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1.
We conducted phylogenetic analyses of the sect. Caprini and its closely related sections within Astragalus. Analyses of a combined dataset including nrDNA ETS and three cpDNA markers using maximum parsimony and Bayesian inference from 44 species of sect. Caprini and its allied taxa yielded congruent relationships among several major lineages. These results largely disagree with previously recognized taxonomic groups, most notably in the following ways: (1) subsects. Caprini and Purpurascentes of sect. Caprini are not natural groups; (2) sects. Alopecuroidei and Laxiflori are nested within sect. Astragalus; and (3) subsect. Chronopus constitutes a separate phylogenetic lineage. Representatives of sects. Astragalus, Alopecuroidei, and Laxiflori share a common ancestor with that of sect. Caprini. Our studies indicate that Astragalus annularis is an outlier species for the genus Astragalus and sect. Caraganella is the first-diverging clade within the genus Astragalus. Results of these analyses are supported by morphology and suggest the need for new taxonomic delimitations, which are forthcoming. Key morphological characters were mapped onto the phylogenetic tree and discussed.  相似文献   

2.
3.
通过对披碱草属中小颖组、宽颖组和长颖组种类外部形态的观察,总结了3组植物外部形态特征的异同,探讨了形态学特征的分类学意义。同时,根据3组植物外部形态性状—花序、小穗、小花、以及内稃的演化趋势,分析了各组的演化关系和系统位置。结果表明:小颖组最原始,宽颖组较进化,长颖组最高级;小颖组可能直接派生了较进化的宽颖组,并在宽颖组的基础上进而产生了最高级的长颖组。此外,本文对披碱草属参试种的系统关系也作了一定程度的探讨,结果显示圆锥披碱草最原始,墨西哥披碱草最进化,其余参试种居于两者之间。上述研究工作为整个披碱草属系统与进化方面的探讨提供了形态学方面的理论证据。  相似文献   

4.
Previous taxonomic assessments of the hydrophytic genus Nuphar Sm. (Nymphaeaceae) have inadequately considered the range of morphological variation existing in the genus. A comprehensive statistical analysis of morphological features among the recognized taxa of Nuphar is presented here, first using 10 fruit characters to delimit the separation of two infrageneric groups of taxa, and secondly using 31 characters to quantify the morphological variation found within sect. Nuphar. Results from combined phenetic analyses provided empirical support for recognition of two infrageneric groups of species in the genus (largely by fruit, stigmatic disk margin, neck, and stigmatic disk size) and for separation of taxa within sect. Nuphar (by leaf size, and fruit disk and neck size). Statistical analyses demonstrate that extensive variation in ranges of character states exists among sect. Nuphar taxa. However, a suite of qualitative and quantitative characters can be used to recognize five species and three subspecies within this predominantly Old World assemblage.  相似文献   

5.
Patterns of variation among all micro-species of Hieracium sect. Hieracium and H. sect. Vulgata known from Denmark and southern Sweden are investigated. Forty-three, possibly independent morphological characters are used. Significant correlations were revealed among the majority of the characters. Multivariate analyses did not reveal any discontinuities in the variation or any discrete groups of species. However, there were obvious correlations between previous taxonomic classifications and the result of the multivariate analyses. Based on the statistical analyses, three sections and 38 informal species aggregates are recognized. H. sect. Bifidum T. Tyler is described anew. The characters that turned out to be most influential in the multivariate analyses, and thus most important for the classification, were the distribution of stellate tomentum on the phyllaries, the amount of glandular hairs and the amount and pigmentation of simple hairs on the phyllaries, the shape of the leaf-base and the regularity of the leaf dentation. The evolution of the group and the taxonomic treatment is thoroughly discussed in the light of the results.  相似文献   

6.
Species delimitation studies based on integrative taxonomic approaches have received considerable attention in the last few years, and have provided the strongest hypotheses of species boundaries. We used three lines of evidence (molecular, morphological, and niche envelopes) to test for species boundaries in Peruvian populations of the Liolaemus walkeri complex. Our results show that different lines of evidence and analyses are congruent in different combinations, for unambiguous delimitation of three lineages that were “hidden” within known species, and now deserve species status. Our phylogenetic analysis shows that L. walkeri, L. tacnae and the three new species are strongly separated from other species assigned to the alticolor-bibronii group. Few conventional morphological characters distinguish the new species from closely related taxa and this highlights the need to integrate other sources of data to erect strong hypothesis of species limits. A taxonomic key for known Peruvian species of the subgenus Lioalemus is provided.  相似文献   

7.
Arctic-alpine plants in the genus Saxifraga L. (Saxifragaceae Juss.) provide an excellent system for investigating the process of diversification in northern regions. Yet, sect. Trachyphyllum (Gaud.) Koch, which is comprised of about 8 to 26 species, has still not been explored by molecular systematists even though taxonomists concur that the section needs to be thoroughly re-examined. Our goals were to use chloroplast trnL-F and nuclear ITS DNA sequence data to circumscribe the section phylogenetically, test models of geographically-based population divergence, and assess the utility of morphological characters in estimating evolutionary relationships. To do so, we sequenced both genetic markers for 19 taxa within the section. The phylogenetic inferences of sect. Trachyphyllum using maximum likelihood and Bayesian analyses showed that the section is polyphyletic, with S. aspera L. and S bryoides L. falling outside the main clade. In addition, the analyses supported several taxonomic re-classifications to prior names. We used two approaches to test biogeographic hypotheses: i) a coalescent approach in Mesquite to test the fit of our reconstructed gene trees to geographically-based models of population divergence and ii) a maximum likelihood inference in Lagrange. These tests uncovered strong support for an origin of the clade in the Southern Rocky Mountains of North America followed by dispersal and divergence episodes across refugia. Finally we adopted a stochastic character mapping approach in SIMMAP to investigate the utility of morphological characters in estimating evolutionary relationships among taxa. We found that few morphological characters were phylogenetically informative and many were misleading. Our molecular analyses provide a foundation for the diversity and evolutionary relationships within sect. Trachyphyllum and hypotheses for better understanding the patterns and processes of divergence in this section, other saxifrages, and plants inhabiting the North Pacific Rim.  相似文献   

8.
The taxonomic histories of two genera, Acyrthosiphon and Aulacorthum, have been controversial because of the ambiguous morphology used as criteria to distinguish these genera. In this study, molecular and morphological characters were analyzed to determine whether the current classification of these genera is reasonable. Two phylogenetic trees based on five genes (COI, COII, srRNA, lrRNA, and EF1a) supported the distinctiveness of Acyrthosiphon and Aulacorthum, and a canonical discriminant analysis using 19 morphological characters showed that the two genera were separated by five morphological characters (HTB, C, Ant.III, HFM, and SIPH). Based on these results, we confirm that the current classification of Acyrthosiphon and Aulacorthum is supported by molecular and morphological characters.  相似文献   

9.
Dendrobium sect. Dendrocoryne is a difficult taxonomic group of allied species and species complexes, occurring on the eastern Australian coastline, Lord Howe Island and New Caledonia. Significant morphological characters were assessed from all key areas of the distribution range. Patterns of variation between species, varieties and hybrids were investigated by principal coordinate analysis. The analyses affirm 12 species in the sect. Dendrocoryne described by Schlechter (1912, 1982) and Dockrill (1969, 1992), including a cluster of small statured D. gracilicaule, D. adae, D. fleckeri, and D. finniganense, and three variable species complexes – D. speciosum, D. kingianum and D. tetragonum. Recently described D. finniganense and D. callitrophilum are interpreted as members of the section. Phylogenetic relationships are presented based on parsimony analysis of 31 morphological characters. Analyses do not support proposals to recognize new genera for D. tetragonum, D. callitrophilum and D. aemulum, or to create new species within D. tetragonum, D. jonesii, D. speciosum and D. kingianum. The phylogeny indicates that rainforest taxa are earlier lineages and xerophytic taxa are more derived.  相似文献   

10.
Multivariate analyses were applied to 96 populations (OTUs) of plants, traditionally referred to Chenopodium atrovirens, C. desiccatum, and C. pratericola, in an attempt to evaluate the numerous and often contradictory taxonomic treatments of plants in this complex. The study consisted of two major parts. The first involved the use of cluster and principal components analyses using 14 morphological characters on the entire set of 96 OTUs to search for phenetically distinct groupings; these analyses were conducted without knowledge of traditional taxonomic designations of individual OTUs. Three reasonably well-defined groups emerged from these preliminary analyses. When traditional taxonomic designations were applied to member OTUs of each group, one group was composed primarily of C. atrovirens, another of C. pratericola and the third of C. desiccatum. The second part of the study utilized canonical analysis to: 1) confirm the integrity of the phenetic groups, 2) to classify OTUs difficult to identify to species using traditional methods, and 3) to provide an evaluation of characters important in the separation of these groups. This analysis confirmed the integrity of the groups and provided a classification to species of nearly all of the otherwise difficult OTUs. In addition, canonical analysis demonstrated that a combination of characters was important in the separation of the phenetic groups.  相似文献   

11.
In this study we present a survey on vegetative anatomy in species of Actinocephalus, Blastocaulon, Eriocaulon, Leiothrix, Paepalanthus, Philodice, Syngonanthus, and Tonina (Eriocaulaceae). Multivariate analyses were used to correlate anatomical characters to taxa and the habitats where the species occur. Root and stem anatomical characters seem to be more affected by environmental factors where these species occur, and seem of little value for delimiting major taxonomic groups within the family. Other characters in the leaves, such as epidermis with thickened wall cells, compartmented substomatal chambers, mesophyll with hypodermis, compact chlorenchyma, collenchymatous bundle sheath extensions, and numerous vascular bundles, were shown to be important for defining species clusters in Leiothrix, Syngonanthus, and Paepalanthus subg. Platycaulon. Similarly, loosely aggregated chlorenchyma caused Blastocaulon, Eriocaulon, Philodice, Syngonanthus sect. Carpocephalus, S. sect. Syngonanthus, and Tonina, genera from humid environments, to cluster. Scape characters appear to be more informative in discriminating groups. This situation probably reflects lower selection pressures determining anatomical characters of this organ.  相似文献   

12.
Hybrids of Lucilia sericata and Lucilia cuprina have been shown to exist in previous studies using molecular methods, but no study has shown explicitly that these hybrids can be identified morphologically. Published morphological characters used to identify L. sericata and L. cuprina were reviewed, and then scored and tested using specimens of both species and known hybrids. Ordination by multi-dimensional scaling indicated that the species were separable, and that hybrids resembled L. cuprina, whatever their origin. Discriminant function analysis of the characters successfully separated the specimens into three unambiguous groups – L. sericata, L. cuprina and hybrids. The hybrids were morphologically similar irrespective of whether they were from an ancient introgressed lineage or more modern. This is the first evidence that hybrids of these two species can be identified from their morphology. The usefulness of the morphological characters is also discussed and photographs of several characters are included to facilitate their assessment.  相似文献   

13.
Pollen grains of 47 taxa of Campanulaceae including 35 taxa of Campanula that represent its five subgenera and nine sections are investigated. Moreover, five species and three subspecies representing three sections in Asyneuma and one species of each genera Legousia, Michauxia, Zeugandra and Theodorovia were studied by light and scanning electron microscopy. The basic shape of the pollen grains was spheroidal. The apertures vary from tri- to hexa-porate. The sculpturing pattern of exine was rugulate-echinate, rugulate-microechinate or in few species rugulate-microreticulate and microechinate. The most valuable characters for subgeneric classification were the length and density of echini. The length of echini were significantly long (> 2 μm) in C. sclerotricha, Legousia falcata and Michauxia laevigata. Pollen grains show low variation in different species of subgen. Rapunculus, but were variable among different species of some groups, such as sect. Rupestres, probably indicating their non-monophyly despite homogeneity with respect to other morphological characters. Pollen morphology does not support recognition of Asyneuma, Legousia, Michauxia, Symphyandra, Theodorovia, and Zeugandra as separated from Campanula, since none of them exhibit any unique feature.  相似文献   

14.
Maximum likelihood trees produced from 18S rDNA sequences separated 14 Xiphinema and five Xiphidorus nematode species from Brazil into distinct groups that concurred with their current morphological taxonomic status. Species belonging to the X. americanum group (X. brevicolle, X. diffusum, X. oxycaudatum, and X. peruvianum) formed a single group that was clearly separated from the other Xiphinema species. As with previous taxonomic studies that noted only minor morphological differences between putative X. americanum group species, separation of these species based upon 18S rDNA sequences was inconclusive. Thus it is probable that instead of comprising distinct species, the X. americanum group may in fact represent numerous morphotypes with large inter- and intra- population morphological variability that may be environmentally driven. Within the cluster representing non X. americanum group species, there was little statistical support to clearly separate species. However, three subgroups, comprising (i) the X. setariae/vulgare complex, (ii) X. ifacolum and X. paritaliae, and (iii) X. brasiliense and X. ensiculiferum were well resolved.  相似文献   

15.
栝楼属基于核糖体ITS序列的系统发育分析   总被引:2,自引:1,他引:2  
栝楼属(Trichosanthes)是葫芦科(Cucurbitaceae)中一个种类较多、药用价值较大的属。本文基于ITS序列分析了栝楼属16个种的系统发育关系。聚类分析表明:在组的划分上,具有分类争议的截叶组(sect. Truncata)与大苞组(sect. Involucraria)形成一大支,处于一亚分枝位置,不支持独立成组。在属内分类地位上,在核酸水平不支持贵州栝楼(T.guizhouensis)为一独立种,结合形态特征建议并入双边栝楼(T.rosthornii)。大方油栝楼(T.dafangensis)与小苞组(sect. Trichosanthes)成为姊妹群,处于一个向叶苞组(sect. Foliobracteola)过渡位置,结合其形态特征,建议作为小苞组(sect. Trichosanthes)成员。  相似文献   

16.

Background

The species-rich genus Aphis consists of more than 500 species, many of them host-specific on a wide range of plants, yet very similar in general appearance due to convergence toward particular morphological types. Most species have been historically clustered into four main phenotypic groups (gossypii, craccivora, fabae, and spiraecola groups). To confirm the morphological hypotheses between these groups and to examine the characteristics that determine them, multivariate morphometric analyses were performed using 28 characters measured/counted from 40 species. To infer whether the morphological relationships are correlated with the genetic relationships, we compared the morphometric dataset with a phylogeny reconstructed from the combined dataset of three mtDNA and one nuclear DNA regions.

Principal Findings

Based on a comparison of morphological and molecular datasets, we confirmed morphological reduction or regression in the gossypii group unlike in related groups. Most morphological characteristics of the gossypii group were less variable than for the other groups. Due to these, the gossypii group could be morphologically well separated from the craccivora, fabae, and spiraecola groups. In addition, the correlation of the rates of evolution between morphological and DNA datasets was highly significant in their diversification.

Conclusions

The morphological separation between the gossypii group and the other species-groups are congruent with their phylogenetic relationships. Analysis of trait evolution revealed that the morphological traits found to be significant based on the morphometric analyses were confidently correlated with the phylogeny. The dominant patterns of trait evolution resulting in increased rates of short branches and temporally later evolution are likely suitable for the modality of Aphis speciation because they have adapted species-specifically, rapidly, and more recently on many different host plants.  相似文献   

17.
Cicadas produce loud calling songs for mate attraction that can be a nuisance to city dwellers in Korea. Exuviae of final instars can be used to estimate population density. We investigated the morphological characteristics of final instar exuviae for five cicada species that are abundant in central Korea: Cryptotympana atrata, Hyalessa fuscata, Graptopsaltria nigrofuscata, Meimuna opalifera, and Meimuna mongolica. The characters analyzed were pro-mesonotum length, pronotum width, pronotum length, head width, abdominal circumference, body length, wing length, and femoral tooth angle. The results of a general linear model showed that species and sex were significant for morphological characters, and the result of post hoc analyses revealed that the mean values of most of the morphological characters measured were significantly different among the five cicada species. Three groups, Cryptotympana atrata, H. fuscata/G. nigrofuscata, and M. opalifera/M. mongolica, were distinctively identified based on most morphological characters. The distributions of femoral tooth angles did not overlap between H. fuscata and G. nigrofuscata, and the distributions of abdominal circumference did not overlap between M. opalifera and M. mongolica. Thus, the exuviae of all five cicada species could be easily distinguished based on morphological characters. We also provide a morphological key for the exuviae of all five cicada species in Korea.  相似文献   

18.
Based on the study of herbarium material, a critical taxonomic account has been provided onCardamine sect.Macrophyllum (Cruciferae) from the Asian territory of the Soviet Union. Different morphological characters were examined but special attention was paid to flowers, nectar glands, pollen grains, fruits and seeds, followed by the anatomical studies of fruits and seeds. 8 species have been recognized which are arranged in 2 subsections underCardamine sect.Macrophyllum viz. 1.Macrophyllae (C. leucantha, C. tomentella, C. macrophylla andC densiflora) and 2.Prorepentae (C. schinziana, C. yezoensis, C. amareaformis andC. prorepens). Phylogenetic trend also has been traced out suggesting preliminary centres of divergency and polymorphism of the treated taxa.  相似文献   

19.
Uromyces appendiculatus, inclusive of three varieties, is distinguished from U. vignae primarily by the position of urediniospore germ pores and putative host specificity. However, opinions concerning these morphological and physiological features as taxonomic characters have varied greatly, and distinction of these species has often been confused. To clarify the taxonomy of these two species, morphological features of urediniospores and teliospores of 225 rust fungus specimens on species of Phaseolus, Vigna, Apios, Lablab, and Dunbaria were examined by light microscopy and scanning electron microscopy. Forty-five specimens were subjected to molecular phylogenetic analyses. As a result, the position of germ pores in urediniospores and the teliospore-wall thickness were considered as good characters to separate three morphological groups. In molecular analyses, the specimens fell into two and three clades based on the nucleotide sequence at D1/D2 domain of LSU rDNA and ITS regions, respectively. One of the D1/D2 clades corresponded to one morphological group whereas another D1/D2 clade included two other morphological groups. In contrast, each of the three ITS clades corresponded to a separate morphological group. Neither morphological groups nor molecular clades were host limited. It is suggested that the three morphological groups that corresponded to three distinct ITS clades constitute distinct species.Contribution no. 186 from the Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan  相似文献   

20.
There are still controversies regarding differentiation between Baccharis species (sect. Caulopterae). In the present work, we compare three species: Baccharis articulata, Baccharis gaudichaudiana and Baccharis trimera, emphasising the importance of anatomy, polypeptide profiles and ultraviolet–visible spectrophotometry as taxonomic characters, utilizing multivariate analysis. Seventy-two populations of the three species were examined. The first two principal components of morphoanatomical data gathered relevant information to classify species (61% of the total variability), with the largest contribution from the stomata density variable (2.105). PCoorA based on protein analysis enabled separation of the species with the first two principal coordinates (67.20% of the total variability). Regarding spectrophotometrical data, the second and third principal components only separated B. trimera from the rest (22.7% of total variability).  相似文献   

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