Genetic variability as expression of the invasion success:the case of the European catfish (Silurus glanis) in fourItalian basins

Silurus glanis is considered a top-priority invasive fish out of its natural range, being recorded in Italian basins since the 1950s. In few decades, S. glanis expanded its distribution along the main Italian basins, picturing a scenario of invasion success. Its invasion success was here analysed throughout the assessment of the genetic variability detected in 15 populations of S. glanis collected from four Italian basins along north-south gradient (Po River basin in the northern, Arno River and Serchio River basin in the central, and Volturno River basin in the southern). Additionally, three populations from native areas of S. glanis in central Europe (Elbe and Rhine River basins) have also been added to the dataset. The genetic variability and structure were retrieved through: i) sequencing of the mitochondrial control region and ii) genotyping of nuclear DNA at 10 microsatellite loci. The genetic outcomes evidenced high levels of genetic variability in each basin, supporting a favourable trait for high colonization potential. Genetic structure inference suggested the presence of two genetic pools, distinctly recorded in adjacent basins of central Italian peninsula and in two distant basins located in norther and southern part of Italian peninsula, probably related to distinct origin of introduced fish.