Studies on the extinction and conservation of plant species diversity

目前关于植物物种多样性的灭绝与保护的研究结果如下：1。确定物种在植物中的实际传播，对保护灭绝物种和保护其遗传多样性具有重要意义。采用电泳分析方法研究了无孢子蕨类植物多裂蕨（Pteris multifiida）群体的遗传结构。结果表明，蕨类植物虽然具有较高的传播能力，但孢子的传播在很大程度上受到限制。对世界范围内濒危水草——水草科水草进行了发育形态学研究。在马拉亚那（Malaccotristicha malayana）中，匍匐轴与根是同源的，因为它有根冠，侧根在母根的维管柱附近内生地形成。该物种在形态上比该科中最不特化的Indotnsticha ramosissima和Tristicha trifaria更特化。最近，我们在鹿子湖发现了更多被认为已经从日本灭绝的新发现。利用扫描电镜观察卵孢子壁纹饰，以确定其分类位置。我们的结果支持这种藻类是日本特有的观点。对芫荽属植物进行了分子系统发育分析。所获得的树并不支持大陆漂移与该属目前的不间断分布有关的假设，但表明这种分布模式可能是第三纪末期分散和灭绝的结果。化石资料表明，槭属在其历史上经历了物种形成和灭绝的重复过程。本文对槭属植物的分子系统发育进行了分析，并对其叶绿体DNA的进化速率进行了评价，为提出物种灭绝的理论提供了基础数据。研究结果表明，东亚和北美的双变异物种群在中新世晚期出现分化，东亚和北美植物群的相似性是由物种群的多次分散、分离和灭绝造成的。少

The present study on the extinction and conservation of plant species diversity had the following results :1.It is important to determine the actual dispersal in plants in order to protect extinction and make conservation of their genetic diversity. An electrophoretic analysis was performed to examine the genetic strcture of polulations in the free-spored fern Pteris multifida. The result suggested that although ferns have high dispersal ability, spore dispersal is limited to a great extent.2.A developmental morphological study was made of the morphologically and ecologically specialized water-weeds, Podostemaceae, which are endangered worldwide. In Malaccotristicha malayana, the creeping axis is homologous with a root, because it has a root-cap and the lateral root initiated endogenously near the vascular cylinder of the mother root. The species is morphologically more specialized than Indotnsticha ramosissima and Tristicha trifaria, the least specialized in the family.3.Recently we r … More ediscovered Nitella gracilens in Lake Ashinoko, which had been believed to beextinct from Japan. In order to examine the taxonomic position of the alga, the oospore wall ornamentation was observed by scanning electron microscopy. Our result supported the view that the alga is endemic to Japan.4.A molecular phylogenetic analysis of the genus Coriaria was performed. A obtained tree does not support the hypothesis that the continental drift was involved in the present disjunct distribution of the genus, but suggests that the distribution pattern may have resulted from dispersal and extinction at the end of the Tertiary.5.Fossil data suggest that the genus Acer had a repetition of speciation and extinction through its history. In order to make basic data to suggest species extionction, we analyzed the molecular phylogeny of Acer and evaluated the evolutionary rate of chloroplast DNA.Our results suggest that the bicariant species disjunct in eastern Asia and North America diverged in late Miocene, and that the similarity between eastern Asian and North American floras resulted from multiple dispersal, disjunction, and extinction of the species groups. Less