Asuka Y, Tomaru N, Munehara Y, Tani N, Tsumura Y, Yamamoto S
Laboratory of Forest Ecology and Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
Mol Ecol. 2005 Jul;14(8):2565-75. doi: 10.1111/j.1365-294x.2005.02585.x.
Half-sib family structure of Fagus crenata saplings was examined in an old-growth beech-dwarf bamboo (Sasa spp.) forest using microsatellite genotypes in parentage analysis to identify the half-sib families in two 50 x 50 m plots: one with 36 adults, 641 saplings and no Sasa cover, the other with 21 adults, 61 saplings and Sasa cover. For large proportions of the saplings (44.6% and 75.4%, respectively) both of their parents were found within the same plot, indicating that pollination events frequently involved short-range pollen dispersal, probably because of the high density of adults in the study population. Although almost all of the adults had half-sib families, the number of offspring in the families was highly variable. In the plot with no Sasa cover, the variation in the number of offspring was significantly explained by the size of parents, i.e. the reproductive success is higher for large adults than for small adults. The half-sibs were aggregately distributed around their parents and the distribution overlapped among different half-sib families, which may be due to the limited seed dispersal and overlapping seed shadows of this species. As expected, there was weak genetic structure in the plot. By contrast, in the plot with Sasa cover, the half-sibs were distributed sparsely with a low density, and the degree of genetic structure was very weak. The difference in the half-sib family structure and genetic structure among saplings presumably reflects the difference in density that should be affected by regeneration dynamics associated with environmental conditions.
在一片老龄山毛榉-矮竹（笹属）森林中，利用微卫星基因型进行亲权分析，以确定日本水青冈幼树的半同胞家族结构，研究对象为两个50×50米的样地：一个样地中有36株成年树、641株幼树且无矮竹覆盖，另一个样地中有21株成年树、61株幼树且有矮竹覆盖。对于很大比例的幼树（分别为44.6%和75.4%），其双亲都在同一样地中被找到，这表明授粉事件频繁涉及短距离花粉传播，可能是因为研究种群中成年树的密度很高。尽管几乎所有成年树都有半同胞家族，但家族中的后代数量差异很大。在没有矮竹覆盖的样地中，后代数量的变化显著地由亲本大小所解释，即大型成年树的繁殖成功率高于小型成年树。半同胞聚集分布在其亲本周围，且不同半同胞家族的分布相互重叠，这可能是由于该物种种子传播有限以及种子阴影重叠所致。正如预期的那样，该样地中存在较弱的遗传结构。相比之下，在有矮竹覆盖的样地中，半同胞分布稀疏且密度较低，遗传结构程度非常弱。幼树之间半同胞家族结构和遗传结构的差异大概反映了密度差异，而密度差异应受与环境条件相关的更新动态影响。
