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题名: 木通科的系统演化与生物地理学
作者: 王峰
学位类别: 博士
答辩日期: 2002
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: 木通科 ; 系统发育 ; 生物地理学 ; 花器官发生 ; 非编码序列
中文摘要: 从花器官早期发生、胚胎学、分支系统学、分子系统学、生物地理学等方面综合研究了木通科的系统发育和演化历史.主要研究结果如下:1.花器官发生木通科植物成熟的花属于功能上的单性花,但早期发生属于两性花的发生方式."2.胚胎学在木通科内,花药壁由表皮、纤维状药室内壁、2~3层中层和分泌型绒毡层组成(日本野木瓜为变形绒毡层).八月瓜的绒毡层细胞为2~4核,五风藤为2核.小抱子形成方式均为同时型,四分体的排列方式有四面体型(猫耳屎、木通属、日本野木瓜、八月瓜和五风藤)和交叉型(木通属、日本野木瓜、八月瓜).在木通属、八月瓜属内以及日本野木瓜中,四分体的排列方式存在多样性.散粉时均为2细胞花粉.早期胚珠直生,双珠被、厚珠心.后期胚珠变为弯生(木通属、五风藤)或倒生(猫耳屎、日本野木瓜).珠孔只有内珠被参与形成.大孢子四分体排列为T型或线型(日本野木瓜、八月瓜),只有线型(猫耳屎和五风藤),只有T型(木通属).反足细胞除猫耳屎之外,都比较小,存在时间短.木通科为寥型胚囊,细胞型胚乳.胚的发育属于紫菀型.根据现有资料,各属之间的区别并不明显,尤其是本科基部类群猫耳屎属,在某些特征方面和较演化的类群八月瓜属比较一致.3.分支系统学对43个形态学性状进行了分支系统学分析,得到68个同等简约树,其50%多数规则一致树的结构,与Loconte&Estes(1989)、Loconteeta1.(1995)、Takhtajan(1997)、覃海宁(1997)族的划分系统基本一致,如基部分支的猫儿屎族,次基部的拉氏藤族,单型的串果藤族和较特化的木通族.4.分子系统学基于所有的分子数据,不管是保守的基因序列如atpB,rbcL和18S(HootetaL.1995a,1995b),还是本研究的非编码序列(转录问隔区、内含子、基因间隔区),木通科作为一个单系类群,都得到了较强的支持.5.生物地理学根据分子系统发育树,猫耳屎属位于基部的位置,而且具有许多较原始的特征,因此,其分布区可能更接近于木通科的祖先分布区.而南美两个属处于较演化的位置,因此,Shuster(1976)的提出的木通科起源于冈瓦纳古陆的假说可能难以成立,如果木通科起源于冈瓦纳古陆,那么作为祖先残遗的南美两属应位于分支树的基部,但分子和形态数据的系统发育分析都不支持这样的结论.木通科的起源地应该在欧亚大陆上.总的来说,花器官发生的特征演化与类群所处的系统位置比较一致,而胚胎学特征与系统位置的关系不明显.大血藤应独立成科.木通科内的族的划分与系统发育的演化水平一致.长萼木通属是否成立需要更多的证据,牛藤果属的地位应予以确立.东亚-南美间断分布的起源在白垩纪初期,隔离分化学说更适于解释这种古老的地理分布格局.
英文摘要: The phylogeny and evolutionary history were comprehensively investigated based on floral organogenesis, embryology, cladistics, molecular systematics and biogeography. The main results were summarized as follows: 1 .Floral organogenesis The mature flowers in the Lardizabalaceae are functionally unisexual, whereas their early developments belong to the bisexual initiation. Based on character analysis, the two initiation patterns of the sepals were all occurred in the basal Decaisnea, each of which was inherited in the derived taxa. The monocyclic initiation of the stamens could be a symplesiomorphy, whereas bicyclic initiation was an apomorphy. The diversity of stamen number could also be an apomorphy. The gain and loss of petals were occasionally occurred in the family and two sampled species with petals {Sinofranchetia chinensis and Holboellia angustifolia} were distantly divergent. The simultaneous initiation of three carpels was plesiomorphic, whereas only two carpels initiation of Sinofranchetia could be apomorphic or automorphic. The complex patterns of carpel initiation in Akebia trifoliata var. australis should only be automorphic for the absence of such pattern in other species. The conduplicate carpels, which could be a synapomorphy of the Lardizabalaceae, together with whorled centripetal initiation of floral organ, were firm evidence of the close relationship between the Laridizabalaceae and the Berberidaceae. 2. Embryology In the family, the anther wall comprised the epidermis, fibrous endothecium, two to three middle layers and secretary taptetum (Staimtonia hexaphylla possessed amoeboid taptetum). Holboellia latifolia had 2~4 nucleied taptetum, but Holboellia angustifoUa only had 2-nucIeied taptetum. Simutaneous cytokinesis followed meiotic divisions in microspore mother cells in all sampled members of the family. The, tetrahedral and decussate tetrads both occurred in Akebia, Stauntonia hexaphylla, and Holboellia latifolia and only decussate tetrads in Decaisnea and Holboellia. The pollen grains shed at 2-celled stage. The early development of ovules were orthotropous, later, became campylotropous (Akebia and Holboellia) and anatropous (Decaisnea and Stauntonia), bitegmic and crassinullate. Only the inner integument formed micropyle. The megaspore mother cells developed into linear or T tetrads (Stauntonia hexaphylla and Holboellia latifolia), only linear tetrads (Decaisnea and Holboellia angustifoUa) and only T tetrads (Akebia). The antipodal cells were small and ephemeral except in Decaisnea. The chalazal functional megaspore developed into a Polygonum embryo sac. The embryogeny conforms to Asterad type and the development of endosperm is of the cellular type. Generally, the embryological characters were not consistent with the phylogenetic relationships. Some characters, such as micorspore and megaspore tetrads form, were shared by distant related taxa, Decaisnea and Holboellia angustifoUa. 3. Cladistics The Lardizabalaceae were caldistically analyzed based on 43 morphological characters sensu lato. The 50% majority rule consensus tree of 68 equally most parsimonious trees showed that, the outgroup Sargentodoxa was nested within the Lardizabalaceae and sister to Boquila with low bootstrap support (52%), the Lardizabalaceae was sister to Nandina, while Menispermwn and Circaeasteraceae were distant, respectively. Within the family, Decaisnea diverged at the very base, to which the tribe Lardizabaleae (incl. Sargentodoxa) was next. Sinofranchetia was not resolved basal but still external to tribe Akebieae, which consist of Archakebia, Akebia, Parvatia, Holboellia and Stauntonia with a bootstrap support of 60%. The two species of Akebia was well supported by a bootstrap value of 87%. The newly erected Archakebia was sister to Akebia with a bootstrap value of 60%. The three genera Parvatia, Holboellia and Stauntonia (PHS) were resolved as trichotomous, with Stauntonia monophyletic (65%). However, Holboellia was not monophyletic for its speceies being paraphyletic to Staimtonia. The main topology was consistent with the tribal classifications of Loconte & Estes (1989), Loconte et al.(1995), Takhtajan (1997) and Qin(1997). The position of Sargentodoxa was questionable for the abnormal variation of character sepal trace. 4. Molecular phylogeny The monophyly of Ladizabalaceae was strongly supported, not only based on conserved gene sequences, but also non-coding region (internal transcribed spacers, intron and intergenic spacers). In all cases, the Lardizabalaceae was always sister to Sargentodoxa. Within the family, the basal clade was Decaisnea, and shared submarginal placentation with Sinofranchetia. The rest taxa of the family shared laminar placentation. The two South American monotypic genera traditionally included in one tribe, but were not consistently supported by molecular data. Generally, gene sequences inclined to reject their sister relationship, except that atpB gene provides low support (64%). Conversely, non-coding sequences all provide strong support for it, as well as combined molecular data. Tribe Akebieae were also strongly supported by molecular data based analysis. Therefor, the tribe classification was also congruent with molecular phylogenetic analysis. ITS, trnL-F separated analysis and combined analysis with rbcL gene did not support the genus Archakebia, except for trnL-F and rbcL combined analysis. ITS trees and combined trees with other sequences also resolved Parvatia as basal to the sampled assemblage of Holboellia and Staimtonia. In some case, Parvatia was nested within Holboellia clade on chloroplast sequences based trees. The nonsynonymous substitutions were more consistent through the familiar ranges than synonymous substitutions and were used for molecular clock estimate. The nonsynonymous substitution rate (Ka) was 3.85 *10~(-11) per site per year after fossil calibration. Therefore, the divergent time between South American clade and Eastern Asian clade was estimated at 130 million years ago (Kimmeridgian of Upper Jurassic) The origin of family was estimated at 143 million years ago (Valanginian of Lower Cretaceous). 5. Biogeography Based on molecular phylogeny, Decaisnea was basal and the South American clade was derived, therefore the South American taxa could not be ancestor of the family and the areas in which Decaisma distributed or assumed to occur would be the craddle of the family. The Gonwanaland origin would be rejected and the Laurasia would be the origin area of the Lardizabalaceae. In the light of the origin time of 143 million years ago, the evolutionary history could be reconstructed as follow: during the end of Jurassic, the ancestor originated in the south of Lurasia, then spreaded into Gonwanaland before the completely separation of Pangaea. Then, the two main clades developed in the isolated environment. The emergence of the Himalayas in the Tertiary caused rich diversity of Eastern Asia Ladizabalaceous plants, whereas the limited habitat and climate made it undeveloped in South America. If the inferred phylogeny for the family was true, the vicariance patterns for the biogeographic history was favored. Generally, the floral early developments are consistent with phylogenetic relationship within the family, while embryological character' show little congruence with the phylogeny. As for taxonomy, the position of Parvatia should be recognized and that oi Archakebia is questionable and needs more evidences. The Eastern Asian and South American disjunct originated in the early Cretaceous following the vicariance events.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/634
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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木通科的系统演化与生物地理学.王峰[d].中国科学院昆明植物研究所,2002.20-25
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