Phylogeographic connections between geographic distribution and genetic structure in the tree species constituting the Japanese beech forest distributed along the Japan Sea side

研究了分布在日本海边的山毛榉林树种的地理分布和遗传结构之间的系统地理联系。首先，对日本海边山毛榉森林中的3种灌木(冬青藤、北方冬青、大叶胡麻)的5个居群的2个个体进行了线粒体DNA的限制性片段长度多态性(RFLP)初步调查。北方海棠和矮生海棠的多态现象很少，而白果海棠表现出较高的多态水平。其次，以12个群体的357个个体为材料，进一步研究了白纹伊蚊mtDNA的RFLP。基因多样性分析表明，西南种群的遗传变异较高，东北种群的遗传变异较大。这种地理格局的变化可能是由于最后一次冰川盛期的地理分布和随后物种的殖民。目前，白枝莲叶绿体DNA(CpDNA)多态区的初步调查和基于cpDNA多态的系统地理分析正在进行中。本文将对白蜡虫的mtDNA和cpDNA的系统地理结构进行比较。这种比较将有助于揭示沿日本海边分布的山毛榉林树种的地理分布和遗传结构之间的系统地理联系。

Phylogeographic connections between geographic distribution and genetic structure were studied in the tree species constituting the Japanese beech forest distributed along the Japan Sea side. First, preliminary surveys on restriction fragment length polymorphism (RFLP) in mitochondrial DNA (mtDNA) were conducted using two individuals from each of five populations of the three shrub species (Ilex leucoclada, Aucuba japonica var.borealis, Daphniphyllum macropodum var.humile), which are component species in Japanese beech forest on the Japan Sea side. Few polymorphism were detected in A.japonica var.borealis and D.macropodum var.humile), whereas I.Leucoclada showed a high level of polymorphism. Second, the RFLP in mtDNA for I.Leucoclada was further studied using 357 individuals from 12 populations. Gene diversity analysis showed that the genetic variation within populations was higher in the southwestern populations man in northeastern populations. This geographic pattern of variation may be due to the geographic distribution in the last glacial maximum and subsequent colonization for the species. Now, a preliminary survey to detect polymorphic regions in chloroplast DNA (cpDNA) and the phylogeographic analysis based on the cpDNA polymorphism are being conducted for I.Leucoclada. The phylogeographic structures of mtDNA and cpDNA in I.Leucoclada will be compared with those in Fagus crenata. This comparison will contribute to reveal the phylogeographic connections between geographic distribution and genetic structure in the tree species constituting the Japanese beech forest distributed along the Japan Sea side.