中国科学院昆明植物研究所机构知识库
Advanced  
KIB OpenIR  > 昆明植物所硕博研究生毕业学位论文  > 学位论文
题名: 梅花草属植物的系统演化与生物地理
作者: 吴丁
学位类别: 博士
答辩日期: 2005
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: 梅花草属 ; 广义形态学 ; 分子系统学 ; 系统演化 ; 生物地理
学位专业: 植物学
中文摘要: 梅花草属Pall7assia L为北温带分布的类群,主要分布于东亚和北美,长期以来被认为与虎耳草科Saxifragaceae系统关系相近,APG(1998,2003)的研究则表明梅花草科与卫矛科Celastraceae近缘。存在的主要问题:(1)梅花草属是否为单系类群;(2)属下单元和种的划分是否合理:(3)属下分类系统及其系统发育关系如何;(4)现代分布格局的成因。本文采用形态学、解剖学、细胞学、抱粉学、分支系统学、分子系统学等多学利·的手段和方法针对上述问题进行探讨。主要研究结果如下:1、叶形态解剖气孔器普遍存在于叶的下表皮,少数种的上表皮也有分布,均为无规则型。叶表皮细胞形状为多边形或不规则形;垂周壁式样可区分为近平直、浅波状和波状。扫描电镜下,气孔器外拱盖内缘为近平滑、浅波状或波状;一些种的保卫细胞两端有加厚;角质膜条纹状,有的条纹隆起,有的条纹上附有颗粒或小孔穴。气孔器类型及下表皮细胞形状的一致性表明梅花草属是一个自然分类群;气孔器的分布、保卫细胞两端加厚、气孔器外拱盖内缘形态以及角质膜特征等对一组的划分和部分种的区分有一定的参考价值。2、抱粉学花粉为近球形至长球形,极而观为三裂圆形;萌发孔为三孔沟或三合孔沟,外壁纹饰为网状。种间特征较为一致,表明梅花草属是一个自然类群。在扫描电镜下,花粉外壁纹饰可区分为三种类型,即:穴一网状、细网状和粗网状,多数组的花粉外壁纹饰仅有一种类型,而sect.Nectalot,.ilobos包括了三种类型,sect,Saxifragastrum有两种类型;萌发孔沟长也存在有较大的差异,突隔梅花草Pdelal呷i沟最长,而峨眉梅花草P.faberi沟最短,与此相应的组或种均分布于中国西南部,表明该地区可能是梅花草属的分化中心。3、细胞学染色体基数有三种类型,即x==7、8和9;绝大多数的染色体长度为1一4μm,属于小染色体类型;染色体多具中部着丝点或亚中部着丝点,属stebbins(1971)的ZA型;染色体多倍化现象明显。现有资料表明,多倍体集中分布于北美,且染色体基数为x=8或9,东亚则以二倍体居多,仅少数高纬度或高海拔分布的种存在多倍体。我国的西南部山区包含有染色体基数的全部类型(x==7、8和9),x=9可能为梅花草属的原始基数。细胞学研究结果对探讨梅花草属的系统演化与生物地理具有重要价值。4、分支系统学通过46个广义的形态性状对梅花草属的主要类群做了分支分析,结果显示:梅花草属为单系类群,属下形成二个大的分支,一支由峨眉梅花草Pfaberi、宝兴梅花草尸labiata和龙场梅花草P.esql,iZolii组成,处于树的最基部,支持率仅为54%;另一支则由其它种类构成,包括分布于北美的类群,支持率为84%。由于同塑性性状居多,分支树的一致性指数不高,分析结果的准确性和可靠性需要进一步检验。5、分子系统学基于ITS、tlnL一F和trnT-L三个DNA分子片段的分支分析:梅花草属为一个单系得到了充分的支持,与其外部形态、叶形态解剖、花粉观察等结果相一致。扁平三裂组为多系,退化雄蕊扁平三裂可能是多次发生的;柱形组的龙场梅花草与唇形组的峨眉梅花草形成一稳定的分支,显示这两个组都不是单系;在ITS系统树中,扁平五裂组与五支组构成一个单系,得到强烈支持(99%),表明五枝组不是一个自然类群。显然,谷粹芝(1987)根据退化雄蕊所建立的分类系统许多组的单系性质并没有获得好的支持,分子结果显示退化雄蕊的特征是多次发生的,在不同的类群间存在着平行演化。6、分类学处理基于形态学·抱粉学、细胞学、分支系统学和分子系统学等多学科的研究,在广泛的野外调查并查阅了大量标本和文献的基础上,对梅花草属进行了分类学修订。梅花草属植物约有59种,其中2个为未详知种;属下分类系统可划为12个组,其中2组为新增,1组为新等级,并发现有11个异名。7、生物地理学基于形态学资料和分子系统学研究结果,对梅花草属的现代分布格局的形成进行推论,喜马拉雅一横断山区为梅花草属的现代分布与分化中心,云贵高原和四川一带则为可能的起源中心,起源于早第三纪甚至晚白至纪。梅花草属现代的分布格局既是物种分化的结果,也是迁移、扩散的结果。晚白至纪或早第三纪初,梅花草属原始类群形成二个分支:一支向西分布,沿着萨彦岭一阿尔泰山高原直到准噶尔海,在第三纪后半期,由于喜马拉雅的隆升,使得那时中国的一些种得到了向西继续迁移;另一支向东分布,经过白令陆桥进入北美,新旧大陆的下陷、白令海峡的最后形成和北极条件在亚洲北部和美洲的确立是梅花草属植物洲际间联系中止和现代分布格局形成的原因。
英文摘要: The genus Parnassia L. was a North Temperate genus distributed over Eurasia and North America. It has long been treated as a subfamily of Saxifragaceae, Parnassioideae. However, recent molecular systematic studied revealed that Parnassiaceae, including Parnassia and Lepturopetalon, was sister to Celastraceae. Controversial questions still remained in Parnassia mainly include: (1) whether Parnassia was a monophyletic group or not; (2) the infrageneric subdivision and the rationality of the species delimitation; (3) the phylogenetic relationships of sections and species within the Parnassia; (4) how the modern distribution of the genus was formed. In this paper, phylogeny and biogeography of the genus Parnassia were documented by means of comprehensive methods involving gross morphology, anatomy, cytology, palynology, and cladistic analyses of morphological data set and DNA sequence (ITS, fr?/L-F and trriT-lS) data sets. The major results were summarized as follows: 1. Leaf epidermis Leaf epidermis of 30 species representing all 9 sections of Ku's (1987) infrageneric divisions of Parnassia were investigated under both light microscopy (LM) and scanning electron microscopy (SEM). It was shown that the stomatal apparatus was anomocytic and present in abaxial epidermis of all species, and in the adaxial epidermis of some species. The leaf epidermal cells were usually irregular or polygonal in shape. The patterns of anticlinal walls were slightly straight, repand or sinuate. Under SEM, the inner margin of the outer stomatal rim was nearly smooth, sinuolate or sinuous, and the articular membrane of the leaf epidermis was striated, sometimes striated to wrinkled, occasionally granular or foveolate. The morphological information of the epidermis showed that Parnassia was a quite natural genus. The characters of the leaf epidermis could serve as a criterion for distinguishing some species and sections. 2. Palynology The pollen morphology of 28 species of Parnassia was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varied from subspheroidal to prolate in equatorial view and was three-lobed circular in the polar view. Pollen grains were usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species were fairly similar to each other. Morphological information regarding the pollen grains also suggested that Parnassia was a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type I, with foveolate-reticulate sculpture; (ii) type II, with a finely reticulate sculpture; and (iii) type III, with a coarsely reticulate sculpture. Most sections of the genus had one type of sculpture of pollen morphology, but Sect, Nectarotrilobos had three types of sculpture and Sect. Saxifragastrwn had two types of sculpture. All three types of sculpture could be found in southwest China, with species with the longest (P delavayi Franch,) and shortest (P faberi Oliv.) colpi, implying that southwest China was the centre of diversification of the genus. 3. Cytology The chromosome numbers and karyomorphology of 22 Chinese species of the genus Parnassia were investigated. The chromosome numbers of 16 species were reported for the first time. Parnassia had three basic chromosome numbers, namely x=7, 8, and 9. Length of mostly chromosome was l~4um, and belonged to the small chromosome type. The karyomorphology of most species was of median-centromeric or submedian-centromeric, and belonged to Stebbins'2A type. From the available data, polyploidization was common in the genus, more extensively in North America, with x=8, 9, All types of the basic chromosome numbers were found in E. Asia, in which the more species with x=9 or 2n=18, with some tetraplpid species mostly distributed in region of higher latitude or altitude. These results implied that x=9 was most likely an archaic basic chromosome number in Parnassia. All three type of the chromosome basic numbers could be found in the southwest China, This also suggested that southwest China was the centre of diversification of the genus. 4. Cladistic analysis of morphological data On the basis of extensive field observation, intensive literature survey and herbarium study, in conjuction with results of morphological, anatomic, palynological and cytological studies, forty-six morphological characters were used for cladistic analysis. Two equally most parsimonious trees were obtained by heuristic search using PAUP, and the consensus tree of them showed that there were two major clades within the genus, The first one was made up of P. faberi, P. labiata and P. esqurolii, but with low bootstrap support of 54%, while the remaining species formed another strongly support one, with a bootstrap support of 84%. All three North American species were clustered on the second clade. The relationships among sections were not well resolved, because of the high level of homoplastic characters in Parnassia, It was inferred that cladistic analysis by using morphological cladistic analysis along the phylogenetic reconstruction of the genus was very difficult. 5. Molecular phylogeny Phylogeny of the genus Parnassia was analyzed by using ITS, trriL-F and trni-L sequences data set separately or collectively, Parnassia was supported as a monophyletic group, which was also congruent with our studies of gross morphology, leaf epidermis, pollen morphology and cytology. Sect. Nectarotrilobos was resolved as polyphyletic, indicating that the flat three-lobed staminodes were evolved more than one time in the genus. P. esqurolii of Sect. Saxifragastrum and P. faberi of Sect. Cladoparnassia formed a robust clade, suggesting that both sections were not monophyletic. In the ITS-tree, Sect. Allolobos and Sect, Nectaroquingquelobos formed a strongly supported clade with a bootstrap value of 99%, revealing that Sect, Allolobos was not monophyletic. In short, Ku's sectional classification of Parnassia based mainly on the staminodes were not well supported. The features of staminodes could be evolved many times and involved parallel evolution. 6. Taxonomic revision Morphological characters and distribution of their states among taxa were reassessed based on the examination on the specimens and field observation, taking consideration of analysis of multidisciplinary data, including comparative embryology, palynology, morphology and DNA sequences, a taxonomic revision of Parnassia was proposed, The genus Parnassia consisted of 59 species including two imperfectly-known species which need to be further studied. Parnssia was divided into 12 sections, two of which were new (namely Sect. Longifolia and Sect. Excandifolia), one being new grade, i.e., Sect. Xiphosandra. 11 previously recognized species were treated as synonyms. 7. Biogeography Based on the phylogenetic results and the statistical analyses of the geographical distribution, the formation of patterns of the geographical distribution of Parnassia was discussed. It was supposed that the Himalayan-Hengduan Mountain area was the centre of distribution as well as centre of diversification of the genus. Yunnan-Guizhou plateau and adjacent Sichuan could be the centre of origin of Parnassia in or even earlier than the early Tertiary, possibly during the late Cretaceous when the North Pacific began to expand. In this paper, we summarized and reevaluated the main issues in the origin, dispersal and diversification of Parnassia, It was diverged in two major routes soon after the archaic form of the genus was originated in East Asia in early Tertiary or late Cretaceous. The first one was dispersed into the Junggar sea area along the Sayan mountains and the Altai plateau westwards. During the late Tertiary, because of the uplift of the Himalayas, some species from China were diversified during the western expansion. The other lineage migrated from East Asia to North America by the Bering land bridge. Because of the formation of the Bering Strait, the exchange between the two continents was not possible and the discontinuity was formed.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/790
Appears in Collections:昆明植物所硕博研究生毕业学位论文_学位论文

Files in This Item:
File Name/ File Size Content Type Version Access License
吴丁.pdf(5396KB)----限制开放-- 联系获取全文

Recommended Citation:
梅花草属植物的系统演化与生物地理.吴丁[d].中国科学院昆明植物研究所,2005.20-25
Service
Recommend this item
Sava as my favorate item
Show this item's statistics
Export Endnote File
Google Scholar
Similar articles in Google Scholar
[吴丁]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[吴丁]‘s Articles
Related Copyright Policies
Null
Social Bookmarking
Add to CiteULike Add to Connotea Add to Del.icio.us Add to Digg Add to Reddit
所有评论 (0)
暂无评论
 
评注功能仅针对注册用户开放,请您登录
您对该条目有什么异议,请填写以下表单,管理员会尽快联系您。
内 容:
Email:  *
单位:
验证码:   刷新
您在IR的使用过程中有什么好的想法或者建议可以反馈给我们。
标 题:
 *
内 容:
Email:  *
验证码:   刷新

Items in IR are protected by copyright, with all rights reserved, unless otherwise indicated.

 

 

Valid XHTML 1.0!
Copyright © 2007-2017  中国科学院昆明植物研究所 - Feedback
Powered by CSpace