Random amplified polymorphic DNA (RAPD) variation among populations of the insular endemic plant Campanula microdonta (Campanulaceae)

RAPD variation was examined in nine populations of Campanula microdonta Koidz., endemic to the Izu Islands, Japan. Ninety-eight bands were obtained for all populations, 94 % of which were polymorphic at least within a population. Shannon's H values were calculated; these have frequently been used in RAPD studies to estimate genetic diversity. The values within populations did not correlate with the allozyme gene diversity estimated by a previous study or with distance from the Japanese mainland. The possible reasons for this discrepancy are different selection regimes between the two markers, higher RAPD mutation rates, and each marker's different coverage of genomes. Cluster analysis of genetic similarities suggested that colonization of each island probably occurred once, except for Miyake Island, where immigration has occurred at least twice.