Krzysztof Kolenda

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 ( Pelophylax sp.) 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 cytochrome b haplotype specific for this southern taxon in frogs from the Barycz river drainage system. We interpret this finding as evidence of admixture between P. kurtmuelleri and the local ridibundus-esculentus water frog population. The origin of the exotic P. kurtmuelleri mitochondrial and nuclear alleles in southwestern Poland could be due to (i) hybridization after a human-mediated introduction of P. kurtmuelleri , (ii) the persistence of ancestral polymorphism in central European P. ridibundus , or (iii) hybridization between P. kurtmuelleri and P. ridibundus in the Balkans followed by the northward expansion of admixed P. 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 of P. kurtmuelleri at the studied site.

The programmed DNA elimination and formation of micronuclei in germ line cells of the natural hybridogenetic water frog Pelophylax esculentus

DNA elimination is a radical form of gene silencing and occurs both in somatic and germ cells. The programmed DNA elimination occurs during gametogenesis in interspecies hybrids that reproduce by hybridogenesis (stick insects, fishes, and amphibians) and concerns removal of whole genomes of one of the parental species and production of clonal gametes propagating the genome of the other species. The cellular mechanisms differ considerably in hybridogenetic insects and fishes but remains unknown in edible frogs Pelophylax esculentus, natural hybrids between Pelophylax lessonae and Pelophylax ridibundus. Here we report DNA elimination mechanism in early developing gonads of diploid and triploid hybrid frogs, studied by TEM, immunofluorescence, and cytochemistry. In gonocytes of both sexes (primary oogonia and prespermatogonia), micronuclei emerge as detached nuclear buds formed during interphase. We found depletion of nuclear pore complexes in micronuclear membrane and chromatin inactivation via heterochromatinization followed by degradation of micronuclei by autophagy. Micronuclei formation does not lead to apoptotic cell death showing that genome elimination is a physiological process. Chromatin elimination via micronuclei in P. esculentus is unique among hybridogenetic animals and contributes to broadening the knowledge about reproductive modes in animals.

Non-native Amphibian Pet Trade via Internet in Poland

Abstract Overharvesting and trade in amphibian populations is one of the causes of their global decline. Online trade not only encourages the exploitation of an increasing number of rare and endangered amphibian species from all over the world but also influences the spread of invasive species. The aim of our research was to investigate the amphibian pet trade conducted in online stores and portals in Poland and determine its potential impact on native species. Between November 2013 and October 2014, we regularly (on a monthly basis) checked sale offers on the websites of the 18 biggest pet shops in the country specialised in exotic animals, on a nationwide auction portal and on three exotic pet fan portals. During the study, we reported 486 offers of 112 amphibian species in online stores and on portals. Most of the offers involved one of the four families of amphibians: poison dart frogs (Dendrobatidae), tree frogs (Hylidae), true toads (Bufonidae) and true salamanders (Salamandridae). Our data show increased interest in amphibians as pets in Poland. At least half of the offered species are possible hosts for the chytrid fungus Batrachochytrium dendrobatidis. However, only one species, the American bullfrog Lithobates catesbeianus (Shaw, 1802), appears to be a potential invasive species. To summarise, the species offered in Poland that are characterised as threatened are predominantly those that are relatively easy to breed and that are popular as pets. Further studies are required to investigate the real threat to wild amphibian populations caused by the pet trade

Batrachochytrium dendrobatidis is present in Poland and associated with reduced fitness in wild populations of Pelophylax lessonae

The fungus Batrachochytrium dendrobatidis (Bd) is a pathogen associated with global declines of amphibians. We used qPCR to detect Bd in 255 samples from 10 Polish populations of 8 species. We found Bd infection in 3 species (Bombina variegata, Pelophylax lessonae, P. esculentus). The infection intensity in P. lessonae reached a maximum of 58400 genomic equivalents of zoospores (GE), and the 2 most heavily infected individuals died. Previous observations of the populations that included infected individuals showed reduced body size, failure to reproduce, and mortalities of adults. These data highlight the importance of emerging diseases, and the need to recognize them as an important factor in conservation of the genus Pelophylax in Poland and Central and Eastern Europe.