Quantitative assessment of forest fragmentation on genetic components of understory herbs.

为了评价森林破碎化对林下草本植物遗传组成的影响，对延龄草两种植物的生殖、种群和遗传特性进行了研究。对北海道东部地区自交不亲和和昆虫授粉的油松种群进行了种子生产调查，结果表明，大种群和/或被丰富森林系列包围的连续种群产生的种子数高于小种群和孤立种群。用等位酶电泳法(6种酶和11个基因座)分析了群体的遗传多样性水平、近交系数和群体结构格局。群体大小对数与多态座位百分率和等位基因丰富度呈显著正相关。此外，在小种群中没有观察到的所有等位基因都是罕见的。为了预测随机变化环境下的未来种群规模，应用转移矩阵模型对长期普查数据进行了研究，并通过田间繁育试验对其种群动态进行了研究。矩阵模型表明，单叶不育期的幼苗和植株等小个体的死亡率很高，从单叶期过渡到三叶期和从三叶期过渡到开花期的概率很低。虽然阿佩特隆具有较强的近交和近交能力，但近亲繁殖占主导地位。此外，随后的资源限制只允许一定水平的繁殖力，而不考虑最初的受精水平。

In order to assess the effects of forest fragmentation on genetic components of understory herbs, reproductive, demographic and genetic characteristics of two Trillium species were studied.Investigation on seed production of, self-incompatible and insect-pollinated, T.camtschatcense populations in eastern Hokkaido revealed that large populations and/or continuous populations surrounded with abundant forest series produced a higher number of seeds than small and isolated populations. The levels of genetic diversity, inbreeding coefficient, and the patterns of local population structure were also assayed using allozyme electrophoresis (6 enzymes and 11 loci). The log of population size had positive and significant relationships with the percentage of polymorphic loci and allelic richness. In addition, all alleles which were not observed in small populations were rare.In order to forecast the future population size under stochastically varying environment, population dynamics of T.apetalon were investigated by application of the transition matrix model to the long-term census data and by breeding experiments in the field. The matrix model demonstrated that mortality rates of small individuals, such as seedlings and plants at the one-leaf sterile stage, were very high and that the probabilities for transition from the one-leaf stage to the three-leaf stage and from the three-leaf stage to flowering were very low. Although T.apetalon had a substantial capacity both for inbreeding and outbreeding, inbreeding was predominant. Furthermore, subsequent resource limitation allowed only acertain level of fecundity, regardless of the original fertilization level.