found in growth rate and time to metamorphosis, as well as in plasticity suggesting that these traits have a capacity to evolve. Our results indicate ample phenotypic variation within and among these closely-located populations despite the low molecular genetic variation. The differences in pond temperature characteristics detected in the study in the three localities may suggest that differential selection is acting in the populations. The strong differentiation found in the larval traits implies that understanding the factors that influence the potential of the populations to adapt to environmental changes may be essential for successful conservation strategies.

Phylogeography of the pool frog Rana (Pelophylax) lessonae in the Italian peninsula and Sicily: multiple refugia, glacial expansions and nuclear–mitochondrial discordance

AbstractAim To infer the evolutionary history of Rana (Pelophylax) lessonae Camerano within its inferred Quaternary refugial range, and to shed light on the processes that have contributed to shaping the patterns of diversity within the southern European peninsulas.Location The Italian peninsula south of the Alps and Sicily.Methods Sequence analysis of a mitochondrial cytochrome b gene fragment in 149 individuals sampled from 25 localities.Results Three mitochondrial DNA (mtDNA) phylogroups were identified, distributed in northern Italy, the whole Italian peninsula south of the northern Apennines, and Sicily. Syntopy between the northern and peninsular lineages was observed close to the northern Apennines. The northern lineage was the most differentiated, showing a net sequence divergence of 4.8 ± 0.8% with respect to the two others, whereas the net divergence between peninsular and Sicilian lineages was 2.6 ± 0.6%. Analysis of molecular variance (amova) revealed that 93% of the overall variation occurred between these three groups. Historical demographic statistics support a recent expansion for both the northern and peninsular groups, but not for the Sicilian group. In both northern and peninsular Italy, such an expansion was likely to have occurred during the last glaciation.Main conclusions Our results suggest that a number of microevolutionary processes were involved in shaping the present genetic structure of R. lessonae in Italy. These encompass allopatric differentiations in three distinct Pleistocene refugia, recent population expansions and secondary contacts. Our results, together with some previous work, support (1) the existence of a suture zone in the northern Apennines, and (2) the possibility of population expansions during the last glacial phase, when a vast widening of the lowland floodplain habitats followed sea‐level fall, particularly in northern Italy. When compared with previous analyses of allozyme data, it appears that the peninsular mtDNA lineage has recently replaced the Sicilian one in southern Calabria, and we suggest that this event occurred due to selective introgression. The implications of such an occurrence for the study of factors underlying the patterns of diversity within this southern European biodiversity hotspot are discussed. Taxonomic implications of the results are also evaluated.

New hypotheses on the systematics of the western Palearctic water frog complex (Anura, Ranidae)

During the past 30 years the number of recognized western Palearctic water frog species has increased from just two at the end of the 1960s to at least 14 today. According to new sequence data from mitochondrial genes (12S rRNA. ND3) undescribed species are believed to occur on Cyprus and in central Asia. Furthermore, genetic data suggest that Anatolian lake frogs represent neither Rana bedriagae nor Rana ridibunda but a separate undescribed species. Due to several specific characters species status may also be awarded to lake frogs from south-western Anatolia which have already been described as Rana ridibunda caralitana. The results of various phylogenetic analyses speak in favour of a very close phylogenetic relationship between Rana saharica and Rana perezi. Both species are clearly separated from the other water frog species, which fall into two clades. One clade includes (Rana lessonae + Rana bergeri + Rana shqiperica), the second comprises the lake frog species Rana ridibunda, Rana bedriagae, the Asian lake frog group, the Cypriote water frogs. Rana cretensis, and Rana epeirotica. While the phylogenetic relationships within the “pool frog clade” are considered to be clear (there is strong evidence that Rana lessonae and Rana bergeri represent sister species), the relationships within the “lake frog clade” remain largely unresolved. However, in all phylogenetic trees obtained Rana epeirotica, Rana cretensis, and the Cypriote lineage branched off earlier than R. ridibunda, R. bedriagae and the Asian lake frog group and therefore seem to represent phylogenetically older taxa.

Regional accents in the Pool Frog? Development of new computer analytical techniques aids bioacoustic separation of Pool Frog populations and may elucidate the status of Norfolk Pool Frogs

Rana lessonae Camerano, 1882 has a well-recorded range across Europe with its distribution recognised as far north as Sweden (lat. 60°N). In recent years new populations have been identified in Arendal. Norway and in Norfolk, England. This study aims to clarify the situation of the Norfolk frogs. Are they native or imported? This paper presents preliminary results of a new approach to this question. By means of various bioacoustic analyses calls of R. lessonae from populations across Europe and Scandinavia have been compared. The water frog species have been subjected to detailed bioacoustic analyses in the past and some characteristics for each species have been determined. We have demonstrated the use of these techniques and developed new methods of analysis that have enabled regional differences in R. lessonae calls to be determined between the populations of Norfolk, Germany and Poland. This in turn may elucidate the situation of the Norfolk Pool Frog.

DNA content in erythrocyte nuclei of water frogs from a pure Rana esculenta population in Dębki (Gdańsk district, Poland)

Rana esculenta is a hybridogenetic hybrid between Rana ridibunda and Rana lessonae. Usually the hybrids, among which diploid and triploid individuals of both sexes were described, live in mixed populations with one of the parental species (L-E or R-E systems). The hybrids also form pure esculenta-esculenta populations (E-E system). 114 individuals from the Baltic Sea region were collected in 1990–1991 and 1998-1999. Blood smears were taken and erythrocyte areas were measured. The erythrocyte area ranged from 318.27 μm2 to 571.82 μ2 and two peaks could be distinguished: 370 μ2 and 460–490 μ2. The smears were then stained according to the Feulgen method and the DNA amount per nucleus was determined by measuring the integrated optical density of the nucleus area. The correlation between erythrocyte size and DNA content was relatively high (0.82). Nevertheless, in some cases the erythrocyte size was not a good indicator of DNA content. Specimens had various DNA content and they formed two distinct groups: one with higher and one with lower DNA content. However, we were not able to discriminate the expected two classes of diploid and triploid individuals. The results indicated that the problem of ploidy is complicated, and we cannot rule out the existence of aneuploids or mosaics among hybrids. The problem needs to be elucidated in combination with other methods, especially because it allows measuring the ploidy level in great number of animals without killing them and thus seems to be very useful for population studies.

Microsatellites: A tool for evolutionary genetic studies of western Palearctic water frogs

Genotypic variation at six of 67 microsatellite loci we developed from Rana ridibunda, containing di- or trinucleotide simplesequence repeats, confirms the value of microsatellites as an evolutionary genetic tool for studying western Palearctic water frogs, a model system characterized by clonal reproduction in natural hybrid lineages. R. ridibunda, Rana lessonae. and their hemiclonal hybrid Rana esculenta, which transmits only its ridibunda genome to gametes, are highly variable in central Poland and northern Switzerland: with one exception (a locus that is part of a coding region), each locus was polymorphic in each taxon when scorable, and the number of alleles was high (in Swiss lessonae-esculenta populations, 1-6 per locus, total 13, for ridibunda genomes; 1-9 per locus, total 23, for lessonae genomes; 3 shared by both genomes). Estimated repeat numbers ranged from 3 to 14 for trinucleotide- and from 6 to 27 for dinucleotide-repeats. Nonamplifying (null) alleles, problematic because they underestimate genotypic variability if undetected, occur in ridibunda genomes of Swiss R. esculenta at one locus: apparent lessonae null alleles at another locus were subsequently resolved for several segregating alleles evidenced by bands of much lower intensity. Two loci had multiple ridibunda alleles in Swiss R. esculenta and thus discriminate between hemiclones. with a resolution superior to that of allozymes. Adding these two loci to our protein electrophoretic data (7 loci) more than doubled the number of hemiclones detected, showed that several allozyme-defined hemiclones are composites of multiple microsatellite hemiclones, and revealed clonal diversity in populations that are uniclonal by allozyme data. The extent to which microsatellite-defined hemiclones result from primary hybridizations or from subsequent mutations in ridibunda genomes of R. esculenta lineages remains to be determined. A sample of newly metamorphosed R. ridibunda from hybrid × hybrid matings collected at a Swiss population in the fall had a significant heterozygote excess at the two loci that varied in ridibunda genomes; this shows that most, probably all, of them originated from inter- rather than intrahemiclonal matings, in accord with the idea that the usual hybrid × hybrid inviability in lessonae-esculenta systems is caused by deleterious recessive alleles on the clonally inherited ridibunda genomes. Three of four microsatellite loci tested amplified in most species of western Palearctic water frogs.

Protein electrophoresis of water frog embryos and tadpoles as a tool of taxonomic identification

The comparison of the zymograms of Idh-b, mpi, and pgm-2 found in tadpoles and embryos with those observed in adult water frogs (Rana lessonae, Rana ridibunda, Rana esculenta) showed that these loci do not exhibit any change in allelic mobility in both larval and adult phases. Hence, they are useful in taxonomic identification and thus provide suitable tools for studies on water frog distribution and ecology.

Types of water frog populations (Rana esculenta complex) in Poland

Poland is inhabited by the two water frog species Rana ridibunda (genotype RR) and Rana lessonae (LL) and their hybrido-genetic hybrid Rana esculenta. Besides diploid (RL) hybrids two triploid (RRL, RLL) forms were found. In most populations the hybrid occurs syntopically with only one of the parental species. Concerning their genotypic structure water frog populations can be subdivided into three systems: the L-E (lessonae-esculenta) system, the R-E (ridibunda-esculenta) system and the E-E (esculenta-esculenta) system. The composition of water frog populations in Poland is highly differentiated. Among 27 population types described from central Europe 18 types were found in Poland. The highest diversity of population types was seen in the R-E system (8 types). In the L-E system three and in the E-E system four different types were found. Among 11170 investigated adult water frogs 690 (6%) presumptive triploid R. esculenta individuals occurred. In western Poland the proportion of triploid individuals and the diversity of population types was higher (7.7% triploid individuals, 13 population types) than in the eastern parts of the country (0.2% triploid individuals, six population types). The distribution picture of triploid individuals in western Poland is similar to that seen in eastern Germany (as a rule a high proportion of triploids occurs) while in eastern Poland the distribution pattern of triploid genotypes resembles the situation observed in the territory of the former Soviet Union (nearly no triploids appear).

Two water frog populations from western Slovakia consisting of diploid females and diploid and triploid males of the hybridogenetic hybrid Rana esculenta (Anura, Ranidae)

We investigated the genomic constitution and the reproduction mode of Rana esculenta from two pure hybrid populations found in western Slovakia, using cytomorphological, karyological and allozyme electrophoretic methods. Both populations were composed of diploid R. esculenta females and diploid and triploid R. esculenta males. A single subadult R. ridibunda female was caught at one of the localities. The females significantly outnumbered the males in both populations. All electro-phoretically investigated triploid R. esculenta males possessed the allopolyploid genomic constitution RLL (one “ridibunda” and two “lessonae” genomes). In the ovaries/testes of diploid females/males, exclusively allelic products characteristic of R. ridibunda were detected, suggesting that they hybridogenetically produced gametes carrying a “ridibunda” genome. On the contrary, the electrophoresis revealed only allelic products characteristic of Rana lessonae in the testes of triploid RLL males from one of the populations. Thus, these males apparently substitute genetically the host species R. lessonae and play the important role in perpetuation of the investigated population.