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1.
In order to investigate morphological variations of Elymus sibiricus L., E. nutans Griseb., and E. burchan-buddae (Nevski) Tzvelev [=Roegneria nutans (Keng) Keng], and to explore their systematic relationships, six morphological characters were measured and compared between the Elymus species. Interspecific hybridizations between E. nutans and E. sibiricus, and E. burchan-buddae were carried out with the aid of embryo rescue. Chromosome pairing behaviour was also analysed at metaphase- I of meiosis in pollen mother cells of F1 hybrids. Morphologic characters, such as length of spikes and length of glumes varied considerably between different individuals of each species, whereas length and width of paleas were quite stable and different between species. The interspecific hybrids were completely sterile and their meioses were irregular. Meiotic configuration of E. nutans × E. burchan-buddae was 7.70I +13.40Ⅱ+0.06Ⅲ+0.08 IV, whereas that of E. sibircus×E. nutans was 11.98I+9.61Ⅱ+0.64Ⅲ+0.39Ⅳ+0.01V. It is concluded from the morphological and cytological study that (1) it is possible to identify the three Elymus species using the palea character, in addition to other traditionally applied characters; (2) Elymus nutans and E. burchan-buddae have a comparatively high genomie relationship, while E. nutans and E. sibircus have a relatively low genomic affinity to one another; and (3) a certain chromosome pairing regulator was presented in the hybrid between E. burchan-buddae andE. nutans.  相似文献   

2.
为了进一步研究Elymus sibiricus L.、E.nutans Griseb.和E.burchan-buddae(Neuski)Tzelev [=Roegneria nutans(Keng)Keng]的外部形态差异及其系统学关系,本文对这三种植物的6个穗部形 态性状进行了观测和比较,并对这三个Elymus种进行了种间杂交及杂种F1的减数分裂染色体配对行 为的分析研究。结果表明:这三个Elymus种的穗长及颖长等性状均变异很大,而内稃的长、宽则变异 不大并具有明显的种间差异。E. nutans×E.barchan-buddae及E.nutans×E.sibiricus的杂种F1均完 全不育,减数分裂不规则。E.nutans×E.burchan-buddae杂种F1的减数分裂构型为:7.70I+13.40 Ⅱ+0.06Ⅲ+O.08 Ⅳ,而E.sibiricus×E.nutans杂种F1的构型为11.98 Ⅰ+9.61Ⅱ+O.64Ⅲ+0.39 Ⅳ+0.01V。由本实验的形态学和细胞学的研究结果得出以下结论:1.利用内稃形态性状结合穗部 其它性状的差异能对这三个物种进行较准确的鉴定;2.E.nutans与E.burchan-buddae的亲缘关系较 近,而E.nutans与E.sibiricus的亲缘关系则较远;3. E,burchan-buddae×E.nutans的杂种Fl中存在着染色体配对控制因子。  相似文献   

3.
Four species belonging to the genus Euplotes have been investigated, namely: E. lynni nov. spec., E. indica nov. spec., E. aediculatus, and E. woodruffi. All populations are from India and were investigated using morphological and molecular markers. The phylogenetic relationships were inferred from small subunit ribosomal rRNA gene (SSU rRNA), internal transcribed spacer (ITS) region, and mitochondrial cytochrome c oxidase subunit I (COI) gene. Predicted secondary structure models for two new species using the hypervariable region of the SSU rRNA gene and ITS2 region support the distinctness of both species. Morphological characters were subjected to principal component analysis (PCA) and genetic variations were studied in-depth to analyze the relatedness of the two new species with their congeners. An integrative approach combining morphological features, molecular analysis, and ecological characteristics was carried out to understand the phylogenetic position of the reported species within the different clades of the genus Euplotes.  相似文献   

4.
Journal of Ichthyology - The species status is justified for the Okhotsk lumpsucker Eumicrotremus ochotonensis based on the morphological characters. The differences from the closely related...  相似文献   

5.
Two new species of Encholirium from the Espinhaço range, restricted to the Diamantina plateau of Minas Gerais state, Encholirium pulchrum Forzza, Leme & O. B. C. Ribeiro and Encholirium diamantinum Forzza, are described and illustrated, and their morphological characters are discussed and compared to those of close relatives.  相似文献   

6.
Morphological similarity among E. trachycaulus, E. virescens, E. violaceus, and E. hyperarcticus has often been noted. Taxonomists have tried to discriminate among these taxa using morphological characters and a number of different relationships among them have been suggested. However, the genetic relationships among these taxa are still unknown. AFLP analysis was used to characterize the molecular diversity of these taxa and to examine genetic relationships among them. A high degree of genetic identity was apparent among 7 accessions of E. virescens. The similarity values ranged from 0.90 to 0.99 with an average of 0.94. The mean similarity values among 3 E. hyperarcticus and among 5 E. violaceus accessions were 0.84 (0.81-0.87) and 0.77 (0.66-0.90), respectively. The similarity values among 17 E. trachycaulus accessions ranged from 0.49 to 0.92 with an average of 0.75. The 5 accessions of E. subsecundus displayed high variation, with similarity values between 0.52 and 0.68 and a mean value of 0.59. Both maximum-parsimony (MP) and neighbor-joining (NJ) analyses showed that all 7 accessions of E. virescens formed a clade, indicating a monophyletic origin. On the other hand, Elymus trachycaulus, E. subsecundus, and E. violaceus were each paraphyletic and separated into different genetically distinct groups. Among these 5 taxa, E. virescens was genetically similar to E. trachycaulus, and E. violaceus was genetically similar to E. hyperarcticus.  相似文献   

7.
The taxonomy of Prunus subgenus Prunus is notoriously problematic and reliable discriminating characters for species and subspecies identification are missing. Principal Component Analysis (PCA) was performed on different morphological data sets and useful diagnostic characters for Prunus spinosa and P. domestica ssp. insititia were found. Many traditionally used morphological characters were found unreliable. The hypothesis of widespread hybridization between Prunus spinosa and P. domestica ssp. insititia in Denmark were examined using PCA and HYWIN. It was found that hybrids between the two taxa are rare in Denmark.  相似文献   

8.
Lim YW  Jung HS 《Mycologia》2003,95(4):694-699
Irpex, one of the most common polypore genera, is easily identified by macro- and microscopic characters. During field trips to Korea's Kangwon Province, some Irpex specimens with conspicuous morphological differences from I. lacteus were collected. Cultural characters and molecular evidence differentiated this new strain from I. lacteus, and this taxon is proposed as I. hydnoides sp. nov.  相似文献   

9.
The morphological characters of Pterophyllum guizhouense sp. nov. were reported and those of P. astartense Harris were supplied and emended. Meanwhile, the significance of cuticle characters chosen in the identification of fossil plants was also discussed.  相似文献   

10.
Evolutionary significance of morphological characters that have traditionally been used for species delineation in the aquatic moss genus Amblystegium was tested by partitioning the environmentally and genetically induced morphological variation and focusing on morphological evolution using comparative methods. Cultivation experiments under controlled condition showed that most of the morphological variation in nature resulted from plasticity. Information regarding genetically fixed morphological variation and genetic similarity derived from polymorphic inter-simple sequence repeat markers was combined into an explicit model of morphological evolution. Maximum likelihood estimates of the model parameters indicated that evolution of most characters tended to accelerate in the most recent taxa and was often independent from the phylogeny. Constraining the different characters to be independent from each other most often produced a less likely result than when the characters were free to evolve in a correlated fashion. Thus, the morphological characters that have traditionally been used to circumscribe different Amblystegium species lack the independence, diagnostic value for specific lineages, and stability that would be required for distinguishing different species.  相似文献   

11.
A cladistic analysis of sequences from the chloroplast gene rbcL was used to determine the systematic affinities of Rhizophoraceae and Anisophylleaceae. This analysis rejects close relationships of Rhizophoraceae with Celastraceae or Elaeocarpaceae, suggested previously, and identifies Erythroxylaceae as sister group within the Malpighiales, supported by several morphological and anatomical characters. Our molecular results also indicate that Anisophylleaceae are nested within Cucurbitales. Although this placement is novel, this affinity is also well supported by shared morphological characters. Tribal and generic relationships within Rhizophoraceae are evaluated with a combination of six molecular data sets (rbcL, atpB-rbcL intergenic spacer, trnL-trnF intergenic spacer, ITS1, ITS2, and 5.8S) and a morphological data set. These relationships are compared with results from previous morphological cladistic analyses. Against the background of the molecular results, we briefly discuss the evolution of morphological characters traditionally used for tribal subdivision as well as characters presumably significant for adaptation to mangrove habitats, namely, aerial stilt roots and vivipary.  相似文献   

12.
New material of Achaeta species was collected from a small portion of the tropical rain forest region of Brazil's east coast. For A. neotropica Cernosvitov, wider ranges of variation of several morphological characters are described and four varieties are recognized. Achaeta iridescens sp.n. differs from other species of the genus by the presence of intestinal pouches in segment VII. Both species are peculiar to Achaeta in that they have compact glandular masses surrounding the male pores and a more posterior origin of the dorsal vessel; they share with a few European and most non-European species the tendency to show a complete regression of some morphological characters, namely the setal follicles, oesophageal appendages and dorsal connection of the third pair of septal glands.  相似文献   

13.
Morphological variation and taxonomic continuum of 110 specimens of Bromus arvensis, B. japonicus and B. squarrosus were analysed to assess the morphological variability of these close taxa. The importance of every morphological character was estimated by the GLM procedure. Stepwise discriminant analysis was used in order to find a set of morphological characters that maximises differences among the species. According to this, the most important characters appeared to be the length of anthers, width of lemma and lemma margin angle shape. The most important characters for the determination of Bromus arvensis was the length of anthers and for B. squarrosus width of lemma. According to the UPGMA cluster analysis, canonical discriminant, classificatory discriminant and principal component analyses, all specimens were separated into three moderately distinct groups which corresponded to the three traditional species. The study showed that qualitative characters were the best for the delimitation of the tax a by statistical analyses and demonstrated the incongruity between the pattern of morphological and genetic (allozyme) variation among the three Bromus species.  相似文献   

14.
The genus Eodiaptomus Kiefer contains six species, five of which are distributed in Asia, and one in Australia and New Guinea. A seventh species, E. sanuamuangae n.sp., is now added from Thailand. It has hitherto been misidentified as E. sinensis (Burckhardt), but can be recognized by various morphologic criteria. In the female, both spines on either wing of the fifth pediger are laterally placed. The third endopodite-segment of P2–P4 has seven, instead of six, setae. The sensory seta on the basis of P5 is extraordinarily long. On the male right antennule, the spine on segment 8 is much reduced, whereas that on segment 15 is relatively strong; the spinous process on the antepenultimate segment is slender, straight, with a hooked tip and as long as the next segment. Morphologically and geographically, E. sanuamuangae n.sp. links the Asian to the Australian forms. The Australian E. lumholtzi (Sars) is redescribed. A detailed morphological comparison is made of all Eodiaptomus spp. Their taxonomic characters, interspecies relationship, and biogeography are discussed.  相似文献   

15.
In the early 1980s, sheepshead minnow Cyprinodon variegates was introduced into the Pecos River, Texas, U.S.A. where it hybridized with the endemic Pecos pupfish C. pecosensis . By 1985, pupfish populations throughout approximately 300 km of the river consisted exclusively of individuals of hybrid origin (intergrades). There was significant ( P <0·05) geographic variation in most morphological characters; the general pattern of variation was of a bidirectional cline centred near Pecos, Texas. At that site, morphology of intergrade populations resembled mostly that of the introduced species. Upstream and downstream from Pecos, morphology shifted progressively toward that typical of the native form. Intergrade populations were morphologically intermediate to the parental forms, showed a rapid approach to random assortment of characters, and generally exhibited greater morphological variability than occurred in either parent species. These observations and the consistent lack of bimodality in frequency distributions of a morphological hybrid index support the contention that intergrade populations comprise panmictic admixtures of C. variegates and C. pecosensis .  相似文献   

16.
Acoustic and morphological characters are very important to distinguish species of Cicadidae. In this study, the morphological and acoustic characters of Cicadatra platyptera Fieber, 1876 (Hemiptera, Cicadidae) collected from Turkey were analysed. The external morphological structures of two species were drawn and photographs of some specimens were taken. We evaluated taxonomically important morphological characters such as body shape, colors, patterns, structure, and genital structure. We evaluated measurements of external morphological structures and acoustics characters of Cicadatra platyptera from Turkey, partly with statistical analyses. Morphological characters were compared and differentiated from the closely related species, Cicadatra atra. The distribution in Turkey including previous records and the material examined were shown on a map, and the distribution in Palearctic Region was given.  相似文献   

17.
Because calcareous sponges are triggering renewed interest with respect to basal metazoan evolution, a phylogenetic framework of their internal relationships is needed to clarify the evolutionary history of key morphological characters. Morphological variation was scored at the suprageneric level within Calcispongia, but little phylogenetic information could be retrieved from morphological characters. For the main subdivision of Calcispongia, the analysis of morphological data weakly supports a classification based upon cytological and embryological characters (Calcinea/Calcaronea) rather than the older classification scheme based upon the aquiferous system (Homocoela/Heterocoela). The 18S ribosomal RNA data were then analyzed, both alone and in combination with morphological characters. The monophyly of Calcispongia is highly supported, but the position of this group with respect to other sponge lineages and to eumetazoan taxa is not resolved. The monophyly of both Calcinea and Calcaronea is retrieved, and the data strongly rejected the competing Homocoela/Heterocoela hypothesis. The phylogeny implies that characters of the skeleton architecture are highly homoplastic, as are characters of the aquiferous system. However, axial symmetry seems to be primitive for all Calcispongia, a conclusion that has potentially far-reaching implications for hypotheses of early body plan evolution in Metazoa.  相似文献   

18.
Delimitation of sections is controversial within the genus Cytisus L. (Fabaceae, Genisteae). A morphological study has been conducted on 19 taxa from sections Alburnoides, Spartopsis and Verzinum to clarify their discrimination. Thirty-five quantitative and qualitative characters were recorded on a maximum of 15 dry or living flowers per taxon. Three multiple correspondence factor analyses (MCFA) were performed on a matrix based on 22 of the 35 recorded morphological characters to (1) compare the variability within and between individuals and (2) distinguish groups among the studied taxa. MCFA showed that both flowers sampled from the same plant or different individuals could represent the morphological variability of a taxon. MCFA also clustered the 19 taxa into three groups corresponding to sections Alburnoides, Spartopsis and Verzinum as defined by Cristofolini and Troia (Taxon 44:733–746, 2006). However, floral morphology has not been sufficient to discriminate taxa within sections. A key of the three studied sections based on floral characters is given.  相似文献   

19.
20.
We analysed the putative hybrid zone between the ground beetles Carabus lewisianus Breuning and C. albrechti Morawitz from the Kanto and Tanzawa Mountains in central Honshu, Japan, using morphological, genetic, and behavioural data. Canonical discriminant analysis of three external and five genital morphological characters revealed an apparent morphological gap, suggesting restricted sympatry in the contact zone. RFLP and molecular phylogenetic analyses of the mitochondrial gene ND5 revealed that haplotypes originating from C. lewisianus introgressed extensively into C. albrechti . Fitting tanh curves to morphological (external and genital) and genetic characters showed differential cline widths and centres, suggesting stronger selection for genital morphology with narrower cline widths, and extensive introgression of the nuclear genes responsible for external characters relative to those controlling genital morphology into the range of C. albrechti . Linkage disequilibria between the morphological characters did not differ from zero, suggesting sufficient recombination occurred in the zone but the effect of small sample sizes was not negligible. Mate choice trials demonstrated that males showed a weak but not significant preference for conspecific mates. We interpret these patterns as evidence for (1) partial reproductive isolation presumably by postmating processes; (2) selection against intermediate genital morphologies, and (3) independent responses of the characters to different evolutionary forces that may cause movement of genital clines and introgression of the mitochondrial gene and external morphology. The movement of the boundaries may have resulted in the particular species distribution patterns in the study area.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 86 , 79–94.  相似文献   

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