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题名: 槭树科的系统学与生物地理学
作者: 田欣
学位类别: 博士
答辩日期: 2003
授予单位: 中国科学院昆明植物研究所
授予地点: 中国科学院昆明植物研究所
导师: 李德铢
关键词: 械树科 ; 金钱械属 ; 械属 ; 比较胚胎学 ; 抱粉学 ; 形态性状分支分析 ; 分子系统学 ; 系统发育 ; 生物地理学
学位专业: 植物学
中文摘要: 本文综合比较胚胎学、抱粉学、形态性状分支分析和分子系统学等多学科手段和方法,对械树科的系统发育进行了重建,集中探讨了械树科两个属间及械属下组间的系统演化关系。并在已有资料的基础上,对械树科的生物地理学问题进行了总结和讨论。主要研究结果如下:1.比较胚胎学首次报道了金钱械属(Dipteronia)的胚胎学特征,并与械属的广布种青榨械(Acer davidii)做对照,总结械树科的胚胎学性状为:花药4室,花药壁的发育为基本型,表皮宿存,药室内壁在花粉粒成熟时有纤维加厚,中层退化,绒毡层为分泌型,胞质分裂为同时型,小抱子四分体多为四面体型排列,成熟花粉粒为2细胞(械属)或3细胞(金钱械属)型;两心皮子房,弯生一倒生型胚珠,单珠被(金钱械属)或双珠被(械属),厚珠心,械属的珠孔由内珠被形成,大抱子四分体线形排列,寥型胚囊,反足细胞暂存,具珠心冠原,承珠盘有或无。比较胚胎学的结果支持械树科与无患子科和七叶树科的近缘关系,同时根据珠被数和成熟花粉粒细胞型的不同,可将械属和金钱械属明显地区分开来。2.抱粉学对械树科2属35种(其中械属20组33种)植物的花粉进行了光镜和扫描电镜的观察,结果显示:本科花粉近球形至一长球形,极面观为三裂圆形。从花粉萌发孔类型看,金钱械属具三孔沟,械属除有3组具三孔沟外,其余均为三沟。从花粉外壁纹饰看,金钱械属2个种和械属的大多数种为条纹状,罕为细条纹-拟网状和皱波状。抱粉学分析显示:按械树科花粉三孔沟到三沟的演化规律,金钱械属可能是械树科的基部类群;鸡爪械组(Seet.Palmota)和穗状械组(Sect.Spicata)可能是械属中与金钱械属关系最密切的类群;柄叶械组(Sect.Indivisa,为细条纹一拟网状外壁纹饰)和楞计卜械组(Sect.Negundo,为皱波状外壁纹饰)则可能代表了械属中较为特化的类群。3.形态性状分支分析通过45个广义的形态性状对械树科的主要类群做了分支分析,结果显示:金钱械属和械属作为姐妹群tjJ以得到较好的形态性状支持,但对于械属内部,则由于分布着大量的同塑性状状态,而不能为属下组间关系的解决提供更多有价值的信息。通过对具体的性状状态分布分析显示,对于象械属这样在形态上分化较大的类群,纯粹的形态学分支分析很难为其系统重建提供较好的解决。4.分子系统学基于对械树科(共涉及99个种,包括变种和亚种)ITS、trnL-F和rPL16内含子三个序列的单独和联合分析,得到如下分析结果:械树科作为单系类群在各个分析中都得到了强烈支持。虽然由于云南金钱械在ITS和lrnL-F序列分析中位置的不确定,使得金钱械属和械属的姐妹群关系没有得到稳固的支持,但在两个叶绿体片段(IrnL-F和rPL16内含子)的联合分析中这两个属的单系结构分别得到了强烈的支持,这也与胚胎学和形态学研究的结果相一致。由于械属显示可能是个快速分化的类群,其辐射演化的方式使得对属下类群的系统重建难以得到完全的解决。分析显示:械组(Sect.Acer)、SectGoniocarPa和sect.sa"harina被支持为一单系类群,但械组(sect.Acer)中地理分布较独立的太白深灰械(A cer ctlesit胡ssP.giraldii)的位置无法确定;东亚特有分布的三小叶械组(Sect:扣liala)、全缘叶械组(Sect.Integrifolia)和五小叶械组(Sect.Pentaphylla)被强烈支持为单系,但其内部关系不明确;另有两个较好支持的单系分支,即十蕊械组(Sect.Decandra)与Sect,Laurtna,桐状械组(sect.Plolclnoiea)与Sect.Campestria在形态上也可得到普遍支持。5.系统学处理基于比较胚胎学、抱粉学、形态学以及分子系统学等多学科的分析结果,对械树科的系统学研究做以下总结:械树科作为一个单系得到较高支持,本科与七叶树科和无患子科关系密切。金钱械属是械树科的基部类群,并和械属构成姐妹群关系。在对单系组确认的基础上,对械属提出一个包括19个组的系统框架。鸡爪械组(Seet.Polmata)和穗状械组(sect,Spicata)可能是械属的基部类群,样叶械组(sect.Negundo)和Sect.Indivisa可能是械属中较为特化的类群,部分组间关系得到一定的支持,但仍需进一步研究的确定。虽然有多学科的证据和较高密度的分子系统学取样,目前的研究表明,械属可能是一个在分化早期就表现出辐射演化的类群,因而其组间关系如果根据目前的定义难于得到进一步的解决。6.生物地理学结合系统学研究结果和现代地理分响J的统计分析,对金钱械属和械属的19个组的生物地理分布格局的形成进行了讨论,推测金钱械属在中国的局限分布可能是第四纪冰期其分布区退缩后形成的(即避难所);械属以横断山一喜马拉雅为核心的北温带分布格局可能是第四纪冰期时械属植物在部分地区(如亚洲的横断山一喜马拉雅地区和北美的落基山和阿巴拉契亚山)保存并向周围分化扩散形成的。结合化石资料、前人的研究基础和对械树科系统发育的分析,对械树科的起源、散布和分化分别作如下推测:械树科可能起源于晚白奎世前后的北美西部地区,在随后不久就分化出金钱械属和械属。械属在始新世和渐新世以后经历两次分化高峰,第一次高峰分化出械属的主要类群,第二次则主要是在种级水平的演化。械属中的部分类群在东亚一北美的间断分布可能是隔离分化的结果,东亚作为械属分布的现代中心和多样化中心,可能只是冰期后的保存中心而不是起源中心。
英文摘要: The phylogenetic relationships of Aceraceae were comprehensively investigated by means of comparative embryology, palynology, morphological cladistics and molecular systematics which, was based on three DNA regions, including nrDNA ITS and cpDNA trnL-F and rph16 intron. Furthermore, biogeography of Aceraceae inferred from fossil data and the multiple data sets was reevaluated and discussed. The results were summarized as follows: 1. Comparative embryology Embryological features of Dipteronia were reported for the first time and compared with A. davidii (Acer). The Aceraceae is characterized by: The anther of each stamen is tetrasporangiate, with five-layered anther wall and falls into the basic type of development (including a persistent epidermis, a fibrous endothecium, two ephemeral middle layers, and a secretory anther tapetum), simultaneous cytokinesis of pollen mother cells, tetrahedral or rarely isobilateral tetrads, and two- (in Acer) or three-celled (in Dipteronia) pollen grains; two campylotropous-anatropous, crassinucellate, unitegminous (in Dipteronia) and bitegminous (in Acer, and a micropyle formed by the inner integument alone), two ovules in each of the two carpels, Polygonum type of embryo sac with ephemeral antipodal cells, an epistase developed from the division of the nucellar epidermal cells, and with or without a hypostase. The embryological features of Aceraceae are related with those of Sapindaceae and Hippocastanaceae. Based on the distinct differences in the numbers of cells in mature pollen grains and the numbers of layers in integuments between Dipteronia and Acer, the two genera can be well distinguished. 2. Palynology Pollen gains of 33 species in 20 sections of Acer, together with two species of Dipteronia were observed by light microscope (LM) and scanning microscope (SEM). The shape of pollen grains in this family varies from subspheroidal to prolate in equatorial view and is 3-lobed circular in the polar view. The aperture types of both species in Dipteronia are tricolporate. This type can also be found in 3 sections of Acer, but most other species in Acer are tricolpate. As for the pollen exine sculpture, both species in Dipteronia and most species in Acer are striate, but two sections in Acer are finely striate-reticulatoid or regulate. By the studies of pollen morphology, it is inferred that: 1) sections Palmata and Spicata may be the closest groups in Acer with Dipteronia; 2) section Indivisa which, has finely striate-reticulatoid exine sculpture, and section Negundo which, has regulate exine sculpture, may be the relatively specialized sections in Acer, and 3) variation from tricolporate to tricolpate is regarded as a evolutionary trend in Aceraceae, so the genus Dipteronia may be more primitive than the genus Acer. 3. Morphological cladistics Based on the forty-five morphological characters sensu lato, a cladistic analysis of the whole family Aceraceae, including the both species of Dipteronia and the major sections of Acer was carried out. It was indicated that: 1) the sister relationship between the two genera of Aceraceae could be well supported by certain distinct characters; and 2) due to the high-level distribution of non-homologous characters in Acer, which could hardly provide more stable information on the reconstruction of the inter-sectional phylogenetic relationships under Acer, and often even mask the true phylogenetic history. It was inferred that the single morphological cladistic analysis is not necessary to result the phylogeny of the morphologically diversified genus well. 4. Molecular systematics Inferred from the separate and combined analyses based on three DNA regions (ITS, trnL-V and rpL16 intron) of Aceraceae, the phylogenetic relationships within the family were discussed in the present paper. The monophyly of the whole family, Aceraceae was strongly supported in all the analyses. The sister relationship between the two genera, Dipteronia and Acer failed to get stable support due to the ambiguous position of D. dyeriana, especially in ITS and trnL-Y analyses. However, these two potential monophylies were well resulted as sister groups with high bootstrap values in the combined analyses based on trnL-F and rpL16 data, which is congruent with morphological analysis. It was deduced that Acer had undertaken a rapid, radical diversification during its evolutionary history, and this evolutionary radiation may be an important cause for the poorly resolved phylogenetic reconstruction. Based on the molecular data analyses, some potential close intersectional relationships were inferred, such as those among sections Acer, Goniocarpa and Saccharina, that among sections Trifoliata, Integrifolia and Pentaphylla, that between sections Decandra and Laurina, and between sections Platanoidea and Campestria, which were also indicated by certain morphological features. 5. Systematic treatment Based on the analyses of multidisciplinary data, including comparative embryology, palynology, morphology and molecular sequences, a systematic treatment of Aceraceae was proposed as following: The monophyly of Aceraceae was strongly supported, and its close relationships with Hippocastanaceae and Sapindaceae were also inferred. The genus Dipteronia was the basal group in the family, and it was sister to the genus Acer. Based on the identification of the monophyly of the sections, the genus Acer was divided into 19 sections. Sections Palmata and Spicata might be basal to the remainders of the genus, and sections Negundo and Indivisa may be specialized goups. Additionally, some intersectional relationships were inferred from the multiple data analyses, although more evidence needed. As for the current research, the phylogenetic relationships within Acer were not well resolved. It is inferred that the genus may have experienced a rapid evolutionary radiation at the early stage of the diversification. Therefore, it is difficult to resolve the relationships of sections as currently defined. 6. Biogeography Based on the phylogenetic results and the statistical analyses of the geographical distribution Dipteronia and Acer (including all the nineteen sections), the formation of patterns of the geographical distribution of Aceraceae was discussed. It was supposed that: 1) The local distribution Dipteronia in China may be explained as that the population of the genus in Asia has retreated to the present distributed regions as "refugia" and survived there during the cooler glacial climates in the Pleistocene. 2) The Himalayan- Hengduan Mountains and other "refugia" conserved some Acer there and then developed and diverged outward from such "center" along different routes, and formed the geographical distribution main in north temperate zone of Acer, whose core distribution is now in the Himalayan- Hengduan Mountains. The historical biogeography of Dipteronia and Acer has been well developed based on the relatively well-documental fossil record and phylogenetic analyses recently. In this paper, we summarized and reevaluated the main issues in the origin, dispersal and diversification of the both genera of Aceraceae. It was deduced as follows: The Aceraceae maybe originate in west North America in about Late Cretaceous and diverge into two genera Dipteronia and Acer soon after. The family migrated from North America to Asia and then Europe by the Bering land bridge, and later exchanged between the two continents, North America versus Eurasia. Referring to the genus Acer, there were two supposed rapidly diversified periods during its development history. The first time might be during the Eocene when the diversification led to most sections of the genus, the second time was after the Oligocene when the diversification was mainly in the species level. The mechanism causing the East Asian-North American disjunctive pattern of some sections in Acer is inferred as vicariance event, and eastern Asia as the present center of diversity should be the center of survival, rather than center of origin.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/664
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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槭树科的系统学与生物地理学.田欣[d].中国科学院昆明植物研究所,2003.20-25
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