Introduction history and population genetics of intracontinental scotch broom (Cytisus scoparius) invasion

Aim Biological invasions at the intracontinental scale are poorly studied, and intracontinental invasions often remain cryptic. Here, we investigate the recent range expansion of scotch broom (Cytisus scoparius) into Norway and clarify whether the genetic patterns support a natural spread or human introduction. Furthermore, we investigate whether plants were moved within the native range and how this influences invasion success. We also infer the level and structuring of genetic diversity within and between the putative native and introduced range. Location Europe
Methods We analysed the chloroplast sequence variation in 267 scotch broom samples from its northern expansion front and from its native range across Europe, including herbarium samples dating back to 1835. For 37 populations, we analysed variation in nuclear single-nucleotide polymorphic markers to study gene flow and genetic diversity. Results We identified 20 different haplotypes, which lacked spatial and temporal distribu...