The endemic vascular plants of Ullung Island, 150 km E of the Korean peninsula, can be grouped into two general classes of progenitor-derivative species-pairs: (1) endemic taxa that differ only slightly in morphological features from their progenitors, the former being regarded sometimes as subspecies; and (2) endemic species that differ conspicuously from continental progenitors. One example of the latter group is Hepatica maxima, common in Ullung island, and differing from other Asian members of the genus in color and size of vegetative organs, fleshiness of leaves, and a lack of leaf spotting. We have investigated this species in context of two alternative hypotheses of speciation. The first hypothesis involves a bottleneck with fixation of rare alleles from the progenitor population, and with endemic populations showing reduced genetic diversity. Genetic ties between the two should be clear. The second hypothesis assumes an increased rate of evolutionary change due to adaptation and loss of constraints after arrival in a new habitat. Such rapid evolution should result in high levels of genetic diversity in endemic populations, and if the changes are substantial, ties to progenitors would be obscured. We have investigated populations of H. maxima as well as possible progenitors H. asiatica, H. insularis, and H. noblilis vars. japonica and pubescens with maternally inherited plastid and nuclear DNA sequences plus AFLPs. Although phylogenetic analysis of plastid markers places H. maxima close to H. asiatica, this tree topology is not supported by high bootstrap values. ITS data alone even suggest a closer relationship to varieties of H. noblilis from Japan. AFLP data show a high number of private alleles for populations of the endemic H. maxima, indicating a genetically isolated position. All data favor the hypothesis of accelerated evolution triggered by loss of selective constraints after arrival in the new volcanic island habitat.

Key words: AFLP, DNA, Hepatica, Korea, speciation, Ullung Island