【作者】 李强；

【导师】 谢树莲；

【作者基本信息】 山西大学 ， 水生生物学， 2009， 硕士

【摘要】 淡水红藻属于淡水藻类中非常少见的类群,它们只能生活在洁净的淡水中,对环境的要求很高。近年来,由于环境污染日益严重,淡水资源的匮乏,已经严重威胁到淡水红藻这一类群的生存,一些种类已经消失,一些种类濒临灭绝。因此,对淡水红藻的研究对于这一种类的保护和开发都有很重要的现实意义。本文简要描述了淡水红藻的形态特征及其研究状况,目前世界有报道的淡水红藻210种,分别隶属于9个目。串珠藻目属于红藻门,真红藻纲,串珠藻目。是淡水红藻中最大的一个目。目前报道的全部串珠藻目植物种类均生活在淡水中。本文以目前获取的来自世界各大洲串珠藻目植物的rbcL基因序列,结合其形态和生物地理特征,构建了该目的系统发育关系,以期探讨整个串珠藻目植物的系统发育关系及发生途径。串珠藻目植物作为淡水中的孑遗植物,对环境因子要求较为特殊,而且其分布区域封闭,特有种多。因此,淡水红藻是研究地球环境的变化及生物自身的演变的重要类群。研究表明,假枝藻属与连珠藻属和托氏藻属同在一个大的分支上,与大多数串珠藻属植物相分离,分化时间较晚的类群;串珠藻属植物中,本文的研究结果倾向于将杂生组归入扭曲组;多芒组和沼生组,这两两组系统关系的确定还需要更多的生物学证据;串珠藻组是串珠藻属中最大的一个组,包含的种类多,且分布广泛。因此,其系统发育关系还需要更多的分子数据进一步研究。另外,结合地理分布对串珠藻目植物进行了生物地理学研究,推测现代串珠藻种类的起源地在北美或大洋洲附近。本文采用SSU和rbcL序列分析重建了红藻门中80个分类群的系统发育关系。其中约有二十几种为淡水产。这些淡水类群也分为两大类,分别属于原红藻亚纲和真红藻亚纲。其中,属于真红藻亚纲的串珠藻目形成独立的一支,其他的淡水类群均与相近的海生类群形成姐妹群。根据所选类群重建的系统发育关系表明,其中最为原始的是原红藻亚纲中红毛菜属的Bangia atropurpurea。真红藻亚纲中最为原始的是胭脂藻属的Hildenbrandia angolensis。根据本研究的结果,奥杜藻属独立于红索藻和串珠藻而独立聚成一支,针对其是否为红索藻或者串珠藻的幼体的争论还有待深入研究。运用红藻门中的5个类群的化石记录标定其中的5个节点,重建红藻门的系统发育关系,结果表明淡水红藻中串珠藻目植物的分歧时间约在450Mya—650Mya。结合古地理复原图推测大部分淡水红藻均由相类似的海生种侵入内陆进化而来。更多还原

【Abstract】 The red algal(Rhodophyta) are a particular group of eukaryotic organisms. Morphologically diverse more than any other group of algae,they range from single cells to large ornate multicellular plants.In addition to a small number of red algal living in fresh water,most of them live in the ocean.In recent years,the increasingly serious environmental pollution and the lack of freshwater resources has been a serious threat to the survival of the fresgwater red algae.Some species have disappeared and some species threatened with extinction.Therefore,the study of freshwater red algae has very important practical significance for the protection and development of this group.This study describes the morphological characteristics of freshwater red algae and the research actuality briefly.At present,it has been reported 210 species of freshwater red algae on the earth,respectively remain with 9 orders.Batrachospermale belongs to Florideophycidae,Rhodophyceae,Rhodophyta.It is the largest order in the Freshwater red algae.At present,all reported Batrachospermale species are living in freshwater.This article constructs a phylogenetic relationship by the rbcL gene sequences coming from currently attainable Batrachospermale in all continents from around the world,combined with its morphological and biogeographical features. Expect to discuss the phylogenetic relationship and the occurrence process in the whole Batrachospermale.Batrachospermale have unique requirements of environmental factors as the leave behind plant in the freshwater.Also,the distributions of the region are closed and it has more endemic species.Therefore,freshwater red algae are the important group which is researched to the change of the Earth’s environment and the evolution of biology of their own.The studies have shown that Nothocladus,Sirodotia and Tuomeyathe are together in a large branch,separating from the majority of Batrachospermum and the disjoin later.In the Batrachospermum,the study results of this paper tend to make Sect.Hybrida fell under Sect.Contorta;Sect.Aristata and Sect.Turfosa,the relationship between these two groups is ensured requiring the more biological evidences.Sect.Batrachospermum is the largest one in Batrachospermum,contains many kinds and is widely distributed.Therefore, their phylogenetic relationship is studied further by more molecular evidences.In addition, we make the study of Batrachospermale biogeography combining the geographical distribution to infer that the origin place of modern Batrachospermum is in the vicinity of North America or Oceania.Phylogenic trees for 80 taxa of Rhodophyta,23 of which were freshwater red algae, were constructed based on SSU and rbcL sequences.The freshwater taxa can divide in to two major groups,Bangiaceae and Florideae.Batrachospermale which belonged to Florideae formed a well-supported monophyletic clade,and displayed a sister relationship with other freshwater taxa and related marine taxa.Based on the constructed phylogenic trees,we proposed that Bangia atropurpurea,belonged to Bangia Roth,Bangiaceae,was the most original species.Hildenbrandia angolensis was the most original species of Florideae.According to the result,Audoinella neither formed a clade with Thorea nor with Batrachospermum,therefore,more research will be needed to solve the problem that if Audoinella was the larva of Thorea or Batrachospermum.Five taxa of Rhodophyta fossil records are use to calibrate five nodes,and to reconstruct phylogenetic relationship of Rhodophyta.The result shows that the divergence time of the freshwater red algae in Batrachospermum is 450Mya-650Mya.According to the antiquity world map,we infer that most of the freshwater red algae are origin from the similar marine species invade to the inland.更多还原