KIM, KI-JOONG*, GYE-SOOK HA, AND HAE-LIM LEE. Department of Biology, Yeungnam University, Kyeungsan, Kyeungbuk, Korea 712-749. - Introgressive hybridization between native and introduced species of Taraxacum.
Taraxacum officinale complex was introduced from Europe into
Korea about a hundred years ago. This species widely occurs on Korean
penninsula and take over the habitats of native species of
Taraxacum and increasingly common in open habitats.
Taraxacum officinale complex produce more aboundant apomictic
seeds than native species, however, some populations also show
facultative sexual reproduction. Native species consist of diploid,
triploid, and tetraploid and show a series of facultative sexual
reproduction. 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.
Key words: biological invasion, cpDNA tree, nuclear ITS tree, phylogeny, Taraxacum