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

森林破碎化对林下草本遗传成分的定量评估。

基本信息

批准号：
10440230
负责人：
OHARA Masashi
金额：
$ 7.3万
依托单位：
HOKKAIDO UNVERSITY (2000)The University of Tokyo (1998-1999)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

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.

为了评估森林破碎化对林下草本遗传成分的影响，研究了两种延龄草物种的繁殖、人口统计和遗传特征。对北海道东部的自交不亲和昆虫授粉的延龄草种群的种子生产进行的调查表明，被丰富的森林系列包围的大型种群和/或连续种群比小型和孤立的种群产生更多的种子人口。还使用等位酶电泳（6 个酶和 11 个位点）分析了遗传多样性水平、近交系数和当地种群结构模式。种群大小的对数与多态位点百分比和等位基因丰富度呈显着正相关。此外，在小种群中未观察到的所有等位基因都很罕见。为了预测随机变化环境下未来种群规模，通过将过渡矩阵模型应用于长期普查数据和田间育种实验，研究了T.apetalon的种群动态。矩阵模型表明，一叶不育期的幼苗和植株等小个体的死亡率非常高，而从一叶期过渡到三叶期以及从三叶期过渡到开花的概率很低。尽管T.apetalon 具有很强的近交和远交能力，但近交仍占主导地位。此外，无论最初的受精水平如何，随后的资源限制只允许一定水平的繁殖力。