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 0 毫秒
1.
Geographical distribution and phenetic variation are studied for a group of related endemic species at present assigned to the genera Hutera and Rhynchosinapis. The presence of Rhynchosinapis hispida is recorded for five localities on the western part of the range studied. The area of R. longirostra is further explored to give twelve localities over an extended area of 100 km. Five additional localities, to give a total of seven, are also recorded for Hutera leptocarpa , and the limits between the area of this species and that of R. longirostra are tentatively established. Some populations which show intermediate and gradative characters between these taxa are referred to two new varieties and to three new genetic forms. The small area where H. rupestris occurs in the adjoining Sierra de Alcaraz is also explored. A numerical study of ten differential characters over fifteen populations of the above taxa, shows an obvious correlation between phenotype and geographical distribution, and sheds light on their possible phylogenetic relationship. Hutera leptocarpa and Rhynchosinapis longirostra seem to be schizoendemics which have recently and independently evolved from ancestors similar to the more widely distributed R. hispida. Hutera rupestris should not be regarded as a relict, but rather as a recent invader into the adjoining calcareous sierras. No solid basis has been found to maintain two separate genera and so the new combinations Hutera hispida and Hutera longirostra are proposed for the basionyms Rhynchosinapis hispida and Rhynchosinapis longirostra respectively. Conservational aspects are also discussed.  相似文献   

2.
OOST, E. H., BRANDENBURG, W. A. & JARVIS, C. E., 1989. Typification of Brassica oleracea L. (Cruciferae) and its Linnaean varieties. The Linnaean concept of Brassica oleracea and its varieties is discussed. In the light of this concept several types are considered and chosen.  相似文献   

3.
JARVIE, J. K. & BARKWORTH, M. E., 1992. Anatomical variation in some perennial Triticeae. Cross-sectional anatomy of glumes and leaf blades was examined in 22 taxa of the perennial Triticeae. The taxa included diploids and polyploids based largely on various combinations of the E, J and S genomes. The objective was to determine how much correlation exists between anatomical characteristics and genomic constitution. The data were analysed by principal co-ordinate and cluster analyses. The results showed that monogenomic species based on different genomes were readily distinguishable on glume and leaf blade features. Most heterogenomic taxa exhibited some aspects of each genome present except in the case of JE allotetraploids, which exhibited no E genome characteristics.  相似文献   

4.
Taxonomic characters for delimitation of Hilliella and Yinshania are discussed. More attention in this study is paid to morphological delimitation of these two genera. The results of the study show that these two genera can be easily separated by two prim  相似文献   

5.
    
Identifying discontinuous entities within species complexes is a major topic in systematic and evolutionary biology. Comprehensive inventories describing and identifying species rapidly and correctly before they or their habitats disappear is especially important in megadiverse regions, such as South America continent, where a large part of the biodiversity is still unknown and remains to be discovered. Species complexes may account for a substantial number of plant groups in the South American flora, and studies investigating species boundaries in such challenging groups are needed. In this context, multidisciplinary approaches are crucial to understanding the species integrity and boundaries within species complexes. Morphometrics, cytogenetics, anatomy, crossing experiments, and molecular markers have been combined in different ways to investigate species complexes and have helped depict the mechanisms underlying the origin of South American species. Here, we review the current knowledge about plant species complexes on the hyperdiverse South American continent based on a detailed examination of the relevant literature. We discuss the main findings in light of the potential evolutionary mechanisms involved in speciation and suggest future directions in terms of integrating multispecies coalescence methods with several complementary types of morphological, ecological, and geographical data in this research field.  相似文献   

6.
泡果荠属Hilliella和阴山荠属Yinshania是十字花科中国特有的两小群植物,但是,它们的分属界定却一直颇有争议。本文结合前人的研究结果重新对这两群植物做了研究,从而进一步确认这两群植物应该界定为两个属,即泡果荠属和阴山荠属。文中比较了两属间重要的性状特征,并指出它们的主要区别在于:泡果荠属果实无假隔膜,种子较大,表面具小瘤状突起,染色体倍性为六倍体(2n=6x=42);而阴山荠属果实有假隔膜,种子较小,表面具网纹,染色体倍性为二倍体(2n=2x=12)。两属其他方面如叶形态、叶表皮结构、被毛类型  相似文献   

7.
    
The European species of Trachelipus Budde-Lund, 1908 are revised. The generic diagnosis is extended. The species T. aegaeus (Verhoeff, 1907), T. arcuatus (Budde-Lund, 1885), T. ater (Budde-Lund, 1896), T. camerani (Tua, 1900), T. dijfkilis (Radu, 1950), T. nodulosus (C. L. Koch, 1838), T. palustris (Strouhal, 1936), T. rathkii (Brandt, 1833), T. ratzeburgii (Brandt, 1833), T. razzautii (Arcangeli, 1913), T. rhinoceros (Budde-Lund, 1885), T. squamuliger (Verhoeff, 1907), T. trilobatus (Stein, 1859), (77 troglobius Tabacaru & Boghean, 1989) and 7T vespertilio (Budde-Lund, 1896) are recognized as valid. Except for T. troglobius , redesriptions, figures and distribution maps are given. A key to species is provided. Nineteen names are new synonyms of the above mentioned ones; nine names become nomina dubia.  相似文献   

8.
Brassicaceae: Species checklist and database on CD-Rom   总被引:1,自引:0,他引:1  
A species checklist has been prepared for the Brassicaceae (Cruciferae) family, providing the first updated list in over 70 years. The family, currently, includes 338 genera and 3709 species. The database contains approximately 14,000 taxonomic names (records). Taxon status and synonymy, taxon name, scientific authority, literature source and source verification, and the basionym are provided for each record. Electronic supplementary material to this article is available at and is accessible for authorized users.  相似文献   

9.
生物系统学面临的难题   总被引:2,自引:0,他引:2  
黄大卫 《动物学报》2001,47(5):593-597
随着对生物多样性和可持续发展的全球性关注,对生物系统学的需求愈来愈大。但许多决策者认为生物系统学是一门古老的学科,谁都可以成为分类学家。这严重地影响了生物系统学的发展。论述生物系统学面临的重大科学问题。包括概念、目标和技术等问题,有利于澄清对生物系统学的一些误解,推进学科的发展,为发挥生物系统学的基础与支撑作用营造一个健康的环境。本文提出了生物系统学的六个科学难题:物种定义是概念难题,物种数量和物种间的相互关系是跨世纪的目标难题,信息管理和鉴定手段是两上技术问题,生物系统学家逐渐减少是一个社会性难题。  相似文献   

10.
11.
Summary Three weedy amaranths (Amarantkus hybridus, A. retroflexus and A. powellii) from nine California sites, three domesticated species (A. caudatus, A. hypochondriacus and A. cruentus) from the USDA plant inventory as well as other sources and a naturally-occurring crop-weed hybrid were studied for numerical taxonomy using morphological and allozyme variation data. The crop and weedy species groups were easily separated and the hybrid populations were found to be intermediate. Surprisingly, very little intraspecific variation was present. Crop, weed and hybrid amaranths were also compared for their yielding ability, harvest index, seed efficiency of grain production and protein, popping quality and other agronomic traits. Although field plot yields were similar among the three groups of species (700 Kg/ha seed without fertilizer treatment and water, ranging to 3000 Kg/ha with fertilizer applications of 170 Kg N/ha, and abundant water), the harvest index of the weedy group was much higher (25–40%) than the domesticated species (10–15%). The allocation of biomass to seed production is positively correlated with seed yield in the domesticated but not in the weedy types, whereas the percentages of biomass as stem material and as seeds are negatively correlated. Several weedy and crop characteristics together should provide the basis of new improved cultivars through genetic recombination and selection.  相似文献   

12.
    
Morphological variability and imprecise generic boundaries have hindered systematic, taxonomical, and nomenclatural studies of Sisymbrium L. (Brassicaceae, Sisymbrieae DC.). The members of this almost exclusively Old‐World genus grow mostly on highly porous substrates across open steppe, semidesert, or ruderal habitats in the temperate zone of the Northern Hemisphere and African subtropics. The present study placed the biological history of Sisymbrium L. into time and space and rendered the tribus Sisymbrieae as monotypic. Five nuclear‐encoded and three chloroplast‐encoded loci of approximately 85% of all currently accepted species were investigated. Several accessions per species covering their whole distribution range allowed for a more representative assessment of intraspecific genetic diversity. In the light of fossil absence, the impact of different secondary calibration methods and taxon sets on time spans was tested, and we showed that such a combinatorial nested dating approach is beneficial. Multigene phylogeny accompanied with a time divergence estimation analysis placed the onset and development of this tribus into the western Irano‐Turanian floristic region during the Miocene. Continuous increase in continentality and decrease in temperatures promoted the diversity of the Sisymbrieae, which invaded the open grasslands habitats in Eurasia, Mediterranean, and South Africa throughout the Pliocene and Pleistocene. Our results support the assumption of the Irano‐Turanian region as a biodiversity reservoir for adjacent regions.  相似文献   

13.
红车轴草原产欧洲,1912年引入我国,作为优良牧草广为栽培利用。由于该种种内变异颇大,在分类学上种内分类群的划分非常困难。本文对黑龙江省东部山区分布的红车轴草进行了种内综合研究,以期对该种种内变异类型的起源和演化趋势提供一些参考性意见。  相似文献   

14.
Tamarix macrocarpa, a species with distribution in Central and North Africa, in the countries bordering the Persian Gulf and in Central and western Asia is recorded for the first time for Europe. Pentamerous flowers and androecium diplostemonous characterize this small tree.  相似文献   

15.
    
R. M. Owens 《Palaeontology》2004,47(3):557-578
Species belonging to genera of three families of the Proetida (Proetidae, Rorringtoniidae and Toernquistiidae) are described from the upper Ashgill of southern Sweden, and the same or related species noted from the adjacent parts of northern and central Europe. Proetidae are represented by Paraproetus brevifrons (Angelin), Ogmocnemis irregularis Kielan, Ogmocnemis jaanussoni sp. nov. and Parvigena putealis sp. nov.; it is argued that all belong to the Cornuproetinae, not Tropidocoryphinae where they were previously classified. Ogmocnemis is resurrected for some Upper Ordovician species included previously in Decoroproetus . The rorringtoniid genera Rorringtonia and Madygenia are recognised for the first time in southern Sweden, and it is argued that these are probably closely related, and both are included in the same family; both are recorded for the first time from Silurian (Llandovery) strata. Zetaproetus is claimed to be a junior subjective synonym of Rorringtonia. Solariproetus , first described from north-west China, is assigned to the Toernquistiidae as a late, derived member, and S. prosthemesos sp. nov. is described from late Rawtheyan strata in the Holy Cross Mountains, Skåne and the English Lake District. Comments are given on the stratigraphical and palaeogeographical distribution of these taxa.  相似文献   

16.
    
Names of 20 presumed taxa in Draba sect. Aizopsis, all based on material from Italy, are considered. Full synonymies are provided, and types are designated (for 14 names) or indicated. Most of the taxa are currently considered unworthy of recognition, of which 16 belong to D. aspera sensu lato. However, the question of whether the Sicilian populations might be distinct from the peninsular populations is still unsettled.  相似文献   

17.
In a lichen sample collected from a tree in Bârlad town (Vaslui County, Romania), a new tardigrade species belonging to the genus Milnesium (granulatum group) was found. Milnesium berladnicorumsp. n. is most similar (in the type of dorsal sculpture) to Milnesium beasleyi Kaczmarek et al., 2012 but differs from it mainly by having a different claw configuration and some morphometric characters. Additionally, the new species differs from other congeners of the granulatum group by the different type of dorsal sculpture, claw configuration and some morphometric characters.  相似文献   

18.
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   

19.
FAVARGER, C. & NIETO FELINER, G., 1988 On the races of Arenoria tetraquetra L. (Caryophyllaceae). The caryological study of some Betic populations of Arenaria tetraquetra northwards from Sierra Nevada has proved that they are polyploids ( 3x, 4x, 5x ). Even though their Rowers are pentamerous, they differ from the Nevadean Arenaria tetraguetra subsp. amabilis (2x ) not only by the chromosome number but also by the micromorphology of the seed coat and the hairiness of the stem internodes. They also differ from Arenaria tetraquetra subsp. tetraquetra , the Rowers of which are tetramerous and the degree of polyploidy higher (6x in the Pyrenees, 7x in the Sierra de Pela eastwards from Sierra de Guadarrama). The authors proposed to give a subspecific status to such Betic polyploid populations with a new combination. They suggest a hypothesis to explain the evolution of the A. tetraguetra polyploid complex.  相似文献   

20.
Nine species of the ostracod genus Sclerochilus which live in British waters are diagnosed and illustrated, including lour new species: S. hicksi, S. rudjakovi, S. schornikovi , and S. whatleyi . The appendages of the genotype, S. contortus , are illustrated for the first time, and many previous records of that species are shown to be erroneous. A pictorial key is provided to facilitate identification.  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