István Sas-Kovács

Genetic diversity and distribution patterns of diploid and polyploid hybrid water frog populations (Pelophylax esculentus complex) across Europe

Polyploidization is a rare yet sometimes successful way for animals to rapidly create geno‐ and phenotypes that may colonize new habitats and quickly adapt to environmental changes. In this study, we use water frogs of the Pelophylax esculentus complex, comprising two species (Pelophylax lessonae, genotype LL; Pelophylax ridibundus, RR) and various diploid (LR) and triploid (LLR, LRR) hybrid forms, summarized as P. esculentus, as a model for studying recent hybridization and polyploidization in the context of speciation. Specifically, we compared the geographic distribution and genetic diversity of diploid and triploid hybrids across Europe to understand their origin, maintenance and potential role in hybrid speciation. We found that different hybrid and parental genotypes are not evenly distributed across Europe. Rather, their genetic diversity is structured by latitude and longitude and the presence/absence of parental species but not of triploids. Highest genetic diversity was observed in central and eastern Europe, the lowest in the northwestern parts of Europe. This gradient can be explained by the decrease in genetic diversity during postglacial expansion from southeastern glacial refuge areas. Genealogical relationships calculated on the basis of microsatellite data clearly indicate that hybrids are of multiple origin and include a huge variety of parental genomes. Water frogs in mixed‐ploidy populations without any parental species (i.e. all‐hybrid populations) can be viewed as evolutionary units that may be on their way towards hybrid speciation. Maintenance of such all‐hybrid populations requires a continuous exchange of genomes between diploids and triploids, but scenarios for alternative evolutionary trajectories are discussed.

After the Last Train Passes: Data on the Fauna from Abandoned Railway Tunnels in Romania

The importance of artificial underground habitats for biodiversity is becoming more and more apparent. Abandoned railway tunnels are artificial, underground habitats of considerable biodiversity, including several species of conservation concern. We surveyed 16 abandoned railway tunnels in 2014 in Romania for the following faunal groups: amphibians, terrestrial isopods, and spiders. Amphibians occurred primarily in flooded tunnels, isopods were present in moist tunnels with woody debris, while spiders were widespread and exhibited the greatest diversity in railway tunnels. Some species of amphibians breed in tunnels. The greatest diversity was observed in the entrance zones of tunnels; because railway tunnels are generally isolated from the surrounding rock, they can be colonized only from the entrances. In areas lacking natural subterranean cavities and habitats, railway tunnels are important habitats for many species, including troglophilic spiders and soil-dwelling isopods.

Winter-active wolf spiders (Araneae: Lycosidae) in thermal habitats from western Romania

Shores of channels with thermal water provide an adequate microclimate for maintaining wolf spiders in activity during winter. Of the spiders collected after the winter survey of 22 thermal habitats from western Romania, 93.02% were juveniles and subadults, while the remaining individuals belonged to the following seven species: Arctosa leopardus, Pardosa amentata, Pardosa proxima, Pirata piraticus, Piratula latitans, Trochosa robusta and Trochosa ruricola. The reproductive period of some species is altered under the influence of neighbouring hot waters, as revealed by the capture of females with egg sacs and spiderlings, during winter.