Origin of the Endangered Tetraploid Adonis ramosa (Ranunculaceae) Assessed with Chloroplast and Nuclear DNA Sequence Data

抄録

Polyploidization is an important evolutionary force in plant speciation, and elucidating the origin and evolutionary history of a particular polyploid is important for understanding the evolution and distribution of plants. We investigated the origin of the endangered tetraploid Adonis ramosa Franch., which is endemic to Japan. To clarify the origin and phylogenetic relationships among A. ramosa and diploid species, we conducted a phylogenetic analysis of the species of Adonis in Japan and Korea using chloroplast trnL-trnF spacer and nuclear ribosomal internal transcribed spacer (ITS) sequences. The sequences of the ITS region of showed that the sequences of A. ramosa were completely consistent with or quite similar to those of A. amurensis Regel & Radde of Hokkaido, Japan, and clearly differed from those of A. amurensis in Korea and three diploid species from Japan and Korea. The results suggest the possibility that A. ramosa is an autotetraploid, and the diploid progenitor is A. amurensis from Hokkaido. The distribution pattern of the ITS haplotype of A. ramosa also indicates range expansion of A. ramosa from northern to southern Japan Ecological divergence and adaptation to new habitats after polyploidization are likely to increase the survival of A. ramosa and enable it to widely colonize in new environments in Japan.