中国铁角蕨科铁角蕨属一新记录杂交种——东方铁角蕨

该研究报道了采自山东省泰安市泰山的铁角蕨科铁角蕨属一中国新记录植物——东方铁角蕨(Asplenium×akaishiense Otsuka),并对其形态特征进行了描述。该物种形态介于过山蕨(A. ruprechtii Sa. Kurata)与细茎铁角蕨(A. tenuicaule Hayata)之间,可能是二者的自然杂交种。     

基于rps4-trnS区序列的证据分析傅氏凤尾蕨和狭眼凤尾蕨的关系

对傅氏凤尾蕨(Pteris fauriei)和狭眼凤尾蕨(Pteris biaurita)的叶绿体rps4-trnS区序列进行PCR扩增和序列分析,再结合NCBI基因数据库中已发表的凤尾蕨科及其邻近类群的rps4-trnS区序列构建系统发育树来分析两者的亲缘关系。结果显示:傅氏凤尾蕨和狭眼凤尾蕨的rps4-trnS区序列未表现出明显差异。结合两者孢子体和配子体形态发育特征以及rps4-trnS区序列的证据,认为傅氏凤尾蕨和狭眼凤尾蕨为同种或为变种关系。     

铁角蕨属4种植物配子体发育的比较研究

以腐叶土为基质培养铁角蕨(Asplenium trichomanes L.)、阿尔泰铁角蕨[A.altajense(Kom.)Grubov]、假大羽铁角蕨(A.pseudolaserpitii folium Ching)和细裂铁角蕨(A.tenui folium D.Don)的孢子,用光学显微镜观察并比较它们的配子体发育过程,以期为铁角蕨属的系统学研究提供基础资料.结果显示,4种铁角蕨属植物配子体均具有:孢子两面型、单裂缝、周壁具褶皱、书带蕨型萌发,成熟原叶体心形,原叶体具有毛状体等共同特征,表明铁角蕨属的演化处于较进化的系统位置,但它们的毛状体形态和细胞数目明显不同,可为属内分系提供依据.研究发现,4种铁角蕨属植物配子体的边缘细胞形状以及假根的形态和数量均有差异,其叶绿体能象单细胞一样进行无丝分裂,强光照射下叶绿体向相邻细胞的侧壁集中等现象.     

用叶绿体rbcL和rps4-trnS区序列确定亚洲特有单型属——篦齿蕨属的系统位置

篦齿蕨属Metapolypodium Ching是亚洲大陆特有植物, 仅含篦齿蕨Metapolypodium manmeiense (Christ) Ching 1种, 分布于中国西南及其邻近地区, 其系统位置一直是一个有待解决的问题。本文用叶绿体rbcL和rps4-trnS区序列探讨篦齿蕨属的系统位置。我们对篦齿蕨及其近缘类群的叶绿体rbcL和rps4-trnS区进行PCR扩增和序列测定。用最大简约法、邻接法和贝叶斯推断法对自测序列结合由GenBank下载的rbcL和rps4-trnS区序列进行独立和联合的系统发育分析, 所构建的系统发生树的拓扑结构基本一致。结果显示: 篦齿蕨属与多足蕨属Polypodium L. emend. Ching的关系较疏远, 而与水龙骨属Polypodiodes Ching和拟水龙骨属Polypodiastrum Ching的成员聚成一个支系, 与栗柄水龙骨Polypodiodes microrhizoma (C. B. Clarke ex Baker) Ching的关系最近。根据本文的研究结果, 我们赞成秦仁昌1978年的分类系统, 即分别承认多足蕨属、篦齿蕨属、水龙骨属、拟水龙骨属和棱脉蕨属Schellolepis J. Sm.为独立的类群。根据分子系统学证据, 宜将栗柄水龙骨转移到篦齿蕨属中。     

江苏铁角蕨的系统位置和多倍体起源

运用分子系统发育分析的方法研究了江苏铁角蕨（Asplenium kiangsuense）的系统位置及其与庐山铁角蕨（Agulingense）的关系,并探讨了该类群可能的多倍体起源方式。结果显示：江苏铁角蕨与庐山铁角蕨可能为同源四倍体,是组成倒挂铁角蕨复合体（Anormale complex）的成员之一;二者在形态特征与基因序列方面均表现一致,接受英文版中国植物志的处理,即把庐山铁角蕨处理为江苏铁角蕨的异名。     

中国蕨类植物孢子形态的研究V. 铁角蕨科

利用扫描电镜对国产铁角蕨科Aspleniaceae 8属59种植物的孢子形态进行了观察。铁角蕨科植物孢子为单裂缝,两侧对称,极面观为椭圆形、宽椭圆形或近圆形;赤道面观为肾形、半圆形、宽椭圆形、椭圆形或近圆形。极轴长17-41 μm,赤道轴长23-60 μm。外壁光滑。周壁较厚,由周壁形成孢子的表面纹饰。主要纹饰类型有6种: (1)窗孔状纹饰。铁角蕨属Asplenium的厚叶铁角蕨A. griffithianum、北京铁角蕨A. pekinense、肾羽铁角蕨A. humistratum属于此种类型。(2)脊状纹饰。铁角蕨属的假大羽铁角蕨A. pseudolaserpitiifolium、毛轴铁角蕨A. crinicaule等7种属于此种类型。(3)翅状纹饰。铁角蕨属有14种属于此种类型,如江南铁角蕨A. loxogrammioides、齿果铁角蕨A. cheilesorum等;细辛蕨Boniniella cardiophylla、过山蕨Camptosorus sibiricus、水鳖蕨Sinephropteris delavayi、对开蕨Phyllitis scolopendrium、疏脉苍山蕨Ceterachopsis paucivenosa和药蕨Ceterach officinarum也属于此种类型。(4)翅脊状纹饰。有铁角蕨属的21种和巢蕨属Neottopteris的6种属于此种类型。(5)角状纹饰。阔足巢蕨N. latibasis属此类型。(6)丝毛状纹饰。只有阔基苍山蕨Ceterachopsis latibasis属此类型。从孢粉学的角度对该科的分类和系统演化进行了探讨。     

中国篦齿蕨属植物（水龙骨科）一新组合种

根据叶绿体rbcL和rps4-trnS序列及叶脉类型、孢子纹饰特征等证据,栗柄水龙骨Polypodiodes microrhizoma（C.B.Clarke ex Baker）Ching属于篦齿蕨属Metapolypodium Ching的范畴,因此将其组合到篦齿蕨属MetapolypodiumChing之下更合理。文中报道了该新组合种,即栗柄篦齿蕨Metapolypodium microrhizomum（C.B.Clarke ex Baker）S.G.Lu et L.H.Yang。     

线蕨属（水龙骨科）的系统发育研究：来自叶绿体rbcL和rps4-trnS序列的证据

线蕨属Colysis 植物主要分布于亚洲热带和亚热带地区,少数种类分布至非洲、澳大利亚(昆士兰)及新几内亚地区.自1849年成立以来,线蕨属的分类范畴和系统位置一直有待确定.本文利用叶绿体基因组的rbcL、rps4基因和rps4-trnS基凶间隔区序列,运用最大简约法和贝叶斯方法分析了线蕨属及其近缘类群的系统演化关系.研究结果显示:(1)线蕨属和薄唇蕨属Leptochilus(含似薄唇蕨属Paraleptochilus)组成一个支持率很高的单系分支(C-L Clade),但是薄唇蕨属的成员位于线蕨属的不同支系内,支持线蕨属和薄唇蕨属合并为一个属;(2)瘤蕨属Phymatosorus单独形成一个单系分支;(3)星蕨属Microsorum是一个多系类群,除Microsorium linguiforme、M.varians和M.pustulatum与马来群岛的Lecanopteris聚在一起外,其他的星蕨属成员均位于不同的支系上.本文的系统发育分析结果为线蕨属和薄唇蕨属的分类处理提供了分子系统学的证据.     

龙骨星蕨与膜叶星蕨的关系:来自叶绿体rbcL、rps4和trnL-trnF、rps4-trnS序列的证据

龙骨星蕨(Microsoriummembranaceumvar. carinatum)是新近发表的一个变种,从形态特征看,它与原变种膜叶星蕨(M. membranaceumvar. membranaceum)可以很容易地区分。但将龙骨星蕨与另外 3种国产星蕨属 (Mi crosorium)植物叶绿体基因组中rbcL、rps4基因和trnL trnF、rps4 trnS基因间隔区进行PCR扩增和序列分析,并与已经发表的真蕨类的相应序列进行比较发现,龙骨星蕨与膜叶星蕨在所研究的 4个DNA片段中均未表现出序列差异(除了trnL trnF区的一个 2bp长度差异外 ),而所比较的其他真蕨类变种间的相应DNA片段均存在一定的差异。因此DNA序列证据不支持龙骨星蕨变种的成立。     

膜叶铁角蕨属的形态系统学研究

膜叶铁角蕨属隶属于铁角蕨科,全世界约有30种,我国分布有18种,是该属植物的分布中心之一。到目前为止,膜叶铁角蕨属的物种数目和物种分类还存在很大争议,一些物种的界限和定义还模糊不清,为了得到一个自然的膜叶铁角蕨属分类系统,还需要对膜叶铁角蕨属的物种分类做进一步研究。该文在前人研究的基础上,对膜叶铁角蕨属10种植物的形态特征,包括孢子形态特征、叶柄和根状茎上的鳞片形态特征、叶片形态、羽片形状以及叶脉特征等进行详细观察分析,探讨了各个形态特征间的关系以及膜叶铁角蕨属植物的物种分类。结果表明:膜叶铁角蕨属植物的叶片及羽片等形态特征存在很大区别,叶柄和根状茎上的鳞片以及孢子形态的种间差异虽然不大,但其在大小、形状、颜色等方面的细微差别仍可作为部分种类的鉴定依据。该研究结果为膜叶铁角蕨属植物的物种分类及进一步研究提供了重要依据。     

超干种子的膜功能与糖组分的研究

采用两相法分离种子质膜,研究超干处理对种子质膜ATP酶活力及膜流动性的影响.结果表明,白菜(Brassica pekinensis(Lour.)Rupr.)、榆树(Ulmus pumila L.)种子经超干处理后,在人工老化和自然老化条件下,与在-20℃条件下贮藏的种子比较,超干贮藏种子质膜ATP酶活力和微粘度无显著变化,过于贮藏种子的效应虽有所下降,但仍比高含水量室温贮藏的对照种子为好.此结果与超干种子具较高活力水平完全一致,说明超干贮藏种子保持了质膜的生理功能,因此提高了种子的耐藏性.高效液相色谱分析结果显示超干种子中还原糖/非还原糖的比值低于高含水量种子,积累的蔗糖、水苏糖含量与超干种子的耐干力有关.玉米(Zea mays L.)种子中不含水苏糖,这可能是玉米种子较其他种子耐干力下降的原因之一.     

Evidence for Maternal Transmission of Chloroplast DNA in the Genus Asplenium (Aspleniaceae,Pteridophyta)

Little is known about the mode of transmission of chloroplasts in ferns, despite the importance of such knowledge for molecular phylogenetic and biosystematic studies. Andersson-Kötto (1930, 1931) inferred from crossing experiments that chloroplasts are inherited biparentally in Asplenium scolopendrium L. Here we present evidence from artificial hybridisation that demonstrates maternal inheritance of chloroplast DNA in the genus Asplenium (Aspleniaceae, Pteridophyta) using length variation in a non-coding spacer (trnL_UAA-trnF_GAA) in the chloroplast DNA.     

Parallel polyploid speciation: distinct sympatric gene‐pools of recurrently derived allo‐octoploid Asplenium ferns

Although polyploidy is widespread, its significance to the generation of biodiversity remains unclear. Many polyploids have been derived recurrently. For a particular polyploid, gene‐flow between the products of independent origin is typical where they come into contact. Here, we use AFLP DNA‐fingerprinting and chloroplast DNA sequences to demonstrate parallel polyploid speciation within both of the ferns Asplenium cimmeriorum and A. gracillimum. Both of these taxa comprise at least two allopolyploids, recurrently derived from the same progenitor pair. Each of these allopolyploids remain genetically distinguishable even with extensive sympatry, and could therefore be considered distinct species. To our knowledge, parallel speciation on this scale amongst recurrent polyploids has not been previously reported. With their parallel origins, these ‘evolutionary replicates’ provide an unrivalled opportunity to investigate how the reproductive barriers and ecological differentiation necessary for speciation arise following polyploidy.     

The Effect of Rain Forest Canopy Architecture on the Distribution of Epiphytic Ferns (Asplenium spp.) in Sabah, Malaysia

Epiphytic plants are a dominant component of the rain forest canopy biota. They represent a significant proportion of canopy plant biomass and diversity, play a key role in nutrient cycling, and support highly abundant and diverse animal communities. Understanding the factors affecting their distribution in this three-dimensional habitat is consequently of great importance, not least because they may be particularly vulnerable to climate change and habitat conversion. Here we investigate how canopy architecture affects the distribution of two species of bird's nest fern ( Asplenium spp.) in pristine rain forest. Both species were found at high abundances ( Asplenium phyllitidis : 136/ha, SE ± 31.6, Asplenium nidus : 44/ha, SE ± 9.2) and their distributions were differentially affected by canopy architecture. Asplenium phyllitidis was found only at heights < 30 m in areas with a thicker lower canopy layer. Asplenium nidus was found at all heights in the canopy and was associated with emergent trees and areas with an open understory. Larger A. phyllitidis were found higher in the canopy while larger A. nidus were found on trunks and branches with a wider diameter. Asplenium nidus seems adapted to withstand the hot dry conditions in the upper canopy and in gaps, and its size is consequently limited only by the size of its support. Asplenium phyllitidis is dominant in areas that are cooler and damper, and so the growth rate of individuals may be limited by light levels. We discuss possible implications of this partitioning for epiphyte communities in the face of climate change and habitat conversion.
     

Fire and ice: volcanic and glacial impacts on the phylogeography of the New Zealand forest fern Asplenium hookerianum

In the Southern Hemisphere there has been little phylogeographical investigation of forest refugia sites during the last glacial. Hooker's spleenwort, Asplenium hookerianum, is a fern that is found throughout New Zealand. It is strongly associated with forest and is a proxy for the survival of woody vegetation during the last glacial maximum. DNA sequence data from the chloroplast trnL-trnF locus were obtained from 242 samples, including c. 10 individuals from each of 21 focal populations. Most populations contained multiple, and in many cases unique, haplotypes, including those neighbouring formerly glaciated areas, while the predominant inference from nested clade analysis was restricted gene flow with isolation by distance. These results suggest that A. hookerianum survived the last glacial maximum in widespread populations of sufficient size to retain the observed phylogeography, and therefore that the sheltering woody vegetation must have been similarly abundant. This is consistent with palynological interpretations for the survival in New Zealand of thermophilous forest species at considerably smaller distances from the ice sheets than recorded for the Northern Hemisphere. Eastern and central North Island populations of A. hookerianum were characterized by a different subset of haplotypes to populations from the remainder of the country. A similar east-west phylogeographical pattern has been detected in a diverse array of taxa, and has previously been attributed to recurrent vulcanism in the central North Island.     

Allozyme analysis of cryptic species in the Asplenium niduscomplex from West Java,Indonesia

In various fern species, a large amount of rbcL sequence variation has been reported, and it is possible that these species contain several reproductively isolated cryptic species. In our previous study on Asplenium nidus L., it was suggested that the plants growing in Mt. Halimun National Park, West Java, Indonesia, consist of several cryptic species based on the results of crossing experiments among rbcL sequence types. In this study, we examined allozyme polymorphisms of five rbcL sequence types found in West Java in order to test the hypothesis that the assemblages of A. nidus delimited based on the rbcL sequences are separate Mendelian populations and gene flow is disrupted by reproductive isolation from one another. The calculated fixation indices suggested that the individuals in each rbcL type are randomly crossing at least in the investigated localities. Nevertheless, these rbcL-based assemblages were genetically differentiated in allozymes that are encoded in their nuclear genomes, and it is also suggested that gene flow is disrupted even between sympatrically distributed pairs of rbcL sequence types. Therefore, our findings support the view that the five rbcL sequence types in West Java are potential cryptic species. Electronic Publication     

Multiple colonizations of a remote oceanic archipelago by one species: how common is long‐distance dispersal?

Aim  It is well established that many groups of plants and animals have undergone long-distance dispersal, but the extent to which this continues beyond initial colonization is largely unknown. To provide further insight into the frequency of gene flow mediated by long-distance dispersal, we investigated the origins of the fern Asplenium hookerianum on the Chatham Islands, and present a review of the contribution of molecular data to elucidating the origins of this archipelago's biota.
Location  Chatham Islands and New Zealand. A. hookerianum is scarce on the Chatham Islands but common in New Zealand, some 800 km to the west.
Methods  We compared chloroplast trnL–trnF DNA sequence data from Chatham Islands' A. hookerianum with extensive phylogeographic data for this genetically variable species in mainland New Zealand.
Results  Our sequencing revealed the presence of two haplotypes in Chatham Islands' A. hookerianum . These haplotypes differed by four mutational events and were each more closely related to haplotypes found in New Zealand than to each other.
Main conclusions  Despite the rarity of A. hookerianum on the Chatham Islands, its populations there appear to derive from at least two long-distance dispersal events from New Zealand, these possibly originating from different areas. We suggest that long-distance transoceanic dispersal, and the gene flow it can mediate, may be more common than is generally appreciated.     

Genetic diversity and phylogeography in two diploid ferns,Asplenium fontanum subsp. fontanum and A. petrarchae subsp. bivalens,in the western Mediterranean

Asplenium fontanum subsp. fontanum and A. petrarchae subsp. bivalens are diploid rock ferns of limestone outcrops of the western Mediterranean region. Asplenium fontanum subsp. fontanum occurs from Valencia through northeastern Spain to the Alpes‐Maritimes and Swiss Jura. Asplenium petrarchae subsp. bivalens occurs only on Majorca, in Valencia and possibly in southern Spain. We analysed allozyme and chloroplast genetic marker diversity in 75 populations of A. fontanum subsp. fontanum and 12 populations of A. petrarchae subsp. bivalens sampled from across their respective ranges. The two species show similar levels of species and population genetic diversity to one another and to other diploid European Asplenium taxa. Both are predominantly outbreeding, as indicated by F_IS = 0.108 and 0.167 respectively. Substantial between‐population differentiation results largely from differentiation between regions. Isolation by distance operates over limited geographic ranges, up to 50 km. In A. fontanum subsp. fontanum, the major geographical differentiation between Valencia and the rest of the taxon range probably represents an ancient range fragmentation. A less pronounced differentiation divides populations in the SW from those in the NE of the range, with evidence for a biogeographic link between the eastern Pyrenees and southeastern France. High diversity in the Pyrenees may either represent ancient population differentiation, or a suture zone. In A. petrarchae subsp. bivalens, populations on Majorca exhibit a subset of the genetic diversity present in Valencia, although the two regions are strongly differentiated by differing allele frequencies. Dispersal from the mainland may have founded Majorcan populations, although a role for in situ island survival cannot be excluded.