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题名: 中国秋海棠属秋海棠组系统学与保护生物学研究
作者: 马宏
学位类别: 博士
答辩日期: 2008-01-25
授予单位: 中国科学院昆明植物研究所
授予地点: 昆明植物研究所
导师: 管开云
关键词: 秋海棠属 ; 秋海棠组 ; 系统学 ; 多样性 ; 保护生物学 ; 繁殖生物学 ; 回归引种 ; 引种驯化
学位专业: 植物学
中文摘要: 秋海棠属秋海棠组(Begonia sect. Diploclinium)是一个亚洲分布组。本文对该组的中国产种类进行了系统学(花粉形态、种皮形态、叶表皮形态及气孔特征、细胞学、分支分类学、分子系统学)的研究。并对中国秋海棠属秋海棠组的濒危等级进行了评估。以本组古林箐秋海棠为对象进行了保护生物学研究,探讨了其濒危机制和相应的解危措施。此外,还对本组植物的繁殖生物学和引种驯化进行了研究和总结。主要的研究结论如下: 1 新种确定 在经过严格的形态比较和相关标本的查阅后,确定了本组的2个新种,并进行了详细的描述。 2 系统学研究 1 花粉形态 通过与其它组的比较,并结合以往的研究表明:中国秋海棠组是一个分化极其多样的类群。由于在花粉形态方面中国秋海棠组内包括了与中国秋海棠属其它组特征相似的种类,因此也可能说明依据宏观形态划分的秋海棠组之所以分化极其多样是因为其中包括了其它组的种类,是一个不自然的类群。侧膜组(Begonia sect. Coelocentrum)和四室组(B. sect. Sphenanthera)为自然的、争议较少的类群。花粉形态的研究不支持棒果组(B. sect. leprosae)的成立。我们认为秋海棠属花粉形态的演化趋势呈现出花粉大小:大→小、外壁纹饰:浅→深的特点,这也是与本属已知传粉昆虫峰类和蝇类的传粉相适应的结果。花粉形态对于秋海棠属下组的划分及种的确定有一定的意义。 2 种皮形态 与花粉形态的研究得出的结论基本一致。此外,中国秋海棠属植物种子大小是沿着大→小的趋势演化的。种皮形态可以作为区分种的依据之一,对秋海棠属下组的划分亦有一定的意义。秋海棠属植物的种子可能存在多种散布方式,单独或几种方式同时起作用,从而达到有效传播种子的目的。 3 叶表皮形态 光镜观察的结果显示,中国秋海棠组种类的下表皮细胞形态具有较高的多样性,同时本组还是国产秋海棠属中唯一具有气孔簇种类的组。与国产邻近组的比较研究表明,尽管光镜下叶表皮综合特征在组等级上一致性较差,但有的性状如毛被性质、垂周壁式样尤其是下表皮细胞的垂周壁式样在同一种秋海棠植物中十分稳定。中国秋海棠组部分石灰岩生境类型的种类其下表皮细胞垂周壁式样与侧膜组的种类高度一致。我们认为秋海棠属植物表皮细胞垂周壁式样的演化趋势为平直→弓形→波状。气孔成簇分布可能与植物的抗逆性有关。 气孔的电镜扫描显示,中国秋海棠属植物存在着非常高的多样性。在组水平上很难找到表现相对一致的气孔电镜扫描特征。蜡质结晶体等附属物与降低蒸腾作用、减少体内水分散失有关。 4 细胞学 如同在花粉特征、种皮和叶表皮形态方面表现出异常复杂的多样性,中国共秋海棠组植物在体细胞染色体数目方面也存在着丰富的变异。结合其它组及以往报道的结果表明,非整倍性变异和多倍化在中国秋海棠属植物的成种过程中扮演着重要的角色。推测X=15是中国秋海棠属植物的染色体基数,2n=30为中国秋海棠属植物原始的染色体数目,通过非整倍性变异和多倍化而衍生出其它类型的体细胞染色体数目。在染色体形态方面,台湾与大陆产种类明显不同,这可能是由于台湾产种类为适应岛屿特殊生境所致。 中国秋海棠组植物的体细胞染色体数目变异范围最大,包括了与其它组基数相同的种类。说明秋海棠组是一个分化极其多样的类群,也可能说明依据宏观形态划分的秋海棠组是一个不自然的类群,其中可能包括了中国秋海棠属其它组的种类。细胞学的研究也不支持棒果组的成立。 5 形态分支分析 由于所选取的性状参数不够多,加之秋海棠属植物的环境饰变普遍存在且程度较高,分支树的分辨率和内部支持率都不高,梳子状结构较明显。一致性指数CI=0.35,表明所选用形态性状中非同源性状所占比例可能较高,从而影响了系统发育重建的可靠性和准确性。 6 分子系统学 trnL-F片断在中国秋海棠属植物中较保守,不适合用于系统学研究。基于ITS序列的分子系统研究表明,秋海棠组表现出明显的多系现象。主要依据子房特征而划分的秋海棠组存在着较多的人为因素,是一个非单系类群;分子系统学的结果同样不支持棒果组的成立。 7 系统学综合结论 综合形态学和分子系统学的研究,我们提出中国秋海棠组的分类系统如下: 为了便于说明,首先将依据宏观形态划分的秋海棠组称为广义秋海棠组(B. sect. Diploclinium s.l.)。 我们认为较自然的中国秋海棠组应该只包括广义秋海棠组中石灰岩生境类型的球茎种类。癞叶秋海棠(B. leprosa)、昌感秋海棠(B. cavaleriei)以及具有相同或类似特性的种类应从广义秋海棠组划分出来,另立为新组或归属侧膜组(需结合更多的侧膜组种类来证明)。分子系统发育树上显示单裂组(B. sect. Reichenheimia)与广义秋海棠组的球茎种类有着较近的亲缘关系,并最先从后者分化出来。将叶片中裂以上的种类从广义秋海棠组提出来而归并到二室组中或新的组中(因为系统树中没有二室组的模式种,二室组的系统位置难以确定)。粗喙秋海棠(B. crassirostris)应从广义秋海棠组中提出来而归入四室组。四室组在中国秋海棠属植物中为自然的单系类群,同时在中国秋海棠属植物中较晚出现。广义秋海棠组中具类浆果的根状茎种类应另立为新的组。广义秋海棠组中其它类型的种类及台湾产种类的归属问题需结合更多其它种类的系统学证据才能加以确定。 3 保护生物学研究 根据IUCN(3.1版)的标准,中国秋海棠组70%以上的种类都处于濒危至极危的状态。以本组古林箐秋海棠(B. gulinqingensis)为研究对象开展的保护生物学研究认为:导致其濒危的首要原因为人为的干扰和破坏,其特殊生境的限制也是主要的原因。此外,还与其自然更新能力差、外来入侵物种的干扰、无性繁殖能力弱等因素有关。相应的解危措施为:首先要加强宣传和保护力度;野外采集或引种时,尽量仅采集一定比例的成熟果实;迁地保护,利用人工无性繁殖的手段扩大引种的种群规模;回归引种,直接恢复或扩大原产地种群规模。 4 繁殖生物学与引种驯化 无论是种子繁殖还是人工无性繁殖,对秋海棠组植物来说都相对较容易。这不仅可以扩大原产地的种群规模,还可以用于回归引种。在引种地大部分中国秋海棠组植物生长状况良好,常见的病虫害也能得到有效控制。
英文摘要: The morphological and cytological characters of the genus Begonia sect. Diploclinium were studied. The phylogenetic relationship of sect. Diploclinium together with other Begonia sections was discussed based on cladistics and molecular phylogenetic studies. The threatened status of Chinese Begonia sect. Diploclinium species was determined on the basis of IUCN Red List Categories and Criteria (Version 3.1). In addition, some notes on production biology and plant introdunction were inferred from the conducted conservation biology studies on sect. Diploclinium species especially on B. gulinqingensis. The main results are summarized as follows: 1 Phylogeny (1) Pollen morphology High diversity existing in pollen morphology was shown in species of sect. Diploclinium. Among them, many shared similarities and might be much more closely related with species of other Begonia sections, and should be excluded from sect. Diploclinium. Thus, the size and sculpture on the surface of pollen are probably one of the best parameters to characterize sections of Begonia effectively. It was also suggested that the species with lager pollens could be more primitive, while those with smaller ones might be much advanced. The proposal of sect. Leprosae was not well supported. (2) Seed micromorphology High diversity in seed mircromorphology was also shown in species of sect. Diploclinium. Among them, many shared similarities and might be much more closely related with species of other Begonia sections, and should be excluded from sect. Diploclinium. Thus, the morphological features of seed are probably the other parameters to characterize sections of Begonia effectively. It was also suggested that the species with lager seeds could be more primitive, while those with smaller ones might be much advanced. The proposal of sect. Leprosae was also not well supported. (3) Characters of leaf epidermis Our study of characters of leaf epidermis under light microscope and scanning electron microscope indicated that high diversity exists in Chinese Begonia. Although the characters did not show its importance to the taxonomy at sectional level of the genus Begonia, it showed some value to the treatment of specific treatment. Additionally, stomatal group is discovered in B. peltatifolia and B. fenicis which might be adapt to the arid surroundings. (4) Cytology Based on this study and literature survey, we infer that aneuploidy and polyplodization have played an important role in the speciation of Chinese Begonia. X=15 is suggested to the basic chromosome number for Chinese Begonia. The other sections of Chinese Begonia might have evolved from sect. Coelocentrum by descending or ascending aneuploidy alteration.Our cytological studies also revealed high diversity in sect. Diploclinium. Among them, many shared similarities and might be much more closely related with species of other Begonia sections. Thus, the somatic chromosome number is probably not a good parameters to characterize sect. Diploclinium of Begonia effectively. The proposal of sect. Leprosae was also not well supported. (5) Cladistics The Constant Index of the strict consensus tree was only 0.35, implying that there were too many non-homoplasy characters were used in cladistic analysis. So the key of phylogenetic studies of the examined taxa was to find out exact characters which could indicate actual evolutionary lineages. (6) Molecular phylogeny Based on both MP and Bayesian analysis using sequence data from internal transcribed spacer (ITS) regions of nuclear ribosomal, it was indicated that sect. Diploclinium based on morphology are polyphyletic. The sect. Leprosae was not supported as monophyletic. Thus the separation of the traditionally accepted sections according to the characters of ovary was not well supported. The existing infragenetic morphology-based system is imperfect. The evolutionary rate of the trnL-F might be too slow to analysis in Chinese Begonia species. (7) Conclusion Based on the morphological, cytological and molecular phylogenetic studies, the sect. Diploclinium was considered an assemblage of taxa strictly around the type species (B. grandis), and reported here in its strict sense, while the traditionally acceptation based on morphology was in the large sense. The plants with tubers and the limestone habitats delimit sect. Diploclinium species from other sections of Begonia. Thus, A few taxonomic implications were inferred: B. leprosa, B. cavaleriei and other sect. Diploclinium s. l. species which share some characters should be excluded from sect. Diploclinium s. str. and incorporated to sect. Coelocentrum or a new section; B. crassirostris should be a member of sect. Sphenanthera; species with modarate to deep lobed leaves should be included in sect. Platycentrum or proposed as a new section; species with modarate to deep lobed leaves should be proposed as a new section; the situation of species from Taiwan remained unclear, it should need to be used in combination with other characters for separating taxa in this complex; two new species B. guaniana and B. gigabracteata were described and illustrated. The evolution of pollens, seeds, and pattern of anticlinal walls of leaf epidermis were speculated. The evolution approach of pollens might be from large size to diminutive, from shallow sculpture on the surface to deep; the evolution of seeds might be from large size to diminutive; while the evolution of attern of anticlinal walls of leaf epidermis might be from straight, arched to undulant. Finally, it was also suggested that the species of the sect. Coelocentrum might be primitive, while these of the sect. Diploclinium might be originated from the ancient species closely related with sect. Coelocentrum species. In correspondingly, sect. Reichenheimia which was also closely related with sect. Diploclinium might be more primitive than sect. Sphenanthera. 2 Conservation biology Our studies on the conservation biology of Chinese Begonia sect. Diploclinium suggested that more than 70% species were in danger of extinct. The main factor threatening to the survival of the Chinese begonias was hunman activities which caused the disturbance or destruction of the habitats. In order to protect this resourse effectively, there are some details should be noted: more knowledge-transference to local people; proper collectiong methods in fieldword; introduction and reintroduction. 3 Production biology and introduction Most of the the Chinese Begonia sect. Diploclinium species had two types of effective productive patterns: asexual and sexual production. It was not only useful to cultivate in greenhouse but also reintroduction in the field to increase the number of population. Some in situ and ex situ conservation studies were conducted by our research group and some results have been achieved.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/272
Appears in Collections:昆明植物所硕博研究生毕业学位论文_学位论文

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中国秋海棠属秋海棠组系统学与保护生物学研究.马宏[d].中国科学院昆明植物研究所,2008.20-25
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