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1.
The shape of the cotyledon lamina and a few other juvenile characters are studied for some 140 taxa of the cruciferous tribe Brassiceae. They cast a number of doubts on the present botanical status of certain taxa, such as Diplotaxis siifolia, Erucastrum cardaminoides and Brassica balearica. The whole tribe Raphaninae appears rather unnatural when viewed from cotyledon evidence, which suggests that beak development and/or fruit reduction have evolved on different occasions. A primitive cotyledon type seems to be that showed by the genus Sinapidendron. It is nowadays still present in Brassica balearica, Oudneya africana and the oriental genus Orychophragmus. Some phenetic lines now represented by Moricandia, Foleyola, Hemicrambe, Diplotaxis and Brassica repanda may indicate ancient evolutionary trends derived from the primitive Sinapidendron-like Miocenic stock. Brassica ancestors could have either resembled B. repanda or evolved along the phenetic line now represented by the Diplotaxis Erucastrum-Brassica complex. A diphyletic or polyphyletic origin for the genus Brassica becomes thinkable.  相似文献   

2.
Summary Chloroplast DNA (cpDNA) variability of 60 taxa of the genus Brassica and allied genera comprising 50 species was studied. RFLPs for seven enzymes were generated and F values were estimated from five frequently cutting enzymes. Phenetic clusterings indicated a clear division of Brassica coenospecies into two distinct lineages referred to as the Brassica and Sinapis lineages. Two unexplored genera, Diplotaxis and Erucastrum, also exhibited two lineages in addition to the genera Brassica and Sinapis. This finding is inconsistent with the existing taxonomic classification based on morphology. Mitochondrial DNA (mtDNA) variability studied from EcoRI RFLP patterns, by hybridizing total DNA with four cosmid clones containing non-overlapping mtDNA fragments, did not show any congruence with cpDNA variation patterns. However, at the cytodeme level, the patterns of genetic divergence suggested by the cpDNA data could be correlated with mtDNA variation. In the Brassica lineage, Diplotaxis viminea was identified as the female parent of the allotetraploid D. muralis. The chloroplast DNAs of Erucastrum strigosum and Er. abyssinicum were found to be very closely related. In the Sinapis lineage, Brassica maurorum was found to be the diploid progenitor of autotetraploid B. cossoneana. B. amplexicaulis showed a very different cpDNA pattern from other members of the subtribe. Brassica adpressa was closest to Erucastrum laevigatum and could be the diploid progenitor of autotetraploid Er. laevigatum. Based on the close similarity of the cpDNA pattern of Diplotaxis siifolia with that of D. assurgens, we have proposed the retention of this species in the genus Diplotaxis. The taxonomic positions of some other species have also been discussed.  相似文献   

3.
黄斑星天牛和光肩星天牛的数值分类研究(鞘翅目:天牛科)   总被引:12,自引:4,他引:8  
陈斌 《昆虫学报》1989,32(3):341-349
本文选取不同地区的黄斑星天牛Anoplophora nobilis(Ganglbauer)、光肩星天牛A. glabripennis(Motsch ulsky)及类似的有代表性的雄性个体作为分类单位(OUT),利用27个性状,分别进行了不同相似性系数基础上的UPGMA法及等价类的模糊聚类法Q型分析,R型聚类分析,也进行了主成分分析研究,结果是一致的.A. nobilis及分布于北方的A. glabripennis不仅在表型图上形成差异很大的两类元,而且在成虫、雄性外生殖器和幼虫上都存在系列特征差异,认为是两个不同的物种,种级相似性系数水平在四个Q分类结果中分别是1.75、1.38、0.15和0.77.以四川为分布中心的A. glabripennis和西北的相比达到种级水平,表现出系列特征差异,认为它们可能是两个不同的物种.  相似文献   

4.
Ruiz A  Wasserman M 《Genetics》1982,101(3-4):503-518
Drosophila buzzatii has been found sympatric in Argentina with a closely-related sibling species, D. serido. The biogeographical, reproductive and chromosomal data allow us to combine these species into an evolutionary unit, the buzzatii cluster. Salivary gland chromosomes also have been used to determine their phylogenetic relationships with other closely related species, showing that the buzzatii cluster species share two inversions—2d2 and 2s6—with the species of the martensis cluster. Both clusters arose from South American populations of the ancestor of the mulleri complex, and we propose to include D. buzzatii and D. serido in the mulleri complex of the repleta group.  相似文献   

5.
A numerical taxonomic analysis was performed on 79 phenotypic characters of 147 imperfect yeast species currently assigned to the genus Candida. The characters used were drawn from two monographs on yeast taxonomy. The analysis revealed 10 clusters of three or more species that were similar at the level of 75% or more, and seven clusters containing only one or two species. None of the 10 major clusters contained exclusively species that were traditionally assigned to the genus Torulopsis, while the 12 Candida species of basidiomycetous affinity fell into three clusters with only one species of ascomycetous affinity included. Statistical determination of the five most important differential characters for each cluster failed to show the property of pseudomycelium/mycelium formation as significant for any cluster. The study provides no evidence to support a distinction between taxa that were formerly divided between the genera Candida and Torulopsis and supports previous proposals that these genera should be fused.  相似文献   

6.
A phylogeny of haemosporidian parasites (phylum Apicomplexa, family Plasmodiidae) was recovered using mitochondrial cytochrome b gene sequences from 52 species in 4 genera (Plasmodium, Hepatocystis, Haemoproteus, and Leucocytozoon), including parasite species infecting mammals, birds, and reptiles from over a wide geographic range. Leucocytozoon species emerged as an appropriate out-group for the other malarial parasites. Both parsimony and maximum-likelihood analyses produced similar phylogenetic trees. Life-history traits and parasite morphology, traditionally used as taxonomic characters, are largely phylogenetically uninformative. The Plasmodium and Hepatocystis species of mammalian hosts form 1 well-supported clade, and the Plasmodium and Haemoproteus species of birds and lizards form a second. Within this second clade, the relationships between taxa are more complex. Although jackknife support is weak, the Plasmodium of birds may form 1 clade and the Haemoproteus of birds another clade, but the parasites of lizards fall into several clusters, suggesting a more ancient and complex evolutionary history. The parasites currently placed within the genus Haemoproteus may not be monophyletic. Plasmodium falciparum of humans was not derived from an avian malarial ancestor and, except for its close sister species, P. reichenowi, is only distantly related to haemospordian parasites of all other mammals. Plasmodium is paraphyletic with respect to 2 other genera of malarial parasites, Haemoproteus and Hepatocystis. Explicit hypothesis testing supported these conclusions.  相似文献   

7.
In species differentiation, characters may not diverge synchronously, and there are also processes that shuffle character states in lineages descendant from a common ancestor. Species are thus expected to show some degree of incongruence among characters; therefore, taxonomic delimitation can benefit from integrative approaches and objective strategies that account for character conflict. We illustrate the potential of exploiting conflict for species delimitation in a study case of ground beetles of the subgenus Carabus (Mesocarabus), where traditional taxonomy does not accurately delimit species. The molecular phylogenies of four mitochondrial and three nuclear genes, cladistic analysis of the aedeagus, ecological niche divergence and morphometry of pronotal shape in more than 500 specimens of Mesocarabus show that these characters are not fully congruent. For these data, a three‐step operational strategy is proposed for species delimitation by (i) delineating candidate species based on the integration of incongruence among conclusive lines of evidence, (ii) corroborating candidate species with inconclusive lines of evidence and (iii) refining a final species proposal based on an integrated characterization of candidate species based on the evolutionary analysis of incongruence. This procedure provided a general understanding of the reticulate process of hybridization and introgression acting on Mesocarabus and generated the hypothesis of seven Mesocarabus species, including two putative hybrid lineages. Our work emphasizes the importance of incorporating critical analyses of character and phylogenetic conflict to infer both the evolutionary history and species boundaries through an integrative taxonomic approach.  相似文献   

8.
Leaf glucosinolates of 42 Diplotaxis and 21 Eruca accessions were studied. Total content ranged from 0.25 to more than 70 g kg(-1) dry wt. The 13 clusters, defined on the basis of glucosinolate composition, belonged to two glucosinolate-rich groups, characterised by the prevalence of a single component, and one low-glucosinolate group, with a profile not dominated by any individual component. A sinigrin-rich cluster (D. ibicensis, D. berthautii, D. ilorcitana, D. siettiana, D. tenuisiliqua, D. brevisiliqua, and D. virgata) and a gluconapin-rich cluster (D. catholica, D.siifolia, D. virgata, and D. ollivieri) included all the species previously classified in the nigra phylogenetic lineage. D. virgata was confirmed to be a critical taxon, with one accession slightly diverging from the others. D. siifolia subsp. vicentina was separated from the others in a glucobrassicin-rich cluster. D. harra, a rather isolated representative of sub-genus Hesperidium, clustered together D. assurgens in a sinalbin-rich cluster. Another well defined cluster was represented by D. brachycarpa (gluconasturtin). The two sub-species of D. erucoides were well differentiated by their glucosinolate profile. The low glucosinolate species: D. tenuifolia, D. viminea, D. cretacea, D. muralis (subgenus Diplotaxis), and E. vesicaria, all previously included in the rapa/oleracea lineage, belonged to seven less defined clusters, mainly differing on the presence/absence or the relative abundance of some components (glucoraphanin, glucolepidin, 4-hydroxy-glucobrassicin, 4-phenylbutyl gls, glucoerucin and neoglucobrassicin). The data support previous taxonomic works. Glucosinolate-rich taxa, with well characterised profiles may be suitable for industrial uses, whereas the variability of edible D. tenuifolia and E. vesicaria may represent a basis for breeding horticultural types.  相似文献   

9.
Phylogeographic and evolutionary studies are necessary to establish solid taxonomic treatments and to implement effective conservation programs. Unfortunately, a well‐argued and well‐founded taxonomic framework is still lacking for some Mediterranean taxa. This is the case of Arenaria section Pseudomoehringia, a group that currently comprises three species endemic to the Iberian Peninsula (A. funiculata, A. suffruticosa, and A. tejedensis) and A. glochidisperma, which is restricted to the Rif mountains, North Africa. However, the taxonomic boundaries and phylogenetic relationships among these species are still uncertain. To explore the evolutionary history and phylogeographic patterns within this section, analyses based on nuclear (amplified fragment length polymorphism and internal transcribed spacer) and plastid DNA markers (psbA‐3’ trnK‐matK and rps16) were performed. Our study has confirmed the monophyly of the section, in which two species are clearly identified (A. funiculata and A. glochidisperma) and an additional species complex (“A. suffruticosa + A. tejedensis complex”) is also supported as a monophyletic clade. The phylogeographic results point toward a dispersal event of a common ancestor of the group from the Iberian Peninsula, giving rise to A. glochidisperma in North Africa. Moreover, A. funiculata and A. glochidisperma are identified as closely related species edaphically differentiated across the Strait of Gibraltar. Our study indicates low levels of a recent gene flow among populations of the “A. suffruticosa + A. tejedensis complex,” which are genetically highly structured and suggest an isolation by distance pattern, probably due to a combination of ecological and geographic barriers. Furthermore, the taxonomic and conservation status of taxa included in Arenaria section Pseudomoehringia has been reviewed.  相似文献   

10.
Population genetics of the nomenspecies Enterobacter cloacae   总被引:2,自引:0,他引:2  
The genetic heterogeneity of the nomenspecies Enterobacter cloacae is well known. Enterobacter asburiae, Enterobacter cancerogenus, Enterobacter dissolvens, Enterobacter hormaechei, Enterobacter kobei, and Enterobacter nimipressuralis are closely related to it and are subsumed in the so-called E. cloacae complex. DNA-DNA hybridization studies performed previously identified at least five DNA-relatedness groups of this complex. In order to analyze the genetic structure and the phylogenetic relationships between the clusters of the nomenspecies E. cloacae, 206 strains collected from 22 hospitals, a veterinarian, and an agricultural center in 11 countries plus all 13 type strains of the genus and reference strain CDC 1347-71(R) were examined with a combination of sequence and PCR-restriction fragment length polymorphism (PCR-RFLP) analyses of the three housekeeping genes hsp60, rpoB, and hemB as well as ampC, the gene of a class C beta-lactamase. Based on the neighbor-joining tree of the hsp60 sequences, 12 genetic clusters (I to XII) and an unstable sequence crowd (xiii) were identified. The robustness of the genetic clusters was confirmed by analyses of rpoB and hemB sequences and ampC PCR-RFLPs. Sequence crowd xiii split into two groups after rpoB analysis. Only three strains formed a cluster with the type strain of E. cloacae, indicating that the minority of isolates identified as E. cloacae truly belong to the species; 13% of strains grouped with other type strains of the genus, suggesting that the phenotypes of these species seem to be more heterogeneous than so far believed. Three clusters represented 70% of strains, but none of them included a type or reference strain. The genetic clustering presented in this study might serve as a framework for future studies dealing with taxonomic, evolutionary, epidemiological, or pathogenetic characteristics of bacteria belonging to the E. cloacae complex.  相似文献   

11.
Evolutionary simplification, or loss of complex characters, is a major theme in studies of body-form evolution. The apparently infrequent evolutionary reacquisition of complex characters has led to the assertion (Dollo's Law) that once lost, complex characters may be impossible to re-evolve, at least via the exact same evolutionary process. Here, we provide one of the most comprehensive, fine-scale analyses of squamate body-form evolution to date, introducing a new model system of closely related, morphologically variable, lizards. Our phylogenetic results support independent instances of complete limb loss as well as multiple instances of digit and external ear opening loss and re-acquisition. Even more striking, we find strong statistical support for the re-acquisition of a pentadactyl body form from a digit-reduced ancestor. Our study reveals that species of the genus Brachymeles exemplify regions of morphospace (body plans) previously undocumented in squamates. Our findings have broad, general implications for body-form evolution in burrowing vertebrates: whatever constraints have shaped trends in morphological evolution among other squamate groups (excluding Bipes) have been lost in this one exemplary clade. The results of our study join a nascent body of literature showing strong statistical support for character loss, followed by evolutionary re-acquisition of complex structures associated with a generalized pentadactyl body form.  相似文献   

12.
试用聚类方法探讨中国雪雀的分类地位   总被引:2,自引:2,他引:0  
应用聚类方法对雪雀属、种及部分亚种的分类地位进行初步探索,选取一定的数量性状,取平均值组成原始数据矩阵。原始数据矩阵再进一步标准化,然后应用距离系数和相关系数进行聚类分析。比较了数量性状的聚类结果与传统的形态特征分类之间的异同,并探讨了雪雀属种级分类单元的亲缘关系和分类地位。  相似文献   

13.
为解决一些山茶科(Theaceae)的分类学问题,该研究在光学显微镜下对山茶科2亚科6属共20种植物的13种叶表皮微形态特征进行了观察,并利用聚类分析和主成分分析对这些特征进行分析,为山茶科的科学分类提供参考资料。结果表明:(1)山茶科20种植物的13种叶表皮微形态特征能够区分种间差异和分类等级,显示了比较全面的分类价值。(2)基于微形态特征的聚类分析和主成分分析结果显示,20个种分为2个大类群以及10个分支,很好地区分了山茶亚科(Theoideae)与厚皮香亚科(Ternstroemoideae),并将大部分分类地位相近的物种归类到一起,较好地反映了物种之间的亲缘关系。(3)该研究结果支持将小黄花茶组(Sect.Luteoflora)作为独立的一个组;支持将重庆山茶(Camellia chungkingensis Chang)从瘤果茶组(Sect.Tuberculata Chang Tax.)中分离;支持将山茶亚科与厚皮香亚科划分为两个较大类群,认为将厚皮香亚科并入五列木科(Pentaphylacaceae)的观点还有待更多实验证据的支持。  相似文献   

14.
Land snails are renowned model organisms in evolutionary ecology, but extensive morphological variation and lack of readily available diagnostic characters often invite taxonomic confusion among closely related species. Satsuma (Luchuhadra) largillierti is an arboreal land snail endemic to Okinawa Island, Japan, in which extensive geographic variation in shell morphology has long caused taxonomic complication. To establish robust species limits among S. largillierti and its allies, we perform molecular and morphological analyses of snails sampled from the entire range of Luchuhadra. Analyses of the mitochondrial cytochrome oxidase subunit 1 gene and nuclear ribosomal internal transcribed spacer sequences divide S. largillierti into two, reproductively isolated groups. Each of these groups includes Satsuma erabuensis and Satsuma sooi, respectively, which occur on a nearby island and were traditionally regarded as distinct species. Morphometric analysis of the genitalia further provides clear difference between the two groups, whereas differentiation in shell morphology is slight if any. These results indicate that the traditional taxonomy has overly depended on inadequate morphological difference and a priori information of island geography, which resulted in oversimplification of complex speciation history in Luchuhadra.  相似文献   

15.
Functional constraints to modifications in triterpene cyclase amino acid sequences make them good candidates for evolutionary studies on the phylogenetic relatedness of these enzymes in prokaryotes as well as in eukaryotes. In this study, we used a set of identified triterpene cyclases, a group of mainly bacterial squalene cyclases and a group of predominantly eukaryotic oxidosqualene cyclases, as seed sequences to identify 5288 putative triterpene cyclase homologues in publicly available databases. The Cluster Analysis of Sequences software was used to detect groups of sequences with increased pairwise sequence similarity. The sequences fall into two main clusters, a bacterial and a eukaryotic. The conserved, informative regions of a multiple sequence alignment of the family were used to construct a neighbour-joining phylogenetic tree using the AsaturA and maximum likelihood phylogenetic tree using the PhyML software. Both analyses showed that most of the triterpene cyclase sequences were similarly grouped to the accepted taxonomic relationships of the organism the sequences originated from, supporting the idea of vertical transfer of cyclase genes from parent to offspring as the main evolutionary driving force in this protein family. However, a small group of sequences from three bacterial species ( Stigmatella , Gemmata and Methylococcus ) grouped with an otherwise purely eukaryotic cluster of oxidosqualene cyclases, while a small group of sequences from seven fungal species and a sequence from the fern Adiantum grouped consistently with a cluster of otherwise purely bacterial squalene cyclases. This suggests that lateral gene transfer may have taken place, entailing a transfer of oxidosqualene cyclases from eukaryotes to bacteria and a transfer of squalene cyclase from bacteria to an ancestor of the group of Pezizomycotina fungi.  相似文献   

16.
中国栎属植物的数量分类研究   总被引:10,自引:1,他引:10  
在全面衡量中国栎属49种4变种性状特征的基础上,观测了25个定性性状和18个数量性状。通过聚类分析,可以将中国栎属分为5个特征明显的表征群,即5组:麻栎组(Section Aegilops)、槲栎组(Section Quercus)、高山栎组(Section Brachylepides)、巴东栎组(Section Engleriana)和橿子栎组(Section Echinolepides)。在主成分分析中,虽然性状的累积贡献率增长不明显,前3个主成分累积贡献率仅有50.4%,但结果仍然显示出和聚类分析同样的结果。说明栎属的分类性状仍存在主要方面,只不过在演化过程中由于性状变异的多样性,产生了多个不同的表征类群。分析结果对我们解决个别有疑问种的分类地位也有启示作用。因此,数量分类方法对解决栎属组间及种间的分类问题有重要的意义。  相似文献   

17.
Hierarchical cluster analysis and principal components have been used to provide a more detailed separation of the collagens into natural taxonomic groupings than previously obtained. These groups strongly reflect the evolutionary development of collagen. The first component separates land- from sea-based animals, primarily based on the hydroxylation of lysine and proline, indicating that control of hydroxylation, a post-translational event, has exerted a dominant influence during evolutionary adaptation. The power of the technique is illustrated by the ability to partially separate the evolutionarily closely related main homothermic species. Furthermore, the genetically different fibrous collagens, Types I and III, are well separated from basement membrane Type IV collagen and the filamentous collagens. The technique could, therefore, in addition to providing a taxonomic grouping, classify any new collagen and provide clues to its evolutionary development.  相似文献   

18.
Light and scanning electron microscopes were used to examine foliar epidermal features such as the shape of epidermal cells, the type of stomatal apparatus and outer stomatal rim in 38 species of 6 genera of the Betulaceae. Four types of stomatal apparatus on mature leaves are recognized in this survey: anomocytic, cyclocytic, non-typical actinocytic and brachyparacytic. The foliar epidermal characters and character states are taxonomically useful for the identification of genera and the division of tribes. The generalized evolutionary scheme for foliar epidermal features is fairly closely correlated with the generic relationships proposed in other studies (Abbe, 1935, 1974; Brunner & Fairbrothers, 1979; Hall, 1952; Kikuzava, 1982; Kuprianova, 1963)and it is clear that foliar epidermal morphology can be an important taxonomic character added to others for determining evolutionary relationships. The explanations of generic relationships are based on our hypothesis that anomocytic stomatal apparatus, uni-layered outer stomatal rim, having not T-pieces at the polar region of guard cells and straight anticlinal wall of lower epidermal cell are from the ancestor (Fig. 1). Sinuolate or sinuate anticlinal wall of lower epidermal cells and non-typical actinocytic stomatal apparatus, present in Corylus, Ostryopsis, Ostrya and Carpinus of the Betulaceae, correlates with the separation of Coryleae from Betuleae. Betuleae including Alnus and Betula is considered primitive with more primitive characters. Of Coryleae, Carpinus might be the most advanced, with brachyparacytic stomatal apparatus and double-layered outer stomatal rim.  相似文献   

19.
Inter-simple sequence repeat (ISSR) amplification was evaluated for its applicability as a genetic marker system to establish relationships among ten Diplotaxis species. ISSR amplification generated multiple banding profiles with the 12 primers from all DNA samples, with an average of 41.2 fragments per primer. This average was clearly higher for the 5′ triple-anchored primers than for other primers. The banding profiles were highly repeatable across separate PCR runs. DNA mixing procedures were found to be appropriate strategies to generate banding patterns representative of each species studied. Similarity values were calculated considering 494 ISSR bands, and a dendrogram was constructed based on the similarity matrix. The ten Diplotaxis species were clustered into two major groups. The first group consists of five species, Diplotaxis tenuifolia and Diplotaxis cretacea, and Diplotaxis muralis with their putative parents (D. tenuifolia and Diplotaxis viminea). In the second group three species are clustered that are closely related (Diplotaxis virgata, Diplotaxis catholica and Diplotaxis siettiana), in addition to Diplotaxis harra, and Diplotaxis erucoides, which has lowest similarity values with the rest of the species studied. The two groups defined in the present work may be concordant with the idea suggested by several authors of a biphyletic origin for Diplotaxis. The genetic relationships among the ten Diplotaxis species estimated by the polymorphism of ISSR markers are in agreement with those previously inferred by other morphological, biochemical and molecular data, indicating the reliability of the ISSR approach for this purpose. Received: 3 January 2000 / Accepted: 31 March 2000  相似文献   

20.
Contrasting with former taxonomic treatments, chromosome numbers and isozyme data support the delimitation of the seminiferous representatives of the Festuca brachyphylla complex in Svalbard into four species: F. baffinensis, F. brachyphylla, F. hyperborea and F. edlundiae. Unique enzyme markers were found for all species. Festuca brachyphylla proved hexaploid, and the others, tetraploid. The chromosome numbers of F. hyperborea and F brachyphylla (as circumscribed at present) are new to Svalbard. Festuca baffinensis is the most distinct species within the complex, probably representing a separate evolutionary lineage. The three other species seem closely related, showing mutually equidistant relationships. Some deviating plants found on disturbed ground might represent hybrid derivatives or an introduced foreign strain of the elsewhere variable F. brachyphylla. Materials of diploid F. ovina from northern Fennoscandia was enzymatically closely related to the F brachyphylla complex in Svalbard. Festuca brachyphylla, F. edlundiae , and F. hyperborea all had a stronger affinity to F ovina than to F baffinensis , indicating that the F brachyphylla complex is an artificial taxonomic group. There are reasons to believe that the origin of the polyploid taxa of the F brachyphylla complex can be traced to diploid species of the F. brachyphylla and F ovina complexes.  相似文献   

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