Data from: Massive invasion of exotic Barbus barbus and introgressive hybridisation with endemic B. plebejus in Northern Italy: where, how and why?

Biological invasions and introgressive hybridisation are major drivers for the decline of native freshwater fish. However, the magnitude of the problem across a native species range, the mechanisms shaping introgression as well as invader's dispersal and the relative role of biological invasions in the light of multiple environmental stressors are rarely described. Here, we report extensive (N=665) mtDNA sequence and (N=692) microsatellite genotypic data of 32 Northern Adriatic sites aimed to unravel the invasion of the European Barbus barbus in Italy, and the hybridisation and decline of the endemic B. plebejus. We highlight an exceptionally fast breakthrough of B. barbus within the Po River Basin, leading to widespread introgressive hybridisation with the endemic B. plebejus within few generations. In contrast, adjacent drainage systems are still unaffected from B. barbus invasion. We show that barriers to migration are inefficient to halt the invasion process and that propagule pressure, and not environmental quality, is the major driver responsible for B. barbus success. Both introgressive hybridisation and invader's dispersal are facilitated by ongoing fisheries management practices. Therefore, immediate changes in fisheries management (i.e. stocking and translocation measures) and a detailed conservation plan, focussed on remnant purebred B. plebejus populations, are urgently needed.mec13390_genotypesMicrosatellite data set (n=692) follows the Structure input file format (Unix format txt) with individual information on a single line (two columns per marker). The file contains loci names (1st row), individual names (1st column), codes for sampling localities (2nd col.) and 3 additional columns (GenBank Acc. n., haplogroup and haplotype for cyt-b mtDNA sequence).mec13390_SimDataset6000indsMicrosatellite data set (n=6,000) simulated with HYBRIDLAB 1.0 (Nielsen et al. 2001). The file is in Genepop format, with 6 populations representing B. plebejus purebreds, B. barbus purebreds, F1, F2, Backcross F1 X B. plebejus and Backcross F1 X B. barbus