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题名: 杜鹃花科白珠树族系统发育与生物地理学
作者: 陆露
学位类别: 博士
答辩日期: 2009-05-18
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: 杜鹃花科 ; 越桔亚科 ; 白珠树族 ; 孢粉学 ; 种子形态学 ; 分子系统学 ; 生物地理学
学位专业: 植物学
中文摘要: 白珠树族(Gaultherieae)是杜鹃花科越桔亚科(Vaccinioideae)中的一个单系群,包括6属约250种,呈典型环太平洋分布,主要分布在热带亚洲和热带美洲。该族内各属的系统位置和属间关系一直以来倍受争议。分子系统学的初步研究虽已确定白珠树族为一单系,但族下系统关系较为复杂,特别是该族最大的属——白珠树属(Gaultheria)为一并系,属下的传统分类也受到了极大挑战。因此有待对该族扩大取样进行全面研究。本研究基于孢粉学和种子形态学实验手段,研究了白珠树族相关形态特征的演化过程,为进一步对该族的分类学修订提供了重要的形态性状;通过分子系统学实验手段,重建白珠树族的系统发育。并结合前人的工作,对白珠树族地理分布样式成因和可能的起源地进行了初步探讨。主要研究结果如下: 1孢粉学 对白珠树属以及越桔亚科11个属,即地桂属(Chamaedaphne)、金叶子属(Craibiodendron)、簇白珠属(Diplycosia)、串白珠属(Eubotrys)、Gaylussacia、木藜芦属(Leucothoe)、南烛属(Lyonia)、Oxydendrum、马醉木属(Pieris)、Satyria和越桔属(Vaccinium)84种86个样品的成熟花粉进行观察。结果表明:白珠树属及越桔亚科其它相关属的四合体花粉大小、萌发孔和外壁纹饰差异较大,具有一定的分类学意义。孢粉学支持Middleton系统的Gaultheria Ser. Trichophyllae和G. Ser. Hispidulae,也支持Satyria和越桔属、地桂属和串白珠属有较近的亲缘关系。越桔亚科花粉形态的演化趋势是由小到大,沟长由短变长、由窄变宽,极面由光滑或多少有些模糊的皱纹状纹饰至皱纹状纹饰,沟间区纹饰的演化趋势由颗粒状通过颗粒-皱纹状至皱纹状。花粉大小和纹饰特征与地理分布有一定的关系。首次发现白珠树属三个种(即:芳香白珠、G. lancifolia和鹿蹄草叶白珠)的花粉表面具有粘丝。 2 种子形态学 选取代表白珠树族6属和相关类群83种90个样品(包含7个变种)的成熟种子进行观察。结果表明:白珠树族的种子在形状、颜色、大小、种翅和种脐结构,特别是初级种衣纹饰和表皮细胞特征和表皮细胞中缝线以及一些特化结构等方面表现了高度的多样化。Andromeda、地桂属、Satyria和Zenobia都具有较独特或在属下较一致的种子形态特征。种子形态学支持了Middleton系统的白珠树属一些属下关系。钝尖椭圆形状、种子扁平、侧部翅化和种脐区域明显突起作为共同衍征有力地支持了‘Eubotryoides + 木藜芦属’分支。种脐突起是串白珠属的共同衍征。推测种子斜锥状为冬绿群(Wintergreen group)一个可能的共同衍征。小型种子是白珠树属美洲类群与东亚类群构成的相关分支可能的共同衍征。负网状初级纹饰是白珠树属部分种+腺白珠属可能的共同衍征。表皮细胞形状对白珠树族没有太大的系统学意义。白珠树族种子形态多样化与地理分布有一定的相关性。种子形态多样化可能是对该类群不同种子散布方式的适应,一些特化的种子结构具有特殊的生态功能。 3 白珠树族分子系统学 利用rpl16、trnL-F、trnG-S和matK四个叶绿体片段,选取环太平洋分布的白珠树族105种121个样品进行分子系统学研究。研究表明:白珠树族和冬绿群均为单系,与前人的结果一致,但得到更强的支持。木藜芦属、串白珠属均为单系。簇白珠属和腺白珠属也为单系,但是嵌入了白珠树属中,使该属成为一并系。Eubotryoides和木藜芦属构成的分支是该族最早分化的类群,但Eubotryoides不能成立,应归入木藜芦属。串白珠属和地桂属位于白珠树族次基部。冬绿群形成了五个单系群:“亚洲—美洲分支”、“北美—日本分支”、“中国—喜马拉雅分支”、“大洋洲—中南美分支”和“东亚—美洲分支”。网状进化同样也可能发生在白果白珠中,该种可能沿着滇东南向东南亚扩散时,经历了这一历史事件,使祖先类群朝着马来群岛的白果白珠原变种演化。新西兰、澳大利亚和塔斯马尼亚分布的所有类群构成单系。Gaultheria insipida、G. strigosa、G. buxifolia 和G. antarctica可能是南美洲类群向大洋洲类群的中间过渡类群。 4 白珠树属“中国—喜马拉雅分支”的分子系统学 利用ITS、rpl16、trnL-F、trnG-S和matK五个分子片段,选取中国—喜马拉雅地区分布的33种(其中31种为已知种,2种为产自西藏墨脱的未知种)90个样品进行分子系统学研究。研究表明:“中国—喜马拉雅分支”分为两个单系群,即大叶类群和小叶类群。大叶类群的演化可能经历了快速辐射进化的过程。大叶鹿蹄草叶白珠可能是一个杂交种,而小叶鹿蹄草叶白珠可能为其母本。短穗白珠和铜钱叶白珠的关系可能是“中国—喜马拉雅分支”中杂交物种形成的一个例子,短穗白珠可能是一个新近形成的杂交种。根据铜钱叶白珠RBGE35在系统树位置的推断,铜钱叶白珠类群内部可能发生了杂交多倍化或叶绿体基因组渐渗。小叶类群可能存在着复杂的网状进化。其近缘类群形态的相异可能是对不同生境趋异适应的表现,而远缘类群形态的相似则是对相同生境趋同响应。 5 白珠树族生物地理学初步研究 白珠树族基部位置和最早分化的主要节点上都显示出该族的祖先分布地是温带北美洲,也即白珠树族起源于温带北美洲,这为杜鹃花科及其科下阶元起源地的“boreotropics”假设又提供了有利的证据。亚洲则可能是白珠树族内相关类群起源地。Gaultheria Sect. Amblyandra和G. Sect. Hispidulae系的东亚北美类群之间具有较近的亲缘关系,也为 “boreotropics”假说中“陆桥”解释提供了有力证据。温带南美洲是大洋洲类群的起源地,这个类群可能分化为两支,一支向热带南美洲扩散,另一支则通过鸟类的越洋传播至大洋洲(新西兰、澳大利亚和塔斯马尼亚)。另外,簇白珠属的形成可能是隔离分化的结果。长距离扩散和隔离分化在白珠树族的演化中均可能发挥了重要作用。
英文摘要: The tribe Gaultherieae, consisting of six genera (ca. 250 species), forms a monophyletic group within subfamily Vaccinioideae of the Ericaceae. It exhibits a distinctive amphi-Pacific distribution and the bulk of the distribution is tropical and subtropical. The intergeneric and infrageneric relationships of Gaultherieae based on morphological study have been debated for a long time. The monophyly of Gaultherieae has been confirmed by preliminary molecular studies up to now, while the systematic relationships in most genera are still unclear and Gaultheria, the largest genus within this tirbe, was determined as a paraphyletic group. Comprehensive sampling is required to further phylogenetic study. In this dissertation, palynology and seed morphology of Gaultherieae were studied for employing more critical characters (synapomorphies) for the reclassification. The phylogeny of Gaultherieae was reconstructed based on the molecular data (ITS, rpl16, trnL-F, trnG-S and matK) with intensive sampling. Origins and biogeographic patterns in Gaultherieae were preliminarily discussed. 1. Palynology The pollen morphology of 86 samples from 84 species of Gaultheria and closely related genera of the subfamily Vaccinioideae, Chamaedaphne, Craibiodendron, Diplycosia, Eubotrys, Gaylussacia, Leucothoe, Lyonia, Oxydendrum, Pieris, Satyria, and Vaccinium was investigated with light and scanning electron microscopy. The tetrahedral size, aperture and exine ornamentation (apocolpia and mesocolpia) of pollen grains are variable. Viscin threads on the pollen grains of members of Gaultheria are reported for the first time. Infrageneric relationships of Gaultheria are discussed on the palynological basis. Pollen data support the sister relationships between Satyria and Vaccinium and between Chamaedaphne and Eubotrys as reported by previous molecular phylogenetic analyses. The evolution of pollen characters is traced by character optimization. It seems that an evolutionary trend of mesocolpium ornamentation within Vaccinioideae from granulate through granulate–rugulate to rugulate is apparent. 2. Seed morphology The seed morphology of 90 samples from 83 species of the tribe Gaultherieae, represented by Chamaedaphne, Diplycosia, Eubotryoides, Eubotrys, Gaultheria, Leucothoe, and Tepuia and its related tribes Andromedeae represented by Andromeda and Zenobia and Vaccinieae by Satyria was investigated with stereoscopic and scanning electron microscopy. The seeds exhibit high morphological diversity in shape, color, size, wing, hilum region, primary ornamentation and epidermal cells. Seed characters corroborate the delimitation of Andromeda, Chamaedaphne, Leucothoe, Satyria, and Zenobia, and some classifications within Gaultheria. Small seeds trend to be evolved from larger ones, and areolate seed coats may have been evolved from a reticulate primary ornamentation. The presence of seed wings, a flattened and ellipsoid-mucronate shape, and distinct hilum protuberances are synapomorphies for the clade comprising Eubotryoides and Leucothoe. Obliquely pyramidal seed shape, small seed size, and areolate primary ornamentation could be potential synapomorphies for some major clades of Gaultherieae. Seeds of the Gaultherieae from East Asia, temperate North America, and the Pacific are more diverse than those from tropical America. Samples from the eastern Himalaya possess the highest variation in seed morphology. The wings and bulging edge cells observed in seeds of Leucothoe suggest wind dispersal. 3. Molecular phologenetics within Gaultherieae The phylogeny of 121 taxa from 105 species within the whole tribe Gaultherieae was estimated from separate and combined analyses of four cpDNA sequence data sets (rpl16, trnL-F, trnG-S and matK). Both Gaultherieae and the wintergreen group are monophyletic with strong support. The monophyly of Leucothoe and Eubotrys is also supported, respectively. Diplycosia and Tepuia are monophyletic but nested within other species of Gaultheria. Eubotryoides was not supported by molecular evidence while a clade comprising species of Eubotryoides and Leucothoe are the earliest diverged within Gaultherieae, with Eubotrys and Chamaedaphne as the next diverged one. The wintergreen group consists of five major clades: an Asian-Amrican Clade, a North Amrican-Japan Clade, a Sino-Himalayan Clade, an Oceania-Latin American Clade and an East Asian-American Clade. Reticulate evolution may be involved in the speciation of G. leucocarpa, which might have spread from China to the Southeast Asia via Southeast Yunnan. All the Oceanian samples form a clade with strong support. G. insipida, G. strigosa, G. buxifolia and G. antarctica might be the phenotypic and genetic transitions between South American and Oceanian taxa. 4. Molecular phologenetics within the Sino-Himalayan Clade The phylogeny of 90 taxa from 33 species (including 2 unknown species) within the Sino-Himalayan Clade was estimated from separate and combined analyses of five DNA sequence data sets (ITS, rpl16, trnL-F, trnG-S and matK). The Sino-Himalayan Clade was resolved to consist of two subclades: the large-leaved one and the small-leaved one. Rapid evolutionary radiation may be involved in the large-leaved subclade due to the low resolution topology of some species. It is likely that the large-leaved Gaultheria pyrolifolia with might be a hybrid and the small-leaved G. pyrolifolia with might be a parent. The peculiar relationship between G. notabilis and G. nummularioides may be an appropriate example for hybrid speciation. G. notabilis might be a recent hybrid. Conflict of the systematic position of G. nummularioides RBGE35 between nuclear and chloroplast genes suggested ThybridizationT and Tpolyploidy, orT introgression of chloroplast DNA occurs during the evolution of the G. nummularioides complex. Reticulate evolution may also be common in the small-leaved subclade. The discordance of the molecular and morphological patterns in the small-leaved subclade could be results of ecological adaption. 5. Preliminary study on the biogeography of Gaultherieae By tracing the geographic distribution onto the Bayes phylogeny from combined analysis with parsimony optimization, a North American origin was assigned to the base of the tribe. It positively supports the boreotropics hypothesis for the origin of the Ericaceae. Asia might be the center of origin for some groups within Gaultherieae. The close phylogenetic relationships among those East Asian – North American samples within Sect. Amblyandra and Ser. Hispidulae to some extent suggest the “Land bridge” explanation for the dispersal of Gaultherieae. The Oceanian taxa may be derived from the temperate South American ancestors. It could be inferred that the Gaultherias in the temperate South America may have dispersed towards both tropical South America and Oceania (New Zealand, Australia). The speciation of genus Diplycosia might be resulted from the vicariance. Long-distance dispersal and vicariance may facilitate evolution of the tribe Gaultherieae.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/374
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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杜鹃花科白珠树族系统发育与生物地理学.陆露[d].中国科学院昆明植物研究所,2009.20-25
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