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 15 毫秒
1.
中国沙棘属种质资源及其生境类型的研究   总被引:21,自引:0,他引:21  
沙棘属植物有7种11亚种,中国产7种7亚种,其中2种2亚种是近年发现的新分类群。因而,我国是沙棘属植物种质资源最丰富的地区,也是沙棘资源蕴藏量最大的地区。沙棘属植物广泛分布于我国西南、西北、华北等地的森林——草原(草甸)过渡地带;从垂直分布角度看,无皮组的种类主要分布于海拔3000m以下的中低海拔地区,有皮组的种类则集中分布于3000m以上的中高海拔地区。根据光照、温度、植被类型等因素其生境类型可分为温性乔木林型、温性灌丛型、寒温性灌丛型和高寒灌丛型4种类型。理塘沙棘、棱果沙棘和卧龙沙棘种群数量少,分布区域狭窄,资源十分有限,应加强驯化研究和迁地保护,并提出了合理开发利用沙棘属种质资源的几点建议。  相似文献   

2.
To evaluate a 16S rRNA gene probe for the identification of staphylococcal species and subspecies, we have augmented previous studies involving 12 staphylococcal species by analysing the remaining 16 species currently classified in the genus Staphylococcus. HindIII- and EcoRI-restricted DNA of isolates from validly described species of Staphylococcus was probed with radiolabelled plasmid pBA2 containing 16S rDNA from Bacillus subtilis. The Dice coefficient was used to assess similarity between the 74 HindIII- and the 81 EcoRI-hybridization patterns obtained from a total of 271 isolates belonging to 31 staphylococcal taxa (28 species, of which three include two subspecies). The use of HindIII yielded a better discrimination of the staphylococci than the use of EcoRI. All of the isolates belonging to the same species or subspecies, except S. hyicus isolates, were recovered as homogeneous clusters using their HindIII hybridization patterns. The phenotypically close taxa were clearly distinguished. Thus, the method presented in this study constitutes a powerful tool for the identification of taxa within the genus Staphylococcus.  相似文献   

3.
A cladistic analysis of the genus Hippophae (Elaeagnaceae) was undertaken. based on 37 characters. The five species of the genera Shepherdia and Elaeagnus were included in the analysis as the outgroup taxa. The operational taxonomic units of Hippophae were the species H. gyantsensis, H. neurocarpa, Hsalicifolia and H. tibetana plus eight subspecies of H. rhamnoides . The analysis revealed 117 or 14 equally parsimonious trees depending on whether the multistate characters were treated as ordered whenever possible, or all characters were treated as unordered. The results are not directly in accordance with any of the formerly proposed taxonomies. After successive weighting only two trees were retained both with ordered and unordered characters and the combinable component (semistrict) consensus trees give support to recognition of the two species in the genus, H. rhamnoides and Hsalicifolia . Three new combinations H. rhamnoides ssp. neurocarpa, H. salicifolia ssp. sinensis and H. salicifolia ssp. yunnanensis (Rousi) Hyvönen are proposed.  相似文献   

4.
For the genus Anthyllis (Fam. Fabaceae, tribe Loteae), with few exceptions, little information is available on the genetic variation among and within species. This genus contains 20 species distributed throughout Europe, Africa, and the Mediterranean basin. The most widespread species is A. vulneraria, and over 30 intraspecies taxa have been identified based on plant morphology. To study the molecular phylogeny of the genus, the sequences of the internal transcribed spacers ITS1 and ITS2 of the nuclear ribosomal DNA of 10 Anthyllis species, including 11 subspecies of A. vulneraria and three subspecies of A. montana, were obtained and analysed together with sequences of five other species of the genus obtained from GenBank. Our results suggest that the genus Anthyllis is not monophyletic and is divided in two main clades: the Anthyllis sensu strictu and the "tetraphylla clade". The former includes most of the Anthyllis species, and the latter includes three annual species more closely related to Lotus. All the taxa were also analysed according to seven chloroplast microsatellites, and these data closely confirm the results obtained with the ITS phylogeny.  相似文献   

5.
6.
'Suture zones' are areas where hybrid and contact zones of multiple taxa are clustered. Such zones have been regarded as strong evidence for allopatric divergence by proponents of the Pleistocene forest refugia theory, a vicariance hypothesis frequently used to explain diversification in the Amazon basin. A central prediction of the refugia and other vicariance theories is that the taxa should have a common history so that divergence times should be coincident among taxa. A suture zone for Ithomiinae butterflies near Tarapoto, NE Peru, was therefore studied to examine divergence times of taxa in contact across the zone. We sequenced 1619bp of the mitochondrial COI/COII region in 172 individuals of 31 species from across the suture zone. Inferred divergence times differed remarkably, with divergence between some pairs of widespread species (each of which may have two or more subspecies interacting in the zone, as in the genus Melinaea) being considerably less than that between hybridizing subspecies in other genera (for instance in Oleria). Our data therefore strongly refute a simple hypothesis of simultaneous vicariance and suggest that ongoing parapatric or other modes of differentiation in continuous forest may be important in driving diversification in Amazonia.  相似文献   

7.
8.
Cricket frogs are widely distributed across the eastern United States and two species, the northern cricket frog (Acris crepitans) and the southern cricket frog (A. gryllus) are currently recognized. We generated a phylogenetic hypothesis for Acris using fragments of nuclear and mitochondrial genes in separate and combined phylogenetic analyses. We also used distance methods and fixation indices to evaluate species limits within the genus and the validity of currently recognized subspecies of A. crepitans. The distributions of existing A. crepitans subspecies, defined by morphology and call types, do not match the distributions of evolutionary lineages recovered using our genetic data. We discuss a scenario of call evolution to explain this disparity. We also recovered distinct phylogeographic groups within A. crepitans and A. gryllus that are congruent with other codistributed taxa. Under a lineage-based species concept, we recognize Acris blanchardi as a distinct species. The importance of this revised taxonomy is discussed in light of the dramatic declines in A. blanchardi across the northern and western portions of its range.  相似文献   

9.
We present a synopsis of the genus Geigeria (Inuleae, Asteraceae). Particular attention is paid to the taxonomic characterization and phylogenetic relationships of the genus, to possible supraspecific groupings, and to the delimitation of taxa, especially at the infraspecific level. Until recently 25 species, 20 subspecies, and 7 varieties have been recognized. In this study we recognize only 20 species, 12 subspecies, and 7 varieties. We describe a new subspecies and variety, and propose 5 new nomenclatural combinations.  相似文献   

10.
11.
Leucadendron is a moderately large genus of Proteaceae almost entirely restricted to the Cape Floristic Region of southern Africa. The genus is unusual in being dioecious and sexually dimorphic. ITS sequence data were obtained from 62 of the 96 currently recognized taxa (85 species and 11 subspecies). Phylogenetic analyses were conducted under Maximum Likelihood and parsimony and resolved nine groups of species with varying degrees of bootstrap support, but relationships between these groups are largely unsupported. The phylogeny conflicts with the current taxonomic arrangement, which is based mainly on fruit morphology. The two sections of the genus, Alatosperma and Leucadendron, and several subsections within these sections, are resolved as non-monophyletic. This means that taxonomically important characters (such as fruit shape) have evolved multiple times, as the species with nut-like fruit (resolved into two of the nine groups) appear to have evolved independently from ancestors with winged fruit. Based on the topology obtained, the life history traits of anemophily, myrmechochory, and re-sprouting have also originated multiple times. Dispersal-Vicariance (DIVA) analysis suggests that the genus had an ancestral area in the Karoo Mountain and Southeastern phytogeographic centres of endemism in the southwestern Cape.  相似文献   

12.
Dolphins of the genus Sotalia are found along the Caribbean and Atlantic coasts of Central and South America and in the Amazon River and most of its tributaries. At present, the taxonomy of these dolphins remains unresolved. Although five species were described in the late 1800s, only one species is recognized currently ( Sotalia fluviatilis ) with two ecotypes or subspecies, the coastal subspecies ( Sotalia fluviatilis guianensis ) and the riverine subspecies ( Sotalia fluviatilis fluviatilis ). Recent morphometric analyses, as well as mitochondrial DNA analysis, suggested recognition of each subspecies as separate species. Here we review the history of the classification of this genus and present new genetic evidence from ten nuclear and three mitochondrial genes supporting the elevation of each subspecies to the species level under the Genealogical/Lineage Concordance Species Concept and the criterion of irreversible divergence. We also review additional evidence for this taxonomic revision from previously published and unpublished genetic, morphological, and ecological studies. We propose the common name "costero" for the coastal species, Sotalia guianensis ( Van Bénéden 1864 ), and accept the previously proposed "tucuxi" dolphin, Sotalia fluviatilis (Gervais, 1853), for the riverine species.  相似文献   

13.
Nauplius (named Bubonium in previous publications) is a mainly Macaronesian and N African genus belonging to the Inula -group of the Asteraceae-Inuleae. Eight species and five subspecies are recognized and a key to all taxa is included. The morphology, phylogeny and phytogeography of the genus are also discussed.  相似文献   

14.
The phylogenetic relationships within the New and Old World hawk-eagle assemblage (genus Spizaetus ; Aves: Accipitridae) were studied using mitochondrial DNA sequences ( cytochrome b , control region). Eighty-four specimens representing all Spizaetus species and almost all currently distinguished subspecies as well as 11 other booted and non-booted 'eagle' genera from the Neotropics, Africa, Eurasia, South Asia and Australasia ( Oroaetus , Harpia , Morphnus , Lophaetus , Stephanoaetus , Hieraaetus , Aquila , Ictinaetus , Spilornis , Pithecophaga , Harpyopsis ) were investigated. Although the basal branching could not be resolved, our investigations clearly indicate that hawk-eagles represent a paraphyletic assemblage and thus their external similarities have to be ascribed to convergent evolution. The New World taxa of Spizaetus cluster together, but the South American species Oroaetus isidori appears embedded within this clade. The taxa from Southeast to East Asia form a clearly separated monophyletic group. It is further divided into two subgroups, which are also characterized by distinct juvenile plumage patterns. Spizaetus africanus , the only African representative of the genus, is found in a mixed cluster consisting of members of the genera Aquila and Hieraaetus . These findings are in accordance with previous studies of other authors based on various molecular markers and different sets of taxa, but disagree with current taxonomy. Therefore, we suggest assigning the species of the genus Spizaetus to three different genera: (1) Spizaetus (including Oroaetus isidori ) in Central and South America and (2) Nisaetus for the Southeast to East Asian group. (3) The African taxon ( Spizaetus africanus ) is discussed to be included into the genus Aquila. Furthermore, we propose to use the former genus name Lophotriorchis Sharpe, 1874, for the monotypic species Hieraaetus kienerii , which has an isolated phylogenetic position.  相似文献   

15.
Centranthus DC. is a mediterranean genus comprising 17 taxa (including 9 species and 7 subspecies). Two new subspecies, namely C. longiflorus subsp. atlanticus and C. calcitrapae subsp. trichocarpus , are described. Affinities within the genus are discussed and four species are newly circumscribed; five new infraspecific combinations are made. Vicariance is demonstrated with the aid of two dot maps.  相似文献   

16.
There is a controversy regarding how many species the genus Lagothrix contains, since the Lagothrix lagothricha subspecies have been recently proposed to be actual species. Clarification of species status is of particular importance in the case of L. l. lugens, because it is the most endangered and its distribution is restricted to the Colombian Andes, a highly deforested region. Using cytogenetic and molecular markers, we obtained evidence indicating that the subspecies status is appropriate for the two taxa occurring in this country. We also report high levels of intraspecific variability in the karyotype. We find evidence for a late Pleistocene separation of the subspecies, and we propose it is the limited area of contact between the taxa that allowed for them to partially differentiate. Am. J. Primatol. 72:1131–1140, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

17.
江孜沙棘和云南沙棘之间谱系分化和亲缘地理   总被引:3,自引:0,他引:3       下载免费PDF全文
研究具有邻近分布的近缘类群的遗传分化和谱系筛选对于进一步揭示物种形成机制具有重要意义。该文以沙棘属(Hippophae)临域分布的两个类群, 江孜沙棘(H. gyantsensis)和云南沙棘(H. rhamnoides subsp. yunnanensis)为研究对象, 进行群体水平上的母系分化研究。前一个种分布于西藏的中西部, 而后者主要分布于青藏高原东南部的云南西北部、四川西部和西藏东南部。两个类群在叶和果实性状存在明显区别。叶绿体在沙棘属植物中为母系遗传。共研究了两个类群14种群109个沙棘个体的叶绿体trnL-F、trnS-G序列; 序列排序后共发现11种单倍型, 江孜沙棘和云南沙棘分别有7种和6种, 两种单倍型为两个类群共享。分支分析和嵌套进化分析进一步表明, 两个类群之间的单倍型相互交错, 单倍型分化与形态上划分的两个类群不一致, 表明它们之间具有十分复杂的谱系筛选过程。这些发现明显不支持以前提出的有关江孜沙棘系统位置的假设。但是, 目前所获得的证据不能区分该物种究竟是通过异域分化还是同倍性杂交起源的。不同种群固定特有单倍型表明, 两个类群都在最后一次冰期可能存在多个避难所。  相似文献   

18.
A plethora of unionid names was established in the nineteenth century by the “Nouvelle Ecole”. Although naiad morphological plasticity is well documented, the currently recognized fauna, with 17 species and subspecies included in the French checklist for the Unio genus, is still based upon morphological characters only. Insights have been provided from molecular data elsewhere in Europe and North Africa, but the French fauna remains unstudied. We present a molecular phylogeny of the Unio genus in France based on COI, 16S and 28S genes; taking up all available data in Europe plus 273 specimens collected in all main French drainages. The results show that there are either three valid species in France, with U. pictorum and U. mancus synonymized, or five, with the subspecies U. crassus courtillieri elevated to species level. Subspecies were generally not recovered, which questions the evolutionary units tacitly implied by subspecific names. Although sampling topotypes is the most reliable way to evaluate the status of a nominal subspecies, major human-induced changes in aquatic hydrosystems challenge the method. Nevertheless, operational taxonomy has to rely on ground-truthed data and we propose to reduce the actual number of valid taxa in France to the seven observed operational taxonomic units.  相似文献   

19.
Biosystematics of the genus Piperia Rydb. (Orchidaceae)   总被引:1,自引:1,他引:0  
Piperia is a North American segregate of Habenaria consisting of 5 taxa (4 species and 1 subspecies). The genus is defined and differentiated from other North American genera of the Habenaria alliance by its morphology and pollination mechanism. All taxa have n = 21 chromosomes. Thin-layer chromatography of fresh leaf extracts and a morphological assessment revealed discrete, but variable, taxa. All species are partially interfertile; however, a high degree of sympatry suggests these species are reproductively isolated. One new combination is proposed: P. elongata subsp. michaelii.  相似文献   

20.
Material of the Miocene hyaenid Adcrocuta eximia from China is analysed statistically. No heterogeneities were found within this material. Comparisons with material from Samos and Pikermi, Greece, show that no taxonomic differentiation between these three samples is warranted. Adcrocuta eximia latro from the Sivalik deposits is provisionally considered a valid subspecies. The species A. australis from Langebaanweg, South Africa is removed from Adcrocuta to the genus Chasmaporthetes . The phylogenetic position of Adcrocuta has been subject to dispute, and for this reason we present a study of the interrelationships of selected hyaenid taxa using numerical cladistic methods. Two equally parsimonious trees of length 47 and consistency index 0.766 were found. Adcrocuta is placed as a sister-group to the Recent Crocuta crocuta , and not as a separate clade as suggested by other workers. Recent hyaenids form a crown-group which does not extend deep into the cladogram. Hyaena hyaena and H. brunnea are not sister-groups, and we resurrect the genus Parahyaena for the latter species.  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