Origin and genetic variability of populations of the invasive plant Rumex alpinus L. in the Giant (Krkonoše) Mountains

Monk's rhubarb, Rumex alpinus L. (R. alpinus), is a perennial plant native to the mountains of Central and Southern Europe. Currently, the distribution of R. alpinus has been partly affected by its utilization as a vegetable and a medicinal herb. In the mountains of the Czech Republic, it is considered an invasive plant, probably introduced into the Krkonoše Mountains by colonists from the Alps. This study's main aim was to verify whether R. alpinus was introduced into the Krkonoše Mountains by alpine colonists or whether it was anthropogenically introduced from the Carpathians. Furthermore, the genetic structure of native and introduced populations of R. alpinus was determined. For the evaluation of genetic structure, 417 samples of R. alpinus were collected from the Alps, Carpathians, Balkan, Pyrenees, and Czech Mountains. In total, 12 simple sequence repeat (SSR) markers were applied. The results of AMOVA showed a high 60% variation within populations, 27% variation among groups, and 13% among the population within groups. The overall unbiased gene diversity was high (^ĥ = 0.55). The higher level of genetic differentiation among populations (FST = 0.35; p < .01) indicated restricted gene flow between populations. Compared to native populations, limited genetic variability was observed in the nonnative populations. It was concluded that local adaptation, low gene exchange, and genetic drift affected the genetic diversity of nonnative R. alpinus. The results support a genetic link between Alpine and Czech genotypes of R. alpinus, while the Carpathians genotypes corresponded to the Balkan genotype.