Variability of NOR patterns in European water frogs of different genome composition and ploidy level

Volume: 11Start Page: 249End Page: 26

Variability of NOR patterns in European water frogs of different genome composition and ploidy level

We studied water frogs from a complex composed of two species: Pelophylax lessonae (Camerano, 1882) (genome LL, 2n = 26) and P. ridibundus (Pallas, 1771) (RR, 2 = 26), and their natural hybrid P. esculentus (Fitzinger, 1843) of various ploidy and genome composition (RL, 2n = 26, and RRL or RLL, 3n = 39). Tetraploids RRLL were found (4n = 52) in juveniles. We applied cytogenetic techniques: AgNO3, chromomycin A3, PI and fluorescent in situ hybridization with a 28S rDNA probe. Results obtained by silver staining corresponded well with those stained with CMA3, PI and FISH. As a rule, NORs are situated on chromosomes 10. The number of Ag-NORs visible on metaphase plates was the same as the number of Ag-nucleoli present in interphase nuclei of the same individual. In all analyzed metaphases, NORs exhibited variations in size after AgNO3 and CMA3 stainings. Sixty-six individuals (out of 407 analyzed) were polymorphic for the localization and number of NORs. Fifty-one diploids had NORs only on one chromosome of pair 10. Three triploids (LLR and RRL) displayed two NORs, and two other triploid RRL individuals displayed one, instead of expected three NORs. In ten individuals extra NORs were detected on chromosomes other than 10 (chromosomes 2 and 9)

Genetic structure of the fire salamander Salamandra salamandra in the Polish Sudetes

We analysed genetic variation within and differentiation between nineteen populations of the fire salamander <i>Salamandra salamandra </i>inhabiting the north-eastern margin of the species range in the Sudetes Mountains (south-western Poland). The results were compared with those obtained recently for the Polish part of the Carpathians. Variation of 10 nuclear microsatellite loci was analysed in 744 individuals to estimate genetic structure, gene flow, isolation and to test for a geographic gradient of genetic variation. Mitochondrial DNA control region (D-loop) of 252 specimens from all localities was used to identify the origin of populations currently inhabiting its north-eastern range. We found little genetic differentiation among populations in the Sudetes indicating substantial recent or ongoing gene flow. The exceptions were one isolated peripheral population located outside the continuous distribution range which displayed extremely reduced genetic variation probably due to a combination of long term isolation and low population size, and one population located at the eastern margin of the Polish Sudetes. Populations inhabiting the Sudetes and the Carpathians formed two separate clusters based on microsatellite loci. In accordance with available phylogeographic information, single mitochondrial haplotype (type IIb) fixed in all populations indicates their origin from a single refugium and may suggest colonization from the Balkan Peninsula. The analysis of geographic gradient in variation showed its decline in the westerly direction suggesting colonization of Poland from the east, however, alternative scenarios of postglacial colonization could not be rejected with the available data

Preliminary genetic data suggest the occurrence of the Balkan water frog, Pelophylax kurtmuelleri, in southwestern Poland

Recent molecular studies have detected the occurrence of exotic water frog species (Pelophylaxsp.) in central and western European populations. Here, we report genetic evidence for the occurrence of the Balkan water frog,Pelophylax kurtmuelleri, in southwestern Poland. We found a high frequency of an allele of serum albumin intron-1 and a mitochondrial cytochromebhaplotype specific for this southern taxon in frogs from the Barycz river drainage system. We interpret this finding as evidence of admixture betweenP. kurtmuelleriand the localridibundus-esculentuswater frog population. The origin of the exoticP. kurtmuellerimitochondrial and nuclear alleles in southwestern Poland could be due to (i) hybridization after a human-mediated introduction ofP. kurtmuelleri, (ii) the persistence of ancestral polymorphism in central EuropeanP. ridibundus, or (iii) hybridization betweenP. kurtmuelleriandP. ridibundusin the Balkans followed by the northward expansion of admixedP. ridibundus. Identical mtDNA haplotypes found in southwestern Poland and localities on the borders between Greece, Albania and Macedonia suggest that this region harboured the source population ofP. kurtmuelleriat the studied site.</jats:p

Genetic structure and differentiation of the fire salamander Salamandra salamandra at the northern margin of its range in the Carpathians

<p>Amphibian populations occurring at the margin of the species range exhibit lower genetic variation due to strong genetic drift and long-term isolation. Limited mobility and site fidelity together with habitat changes may accelerate genetic processes leading to local extinction. Here, we analyze genetic variation of the fire salamander subspecies <em>Salamandra s. salamandra </em>inhabiting the Outer Carpathian region in Poland, at the northern border of its distribution. Nuclear DNA polymorphism based on 10 microsatellite loci of 380 individuals sampled in 11 populations were analysed to measure gene flow between subpopulations and possible long-term isolation. Mitochondrial DNA control region analysis among 17 individuals representing 13 localities was used to detect the origin of populations which colonized Northern Europe after the last glaciation. Overall, pairwise F ST’s and AMOVA test of ‘among group’ variation showed little differences in the allele frequencies and relatively high local gene flow. However, Bayesian clustering results revealed subtle structuring between eastern and western part of the studied region. Two extreme marginal populations from the Carpathian Piedmont revealed reduced genetic variation which may be attributed to strong influence of genetic drift. Only one mitochondrial DNA haplotype (type IIb) was found in all individuals and suggest that after the Last Glacial Maximum <em>Salamandra salamandra </em>migrated to the North-Western Europe from the single glacial refugium placed in the Balkan Peninsula.</p