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1.
A detailed study of Ranunculus subgenus Batrachium was undertaken on material from SW Skåne, S Sweden. 38 populations were sampled including 5 from outside the study area. A comprehensive morphological investigation of the variation pattern, which included biometric analyses, led to a reassessment of diagnostic characters. 64 chromosome counts were made from 28 populations. Minor differences in karyotype constitution between species were demonstrated. Crossing experiments involving 4 species were carried out, and F, was analysed as regards morphology, compatibility, meiosis and seed set. The two diploid species (2n=16), R. fluitans and R. circinatus , are shown to be homogeneous and reproducing vegetatively in S Sweden. The tetraploid R. peltatus is outcrossing and probably self-incompatible, whereas the likewise tetraploid R. baudotii is self-compatible and mainly self-pollinated. These tetraploids are interfertile, but morphologically distinct and kept apart by different ecological demands. Hexaploids, generally referred to two separate species, R. aquatilis and R. trichophyllus , are automatically self-pollinated in bud (sometimes cleistogamous). All characters used to distinguish these two species are found to be variable and readily modified. Crosses between typical R. aquatilis and typical R. trichophyllus are fully fertile. A division into two species seems untenable. ( R. trichophyllus is treated as conspecific with R. aquatilis ). Semifertile, natural pentaploid hybrid derivates with varying chromosome numbers between R. aquatilis and R. peltatus were found, and have also been experimentally synthesized. The variation pattern in S Sweden deviates in sereral respects from that reported by Cook based mainly on C and W European material.  相似文献   

2.
BACKGROUND AND AIMS: Melocacatus paucispinus (Cactaceae) is endemic to the state of Bahia, Brazil, and due to its rarity and desirability to collectors it has been considered threatened with extinction. This species is usually sympatric and inter-fertile with M. concinnus, and morphological evidence for hybridization between them is present in some populations. Levels of genetic and morphological variation and sub-structuring in populations of these species were assessed and an attempt was made to verify the occurrence of natural hybridization between them. METHODS: Genetic variability was surveyed using allozymes (12 loci) and morphological variability using multivariate morphometric analyses (17 vegetative characters) in ten populations of M. paucispinus and three of M. concinnus occurring in the Chapada Diamantina, Bahia. KEY RESULTS: Genetic variability was low in both species (P = 0.0-33.3, A = 1.0-1.6, H(e) = 0.000-0.123 in M. paucispinus; P = 0.0-25.0, A = 1.0-1.4, H(e) = 0.000-0.104 in M. concinnus). Deficit of heterozygotes within the populations was detected in both species, with high values of F(IS) (0.732 and 0.901 in M. paucispinus and M. concinnus, respectively). Evidence of hybridization was detected by the relative allele frequency in the two diaphorase loci. High levels of genetic (F(ST) = 0.504 in M. paucispinus and 0.349 in M. concinnus) and morphological (A = 0.20 in M. paucispinus and 0.17 in M. concinnus) structuring among populations were found. CONCLUSIONS: The Melocactus spp. displayed levels of genetic variability lower than the values reported for other cactus species. The evidence indicates the occurrence of introgression in both species at two sites. The high F(ST) values cannot be explained by geographical substructuring, but are consistent with hybridization. Conversely, morphological differentiation in M. paucispinus, but not in M. concinnus, is probably due to isolation by distance.  相似文献   

3.
4.
We examined 532 specimens representing eight species of Didymaea (Rubiaceae) to describe their leaf architecture. Characters observed in the herbarium specimens and cleared leaves were leaf base, apex, and margin; trichome type and distribution; vein orders from primary to higher order veins, veinlets, and ultimate marginal vein. Six morphometric variables were analyzed using variance and principal component analysis to identify which characters are useful to distinguish species. Most of the species present brochidodromous venation pattern, except D. hispidula, which has eucamptodromous venation pattern; Didymaea floribunda is unique in having cylindrical and bicellular trichomes. Principal component analysis revealed that 78% of the total variation is mainly related to leaf maximum width. Variance analysis showed significant differences between D. microflosculosa and the other species. Architectural features were useful for differentiating all the species, and an identification key for the species of Didymaea based only on leaf characters is presented.  相似文献   

5.
The New Zealand fernPolystichum richardii is shown to comprise at least two evolutionary lineages. A narrow-scaled morphological form and a wide-scaled morphological form are recognised. Principal Component Analysis of a set of frond, soral and spore characters supports this morphological separation. Amplified Fragment Length Polymorphism (AFLP) DNA fingerprinting shows that the two morphological forms are also genetically distinct. They are sympatric across a broad area of central New Zealand, and often grow together without apparent ecological separation at the local level. Both are known to form sterile hybrids withP. vestitum, suggesting that both morphological forms ofP. richardii are at least partially outcrossing. The morphological and genetic distinctiveness of these two morphological forms, combined with their sympatric distributions and their (at least partially) outcrossing mating systems, merits their recognition as separate species.  相似文献   

6.
Variability of morphological characters and Inter Simple Sequence Repeat (ISSR) markers is studied in a mixed multispecies sympatric growth of wild roses in Lugansk province of Ukraine. Several methods of data analysis are used, such as Principal Coordinates Analysis, cluster analysis (UPGMA), and Bayesian analyses of population structure with the Structure 2.2 and NewHybrids programs. The results indicate that there are four species growing at the site, viz. R. canina, R. villosa, R. dimorpha, and R. podolica, as well as various hybrids between them. The hybrid nature of the specimens is confirmed by molecular data, however they are not intermediate between the parental species as to their morphology. The hybrids either coincide morphologically with one of the parents, or demonstrate novel combinations of diagnostic characters.  相似文献   

7.
The intraspecific relationship of selected wood anatomical characters with stem diameter, plant height, and altitude was investigated in four NepaleseRhododendron species:R. anthopogon, R. lepidotum, R. campanulatum, andR. arboreum, i.e., two shrubs, one subtree, and one tree. We studied 23 to 27 specimens for each species.R. anthopogon grew from 3,380 to 4,950 m,R. lepidotum from 2,060 to 4,720 m,R. campanulatum from 2,790 to 4,140 m, andR. arboreum from 1,430 to 3,460 m. Multiple regression analysis and actual distribution of character values show that the wood anatomical characters having a significant correlation with non-anatomical factors differ between species. The number of significant characters are two inR. anthopogon andR. campanulatum, five inR. lepidotum, and nine inR. arboreum and tends to be small in species having smaller altitudinal ranges. Average pore area, most strongly correlated with non-anatomical factors in interspecific variation, is significantly correlated only inR. lepidotum andR. arboreum. The general trends in intraspecific variation among four NepaleseRhododendron species differ from the trends found in interspecific variation within the genus and are characteristic of each species.  相似文献   

8.
Leaf anatomy is compared for all species of Raoulia. The species are tabulated according to their lamina structure. Noteworthy anatomical features are lamina type and grade of differentiation, stomatal position, epidermal and cuticle thickness, shape of mesophyll cells, presence or absence of central clear cells, sclerenchyma caps, abaxial collenchyma and protruding midrib. It is shown that leaf anatomy data provide characters which are taxonomically useful in Raoulia. The main subgenera are supported except that the leaf anatomy of R. haastii is anomalous and that of R. youngii is typical of R. subg. Raoulia rather than R. subg. Psychrophyton. The leaf anatomy of R. petriensis is unique in the genus.  相似文献   

9.
Impatiens pterocaulis S. X. Yu et L. R. Zhang, a new species of the Balsaminaceae from Yancha, Longlin, Guangxi Region, is described and illustrated. This species is similar to I. wilsonii in having nearly white flowers, 4 lateral sepals and a racememos inflorescence, but differs by having winged stems, very short‐spurred lower sepal, yellowish flowers and an acuminate dorsal petal apex. Pollen characters and leaf epidermal micro‐characters of these two species were studied, and the results support that the two species should be kept separate.  相似文献   

10.
A revision of the genus Calvoa Hook. f. (Melastomataceae) is presented. Principal Component Analyses (PCA) and Cluster Analyses (UPGMA) were performed to elucidate three cases of difficult species delimitation and infraspecific variation, with the following results. (1) The separation between C. crassinoda Hook. f. and C. grandifolia Cogn. was clear in the results obtained with both methods. (2) The group of the West-Central African species Calvoa angolensis A. Fern. & R. Fern., C. calliantha Jacq.-Fél., C. monticola A. Chev., C. pulcherrima Gilg ex Engl., C. sapinii De Wild., C. seretii De Wild., C. sinuata Hook. f. and C. subquinquenervia De Wild, proved difficult to resolve with either analysis, but the Cluster Analysis produced results which are more consistent with the identification of the specimens. (3) Neither of the two analyses supported the recognition of infraspecific categories in Calvoa orientalis Taub. Eighteen species are recognized in the genus. The new species Calvoa Jacques-felixii E. Figueiredo is described and the new combination Calvoa seretii subsp. wildemaniana (Exell) E. Figueiredo is made. Four lectotypes are designated. The conservation status of some taxa is discussed. Six species are considered rare and possibly under threat.  相似文献   

11.
The phyletic position of the Macaronesian Ranunculus species R. cortusifolius was investigated in an analysis of meiotic metaphase I in a series of interspecific hybrids (eight diploid species, nine genome combinations, 25 F1's). The exceptionally large size of the R. cortusifolius chromosomes, previously described via cytophotometry, was confirmed and allowed a positive identification of the constituent haploid chromosome sets in all hybrid meiotic preparations studied. MI was largely univalent-unpaired, with 0 to average 1–2 bivalent-chiasmate pairs (2 n = 16), sporadic non-bivalent sticky groupings and occasional (two hybrids) loose segmental associations (figured). The comparative study of the univalent-bivalent meiotic profiles for the various genome combinations showed that the R. cortusifolius genome has diverged almost as widely from the genomes of species in its own taxonomic group (sect. Pterocarpa Ovcz.) as it has from those of certain morphologically diverse, progressive species from two other sections (sect. Xiphocoma , sect. Ranunculus ). The morphological conservatism of R. cortusifolius in the face of wide genetic divergence is discussed; an explanation invoking as its most important single cause excessive genome size, on a pre-adaptive model (Waddington & Lewontin), is favoured.  相似文献   

12.
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   

13.
Abstract. Morphological variation among freshly caught specimens resembling Folsomia quadrioculata Tullberg was examined using principal components analysis and canonical variates analysis. Two distinct groups were identified corresponding with F. quadrioculata and F.manolachei Bagnall. Previous workers have questioned the specific status of F.manolachei and regarded these two species as inseparable using morphometric characters. A study of specimens previously identified as F. quadrioculata suggested that many were mis-identified and that F.manolachei is more abundant in the British Isles than is usually thought. Variation in some characters traditionally used to identify Folsomia species was examined and a method for distinguishing adult and juvenile F.quadrioculata from F.manolachei is provided. The synonomy of F.nana Gisin with F.manolachei is supported. The separation of F.diplothalma Axelson from F. quadrioculata is discussed, concluding that no characters are known which can reliably separate British specimens of these species.  相似文献   

14.
This paper reports the chromosome numbers and karyotype analysis of Speirantha gardenii, which is endemic to China. The material was collected from Huang Shan, Anhui. It is a diploid species. Its somatic chromosome is 2n=38=22m+6sm+10st. The 9th pair is submedian centromere chromosomes, but it has two constrictions. The secondary constriction is on the short arm near centromere. Of the 19 chromosome pairs,secondary constriction is present only in this pair.  相似文献   

15.
16.
 In 17 populations of the tetraploid agamospecies R. variabilis, 10 enzyme systems have been studied by horizontal starch gel electrophoresis, and compared to previous data of 3 populations of the diploid sexual species R. notabilis. Allozymic and genotypic diversity of 12 polymorphic loci, and multilocus genotype diversity in R. variabilis compares to other apomictic taxa, confirming the assumed apomictic mode of reproduction previously found in 3 populations. A cluster analysis based on genetic distance values separated the two taxa, the populations of southeastern Austria sympatric with R. notabilis showing no closer relationships to the sexual species than the allopatric ones. The R. variabilis populations of the circumalpine regions are separated as a rather uniform group, those of the Bohemian massif as another, more heterogeneous group. This geographic differentiation is mainly due to genotypic variation, which is higher in the Bohemian massif than in the circumalpine group, and lower in areas where R. variabilis is sympatric with R. notabilis. Proportion of multilocus genotypes within populations (G/N), genotype diversity (D), and genotype evenness (E) measures indicate facultative recombination events with fixation and clonal reproduction of new recombined genotypes, which is regarded as the most important factor for the evolution of new lineages in goldilocks. Morphometric data of the R. variabilis and R. notabilis populations studied by cluster and principal coordinate analyses clearly separated the two taxa, and indicated a slight geographic differentiation with in R. variabilis corresponding to the results of isozyme data. A principal coordinate analysis of R. variabilis individuals based on stem and fruit characters showed a clinal variation, but no clear separation of groups. The variation found in this PCoA is almost completely covered from the most widespread clone (genotype I), and also from individual genotypes. The implications of the results on different species concepts for apomicts are discussed. For R. variabilis, no taxonomic conclusions can be drawn from the present data set. Received December 15, 1999 Accepted November 15, 2000  相似文献   

17.
Abstract The effect of plant size on reproduction in four species of alpine Ranunculus (R. muelleri, R. dissectifolius, R. graniticola and R. niphophilus) was investigated in two sites over two seasons in the field on a total of 190 plants. The effects of plant size (number of leaves) and number of flowers on the number of anthers, ovules and seed per flower and per plant were determined. There was a positive relationship between several measures of reproduction and plant size in all four species, indicating that reproduction is size-dependent. All the results indicate that the main factor controlling the amount of seed produced by alpine Ranunculus is the size of the plant. Specifically, bigger plants produced more seed by producing more flowers, not by producing more ovules per flower, or higher seed set per flower. Correspondingly, bigger plants produced more anthers by producing more flowers, rather than by producing flowers with more anthers. The total number of seeds produced by a plant was directly proportional to plant size in the four species. Therefore, reproductive effort should not vary with plant size in the four species.  相似文献   

18.
Ranunculus is a large genus with a worldwide distribution. Phylogenetic analyses of c. 200 species of Ranunculus s.l. based on sequences of the nrITS using maximum parsimony and Bayesian inference yielded high congruence with previous cpDNA restriction site analyses, but strongly contradict previous classifications. A large core clade including Ranunculus subg. Ranunculus, subg. Batrachium, subg. Crymodes p.p., Ceratocephala, Myosurus, and Aphanostemma is separated from R. subg. Ficaria, subg. Pallasiantha, subg. Coptidium, subg. Crymodes p.p., Halerpestes, Peltocalathos, Callianthemoides, and Arcteranthis. Within the core clade, 19 clades can be described with morphological and karyological features. Several sections are not monophyletic. Parallel evolution of morphological characters in adaptation to climatic conditions may be a reason for incongruence of molecular data and morphology-based classifications. In some mountainous regions, groups of closely related species may have originated from adaptive radiation and rapid speciation. Split decomposition analysis indicated complex patterns of relationship and suggested hybridization in the apomictic R. auricomus complex, R. subg. Batrachium, and the white-flowering European alpines. The evolutionary success of the genus might be due to a combination of morphological plasticity and adaptations, hybridization and polyploidy as important factors for regional diversification, and a broad range of reproductive strategies.  相似文献   

19.
Previous systematic treatments of the neotropical palm genus Hyospathe have recognized from two to 18 species. An explicit, quantitative, repeatable sequence of operations for delimiting and testing groups of specimens and applying species concepts is carried out. Multivariate statistical analysis of morphological data is used to delimit and test groups of specimens. Cluster analysis is used to distinguish between characters and traits. Analysis of qualitative and quantitative characters reveals six groups of specimens, and the Phylogenetic Species Concept is applied to these groups. Two species, H. peruviana Henderson and H. frontinensis Henderson, are described as new. One of the specimen groups is large and widespread, and six geographically separate subgroups can be recognized within it. These subgroups can be distinguished by one or more significantly different quantitative characters. A Phylogenetic Subspecies Concept is applied to these subgroups. Three subspecies, H. elegans subsp. costaricensis Henderson, H. elegans subsp. sanblasensis Henderson, and H. elegans subsp. tacarcunensis Henderson are described as new, and two new combinations are made: H. elegans subsp. sodiroi (Dammer ex Burret) Henderson and H. elegans subsp. concinna (H. E. Moore) Henderson. One subspecies occurring in the Amazon region is complex morphologically and is not resolved by the methods used here.  相似文献   

20.
濒危物种小勾儿茶的重新发现   总被引:3,自引:0,他引:3  
在距离濒危物种小勾儿茶模式标本产地约130 km处的湖北省五峰县后河国家自然保护区中重新发现了小勾儿茶Berchemiella wilsonii (Schneid.) Nakai。威尔逊1907年在湖北省兴山县采集到小勾儿茶的模式标本有花,无果实。我们在五峰县采集了小勾儿茶的花和果实标本并对其果实特征予以补充描述。  相似文献   

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