首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The first overall study of pericarp anatomy ofCoriaria is presented to discuss its evolution and relationships within a genus. All 14 species investigated (including 11 narrowly defined species) have somewhat bilaterally flattened mature fruits with five to seven (or more) longitudinal costae. They share a usually nine-(or more-)cell-layered (at intercostal region), stratified mature pericarp, which is basically constructed by an exocarp, an outer, a middle and an inner zone of mesocarp, and an endocarp. While a multi-layered endocarp is composed of circumferentially elongate fibres, a multi-layered inner zone of the mesocarp comprises longitudinally elongate fibres. Despite its uncertain systematic value, the presence of those fibres arranged crisscross is a characteristic feature of the genus. Comparisons among species indicate thatCoriaria terminalis, a species of the Eastern Hemisphere, retains a basic or archaic, well-stratified pericarp structure similar to the one found in all the species investigated of the Southern and Western Hemisphere, and that four species of Asia,Coriaria napalensis, C. sinica, C. intermedia andC. japonica, share a specialized structure (lacking the outer zone of the mesocarp) indicative of their mutual close affinity. Comparisons further suggest distinctness ofCoriaria intermedia, as well as variously derived position ofC. myrtifolia andC. japonica.  相似文献   

2.
The familiar limits ofVerbenaceae are controversial, ranging from a sensu lato arrangement of seven subfamilies until a sharply defined sensu stricto group consisting of only some genera from subfam.Verbenoideae. Iridoid contents of genera belonging toVerbenaceae s. l. were examined through a cladistic analysis, using outgroup analysis to evaluate character polarity within the ingroup. The cladogram obtained shows the distribution of the species according to their iridoid content.  相似文献   

3.
鸢尾属分子系统发育学研究进展   总被引:1,自引:0,他引:1  
鸢尾属植物具有重要的观赏价值和经济价值,研究该属属内系统演化关系对该属种质保存、利用和遗传育种具有重要意义.目前,有关鸢尾属各分类单元的系统学关系长期处于争议状态.因此,该文以经典分类系统主要观点为基础,从不同分类单元的系统关系总结了鸢尾属分子系统发育学研究进展.结果表明:现有分子系统发育学研究结果大多支持鸢尾属为并系...  相似文献   

4.
Berch  S.M.  Allen  T.R.  Berbee  M.L. 《Plant and Soil》2002,244(1-2):55-66
Through traditional culturing and molecular characterization, we have determined that five putative species and 2 polyphyletic assemblages of fungi produce ericoid mycorrhizae in Gaultheria shallon, other Ericaceae and Epacridaceae. Using phylogenetic analysis of ITS2 sequences in GenBank, we have confirmed that most of these fungi occur in North America, Europe, and Australia. The low recovery rate of culturable ericoid mycorrhizal fungi from Gaultheria shallon may partly be explained by the fact that most mycorrhizal root segments contain an unculturable basidiomycete, revealed by direct amplification, cloning, and sequencing of LSU fungal DNA from root. Molecular characterization and phylogenetic analysis are powerful tools in revealing the geographic distribution and identity of ericoid mycorrhizal fungi.  相似文献   

5.
The molecular phylogeny of 36 specimens of JapaneseAmanita species was studied based on nucleotide sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. The phylogenetic tree obtained supported the traditional classification systems of Bas (1969) and Singer (1986), which are based on morphological characters, in the division of the genusAmanita is divided into subgeneraAmanita andLepidella by the amyloidity of basidiospores. However, at section-level, we suggest that subgenusAmanita should be divided into three sections (Amanita, Vaginatae, andCaesareae). Our results also showed the necessity to modify the taxonomic treatments at section-level in the subgenusLepidella. It appears that the establishment ofA. muscaria andA. pantherina from a common ancestral species might be a very recent event, or these might be lower taxa of same species. As for three subspecies ofA. hemibapha and three varieties ofA. vaginata, it is necessary to grade up their taxonomical ranks from subspecies/variety to species. A new combination,A. javanica, is proposed forA. hemibapha subsp.javanica.  相似文献   

6.
Freshwater gomphonemoid diatom phylogeny: preliminary results   总被引:1,自引:0,他引:1  
Kociolek  J.P.  Stoermer  E.F. 《Hydrobiologia》1993,(1):31-38
A cladistic analysis of eleven freshwater gomphonemoid diatom taxa yielded three equally most parsimonious cladograms. The three cladograms suggest Gomphoneis Cleve is non-monophyletic as originally and recently circumscribed. Gomphoneis elegans and G. transsilvanica (Pant.) Krammer are more closely related to Gomphopleura Reichelt ex Tempère than to other members of the genus. Gomphoneis geitleri Kociolek & Stoermer appears to represent a monotypic lineage. Among the taxa with differentiated apical pore fields Gomphonema kaznakowi Mereschkowsky appears to be primitively astigmate.The three cladograms vary with regard to systematic affinities among the Gomphoneis herculeana (Ehrenberg) Cleve group, Miocene gomphonemoid species from Idaho (USA), gomphonemoid taxa from East Africa and Gomphonema sensu stricto. Despite variability in number of puncta rows per stria and presence of an axial plate in the Miocene species from North America, inclusion of these taxa in the analysis provided better resolution of relationships than if they were excluded.  相似文献   

7.
The tribePlucheeae (Benth.)A. Anderb., has been analysed cladistically by means of a computerized parsimony program (Hennig 86), using theArctotideae as outgroup. The results of the analysis are presented in a consensus tree and one cladogram. Four major monophyletic subgroups can be recognized: TheColeocoma group (3 genera), thePterocaulon group (3 genera), theLaggera group (6 genera), and thePluchea group (12 genera). All recognized genera are described and most genera are supplied with taxonomical notes including comments on their taxonomic status. Genera such asBlumea, Pluchea, andEpaltes are demonstrated to be unnatural assemblages.Monarrhenus andTessaria are both closely related to thePluchea complex. The old generic nameLitogyne Harv. has been taken up for one species ofEpaltes, the genusRhodogeron is reduced to a synonym ofSachsia, and the following new combinations are made;Litogyne gariepina (DC.)A. Anderb., andSachsia coronopifolia (Griseb.)A. Anderb.  相似文献   

8.
9.
Sequence variation in chloroplast DNA (cpDNA) as measured by DNA reassociation was examined in 12 grass species to address systematic problems in thePoaceae at the subfamilial and tribal levels. Two species,Petunia (Solanaceae) andGlycine (Leguminosae), were included to determine degrees of sequence divergence in cpDNA between monocots and dicots. The data were analyzed phenetically and phylogenetically. Species were segregated into four major groups that corresponded to the subfamiliesPooideae, Oryzoideae, Chloridoideae, andPanicoideae. Representatives of thePooideae andOryzoideae grouped together as did members of theChloridoideae andPanicoideae. ThePooideae split into two major groups corresponding to the recently recognized supertribesTriticanae andPoanae. Internodes between subfamily branches were short which might indicate a burst of divergence in the family early in its evolution. Sequence similarity values between the monocot grass species and the two dicot taxa ranged from 0.15 to 0.27, representing the highly conserved sequences of the chloroplast genome.  相似文献   

10.
The pericarp structure has been investigated in 11 species representing the genera of the subfamily Pogostemonoideae (emend. Cantino et al. 1992): Anisomeles, Colebrookea, Comanthosphace, Leucosceptrum, Pogostemon and Rostrinucula . The pericarp structure of Anisomeles, Colebrookea and Pogostemon have been found to resemble that of the subfamilies Lamioideae or Nepetoideae. The three related genera, Comanthosphace, Leucosceptrum and Rostrinucula have been found to have a divergent type of pericarp, which lacks sclerenchyma and has druses and a type of cells with scalariform secondary thickenings in the mesocarp. The three genera are suggested to be extraneous in Pogostemonoideae and their systematic position is uncertain.  相似文献   

11.
Howe AT  Bass D  Chao EE  Cavalier-Smith T 《Protist》2011,162(5):710-722
Glissomonadida is an important cercozoan order of predominantly biflagellate gliding bacterivores found largely in soil and freshwater. Their vast diversity is largely undescribed. We studied 23 mostly newly isolated strains by light microscopy and sequenced their 18S rDNA genes; nine represent new species. For two misidentified ATCC 'Heteromita triangularis' strains, we establish novel gliding genera and species: the sandonid Mollimonas lacrima, the only glissomonad forming anterior and posterior pseudopodia, and Dujardina stenomorpha, a strongly flattened member of the new family Dujardinidae. A new strain from Oxfordshire grassland soil is the first reliably identified isolate of the virtually uniflagellate, smooth-gliding glissomonad genus, AllantionSandon, 1924. Phylogenetic analysis and cytological features reveal Allantion to be a member of Allapsidae. Sandona limna and Bodomorpha prolixa from Lake Baikal and Sandona hexamutans from volcanic Costa Rican soil are described as new species. Fifteen glissomonad strains were from grassland beside Lake Baikal. We describe two as new species of Sandona (S. heptamutans and S. octamutans); the others included strains of Sandona and Allapsa species that have already been described; and three were new species of Sandona and Allapsa but these died before being described. We discuss the ecological and evolutionary significance of these new strains.  相似文献   

12.
Within the Mediterranean complexCarduncellus-Carthamus, taxonomic classification has proven problematic. Numerous attempts to clarify the relative systematic boundaries have included splittingCarduncellus andCarthamus into several genera, but none of these proposed classifications have been generally accepted. For a comprehensive resolution of the relationships within this group, we used sequences of the Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA. The results indicate that the complex should be classified into four genera:Carduncellus, Carthamus, Femeniasia andPhonus. The relationship between the western group (Carduncellus, Femeniasia andPhonus) and the eastern genusCarthamus are not resolved by analysis of ITS sequences, but the two groups are probably not close relatives. The ITS classifications corresponded with biogeography and less with morphological characters, which have also been the main source of confusion in traditional classifications. Most of the unusual morphological features in theCarduncellus-Carthamus complex appear to be reversals to ancestral character states.  相似文献   

13.
14.
应用通用引物扩增了凸加夫蛤(Gafrarium tumidum锯齿巴非蛤(Paphia gallus细纹卵蛤(Pitar striatum钝缀锦蛤(Tapes dorsatus裂纹格特蛤(Marcia hiantina) 5种帘蛤科贝类COI基因片段,并与GenBank数据库收录的加夫蛤(Gafrarium pectinatum沟纹巴非蛤(Paphia exarata日本卵蛤(Pitar japonicum日本格特蛤(Marcia japonica四射缀锦蛤(Tapes belcheri )5种帘蛤科贝类的同源序列进行比对分析。结果表明:所有物种扩增片段长度均为616 bp,序列A+T平均含量(62.9%)明显高于G+C含量。在 616个位点中,保守位点数为282个,变异位点数为334个,其中简约信息位点数为283个。以COI基因片段序列为标记,以海螂科砂海螂(Mya arenaria)作外群,构建了帘蛤科贝类的系统进化树,其拓扑结构显示:细纹卵蛤和日本卵蛤聚为一枝,凸加夫蛤和加夫蛤聚为一枝,锯齿巴非蛤和沟纹巴非蛤聚为一枝,四射缀锦蛤单独聚为一枝,钝缀锦蛤、裂纹格特蛤和日本格特蛤聚为一枝,最后所有帘蛤科物种聚为一枝,与外群相区别,其结果与传统形态分类基本一致。研究表明,线粒体COI基因作为帘蛤科贝类DNA条形码在物种鉴定方面具有可靠性,可以作为物种分类的重要辅助手段。  相似文献   

15.
Restriction site mapping of chloroplast DNA from 31 species representing 26 genera of theRanunculaceae was performed using eleven restriction endonucleases. The chloroplast genome varies in length from approximately 152 to 160 kb. Length variants are frequent in theRanunculaceae and range from usually less than 300 bp to rarely 1.5 kb. The inverted repeat is extended into the large single copy (LSC) region by 4–4.5 kb inAnemone, Clematis, Clematopsis, Hepatica, Knowltonia, andPulsatilla. Several inversions are present in the LSC-region of the cpDNA in all these genera and inAdonis. The frequency of restriction site mutations varies within the chloroplast genome in theRanunculaceae between 4 and 32 mutations per kilobase, and is lowest in the inverted repeat and the regions containing the ATPase-genes and the genespsaA, psaB, psbA, rpoB, andrbcL. A total of 547 phylogenetically informative restriction sites was utilized in cladistic analyses of the family using Wagner, Dollo, and weighted parsimony. These three parsimony analyses result in different tree topologies. Four, six, and one equally most parsimonious trees were obtained with Wagner, Dollo, and weighted parsimony, respectively. The amount of support for the monophyletic groups was evaluated using bootstrapping and decay analysis. All three parsimony methods suggest thatHydrastis is the sister group to the remainder of theRanunculaceae, and that theAnemone-Clematis group, which shares several derived cpDNA rearrangements, is monophyletic. Only a few of the traditional groups in theRanunculaceae are supported by cpDNA restriction side data. Only Dollo parsimony provides support for the hypothesis thatThalictroideae andRanunculoideae are monophyletic.  相似文献   

16.
17.
Phylogenetic analyses based on morphology placeAnaxagorea and other taxa with granular monosulcate pollen, as in otherMagnoliales, at the base ofAnnonaceae. Taxa with columellar tetrads, granular tetrads, and inaperturate monads form a derived clade. To test the systematic importance of palynology, we analyzed the data set with pollen characters removed. The result was lower resolution and a different rooting of the family, betweenUvariopsis and other groups with columellar tetrads.Anaxagorea and other monosulcates are higher in the tree, implying that granular monosulcate pollen, laminar stamens, and irregular endosperm ruminations are reversals. This rooting is highly unparsimonious when pollen characters are included, and only weakly supported over theAnaxagorea rooting when pollen is excluded. Together with preliminary molecular analyses, these experiments confirm the special value of palynology in systematics ofAnnonaceae. This paper is dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday  相似文献   

18.
The squirrel family, Sciuridae, is one of the largest and most widely dispersed families of mammals. In spite of the wide distribution and conspicuousness of this group, phylogenetic relationships remain poorly understood. We used DNA sequence data from the mitochondrial cytochrome b gene of 114 species in 21 genera to infer phylogenetic relationships among sciurids based on maximum parsimony and Bayesian phylogenetic methods. Although we evaluated more complex alternative models of nucleotide substitution to reconstruct Bayesian phylogenies, none provided a better fit to the data than the GTR+G+I model. We used the reconstructed phylogenies to evaluate the current taxonomy of the Sciuridae. At essentially all levels of relationships, we found the phylogeny of squirrels to be in substantial conflict with the current taxonomy. At the highest level, the flying squirrels do not represent a basal divergence, and the current division of Sciuridae into two subfamilies is therefore not phylogenetically informative. At the tribal level, the Neotropical pygmy squirrel, Sciurillus, represents a basal divergence and is not closely related to the other members of the tribe Sciurini. At the genus level, the sciurine genus Sciurus is paraphyletic with respect to the dwarf squirrels (Microsciurus), and the Holarctic ground squirrels (Spermophilus) are paraphyletic with respect to antelope squirrels (Ammospermophilus), prairie dogs (Cynomys), and marmots (Marmota). Finally, several species of chipmunks and Holarctic ground squirrels do not appear monophyletic, indicating a need for reevaluation of alpha taxonomy.  相似文献   

19.
Morphological and cytological investigations were carried out inStachys beckeana Dörfler & Hayek andS. recta L. subsp.sarajevensis sensuHayek. These two taxa have the same morphological characteristics (shape and indumentum of leaves; morphology of sepals, petals and fruits) and both have 2n = 2x = 34 chromosomes. They cannot be considered as different taxa;S. beckeana Dörfler & Hayek is the valid name (synonyms:S. recta L. subsp.sarajevensis sensuHayek,S. hayekii Malý,S. recta L. subsp.hayekii Malý).
Erster Beitrag zur Neubearbeitung der Artengruppe derStachys recta L.  相似文献   

20.
The pericarp anatomy of representatives of all subgenera and sections of the genus Rosa was studied. All species have the same basic pericarp structure: it is composed of inner and outer endocarps, mesocarp and exocarp formed by the epidermis and hypodermis. The differences concern mainly the thickness of particular layers, and the shape and size of their cells. Cells of the endocarp and mesocarp are thick-walled. The only exception is Rosa rugosa mesocarp, which is composed of rather thin-walled cells with a large lumen. The endocarp structure of Rosa achenes resembles the drupe of the genus Prunus s.l. and drupelets of Rubus species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号