Poa annua L. is the only non−native vascular plant that was successfully established in the maritime Antarctic. This project aimed to determine the amount of genetic and epigenetic variation within and between two populations of P. annua , one from South Shetland Is. (Antarctic) and the other one from Central Europe. We applied two AFLP marker systems, using endonucleases that recognised the same restriction site but differed in their sensitivity towards methylation. The Antarctic population differed from the Polish one both at the genetic and epigenetic levels. Genetic variability in the Antarctic population was lower than in the Polish one. Some loci in the Antarctic population showed signs of selection. The difference between Polish and Antarctic populations might be due to a weak bottleneck effect followed by population expansion. Using only epigenetic markers, the Ant − arctic population exhibited increased variation level compared to the Polish one. These may have resulted from plastic responses to environmental factors and could be associated with survival in extreme conditions.
The brown bullhead (Ameiurus nebulosus) is an invasive species of fish fauna in Poland. This species is widespread throughout the country but its abundance and characteristics of populations present in water reservoirs are relatively little known. Aim of this study was to determine the abundance and characteristic of the population of brown bullhead in the Domaszne Lake. The control fish catches were carried out three times in 2012 and 2013 years (spring, summer, autumn). Brown bullhead had a small share in the structure of fish abundance (2.7%) and biomass (7.5%), but his presence was reported in results of all control fishing. Relative abundance of brown bullhead averaged about 7.8 CPUE and biomass about 505.5 WPUE. The fishes the greatest total length and weight had in the spring (Tl = 18.5 cm, W = 77.7 g) but the highest value of the coefficient of condition (K = 2.08) in summer were noted. Brown bullhead with a total length from 16 to 18 cm accounted for as much as 59% of the population and distribution of size structure confirm a fact that has a stable population.