In order to measure the degree of gene flow between native and introduced species, we analyzed the maternally inherited chloroplast DNA markers and biparentally inherited nuclear DNA markers from 130 populations of Taraxacum . Nuclear ITS tree show the morphologically circumscribed species boundaries both in native and introduced species. However, cpDNA trees was substantially different from that of nuclear rDNA and show mixed patterns between European and Asian species. The results suggest that the introgressive hybridizations are relatively common between native and introduced species of Taraxacum . The unidirectional intrgression from introduced species into native species is one of major driving force to extiction of native populations.
Hybridizations are relatively rare among native species because of disjunctive distribution.