Studies on the relationship between genetic diversity within the fungus that specifically occur on Fagus crenata supule and its host distribution.

为了寻找影响真菌分布的主要因素，比较了日本大片地区采集的金针菇(Fagus Crenata Cuulus)上的长圆环藻(Dasyscyphella Longistipiata)(透明藻科，黑伞目，散肌菌，子囊菌门)的ITS序列多样性。在每个采样点每隔5m采集5~20个幼虫，得到单孢子菌株。在来自12个地点的120株分离物中，检测到38种单倍型，所有群体中均检测到单倍型H12，占总分离物的43%。此外，H28(15%)和H10(10%)是三种主要的单倍型。根据统计简约性，这三种单倍型被放置在单倍型网络的内部分支中。嵌套的分支分析并不表明地理上的隔离。分子方差分析将群体内的遗传多样性归因于遗传多样性。遗传距离与地理距离无关，也与寄主的系统发育群无关。这些事实表明，日本纵纹夜蛾的种群构成了一个大的连续体。然而，日本西南部地区和东北部地区的遗传多样性较高。这种遗传分布格局表明，当前种群起源于日本西南部具有较高遗传多样性的冰川时期的祖先种群，随后随着寄主的扩张而不断扩张，在日本中部由于寄主的灭绝而遗传多样性下降，而在日本东北部由于寄主的持续分布而保持多样性。

To search for major factors that affected fungal distribution, ITS sequence diversity of Dasyscyphella longistipitata(Hyaloscyphaceae, Helotiales, Disomyoate, Ascomycota) that occur on Fagus crenata cupulus obtained from wide areas in Japan were compared. Five to 20 cupules were collected every 5m apart at each sampling site, and single-spored isolates were obtained. In 120 isolates obtained from 12 sites, 38 haplotypes were detected, and the haplotype H12(43% of the total isolates) was detected from all the populations. In addition, H28(15%) and H10(10%) consisted of the three major haplotypes. These three haplotypes were placed in inner clades in the haplotype network based on statistical parsimony. Nested clade analysis did not indicate geographic isolation. Analysis of molecular variance attributed the genetic diversity for the diversity within the population. Genetic distance was not found to be correlated with geological distance, and no relationship was found with the phylogenetic grouping of the host. These facts suggested the whole the populations of D.longistipitata Japan form a large continuum. However, genetic diversity was higher in south-western areas and north eastern areas in Japan. This genetic distribution pattern suggests that the current population initiated from the ancestral population in the glacier period with high genetic diversity in south-western Japan, followed by the continuous expansion along with the host expansion, decrease of the genetic diversity in the middle Japan due to the extinction of the host, while keeping diversity due to continuous distribution of the host in the north-east Japan.