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题名: 极度濒危植物五针白皮松保护生物学研究兼论松属白皮松组分子系统学和生物地理学问题
作者: 张志勇
学位类别: 博士
答辩日期: 2003
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: 五针白皮松 ; 松属 ; 白皮松组 ; 濒危原因 ; 保护生物学 ; 分子系统学 ; 生物地理学 ; 分子钟
学位专业: 植物学
中文摘要: 通过对五针白皮松生物学特性、分类地位、种群生态、群落生态、解剖生态、生理生态和遗传多样性的研究,报道了五针白皮松的濒危状况、探讨了其濒危的生态学和生物学因素,提出了相应的保护措施,同时就松属白皮松组分子系统学和生物地理学的一些问题进行了研究,主要研究结果如下:1.五针白皮松的生物学特性五针白皮松根尖纵切面和幼根横切面的解剖结构与其它松属植物一致。根尖由根冠、生长区、伸长区和根毛区四个部分组成。幼根横切面可以明显分为表皮、皮层和中柱三部分,初生木质部4个。在横切面上,五针白皮松初生叶横切面可明显分为表皮、叶肉和维管组织,下皮层不存在,叶肉有背腹之分;树脂道通常2个。次生叶的轮廓呈三角状半圆形,可分为表皮、下皮层、叶肉组织和维管组织(l个维管束);边生树脂道3-5个:气孔开口属红松型。次生叶表皮由表皮细胞、气孔及气孔间的连接细胞和石细胞组成;气孔副卫细胞4-6个,多为不规则长矩形,每两个气孔间连接细胞1-2个,在连接细胞旁有1-2个石细胞,与白皮松相似。五针白皮松茎的初生结构分为表皮、皮层、髓及初生维管组织;树皮最外面为周皮,木栓层在横切面是由一些长方形平行排列的厚壁细胞组成,成薄片状剥落;次生韧皮部由筛胞、含单宁或树脂的韧皮薄壁细胞、蛋白质细胞等组成,筛管和韧皮薄壁细胞排列较规则。筛胞为细长管形。五针白皮松花粉由本体和气囊组成,花粉全长约86.3±11.0μm,体长60.3±8.5μm,体高45.3士4.5μm;侧面观花粉本体卵圆形,极面观本体椭圆形,气囊半球形,表面有网纹。五针白皮松的染色体基数为x=12,核型公式为2n=2*=24=24m(6SAT),属于lA型核型;五针白皮松间期核为复杂染色体中心型,前期核为连续型。2.五针白皮松的分类地位传统分类学、实验分类学和分子系统学的研究结果均表明五针白皮松属于白皮松组subsect.Gerardianae亚组,也有可能代表一个亚组;五针白皮松是一个独特分类单位和进化单元,具有重要的保护意义。3.五针白皮松种群生态学研究五针白皮松种群年龄结构和大小级结构总体上为中间宽,两头窄,个体数最多的年龄级和大小级较大,缺乏小年龄级和大小级的个体,自然更新差,年龄结构偏大,种群呈衰退迹象。种群生存曲线界于DeeveyA与DeevyB之间。由于种群总的个体数量太少,容易受各种随机和非随机干扰的影响,种群灭绝的概率很大。4.五针白皮松群落生态学研究五针白皮松分布的群落中主要树种种间联结性的定量分析结果表明,两个有五针白皮松分布的群落总体种间关联性为显著正相关,其中半阳坡上的群落为正相关,半阴坡上的群落为显著正相关,五针白皮松分布的群落有从针阔叶混交林向常绿阔叶林演替的趋势。五针白皮松与其它树种总体上无关联性,表明五针白皮松是一个阳性树种,它与其它物种的共同出现往往是由于随机的因素。结合五针白皮松年龄结构并联系云南松与其它物种关系,本文推测在长期的植被演化过程中被阔叶树种排挤可能是五针白皮松濒危的原因之一。5.五针白皮松解剖生态学研究与云南松和华山松两种松树比较,五针白皮松叶的生态解剖特点更接近云南松,具有更多的强阳性叶特征,如表皮细胞大小、表皮和下皮的厚度等;叶肉组织致密度介于云南松和华山松之间;五针白皮松的气孔器大小是三种松树中最大者,可能意味着五针白皮松适应更加湿润(降水量更大)凉爽的气候。五针白皮松对光、温度和水分的要求表明它可能更加适应高海拔生态条件,目前五针白皮松分布的地点海拔只有2000m左右,可能不是它最适宜的生活环境。6.针白皮松生理生态学研究通过测定五针白皮松幼苗在不同有效光辐射下光合速率的变化,发现它的光补偿点(0.5μmolm-2S-1)与云南松(11.1μmolm-2S-1)相差无几,而与华山松(5.8μmolm-2s-1)的光补偿点则相差很大,可见五针白皮松是一个喜光树种;从五针白皮松幼苗的气温一光合速率曲线来看,它的最适光合作用气温为20℃,也与云南松一致,说明它可能与云南松一样,适宜温凉的气候条件,但是它在气温10℃时的光合速率高于35℃时的光合速率,说明它可能比云南松更喜凉爽的气候。7.五针白皮松保护遗传学研究RAPD14个随机引物共扩增出93条RAPD谱带,其中6条为多态带,多态位点百分率仅为6.45%,遗传多样性极低;shannon指数I和Nei指数h在种内也只有0.020和0.030,两个亚居群间(半阴坡亚居群与半阳坡亚居群)遗传分化程度不高,遗传分化系数几,为0.110,与大多数松科植物近似,居群每代迁移数为4.0320 ISSR17个随机引物共扩增出73条ISSR谱带,其中9条为多态带,多态位点百分率仅为12.3%,Shannon指数I和Nei指数h在种内也只有0.029和0.048,两个亚居群间(半阴坡亚居群与半阳坡亚居群)遗传分化系数Gst只有0.119。ISSR与RAPD的结果吻合。五针白皮松极低的遗传多样性可能是由于它在演化过程中遭受过严重的灾害,造成严重的瓶颈效应,丧失其大部分遗传变异。在随后的演化过程中由于遗传漂变、自交衰退等小种群现象,导致遗传多样性的进一步丧失。人类的干扰也是导致五针白皮松遗传多样性降低的因素之一。 8.五针白皮松的濒危机制和保护措施五针白皮松的是一种极危物种,主要表现为地理分布非常局限、种群数量极低并呈衰减趋势、与其它物种竞争中处于劣势、当前环境不太适宜生存及遗传多样性极低等。濒危的内在因素主要有结实率低且自然条件下由种子转化为幼苗的转化率极低、竞争力差、遗传多样性极低;濒危的外在因素主要有进化历史上可能经历过灾害性地质历史事件、灾害性的天气、人类活动破坏。针对五针白皮松严重的濒危状况,本文提出尽快建立五针白皮松保护区、开展迁地保护、加强公众教育等保护措施。9.松属白皮松组分子系统学本文补充测定了部分白皮松组部分种的rbcL、matK、rPI20-rPs18基因间隔区和trn犷内含子序列以及五针白皮松的ITs序列,并测定了22种松树的rPll6内含子序列,在此基础上构建分子系统树,得到以下结果:l)rPll6内含子的系统学意义本文首次将rPll6内含子用于裸子植物系统发育分析,rPll6内含子在松属内和白皮松组内的变异速率低于rP12O-rpsls基因间隔区和脚口tK基因,当rPll6内含子的插入缺失编码为0/1性状后,它的平均成对距离就大于matK基因(松属内0.016vs0.015;白皮松组内0.008vs0.006),由于它们长度相当,所以rPll6内含子具有更多的信息位点(41vs37)。在松属内rPll6内含子并不是cpDNA上进化最快的区域,但是由于它具有相当数量的有系统学意义的插入缺失,当这些插入缺失编码后,可用于属下种间系统发育分析。2)白皮松组为并系类群五个cPDNA基因片断联合分析的结果中,亚洲的白皮松组成员与白松组的成员(包括扁叶松)聚在一起,形成一个单系,并得到100%的靴带值支持,白皮松组其它在美洲的成员构成这个分支的姐妹群,证明白皮松组为并系类群;在ITS树上,白皮松组也为并系。由于本研究取样充分,统计检验可靠(靴带值高),因此结果更加可靠。3)白皮松组各亚组的范畴及其系统学关系Price etal(1998)的subsect.Cembroides是一个并系类群。广义的subsect.Cembroides(包括尸陀edows脚l')下有四个主要的传代线:l)P.nelsonii;2)P.rzedowskii;3)P. maximartinezii和pinceana;4)P.cembroides种群复合体。这些传代线中尸nelsonii应该独立为亚组,其它各传代线在五个cPDNA基因片段联合树上构成一个支持率很高的分支,它们应当组成一个亚组。P.krempfii在五个cpDNA基因片段单独和联合分析的结果中与白松组或subsect.GerQrdianoe有较为密切的关系,ITs树上则为整个白松亚属的基部类群。因此,P.krempfii是一种非常孤立的松树,其系统位置比较靠近白松组或subsect.Gerardianae。Subect.Gerardianae由五针白皮松、白皮松和西藏白皮松组成,是一个稳定的单系。但是,三者之间的关系却有相互矛盾之处,cPDNA的结果支持白皮松和西藏白皮松的姐妹群关系,然后才与五针白皮松聚在一起,ITS的结果却支持五针白皮松首先和西藏白皮松构成姐妹群,然后才与白皮松聚在一起。subsect.Balfourianae是一个很好单系类群:亚组下三个种的系统学关系没有确定,在rPll6树上,P.aristata和P.longaeva首先聚在一起,然后才和尸baoriana构成姐妹群,支持率分别都为70%。但rbcL的结果却与此相反,首先是Pbalfouriana和P longaeva形成单系,然后才与P.aristata聚在一起:本文结果不支持将P.aristata独立为亚组的观点。根据前人研究结果和本文的分析,本文提出一个松属白松亚属新系统。10.松属白松亚属的生物地理学松属白松亚属广泛分布于亚洲、欧洲、北美及中美。白皮松亚组成员西藏白皮松、五针白皮松和白皮松分别分布于喜马拉雅山区西北部至阿富汗、云南东北部和中国中部;单型的扁叶松亚组分布于越南Dalat东部山区;狐尾松亚组主要分布于美国南部各洲高海拔地区;单型的连叶松亚组分布于墨西哥Nuevo Le6n南部、Tamaulipas西部和San Luis Potosi部分地区;墨西哥白皮松亚组分布于从美国爱达荷州南部(42oN)到墨西哥Puebla(180°N)的半干旱地区。美国南部到墨西哥是白松亚属的现代分布和分化中心。本文利用rbcL作分子钟推测了原置于白皮松组的各个种在松属各主要传代线上的分异时间,结果表明连叶松亚组和狐尾松亚组最早分化出来,时间大约在晚白至纪马斯特里赫特期到早古新世丹尼期之间(64.8Ma),两者的分化时间为始新世鲁帝特期(43.2Ma);白皮松亚组分化出来的时间为早古新世坦尼特期(约54Ma);扁叶松亚组和墨西哥白皮松亚组大约在始新世鲁帝特期(43.2Ma)出现;白皮松和西藏白皮松直到中新世托尔通期(10.8Ma)才出现。分子钟计算各类群的分异时间与化石记录比较吻合。结合化石资料本文推断,松属白松亚属的起源时间应该不会晚于晚白呈纪,原置于白皮松组的一些类群的地理分布格局可能是隔离分化的结果;白皮松亚组成员的分布格局与青藏高原的隆起有密切关系。
英文摘要: Pinus squamata X. W. Li is an extremely endangered pine in Yunnan, SW China with only 32 individuals in the field. The endangered situation was comprehensively documented in the present paper. The causes of endangerment and strategies for protection were investigated and discussed by analyzing the biological characteristics, the population ecology, the community ecology, the eco-anatomy, the physiological ecology and the genetic diversity of the target species and by identifying the taxonomic status. The molecular phylogeny and biogeography of sect. Parrya of Pinus were also investigated. The main results are summarized as follows. 1. Biological characteristics of P. squamata The structure of root tip in P. squamata is- divided into four parts: the root cap, meristematic region, elongation region and maturation region in the longitudinal section of the root tip. The primary structure of the roots contains epidermis, cortex and vascular tissues in the transverse section of primary roots. The primary root has four bundles of primary xylems. In transverse section, the primary leaves of P. squamata are divided into three parts, epidermis, mesophyll cells and one vascular bundle. The primary leaf is bifacial. There are two marginal resin ducts. The secondary leaves are divided into epidermis, hypodermis, mesophyll cells and vascular bundle. There are 3-5 marginal resin ducts. The stomata hatch belongs to the Korean-pine type. The epidermis of secondary leaf consists of epidermis cells, stomata, link cells between stomata and stone cells. The stoma consists of 4-6 irregular rectangular subsidiary cells and 2 kidney-shaped guard cells. There are 1-2 stone cells besides the link cells. The characteristics of leaf epidermis are similar to that of P. bungeana. The primary structure of the stem is composed of epidermis, cortex, pith and primary vascular bundles. The outer layer of the bark is periderm, The cork consists of parallel-arrayed oblong stereids, exfoliated lamelloselies. The secondary phloem consists of sieve cells, parenchyma cells containing tannin or resin. The sieve cell is long thin-tabulate. The pollen grains of P. squamata consist of two parts, a central body and two sacci. The length of the pollen grain is 86.3±11.0 um. The length of the central body is 60.3±8.5 um, while the height of the body is 45.3±4.5um. The body is ovoid in the lateral view, elliptical in polar view. The sacci are semi-spherical, possessing reticulate sculptures. The somatic chromosome numbers of P. squamata are 24. Its karyotype is formulated as follows: 2n=2x=24=24m (6SAT). The karyotype belongs to Stebbins' 1A type. The resting nucleus belongs to complex chromocenter type. The mitotic prophase chromosome belongs to the continuous type. 2. Taxonomic status of P. squamata The results of traditional taxonomy, experimental taxonomy and molecular systematics reveal that P. squamata either belongs to the subsect. Gerardianae or represents a subsection of its own. P. squamata is a unique taxon and significant evolutionary unit. It is related to P. burigeana and P. gerardiana but their relationships need to be confirmed. 3. Population ecology of P. squamata The age structure and size structure show that P. squamata population tends to decline as the population has few young individuals or small size individuals. The highest proportion of individuals occurred at the 33-year age class. The survivorship curve of P. squamata is between Deevey A and Deevey B. With few young individuals, and small size individuals, the population of P. squamata is susceptible to disturbance and has high risk of extinction. 4. Community ecology of P. squamata The interspecific association of P. squamata with other dominant woody species in its community was analyzed. The results indicate significantly positive correlation of the association of overall woody species in the two communities. There is also significantly positive correlation in the community on the north-east facing slope, but only a positive correlation in the community on the south-west facing slope. The results imply that the communities with P. squamata may be in succession from mixed coniferous and broad-leaved forest to evergreen broad-leaved forest. P. squamata has no significant correlation with other woody species, its co-occurrence with other trees may be by chances. Its. requirements for survival may be depressed by evergreen broad-leaved woody species. 5. Eco-anatomy of P. squamata Compared with P. yunnanensis and P. armandii, P. squamata is similar to the former in terms of its eco-anatomic characteristics, such as the size of epidermis cells, the thickness of epidermis and the hypodermis. P. squmata is a kind of sun plants like P. yunnanensis. The density of mesophyll is between that of P. yunnanensis and P. armcmdii. The stomatal apparatus in P. squamata is the largest in size, while the stomata density in P. squamata is the lowest among three pines. The size of stomatal apparatus and density of stomata in P. squamata may indicate its adaptation to more humid and cooler climate, which implies that the present habitat may not be the most preferable environment for P. squamata. 6. Physiological ecology of P. squamata Through measuring the net photosynthetic rate of seedlings under different effective radiation of photosynthesis, we conclude that the light compensation point (10.5μmol·m~(-2)·s~(-1)) of P. squamata is very close to that of P. yunnanensis (ll.l μmol·m~(-2)·s~(-1)), but much higher than that of P. armandii (5.8μmol·m~(-2)·s~(-1)) . This confirms that P. squamata is one kind of sun trees like P. yunnanensis. At 20 ℃ air temperature in P. squamata and P. yunnanensis and at 15℃ in P. armandii, the photosynthetic rate is the highest. As the photosynthetic rate at 10 ℃ air temperature is higher than that at 35 ℃ air temperature, P. squamata may prefer to cooler climate comparing with P. yunnanensis. 7. Genetic diversity of P. squamata Based on two molecular markers, RAPD and ISSR, the extraordinary low genetic variation of P. squamata was detected. The Shonnon index (I), the percentage of polymorphic loci (P) and Nei index (h) are 0.020, 6.45, and 0.030, respectively at species level based on RAPD markers. The results of ISSR are consistent with those detected by RAPD. The Shonnon index (I), the percentage of polymorphic loci (P) and Nei index (h) at species level revealed by ISSR markers are 0.029, 12.3 and 0.048, respectively. The genetic variation of the subpopulation of the southwestern facing slope is much higher than that of the subpopulation of the northeastern-facing slope. The genetic differentiation between the two subpopulations is low. The coefficients of gene differentiation (GJ calculated from RAPD and ISSR data are 0.110 and 0.119. The gene flow between the two subpopulations is frequent (JVw=4.032 for RAPD, JVm=3.696 for ISSR). We postulated that this ancient pine may have experienced disasters or strong bottlenecks during its long evolutionary history, which made the loss of the genetic variation. And the gene drift and inbreeding in post-bottlenecked small populations may partially attribute to the loss of genetic diversity. The human activities at present, such as logging and farming, may have further declined the genetic diversity in P. squamata. 8. Causes of endangerment and strategies for conserving the extant population of P. squamata P. squamata is a critically endangered species with a small population of only 32 individuals. Its geographical distribution is very restricted, with a very small and declining polulation and its competitive ability with other tree species is weak. The present environment is not preferable for survival and its genetic diversity is extremely low. The intrinsic factors for its endangered status mainly include the low setting percentage, the low rate of seed germination under natural conditions, the weak competitive ability and the low genetic diversity. The extrinsic factors for its endangerment may include the followings: the geological disasters during its evolutionary history, aridity in the Spring season and the disturbance of human activities. In order to conserve this rare and endangered pine, some strategies were recommended, such as to establish a natural reserve, ex situ conservation, and to reinforce public education. 9. Molecular phylogeny of Pinus sect. Parrya The rbcL and the matK genes, the rpl20-rps\8 spacer and the trnV intron of the chloroplast genome and the nuclear ribosomal ITS regions of some pines in sect. Parrya were sequenced. The rp/16 introns of 22 species of pines were also sequenced. Phylogenetic inferences were conducted based on those sequences data.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/666
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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极度濒危植物五针白皮松保护生物学研究兼论松属白皮松组分子系统学和生物地理学问题.张志勇[d].中国科学院昆明植物研究所,2003.20-25
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