To test these hypotheses, we analyzed 400 C. punctorium specimens from several native and two invaded locations throughout the species' European range. We used a set of microsatellite loci, nuclear 28S rDNA, and mitochondrial COI sequences, to infer genetic structure and signatures of isolation. We also employed morphological measurements to show phenotypic differentiation of lineages. In addition, we estimated the frequency of eggsac parasitism in selected native and historical expanding populations to gather insights in the role of parasite release during the range expansion. Finally, we use multivariate comparisons between the realized niches of native and expanding populations to predict the species' historical and current potential distribution and to identify climatic factors associated with genetic differentiation of lineages and expansion success.