Abstract
Haploid liverwort Conocephalum conicum is known to be composed of several types (C, A, L, S, J, T and FS). The level of genetic variability of C. conicum was surveyed using starch gel electophoresis at putative18 enzyme loci from 7 natural populations in Kyushu, Kanto and Tohoku districts. We found two new types which were different not only from either FS or T type, but also from J type in isozyme band patterns, and named them YFS and KYT type. The average heterozygosities of J type from several populations in Kyushu district and Goyosan in Tohoku district were 0.142 and 0.163, respectively. Those of FS and T types from Takaosan in Kanto district, YFS and KYT type from Yakiyama in Kyushu district were 0.146, 0.104, 0.263 and 0.240, respectively. A parameter of genetic differentiation between populations (Gst) of the J type were 0.045. This study has confirmed the previous results that the high levels of genetic variability are maintained in natural populations of Kyushu district. High level of genetic variability and low genetic differentiation of Kyushu populations in this haploid plant as well as the data showing high level of Gst among the geographically distant populations in various parts of Japan may be explained by the hypothesis that the dominant factor determining the genetic structures of this liverwort is random genetic drift with little migration between different regions of Japan. The finding of various types of C. conicum in Japaneses populations together with the clear difference in isozyme patterns between types supports the idea that these types are different biological species.
