Biosystematic Study of Japanese Conocephalum japonicum (Hepaticae) based on rbcL Sequence and Allozyme Data

概要

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In order to examine possible nucleotide sequence variations in the rbcL gene of Conocephalum japonicum, we collected plant materials from 52 localities representing the geographical distribution of the species in Japan. We determined 1304 nucleotide sequences and found two kinds of rbcL sequences differing by 6 nucleotides. Their distribution areas were clearly demarcated as north or south of latitude 42-43°N in Hokkaido. We identified the two rbcL types as JN (Japan North) and JS (Japan South) types. The geographical boundary of these two rbcL types is nearly identical to the northern limit of the distribution range of Fagus crenata in Japan. We could not find any morphological differences between the JN and JS types. In Abuta, Hokkaido, the two rbcL types were growing together within small research areas measuring 25m×15m (JN type: 10 and JS type: 8 individuals). We performed an allozyme analysis on this population, and observed tight associations between the allozyme and rbcL variations: the JS type had Est-3a and Tpi-1a alleles, whereas the JN type had Est-3b and Tpi-1b. These findings suggest that these two rbcL types of C. japonicum might be two reproductively isolated cryptic species.
2003-06-09