蕨类植物起源与系统发生关系研究进展

蕨类植物是一群非常古老的植物,在其漫长的演化历史中丢失了大量的系统发生信息,因此重建其系统演化关系是蕨类植物学家所面临的重要任务之一。近年来的分子系统学研究已经确立了一些类群的系统关系,但现存的蕨类分类系统和系统发生关系还有很多谜团有待揭开。化石记录表明蕨类植物最早出现于大约4亿多年前,但大部分现代真蕨类缺少足够的化石证据。它们的起源时间和方式及其内部各类群的系统发生关系等诸多问题的解决,还有待于大量形态学和不同分子水平上的实验数据的进一步积累,并结合其直接的化石证据进行综合研究。     

石松类和蕨类植物研究进展: 兼论国产类群的科级分类系统

综述了石松类和蕨类植物系统发育的最新研究成果。目前研究表明传统的蕨类植物概念(包括石松类和蕨类)需要修订, 一个关于蕨类植物的分类系统也已经发表。中国的植物多样性很丰富, 包括了世界上石松类和蕨类植物主要类群的代表。我们利用rbcL基因序列(包括国产蕨类63科中的62科179属184种)构建了系统发育树。基于rbcL序列分析所获得的石松类和蕨类各主要类群间的系统演化关系同以往对各个特定类群开展的较为密集的类群取样和多性状分析(形态学＋分子序列证据)的结果基本一致。在参考Smith等人系统的基础上, 我们尝试性地对中国石松类和蕨类植物进行了科级水平上的系统发育重排。     

蕨类植物的起源演化:对"古老"类群的重新审视

一般认为,蕨类植物是一群非常古老的植物,其演化历史可以追溯到4亿多年前。近十几年来,由于多种研究手段的应用,特别是分子系统学的异军突起,在蕨类植物起源演化方面取得了重要进展,使我们可以重新审视这一古老植物类群的演化历史。本文与传统观点相对比,简述了蕨类植物在分类范畴、起源演化及其重要类群间的系统演化关系方面的最新进展。     

中国现代石松类和蕨类植物分类系统概览

回顾了蕨类植物的系统分类简史,介绍了世界上石松类和蕨类植物分类研究的最新成果,即石松类和蕨类是维管植物中的两大类群,其系统发育关系逐渐明确,分类系统已经得到更新。基于新的分类系统,中国石松类有1亚纲、3目、3科;蕨类有4亚纲、11目、37科及12亚科。     

介形类系统分类与起源演化的形态、分子和化石证据

介形类(Ostracoda)因其丰富的化石记录和广布的海陆现生代表类群,而被认为是进化生物学中研究生物多样性产生机制和演变历程的颇具潜力的重要模式生物。介形类在甲壳亚门中的谱系发生位置、起源及其内部各类群间的系统关系还存在诸多争议。基于其体制构造的形态学特征,介形类被归入甲壳亚门下的颚足纲(Maxillopoda),但来自18S rDNA序列数据分析却显示Maxillopoda不是单系群。基于化石记录和壳体形态特征,高肌虫(Bradoriida)长期以来被认为是介形类的一个祖先类群,但保存有软躯体的早寒武世化石的研究表明,Bradoriida不是介形类甚至可能也不属于甲壳类。不同的研究者所强调的壳体和肢体形态特征各异,导致介形类最大的现生类群速足目(Podocopida)的四个超科之间的关系也存在诸多推测。壳体和肢体特征在系统演化意义上的不兼容,需要分子生物学等证据的介入。分子、形态和化石证据的积累及各种信息整合是系统演化研究的必然趋势。     

中国蕨类植物区系地理若干问题研究进展

在简述蕨类植物系统发生关系、传统分类系统与基于分子系统学的现代分类系统的基础上,概述了中国蕨类植物区系地理研究的现状及最新进展,并对今后的研究工作进行了展望。根据分子系统学研究,传统的蕨类植物门以及一些蕨类植物类群并不是自然类群。中国蕨类植物区系及分布的基本规律是东南多、西北少,华南、西南极为丰富,西南地区是许多温带属的分布中心。分析了中国蕨类植物区系研究的主要问题,指出关于蕨类植物在生态系统中发挥的作用,特殊生境研究、数值分析方法在蕨类区系地理中的应用,区系地理学与其他学科的交叉是今后可能的热点与亟待加强的几个领域。     

苔藓动物的起源与系统发生研究进展—形态学和分子生物学的证据

苔藓动物是后生动物中的一个重要类群。然而,和其它主要后生动物类群相比,长期以来对它的系统学研究却相对滞后。其起源,系统发生地位以及与其它后生物门类之间、其内部各高级分类群间的谱系发生关系一直存在争议。一般认为它是介于原口动物和后口动物之间的过渡类群。但是,近年来的分子系统学研究已经证实了它的原口归属。古生物学资料表明,虽然苔藓动物的大多数类群在奥陶纪已经分化出来,但它在寒武纪却缺乏任何化石记录。另外,苔藓动物起源的时间和方式、其内部各类群间的系统发生关系特别是现生类群和化石类群之间的关系等诸多问题的解决,还有待于大量的形态学和不同的分子数据的进一步积累,并结合其地层分布等各种相关资料进行综合研究。     

多足动物亚门主要类群的谱系发生与谱系年代分析——基于形态、化石和分子的综合数据

多足动物可能是最早入侵陆地环境的无脊椎动物之一。随着泛甲壳动物大类的确立,多足动物亚门的谱系发生问题已成为节肢动物研究中的焦点。基于表型性状的系统学研究中,多足动物亚门在节肢动物门中的系统分类和单系性等问题一直存在争议;化石记录的稀少又使多足动物的起源及演化历史变得迷雾重重。近年来分子系统学的进展为深入探讨多足动物谱系发生问题开辟了新的途径;分子定年的应用为探讨多足动物起源、登陆等早期演化问题提供了新的手段。谱系年代学综合了化石记录和分子定年两方面的优势,为更加精确地讨论多足动物起源、内部类群分歧时间及其地质背景奠定了基础。谱系年代分析显示,多足动物类起源于寒武纪晚期或更早;多足动物内部类群的分歧不晚于奥陶纪;而化石证据显示,多足动物的登陆事件也可能发生在这一时期,多足动物内部类群的分歧事件(及食性分化)可能与登陆过程有关。精确的多足动物亚门谱系发生关系以及谱系年代学细节还有待于进一步综合系统学、多基因和多重化石参照点的合理分析加以深入和完善,进而为早期陆地复杂生态系统的建立提供新的证据。     

壳斗演化的假说及分子系统学和化石证据

壳斗作为壳斗科Fagaceae的重要特征, 其起源、演化和多样性形成长期以来为系统学家们所关注, 有众多的观点和假说。本文在综合这些假说的基础上, 结合分子系统学和大化石证据, 讨论了壳斗演化的规律。研究结果支持壳斗具枝性性质, 来源于二歧聚伞花序最外侧小枝的假说。在比较3个壳斗演化模型的基础上, 根据4种分子系统关系的一致性重建了壳斗的演化历史: 壳斗是单系起源; 水青冈属的2果4裂瓣壳斗是最早分化的壳斗类型, 三棱栎型壳斗是较晚分化的类型; 并支持具有内裂瓣的金鳞果类型壳斗可能与其他横切面为圆形的壳斗有较近的共同祖先。这一结果也得到了多个大化石证据的支持。壳斗科多个分子系统关系的一致性和壳斗化石证据共同证实了壳斗演化的规律是从开裂向裂瓣融合、逐步简化、多向发展; 支持开裂壳斗、坚果三角形、较小、具棱或狭翅是祖征, 融合壳斗、坚果圆形、较大、不具棱是衍征。这些结果为进一步探索壳斗科的演化历史和系统发育提供了新的证据。     

分子系统学在微体古生物及相关领域中的应用

核酸（ＤＮＡ和ＲＮＡ）和蛋白等生物大分子（尤其是它们的序列资料）可作为重要的生物性状用于系统分类和演化等主题的研究。相对于形态学性状而言,分子性状不仅是前者的补充,而且具有许多前者无法比拟的优点;比如ＤＮＡ作为遗传信息的直接载体能较准确地反映生物类群之间的系统发生关系、信息量巨大、易于定量化和进行计算机分析等等。分子古生物研究包含两个方面：一、发掘化石生物分子,以提供历史生物界演化过程中的直接遗传学证据以及检验分子演化速率等方面的独特数据;二、利用现代分子生物学数据,探讨化石生物界的系统发生问题。上述两个研究方向均已成为当今演化生物学领域的热点。有孔虫等具有重要化石记录的微体生物的分子系统学研究已经开始。随着现生的和化石的生物分子资料的逐渐积累,预期在不久的将来,分子资料将成为微体古生物研究中不可缺少的重要数据之一。     

Reproductive Biology of the Pteridophyta

Because of the homothallic nature of many pteridophytes, two categories of mating are possible: intragametophytic selling (the origin of both gametes from a single gametophyte) and inter-gametophytic mating (the origin of each gamete from a different gametophyte).Various morphological and genetical criteria (placement of the gametangia on the thallus, their sequence of ontogeny, the capacity for simple polyembryony and genetic self-incompatibility) can be used to indicate the relative probability of intragametophytic selfing or intergametophytic mating. Only the former has genetic significance (i.e.complete homozygosity); if the latter is evidenced, then detailed studies of population variability are required to ascertain the breeding system.
Three types of reproductive systems involve the gametophyte generation: intragametophytic selfing, intergametophytic mating and apogamy. Apogamy generally offers the shortest gametophyte generation and the least evolutionary potential, intergametophytic mating systems generally have the longest gametophyte generation and the greatest evolutionary potential, and intragametophytic mating systems are intermediate in both respectS. It is envisioned that the interaction between gametophyte ecology and evolutionary potential is important in the evolution of a taxon's reproductive system.     

Reproductive biology of the Pteridophyta. II. Theoretical considerations

Because of the homothallic nature of many pteridophytes, two categories of mating are possible: intragametophytic selling (the origin of both gametes from a single gametophyte) and inter-gametophytic mating (the origin of each gamete from a different gametophyte).Various morphological and genetical criteria (placement of the gametangia on the thallus, their sequence of ontogeny, the capacity for simple polyembryony and genetic self-incompatibility) can be used to indicate the relative probability of intragametophytic selfing or intergametophytic mating. Only the former has genetic significance (i.e.complete homozygosity); if the latter is evidenced, then detailed studies of population variability are required to ascertain the breeding system. Three types of reproductive systems involve the gametophyte generation: intragametophytic selfing, intergametophytic mating and apogamy. Apogamy generally offers the shortest gametophyte generation and the least evolutionary potential, intergametophytic mating systems generally have the longest gametophyte generation and the greatest evolutionary potential, and intragametophytic mating systems are intermediate in both respectS. It is envisioned that the interaction between gametophyte ecology and evolutionary potential is important in the evolution of a taxon's reproductive system.     

Unresolved problems on the origin and early evolution of land plants.

The origin of land plants or embryophytes from the Charophyceae is generally accepted today by the botanists. In fact, numerous morphological, cytological, ultrastructural, biochemical and molecular characters are shared in these organisms. A fundamental problem is still constituted by the evolution of the sporophyte, i.e. the appearance of two different phase cycles (gametophyte/sporophyte alternance), although two theories ("antithetic" and "homologous") try to explain this evolutionary event.However, another phylogenetic dilemma is represented, in my opinion, either by the formation of bryophytes or by the transition from these first land plants to the pteridophytes, considering them at whole organism level.The bryophyte gametophyte is the most elaborate of the land plants. It presents several complex characters, principally the growth developmental form, the appearance of multicellular sex organs, antheridia and archegonia. Also the sporophyte shows a complicated structure that is not found in the other land plants or tracheophytes. The sporangium, in particular, exhibits some intricate morphological traits such as the peristome of true mosses for spore dispersion, the elaters of liverworts and the indeterminate growth in the hornworts.The pteridophytes are represented especially by their dominant sporophyte. This latter has the capacity to produce multiple sporangia and, in many cases, two kinds of spores which develop in male and female gametophyte (heterosporous pteridophytes). Another important characteristic of this sporophyte is its ability to become independent of the gametophyte. However, one of the most innovative character is the formation of true vascular elements (xylem and phloem).All these very large evolutionary jumps are discussed on the basis of the phyletic gradualistic neo-Darwinian theory and the punctuated equilibrium theory of Eldredge and Gould. In this context other genetic evolutionary mechanisms are also considered.Nevertheless, the origin of bryophytes and pteridophytes remain, at the moment, a mystery.     

蕨类植物的VA菌根与蕨类植物系统演化关系的研究

通过对云南热带、亚热带生长的２５６种蕨类植物ＶＡ菌根的调查,发现蕨类植物ＶＡ菌根营养者所占的比例低于被子植物;在真蕨类植物中,植物具有由ＶＡ菌根营养经兼性ＶＡ菌根营养向自养方向进化的趋势。     

Cross-phytogroup assessment of foliar epiphytic mycobiomes

The foliar surface forms one of the largest aboveground habitats on Earth and maintains plant-fungus relationships that greatly affect ecosystem functioning. Despite many studies with particular plant species, the foliar epiphytic mycobiome has not been studied across a large number of plant species from different taxa. Using high-throughput sequencing, we assessed epiphytic mycobiomes on leaf surfaces of 592 plant species in a botanical garden. Plants of angiosperms, gymnosperms, and pteridophytes were involved. Plant taxonomy, leaf side, growing environment, and evolutionary relationships were considered. We found that pteridophytes showed the higher fungal species diversity, stronger mutualistic fungal interactions, and a greater percentage of putative pathogens than gymnosperms and angiosperms. Plant taxonomic group, leaf side, and growing environment were significantly associated with the foliar epiphytic mycobiome, but the similarity of the mycobiomes among plants was not directly related to the distance of the host evolutionary tree. Our results provide a general understanding of the foliar fungal mycobiomes from pteridophytes to angiosperms. These findings will facilitate our understanding of foliar fungal epiphytes and their roles in plant communities and ecosystems.     

Breeding Systems of Three Tree Ferns: Alsophila firma (Cyatheaceae), Cyathea stipularis (Cyatheaceae), and Lophosoria quadripinnata (Lophosoriaceae)

Abstract Breeding-system data have been available for a large number and diverse array of angio-sperms for a relatively long time. In contrast, breeding systems of ferns and their allies (pteridophytes) have only recently been examined, and breeding-system data from natural populations of sporophytes are still lacking for pteridophytes representing many life-history strategies. Few studies, for example, have examined breeding systems of tropical pteridophytes, and no breeding-system data are available for tree ferns. We therefore examined the breeding systems of three species of tree ferns from Costa Rica, Alsophila firma (Cyatheaceae), Cyathea stipularis (Cyatheaceae), and Lophosoria quadripinnata (Lophosoriaceae) using enzyme electro-phoresis. Genetic data were used to estimate intragametophytic self-fertilization and F , the fixation index. Analysis of genetic data indicates that the gametophytes of these three species predominantly cross-fertilize; all three species would be characterized as outcrossers. However, some population-to-population variation in breeding system was detected in all three species. Outcrossing also typifies a diverse array of temperate ferns. Thus, despite the potential for self-fertilization, outcrossing appears to characterize the majority of pteridophytes representing a variety of evolutionary lineages, life-history strategies, and environments.     

中国蕨类植物细胞分类学研究概况

中国蕨类植物类群十分丰富,由63科230属约2600种组成,其中约有10％的种类为中国特有。迄今为止,中国蕨类植物进行过染色体计数的种类约有395种,仅占中国蕨类植物总数的15％,其中48％为多倍体。本文对中国蕨类植物细胞分类学研究的历史和现状进行了综合评述。文中论述了蕨类植物染色体数目和染色体基数在系统学上的应用以及蕨类植物染色体组型分析、多倍化、无融合生殖、多倍体复合体及网状进化的研究概况。中国20多年的蕨类植物细胞分类学研究表明,蕨类植物的染色体数目、基数、组型分析、多倍化及其繁殖方式对蕨类植物的分类、起源和演化的研究都有重要作用,对种及种复合体的鉴定、科属的划分也有重要的参考价值。并对中国蕨类植物细胞分类学研究提出了一些建议。     

Pteridophyte fungal associations: Current knowledge and future perspectives

Current understanding of the nature and function of fungal associations in pteridophytes is surprisingly patchy given their key evolutionary position, current research foci on other early-branching plant clades, and major efforts at unravelling mycorrhizal evolution and the mechanisms underlying this key interaction between plants and fungi. Here we provide a critical review of current knowledge of fungal associations across pteridophytes and consider future directions making recommendations along the way. From a comprehensive survey of the literature, a confused picture emerges: suggestions that members of the Lycopsida harbour Basidiomycota fungi contrast sharply with extensive cytological and recent molecular evidence pointing to exclusively Glomeromycota and/or Mucoromycotina associations in this group. Similarly, reports of dark septate, assumingly ascomycetous, hyphae in a range of pteridophytes, advocating a mutualistic relationship, are not backed by functional evidence and the fact that the fungus invariably occupies dead host tissue points to saprotrophy and not mutualism. The best conclusion that can be reached based on current evidence is that the fungal symbionts of pteridophytes belong to the two fungal lineages Mucoromycotina and Glomeromycota. Do symbiotic fungi and host pteridophytes engage in mutually beneficial partnerships? To date, only two pioneering studies have addressed this key question demonstrating reciprocal exchange of nutrients between the sporophytes of Ophioglossum vulgatum and Osmunda regalis and their fungal symbionts. There is a pressing need for more functional investigations also extending to the gametophyte generation and coupled with in vitro isolation and resynthesis studies to unravel the effect of the fungi on their host.     

Patterns of genetic variation detected by RAPDs suggest a single origin with subsequent mutations and long-distance dispersal in the apomictic fern Dryopteris remota (Dryopteridaceae)

Debates on speciation processes in pteridophytes have revived. In order to study the evolutionary origin of an apomictic fern species, we investigated the genetic variation in the strictly agamosporous Dryopteris remota. We determined the genotypes of 22 individuals from many different locations within the species' European distribution and of 20 individuals from a Swiss population. A previous study on isozyme variation showed no intraspecific genetic variation in a similar sample set (Schneller and Holderegger, 1994, American Fern Journal 84: 94-98). In contrast to this, four out of 12 random amplified polymorphic DNA (RAPD) primers tested revealed low genetic diversity among individuals of D. remota from different locations. Intrapopulational genetic variation was also very low, but in the single population studied, a unique multiband genotype could be detected. The geographic distribution of genetic variation found in D. remota was best explained by the assumption of a single origin, the accumulation of somatic mutations during spread, and occasional, but effective, events of dispersal over large distances. The present study thus stresses the importance of long-distance dispersal in evolutionary processes and biogeography of ferns.