【作者】 杨娟；

【导师】 赵桂仿；

【作者基本信息】 西北大学 ， 植物学， 2008， 博士

【摘要】 金钱槭属（Dipteronia Oliv.）隶属于槭树科（Aceraceae）,是北温带植物区系中古老、残遗的木本属之一,为中国特有属。属下仅包括金钱槭（D.sinensisOliv.）和云南金钱槭（D.dyerana Henry）两个种。该属植物的现代分布区和化石分布区存在显著的差异,其化石存在于东亚及北美的第三纪,而现今仅残存分布于中国的秦岭山脉及其以南的横断山脉和云贵高原等地,居群小而分散,数量极其有限,因此被列为我国珍稀濒危保护植物。本研究利用AFLP分子标记、叶绿体微卫星（cpSSR）标记以及叶绿体基因非编码区（trnL-trnF,trnD-trnT,rps12-rpL20,rps16 intron）序列研究了金钱槭属内金钱槭17个群体和云南金钱槭4个居群的遗传多样性水平和居群遗传结构、及其与地理格局之间的关系,并提出相应的保护策略;检测物种及种内群体水平的叶绿体DNA单倍型类型和多样性,分析了金钱槭属叶绿体DNA单倍型的地理分布,推测该属植物可能的冰期避难所。探讨了该属植物种群进化历史及属内两物种的遗传分化。主要的研究结果如下:1、遗传多样性分析表明:金钱槭属内金钱槭（AFLP:H=0.3319,Hsh=0.4880;cpSSR:H_T=0.9676）和云南金钱槭（AFLP:H=0.3047,Hsh=0.4450;cpSSR:H_T=0.9144）皆具有较高的遗传多样性水平,而且金钱槭的遗传多样性高于云南金钱槭。2、居群遗传结构分析表明:金钱槭属内金钱槭和云南金钱槭种间产生了较大的分化(AFLP:F_ST=0.3904,p＜0.001;cpSSR:F_ST=0.4424,p＜0.001);种内群体间的遗传分化程度也较大(AFLP:金钱槭:G_ST=0.3678;云南金钱槭:G_ST=0.3266)(cpSSR:金钱槭:G_ST=0.8120;云南金钱槭:G_ST=0.7067),群体间的基因流匮乏。相关性检验表明:种间、群体间的地理隔离是造成其遗传分化程度较大的主要原因。3、基于前人研究基础之上的分子系统发育分析发现:金钱槭属内的两物种金钱槭与云南金钱槭并不总是聚成一个单系群,云南金钱槭常被置于槭属内,表明两物种种间已经产生了剧烈的分化;与金钱槭相比,云南金钱槭是更加进化的物种。4、基因组的AFLP标记和叶绿体SSR标记结果比较表明:金钱槭属内叶绿体基因组是通过母系遗传的;本研究两物种的花粉流与种子流的基因流比值为:金钱槭:5.4;云南金钱槭:3.0,表明:在金钱槭和云南金钱槭种内有限的基因流水平中,花粉传播为主要的基因交流方式。5、叶绿体DNA单倍型分析表明金钱槭属内金钱槭和云南金钱槭种间无共享单倍型,叶绿体SSR标记和基因序列分析表明:金钱槭属植物存在多个分散的冰期避难所,其中云南金钱槭主要避难于其现今分布的云南省东南部地区,而金钱槭由于其分布区比较广泛,主要的避难所有秦岭山脉、大巴山山脉、伏牛山山脉、武陵山脉、神农架山脉等。6、种群历史动态分析（Tajima’s D=-1.045,P＞0.01,Fu and Li’s D^*=-1.175,P＞0.01,Fu and Li’s F^*=-1.316,P＞0.01）和叶绿体单倍型网状关系图（未呈星状）皆表明该属植物进化历史上未曾发生明显的扩张,推测其现今的地理分布很可能是最后一次冰期退却时分布的保存。7、生境的破坏是导致金钱槭属植物濒危的主要原因。cpSSR分析揭示了每个居群都有其特有单倍型,而且发现该属植物进化历史上未曾发生明显的种群扩张。因此,建议采取以下保护策略:①尽可能的对所有的金钱槭属植物的每个居群的具体生境加以保护;②对遗传多样性较高的群体进行保护以维持其较高的遗传变异水平;③对遗传多样性较低的居群应考虑从其他自然群体移栽金钱槭个体以增加群体的遗传变异;④在对金钱槭和云南金钱槭居群进行就地保护的同时开展迁地保护也是必要的;⑤在迁地保护取样时尽可能从更多的自然群体中取样,通过加大居群间种子和幼苗的交换,人为制造大居群、大空间,创造基因交流和重组的条件,以保存物种尽可能多的遗传变异。更多还原

【Abstract】 The genus Dipteronia Oliv.（Aceraceae）,endemic to China,consists of two species, D.sinensis Oliv.and D.dyerana Henry.Both species are rare and endangered,are only found in the Qinling Mountains,Hengduan Mountains and Yunnan-Kweichow Plateau in China,and have only small and sparsely distributed populations with limited individual numbers.Therefore,they have been listed as Chinese Rare and Endangered Plant Species.Dipteronia is one of the woody relic genera in the floristic region of the northern temperate zone.The fossil record shows that species of this genus were once distributed in China（late Eocene）and North America（from the late Paleocene to the early Oligocene）in the Tertiary（Amy and Steven 2001;WGCPC 1978;Manchester 1999）.Based on AFLP markers,cpSSR markers,and the sequences of several chloroplast non-coding regions（trnL-trnF,trnD-trnT,rps12-rpL20,rps16 intron）,the aims of this study are:to characterize genetic structure and intra-species genetic diversity of 17 populations within D.sinensis and 4 populations within D.dyerana,as well as the relationship of genetic structure and geographical distribution among populations;to propose the corresponding protect strategies;to examine the type and diversity of chloroplast haplotypes within species and populations;to analyze the distribution of chloroplast haplotype and presume the possible ice age refuge of this genus;and to discuss the species evolution history and the inter-species differentiation.The main results of this study are as follows:1.The genetic diversity analysis found that both species had a high level of genetic diversity,and there were higher level of genetic diversity in species D.sinensis （AFLP:H=0.3319,Hsh=0.4880;cpSSR:H_T=0.9676）than in D.dyerana（AFLP: H=0.3047,Hsh=0.4450;cpSSR:H_T=0.9144）.2.The genetic differentiation showed that there occurred a significantly high level of genetic differentiation between D.sinensis and D.dyerana(AFLP:F_ST=0.3904, p＜0.001;cpSSR:F_ST=0.4424,p＜0.001),Significantly high differentiation was also detected among populations within D.sinensis(AFLP:G_ST=0.3678,cpSSR: G_ST=0.8120)and within D.dyerana(AFLP:G_ST=0.3266,cpSSR:G_ST=0.7067), the gene flow between populations was limited,The Mantel test between the genetic distances and geographical distances suggested that high genetic differentiation among populations within D.sinensis and D.dyerana might be caused by geographical isolation.3.Based on the former study of molecular phylogenetic,Dipteronia species did not always form a clade,species D.dyerana was sometimes embedded within Acer species.It shows that there occurred a significantly high level of genetic differentiation between D.sinensis and D.dyerana,and D.dyerana was considered to evolve faster than D.sinensis.4.The comparative result of nuclear AFLP markers and chloroplast SSR markers generated in the present study are interpreted under the assumption of maternal inheritance of the chloroplast genome in Dipteronia.The gene flow ratios found low ratios of pollen flow to seed flow（5.4:1 in D.sinensis vs 3.0:1 in D.dyerana）, thus,indicating that the gene flow in both D.sinensis and D.dyerana was mainly contributed by pollen rather than by seeds.5.No common chloroplast haplotype was observed between the species.The combined analysis with cpSSR and chloroplast non-coding gene sequences found that there were several disperse glacial refugia within species of Dipteronia,the main glacial refugia for species D.dyerana was its recent distribution southeastern-yunnan province,and with abroad distribution,the main glacial refugia of D.sinensis were Qinling mountains,Daba mountains,Funiu mountains, Wuling mountains and Shennongjia mountains.6.The population history dynamic analysis（Tajima’s D=-1.045,P＞0.01,Fu and Li’s D^*=-1.175,P＞0.01,Fu and Li’s F^*=-1.316,P＞0.01）and chloroplast haplotype network（not like star）suggested that Dipteronia might not have obvious expansion during its evolutionary history,and inferred that the recent geographical distribution of this genus might be the distribution conservation of which in the last ice age.7.The main reason to make the Dipteronia plant endangered was destroying of its habitats.Because of cpSSR revealed that each population has its own haplotypes, and Dipteronia might not have obvious expansion during its evolutionary history, the main protect strategies are as follows:①To protect the habitat of each population to the greatest extent;②To protect the population which have high genetic diversity in order to maintain the high genetic variance;③To transplant individuals to the population with low genetic diversity from other natural populations in order to increase the genetic variance;④The in situ conservation as well as the ex situ conservation were all necessary for this genus protection.⑤The sampling strategies for ex situ conservation was sampling individuals from natural populations as much as possible,and by enlargement the exchange of seeds and young plants among populations,to make big population,great space,and create the chance for gene flow and gene recombine in order to preserve the most genetic variance to the greatest extent.更多还原