Abstract
Boreal coniferous forests in Japan were dominated by Picea during the Last Glacial Age. Extant Picea species have fairly similar morphology, and identification of fossil Picea species is often difficult even from its cone. We tried to identify Picea fossils using chloroplast DNA sequence. We collected fossil samples of the Last Glacial Age in the Tohoku District. DNA regions examined were two intergenic spacer regions about 200 base pairs selected by comparing DNA sequences among extant Japanese Picea species. Fossil DNA was sequenced by the polymerase chain reaction (PCR). We succeeded in sequencing five cones from Dekijima and one branchlet from Mameda, Aomori Prefecture. The sequences of five cones agreed with that of extant P. glehnii, and that of the branchlet with extant P. koyamae and P. shirasawae. Morphological identification of the five fossil cones resulted in two P. glehnii and one P. maximowiczii cones, and the remaining two not identifiable because of poor preservation. Although the fossil branchlet obtained from Mameda was not identifiable to species, cones collected from the same horizon were identified as P. koyamae. DNA and morphological identifications corresponded except for the cone identified as P. maximowiczii. This study showed a successful DNA analysis of fossil cones and needles and the value of DNA for identifying fossil species.
