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题名: 单子叶植物高级分类阶元系统学及其水生起源
作者: 李晓贤
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: 周浙昆
关键词: 单子叶植物 ; 高阶分类单元 ; 化石历史 ; 形态性状分支分析 ; 分子系统学 ; 水生起源
中文摘要: 通过单子叶植物化石历史的归纳分析、形态学分支分析和分子系统学等多学科手段相结合的综合分析,本文讨论了:单子叶植物起源时间、地点、生境及可能的祖先以及单子叶植物高级分类阶元系统的演化及各主要谱系之间的系统演化关系,主要结果如下:1.单子叶植物化石历史总结分析了单子叶植物的化石资料,结合前人的研究基础和对单子叶植物高阶分类单元系统发育的分析,对单子叶植物化石历史、起源时间、地点、生境及可能的祖先分别作如下推测:由于环境和地理分布等限制引起单子叶植物的早期化石较为稀少,并且多数化石保存较差,诊断性状难辩,造成单子叶植物化石的错误鉴定。目前已知的最早的确凿无疑的单子叶植物化石是霉草科(Triirieaceae)的抱粉化石,对研究单子叶植物的起源时间和随后的分化具有重要的意义。化石研究结果支持木兰类植物和单子叶植物之间存在极为亲密的亲缘关系。化石记录分析和分子钟起源时间推断表明:单子叶植物的起源时间不少于looM",大约在白至纪的阿普梯至阿尔必期(APtian一Albian)。古老的单子叶植物祖先类群的生长古环境是否是热带有待进一步研究证明。单子叶植物很可能是沼生起源的,随后为了适应环境,逐步向水生或沼生、陆生、腐生或寄生方向演化。2.形态学分支分析选取了单子叶植物的49个科级类群和其他13个基部被子植物类群做为研究对象,采用不赋根的外类群方法,选用93个形态性状进行系统发育分析。基于1684棵树的严格一致树显示:古草本类植物(52%),泽泻目(67%),露兜树目(55o),姜目(900/0),以及广义的香蒲科(包括黑三梭柳(93%)为单系类群。古草本类植物和单子叶植物是姐妹群关系。在单子叶植物内部,最基部的类群是由具有网状脉的类群薯锁科、百部科和孩葵科构成。性状状态间存在着较多的平行和逆转进化,这在一定程度上影响了系统发育重建的准确性。此外,所选择的性状状态之间的演化很可能是平行的、多次的或者是特化的状态,因此,这样复杂的演化关系很难通过简约化的分支分析来重建。如此形态学系统分支分析得到的单子叶植物的具网状脉的基部类群构成和与古草本植物之间的姐妹群关系需要谨慎对待。为了避开对系统学分析造成干扰的误导性状很可能需要结合DNA序列分析,从而得到更深的了解。3.分子系统学基于对单子叶植物58科86属101种和单沟花粉类双子叶植物和三沟花粉类双子叶植物28科40属50种的matK,rbcL和185rDNA序列的单独分析和联合数据分析,以及对心皮融合和习性两个形态性状的系统演化重建,得出如下结果:本文的分子系统学研究结果支持由胡椒目、樟目、木兰目和林仙目构成的真木兰类植物是单子叶植物的姐妹群,姐妹群关系在三个基因联合分析中得到98%的支持率。联合分析鉴定出11个单子叶植物主要谱系和10个其他被子植物谱系中(单子叶植物主要谱系:葛蒲目,广义泽泻目,无叶莲科,薯预目,露兜树目,天门冬目,百合目,棕搁目,禾本目,姜目,鸭茹草目;其他的被子植物谱系有:Amborellaceae,睡莲目,木兰藤目,金鱼藻目,真双子叶植物,金粟兰目,真木兰类复合群(木兰目,樟目,林仙目,胡椒目)。在单子叶植物内,葛蒲目(葛蒲属)是单子叶植物最早分化的一个谱系,广义的泽泻目(包括天南星科和岩曹蒲科)紧随其后分化出来,二者依次和其余单子叶植物类群构成姐妹群关系。葛蒲目和其他所有单子叶植物之间的姐妹群关系,在三个基因片断的联合分析中得到97%的强烈的靴带值支持。无叶莲科紧随广义的泽泻目之后分化出来,无叶莲科和剩余的单子叶植物类群形成姐妹群的关系,并得到了较高的支持率。继无叶莲科之后分化的类群形成两个大的分支:一支是由露兜树目和薯拔目构成,二者形成姐妹群的关系:另一支是由天门冬目、百合目和鸭拓草类复合群组成,三者之间的目一姜目之间的关系,有待进一步解决。值得注意的是,无叶莲科的其他单子叶植物类群(除葛蒲目和泽泻目外)之间的关系在本文中获得较高的支持率,以及薯预目和天门冬目作为单系类群在序列联合分析中都得到了较好的靴带值支持,而这些在以往的研究中通常支持率较低。鉴于首蒲科和无叶莲科独特的系统演化位置,本文支持将其分别独立成首蒲目和无叶莲目的分类学界定。广泛分布于北温带湿地的曹蒲目和主要分布于北温带(但个别更广布)淡水或沼泽环境中的广义泽泻目依次是单子叶植物的最早期分化的两个谱系,而单子叶植物的姐妹群是真木兰类复合群。结合本文的系统学研究结果和前人对单子叶植物起源方面的研究,关于单子叶植物的水生起源问题进行了讨论,推测单子叶植物现存的最古老的谱系确定是沼生的,这一推论和本文对单子叶植物化石历史的研究得到的结果相吻合。对于整个被子植物而言,被子植物的习性原始状态仍然不清楚;离生心皮是被子植物的原始性状。就单子叶植物而言,基于习性和心皮融合的系统演化结果表明:(1)单子叶植物的习性祖先状态和心皮融合祖先状态不十分明确,但离生心皮在单子叶植物内部是衍生状态或者是合生心皮的逆转演化。(2)习性和心皮融合的演化重建结果均支持单子叶植物和胡椒目之间的关系比单子叶植物和真木兰类的其他三个成员之间的关系更加亲密。
英文摘要: The higher-level phylogeny and aquatic origin of the monocotyledons were comprehensively investigated by means of statistical analyses of the fossil history of the monocotyledons, morphological cladistics and molecular systematics which was based on three DNAregions, including cpDNAmatK and rbcL and nrDNA 18s rDNA. The results were summarized as follows: 1. The fossil history of the monocotyledonsBased on the overview of the fossil history and the higher-level phylogenetic results of monocotyledons, the inferences were proposed as follows:Our investigation of the putative monocotyledonous fossils revealed that the fossil record of monocotyledons, particularly during the Cretaceous, is sparse and generally preserved poorly which should be responsible for the difficulties of recognizing and discriminating these monocotyledons remains. This is partly attributable to the low diversity, or severely limited in ecological or geographical distribution. The earliest unequivocal evidence of monocotyledons in fossil record is the occurrence,of triuridaceous flowers which are very significant for the origin and divergence of monocotyledons. Our results support that there are intimate phylogenetic relationships between the monocotyledons and magnolinoids which were also indicated by many molecular research. Considering the fossil record combined with molecular clock data, we estimated the age of extant monocotyledons is at least 100 million years before present (Aptian-Albian in Cretaceous). More data from various research are needed to prove whether the ancestral monocotyledons origined from tropical paleoenvironment. Our results also suggest' that all monocotyledons originated as marsh plants, to adapt to a new environment, envolved from marsh groups to aquatic groups, or to terrestrial groups, or to saprophytes or parasites groups. 2. Morphological cladisticsSixty-two species including 49 representatives of monocotyledons and 13 other angiosperms samples were cladistically analyzed with unrooted outgroup methods based on 93 morphological characters. The results supported that paleoherbs and monocotyledons are a sister groups. The basic taxa of monocotyledons are composed by reticulate-venation groups which were Dioscoreaceae, Stemonaceae and Smilaceae. The strict consensus tree showed that the paleoherbs groups with 52% bootstrap value, Alismatales with 67% bootstrap value, Pandanales with 55% bootstrap value, Zingiberales with 90% bootstrap value, and Typhaceae s.l. (including Sparganiaceae) with 93% bootstrap value, all these clades were monophyletic.The resolution and support of the topogy were generally low which implied that the non-homoplasy character were relatively in high degree which means that we should be carefully to explain the results. We assumed that the key problem for the phylogenetic studies on these species was to find the exact characters that may imply the real evolutionary history. 3. Molecular systematicsPhylogenetic relationships of 86 families 126 genera 151 species of angiosperms, including 58 families 86 genera 101 species of monocotyledons, were inferred from mafK, rbcL and 18s rDNA sequences in the present paper. These samples represented the major lineages of monocotyledons and the basal angiosperms. The analyses of three separate data sets and various combined dada sets were performed using the parsimony methods. Based on analyses of combined data sets of three genes, we reconstructed the evolution of two important traits, habits and carpel fusion.Trees resulting from the parsimony analysis are similar to those generated by earlier single or multiple gene analyses, but their strict consensus tree provides much better resolution of relationships among major clades. The eumagnolinoids composing of Magnoliales, Laurales, Canellales, Piperales appear as sister to the whole monocotyledons, which receives 98% bootstrap support in the combined analyses of three gene. The monophyly of eleven clades of monocotyledons (Acorales, Alismatales s.l., Petrosaviaceae, Dioscoreales, Pandanales, Asparagales, Liliales, Arecales, Poales, Zingiberales, Comelinales) and ten clades of other angiosperms (Amborellaceae, Nymphaeaies, Austrobaileyales, Ceratophyllales, eudicots, Chloranthales, Magnoliales, Laurales, Piperales, Canellales) was supported in the strict consensus tree of combined analyses. The results showed that Acorales (Acorus) is a sister group to all the other monocotyledons, which received 97% bootstrap value in the combined analysis of three genes. A clade comprising Alismatales s. 1. (including Araceae and Tofieldiaceae) is diverged as the next branch, sister to remaning monocotyledons. Following the Alismatales s.l. clade, Petrosaviaceae are placed as a sister group of the clade comprising the Dioscoreales-Pandanales clade, Asparagales, Liliales and commelinoids. The sister-group relationships is strongly supported between Petrosaviaceae and the remaining monocotyledons (except for Acorales and Alismatales s. L), between Dioscoreales and Pandanales, between Commelinales and Zingiberales in the combined analyses of two genes and three genes. However, the phylogenetic relationships among Asparagales, Liliales and commelinoids are still uncertain in current analyses. In commelinoids, the relationships of Arecales and Poales still need more research in future. Furthermore, it is noteworthy that the sisiter relationship between Petrosaviaceae and the remaining monocotyledons (except for Acorales and Alismatales s. 1.) and the monophyly of Dioscoreales and Asparagales were strongly supported with a bootstrap value more than 90%, which generally received a bootstrap value less than 50% in the previous studies. Considering the special position of Acoraceae and Petrosaviaceae, we support the taxonomical treatment of Acoraceae and Petrosaviaceae in their own order Acorales and Petrosaviales.Combining our phylogenetic results with those of earlier studies about the origin of monocotyledons, the aquatic origin hypothsis was discussed. It is supposed that the most primitive extant monocotyledons were marsh which provided another proof for the inference of the fossil history of monocotyledons.Our character reconstructions indicate that the ancestral habit in whole angiosperms is still unclear, and apocarpy is ancestral for the basal angiosperms. In the case of monocotyledons, the ancestral characters of habit and carpel fusion are equivocal, but it is possible for the apocarpy to be derived feature in monocotyledons or apocarpy in monocotyledons represented a reversal from syncarpy. The results of our character reconstructions elaborate that monocotyledons are more closely related to Piperales than to other three groups of magnolinoids.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/748
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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单子叶植物高级分类阶元系统学及其水生起源.李晓贤[d].中国科学院昆明植物研究所,2005.20-25
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