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题名: 雪胆属的分子系统演化与生物地理学研究
作者: 李洪涛
学位类别: 博士
答辩日期: 2007-06-08
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: 李德铢
关键词: 雪胆属 ; 分子系统学 ; 系统演化 ; 生物地理
学位专业: 植物学
中文摘要: 雪胆属Hemsleya为东亚分布区型中国-喜马拉雅分布区亚型,分布于中国的西南至东南以及邻近的越南、泰国、印度和尼泊尔等国,中国是本属的现代分布中心。该属的系统学研究中还有以下几个问题需要解决或确认:(1)雪胆属是否是一个单系类群;(2)它的姊妹类群是谁;(3)马铜铃是否能构成一个单型亚属;(4)传统的属下分类系统是否合理;(5)形态性状的演化与系统发育的关系如何;(6)现代地理分布格局的成因。 该属到目前为止还没有完整的分子系统学研究,本文综合形态学和分子系统学的研究手段,对雪胆属进行了系统重建,主要研究了雪胆属的姊妹类群、属的范畴、属下系统关系,并对生物地理学进行了初步探讨。主要结果如下: 1、形态学研究 对以前研究中形态性状的一些模糊和不确定的认识予以了澄清:块茎成串是一种普遍存在的现象;花冠类型除典型的平展、前伸和反卷外,H. dipterygia、H. delavayi和H. mitrata的花冠是介于平展和反卷的过渡类型。通过结合形态性状和分子系统学研究,发现并确立了新种H. kunmingensis。 2、姊妹类群研究 分子系统学的研究结果表明,在两个可能的姊妹群中,锥形果属与雪胆属的系统关系更为紧密,雪胆属的姊妹群是锥形果属,而并非先前研究中认为的可能是锥形果属和绞股兰属共同构成雪胆属的姊妹群。 3、分子系统学研究 基于ITS、rpl16和trnH-psbA三个基因序列对雪胆属及其近缘属25种以及基于ITS、rpl16、trnH-psbA、trnS-trnR和RPB2五个基因序列对雪胆属及其近缘属25种进行分子系统学研究的结果表明:雪胆属是一个单系类群,属下形成两支,一支由H. graciliflora构成的单型亚属马铜铃亚属,另一支则为其余所有种组成的雪胆亚属。 分子系统学的研究结果在整体上支持李德铢的分类系统,该分类系统中的8个自然类群有7个在分子系统树上得到了反映和支持,只有曲莲亚组这一类群没有获得相应的反映和支持。雪胆属的系统演化与现代地理分布联系密切,地理因素在该属的系统演化中发挥着重要作用。 分子系统学研究也揭示出形态性状的进化规律:花冠的进化是由膜质平展的类型向肉质前伸和肉质反卷两个方向分别演化,后者是演化的总体趋势,肉质反卷类型也朝向两个方向演化,其一为由平展经历反卷的过渡类型到盘状花冠,另一则为由平展经历反卷的过渡类型到灯笼状花冠。块茎由无地下块茎向有地下块茎演化。复叶的小叶数由5-7小叶向7-9小叶演化。种子由有种翅向种翅退化、无种翅演化,由适应风力传播的小种子向适应度过不良环境的具发达胚和坚硬种皮的种子演化。 4、分类学处理 综合传统系统分类与分子系统学研究,在李德铢系统的基础上对雪胆属作了分类学修订,其基本构架同李德铢的分类系统,但取消了其中的曲莲亚组和蛇莲亚组,建立了新组征镒雪胆组,同时对各组、亚组的种的组成进行了部分调整。 5、生物地理学研究 基于先前的研究成果和分子系统学研究,对雪胆属的现代地理分布格局的形成进行了探讨,康滇古陆是雪胆属的分化中心(多样化中心),起源中心与分化中心大部分重叠,但起源中心偏向于多样化中心的东侧,该属可能起源于早第三纪末晚第三纪初(渐新世至中新世)。 雪胆属的系统演化与其地理分布密切相关,隔离分化在雪胆属植物的系统演化中起着关键的作用,隔离分化是物种分化、新物种形成的主要动力。在雪胆属早期的系统演化过程中,传播扩散是该属分布区扩张的主要因素,而在以后的系统演化进程中隔离分化起着主导作用,雪胆属植物现代地理分布格局的形成是两者共同作用的结果,尤其是隔离分化在中后期的演化中起主导作用。
英文摘要: The genus Hemsleya Cogn. a Sino-Himalayan element, is distributed in southern China, and adjacent northern Vietnam, northern Thailand, northeastern India and eastern Nepal. China is the center of modern geographical distribution. Controversial themes still retained unresolved in Hemsleya as follows: (1) whether Hemsleya was a monophyletic group or not; (2) which group was its sister group; (3) whether H. graciliflora built a monotype subgenus or not; (4) the phylogenetic relationships of sections and species within Hemsleya; (5) the relationships of morphologic characters and phylogenesis; (6) how the modern distribution of the genus was formed. This paper presented the first molecular phylogeny of the genus Hemsleya using nuclear RPB2, ITS, and plastid trnH-psbA, rpl16 and trnS-trnR DNA sequences to reconstruct the phylogenetic relationships among Hemsleya species. Focuses of the study were made to include the sister relationships of Hemsleya, circumscrption of Hemsleya, intrageneric phylogenetic relationships, and biogeography. The major results were summarized as follows: 1. Morphology Morphological characters are most important evidence of identification, classification and taxonomy. Our studies on morphology clarified some morphological characters. Bunchy tubers are ubiquitous in the Hemsleya. Except typical rotatable, bowl-like, and spherical, umbraculiform or patelliform corollas, there are intermediate corolla forms, such as in H. dipterygia, H. delavayi and H. mitrata. Based on morphological and molecular evidence, it was suggested that Hemsleya could harbor more than 24 species. Consequently, a new species, H. kunmingensis, was discovered and described. 2. Sister group Subtribe Gomphogyninae is composed of the genera Hemsleya, Gynostemma and Gomphogyne. Analyses of molecular data based on ITS, rpl16 and trnS-trnR sequences revealed that the Gomphogyne was the only sister group of Hemsleya. It did not corroborate the results of previous studies, which it dealt the Gomphogyne and Gynostemma as the sister groups of Hemsleya. 3. Molecular phylogeny Analyses were carried out based on ITS, rpl16 and trnH-psbA DNA sequences of 25 taxa of Hemsleya and related genera and based on ITS, rpl16, trnH-psbA, RPB2 and trnS-trnR of 25 taxa, respectively. The results showed that the genus Hemsleya was a monophyletic group with two clades corresponding to the two subgenera: Graciliflorae and Hemsleya. Subgenus Graciliflorae only contained a species, H. graciliflora, and the subgenus Hemsleya harbored all remaining species. The molecular phylogeny was corresponding to Li’s classification in principle. The topologies of molecular phylogenetic tree covered seven natural groups of Li’s classification, while subsection Amabiles was not supported. The phylogeny of Hemsleya correlated well with the geographic distribution of the species. It was suggested that geography, habitat and other ecological factors would predominantly act as vital driving forces in the evolution of Hemsleya. The molecular phylogeny also revealed the evolution of morphologic characters, thus the character-state transformations can be inferred as follows: Tracing the corolla on the molecular phylogeny suggested that the membranous patulous radiate corollas were ancestral character in the Hemsleya, and they were evolved towards carnificate bowl-like corollas and carnificate revolute spherical or patelliform corollas. Palmate compound leaves comprising less than 7 leaflets, stems without tubers and seeds with seed-wing represented the ancestral stage in the Hemsleya; on the contrary, palmate compound leaves comprising more than 7 leaflets, stems with tubers and seeds without seed-wing represented the derived stage. 4. Taxonomic revision A taxonomic revision of Hemsleya was proposed based on analyses of multidisciplinary data. The systematic treatment was generally in agreement with Li’s classification, but subsections Amabiles and Sphaerocarpae were excluded, simultaneous, the new section Chengyihanae was proposed. Meanwhile, the systematic position of some species among sections and subsections of Hemsleya was re-revaluated and rearranged. 5. Biogeography Based on the molecular phylogeny and the statistical analyses of the geographical distribution, the modern patterns of the geographical distribution of Hemsleya were discussed. It was proposed that Kangdian ancient landmass was the center of distribution and diversification of Hemsleya, as well as the center of origin. Furthermore, the center of origin was in the east of Kangdian ancient landmass. The genus Hemsleya could be originated at the transition of between Paleogene and Neogene (Oligocene and Miocene). The relationships of between phylogeny and geographic distribution suggested that vicariance acted as the key role to the evolution of Hemsleya. It was the major driving forces for differentiation and speciation of Hemsleya. At the early stage of evolution of Hemsleya, dispersal acted as the main factors of expanding distributional area. Subsequently, vicariance became the dominant factors. The modern geographical distribution of Hemsleya was the results of dispersal and vicariance, while vicariance was the vital factor at later stage.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/170
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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雪胆属的分子系统演化与生物地理学研究.李洪涛[d].中国科学院昆明植物研究所,2007.20-25
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